a thesis submitted for the degree of doctor of …688962/s...archaeomalocological methods, forager...

Archaeomalocological methods, forager decision-making, and intertidal

ecosystems: Two millennia of mollusc exploitation on a remote Pacific atoll. Matthew Harris

BA (Hons)

A thesis submitted for the degree of Doctor of Philosophy at

The University of Queensland in 2017

School of Social Science

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Abstract

Marine mollusc shells are excellent proxy records for human behaviour and environmental archives

as they are ubiquitous in coastal archaeological deposits and preserve well compared with other

marine fauna. Archaeomalacology, the study of molluscs from archaeological sites, has generated

new data on the role of coastal environments in the human story, elucidating patterns of forager

behaviour, human impacts to the environment, the role of marine foods in coastal palaeo-

economies, and responses to changes in climate and environments both within and outside the

Pacific Islands. Molluscs are also critical to the functioning of coral reefs and intertidal ecosystems,

and as such, can be useful in tracking long-term trajectories of change in marine environments. This

thesis presents the first high-resolution study of the archaeomalacological record of Ebon Atoll,

Republic of the Marshall Islands, eastern Micronesia, demonstrating that molluscs had been a stable

component of the diet for two millennia.

Atolls, consisting primarily of unconsolidated biogenic sediments atop a narrow reef platform that

surrounds a lagoon, have long been considered marginal environments for human habitation. A lack

of standing fresh water, poor soils for agriculture, and exposure to storms and extreme weather due

to low elevation present considerable challenges for inhabitants in the past as they do today. The

relatively small land area is, however, bounded by an expansive reef platform which hosts a rich

and diverse range of mollusc species, offering an easily accessible source of protein and other

minerals not available in terrestrial foods.

Nevertheless, mollusc remains from Marshall Islands archaeological sites have been assessed only

in broad terms as part of synthetic works on settlement and subsistence patterns in the archipelago.

This thesis presents a detailed analysis of mollusc remains from a number of archaeological sites on

Ebon Atoll, using a newly developed quantification protocol that incorporates a greater number of

non-repetitive shell elements, and a new method for tracking forager decision-making in tropical

intertidal settings. In addition, a review of the archaeological literature pertaining to human impacts

to molluscs during the prehistoric period of the Pacific Islands facilitated investigation of these

processes on Ebon Atoll. No discernible human impacts were noted, and mollusc assemblages from

Ebon Atoll spanning two millennia of occupation were consistently rich, even, and diverse,

incorporating a broad range of taxa from different habitats. Variation in assemblage composition is

likely related to the configuration of intertidal habitats on windward and leeward exposed islets,

rather than site function or alterations to marine environments. These results indicate that this

generalised foraging strategy, low human populations and a productive marine environment

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produced sustained yields of molluscs by spreading impact across trophic levels and functional

groups. These data contest traditional perceptions of atolls, and are in line with current discourses

that challenge traditional notions of small islands, and especially atolls as remote, isolated and

marginal settings for human habitation.

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Declaration by author

This thesis is composed of my original work, and contains no material previously published or

written by another person except where due reference has been made in the text. I have clearly

stated the contribution by others to jointly-authored works that I have included in my thesis.

I have clearly stated the contribution of others to my thesis as a whole, including statistical

assistance, survey design, data analysis, significant technical procedures, professional editorial

advice, and any other original research work used or reported in my thesis. The content of my thesis

is the result of work I have carried out since the commencement of my research higher degree

candidature and does not include a substantial part of work that has been submitted to qualify for

the award of any other degree or diploma in any university or other tertiary institution. I have

clearly stated which parts of my thesis, if any, have been submitted to qualify for another award.

I acknowledge that an electronic copy of my thesis must be lodged with the University Library and,

subject to the policy and procedures of The University of Queensland, the thesis be made available

for research and study in accordance with the Copyright Act 1968 unless a period of embargo has

been approved by the Dean of the Graduate School.

I acknowledge that copyright of all material contained in my thesis resides with the copyright

holder(s) of that material. Where appropriate I have obtained copyright permission from the

copyright holder to reproduce material in this thesis.

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Publications during candidature

Peer-reviewed papers

Harris, M. and M.I. Weisler. 2017. Two millennia of mollusc foraging on Ebon Atoll, Marshall

Islands: sustained marine resource use on a Pacific atoll. Archaeology in Oceania (accepted

Jun 2017).

Harris, M., P. Faulkner and B. Asmussen. 2017. Macroscopic approaches to the identification of

expedient bivalve tools: A case study investigating Polymesoda (=Geloina) coaxans

(Bivalvia: Corbiculidae) shell valves from Princess Charlotte Bay, Queensland, Australia.

Quaternary International 427, Part A:201-215.

Harris, M. and M.I. Weisler. 2016. Prehistoric human impacts to marine molluscs and intertidal

ecosystems in the Pacific Islands. Journal of Island and Coastal Archaeology (accepted Dec

2016).

Harris, M. and M.I. Weisler. 2016. Intertidal foraging on atolls: prehistoric forager decision

making at Ebon Atoll, Marshall Islands. Journal of Island and Coastal Archaeology

12(2):200-223.

Harris, M., A.B.J. Lambrides and M.I. Weisler. 2016. Windward vs. leeward: Inter-site variation in

marine resource exploitation on Ebon Atoll, Republic of the Marshall Islands. Journal of

Archaeological Science: Reports 6:221-229.

Harris, M., M.I. Weisler and P. Faulkner. 2015. A refined protocol for calculating MNI in

archaeological molluscan shell assemblages: a Marshall Islands case study. Journal of

Archaeological Science 57:168-179.

Publications included in this thesis

Several chapters within this thesis are composed of manuscripts accepted for publication in peer-

reviewed journals. The research design, analysis of data, interpretation of results, writing,

submission and revisions of each manuscript were performed primarily by myself.

Chapter 2: ‘Prehistoric human impacts to marine molluscs and intertidal ecosystems in the Pacific

Islands’ has been peer-reviewed and accepted for publication in Journal of Island and Coastal

Archaeology.

Contributor Statement of contribution

M. Harris (Candidate) Collation and Review of literature (100%)

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Wrote and edited the paper (70%)

M.I. Weisler Wrote and edited the paper (30%)

Chapter 3: ‘A refined protocol for calculating MNI in archaeological molluscan shell assemblages:

A Marshall Islands case study’ has been peer-reviewed and accepted for publication in Journal of

Archaeological Science.


M. Harris (Candidate) Research conception and design (60%)

Analysis and interpretation of data (80%)


M.I. Weisler Research conception and design (20%)

Wrote and edited the paper (17.5%)

P. Faulkner Research conception and design (20%)


Wrote and edited the paper (17.5%)

Chapter 4: ‘Intertidal foraging on atolls: Prehistoric forager decision making at Ebon Atoll,

Marshall Islands.’ has been peer-reviewed and accepted for publication in Journal of Island and

Coastal Archaeology.







Chapter 5: ‘Windward vs. leeward: Inter-site variation in marine resource exploitation on Ebon

Atoll, Republic of the Marshall Islands.’ has been peer-reviewed and accepted for publication in

Journal of Archaeological Science: Reports.

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A.B.J. Lambrides Research conception and design (40%)





Chapter 6: ‘Two millennia of mollusc foraging on Ebon Atoll, Marshall Islands: sustained marine

resource use on a Pacific atoll.’ has been peer-reviewed and accepted for publication in

Archaeology in Oceania.








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Contributions by others to the thesis

Professor Marshall Weisler was my principal supervisor and directs the Marshall Islands

archaeological research project that this thesis forms a part of. This project was initiated in 1993,

and Weisler formulated the initial research questions and project aims, and provided supervision,

direction and feedback throughout the process of analysing the data and producing the peer-

reviewed articles presented in this thesis.

Patrick Faulkner was my associate supervisor and provided feedback and guidance during

publication of the peer-reviewed manuscripts presented in this thesis. Faulkner collaborated with

myself and Weisler on a single manuscript (Chapter 3), and provided guidance on the identifcatoin

protocols used in analysis of mollusc remains.

Ariana Lambrides was a member of the Marshall Islands archaeological research project initiated

by Weisler. Lambrides collaborated with myself and Weisler on a single manuscript (Chapter 5)

providing data from other faunal classes and contributing to the creation of the manuscript.

Statement of parts of the thesis submitted to qualify for the award of another degree

No part of this work was submitted to qualify for the award of another degree.

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Acknowledgements

I would like to thank first my academic supervisors, Professor Marshall Weisler and Dr. Patrick

Faulkner for their assistance, guidance and mentorship throughout my candidature. This thesis

forms part of a larger project in the Marshall Islands initiated by Professor Weisler, and I am

grateful to have been able to contribute. I am exceptionally grateful to have been given the

opportunity to work with Marshall, who has provided endless feedback and on manuscript drafts,

opportunities for work, and helped me to develop my skills as a researcher and an illustrator.

I also thank Josepha Maddison of the Historic Preservation Office, Ministry of Internal Affairs, and

Lajan Kabua, former Mayor of Ebon Atoll for their permission to conduct fieldwork on Ebon. I

would also like to thank the people of Ebon for welcoming us, and especially to Lyn, Dom, Riem,

Josen, Frankie, Nashir, Lister, Jolie, and Jin for their assistance in the field. This thesis was supported

by The University of Queensland School of Social Science and an Australian Government Research

Training Program Scholarship, the Donald Tugby Archaeological Research Award, and School of

Social Science travel grants and awards. Ebon fieldwork was supported by a grant to Marshall Weisler

from the Office of the Deputy Vice Chancellor (Research).

My fellow PhD candidates, especially Aleisha Buckler (and Judd, Brad, Sonya, Katie, Mark and

Hannah), Dale Simpson, Emma James, Tam Smith, and Xavier Carah for their constant support,

friendship, and occasional intellectual conversation. Without these friends around, this whole thing

would have been a lot more difficult. Pat Faulkner has acted both as an academic supervisor and, but

also as a great friend and mentor. Pat is a truly exceptional person and a world-class researcher, and has

been a great support throughout my candidature. I must also thank Dr. Glenys McGowan for her support

professionally by providing my opportunities to teach, but also personally for her constant support and

encouragement throughout my candidature. Thanks also to Dr. Andrew Sneddon for providing me with

opportunities for work and professional development throughout my candidature.

To my family - Lisa, Mike, Ross, Jen, Bonny, Laura, Doug, Chris, Pam, Jo-anne, Jack, Charlie, Billy

and Ellen. Mum, Ross, Dad, and Jen, I can never thank you enough for everything you have done for

me. To Mum and Dad for fostering my curiosity and for lugging a reef’s worth of shells and rocks

collected from beaches around the country when we were travelling in ‘96. Nan, who helped me sneak

so many of the shells and rocks back into the car or caravan after I was told that I already had too many,

I can never thank you enough, for everything. We all get our good qualities from you. To Laura and

Doug, thanks for being patient of all the rescheduled dinners and breakfasts when deadlines were

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drawing near. I am constantly grateful and humbled to be the brother of someone so strong. To my

newest family members, Chris, Pam, Jo-anne, Jack and Charlie. Thank you all for welcoming me into

your family, and your home. I promise I’ll make Thursday dinner forever if you let me stick around. To

Billy and Ellen, thanks for being incredible friends. Looking forward to lazy weekends in Lennox if

you’ll have us. Finally, I would like to thank Ariana. I could never have managed it without you.

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Keywords

Atoll archaeology, Pacific Islands, archaeomalacology, shell midden studies, island and coastal

archaeology, marine subsistence, Marshall Islands, Micronesia, archaeological methods,

zooarchaeology.

Australian and New Zealand Standard Research Classifications (ANZSRC)

ANZSRC code: 210106, Archaeology of New Guinea and Pacific Islands (excl. New Zealand),

50%

ANZSRC code: 210102, Archaeological Science, 40%

ANZSRC code: 210199, Archaeology not elsewhere classified, 10%

Fields of Research (FoR) Classification

FoR code: 2101, Archaeology, 100%

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Table of Contents

Abstract ................................................................................................................................................. i

Declaration by author .......................................................................................................................... iii

Publications during candidature .......................................................................................................... iv

Peer-reviewed papers ...................................................................................................................... iv

Publications included in this thesis ..................................................................................................... iv

Contributions by others to the thesis .................................................................................................. vii

Statement of parts of the thesis submitted to qualify for the award of another degree ...................... vii

Acknowledgements ........................................................................................................................... viii

Keywords ............................................................................................................................................. x

Australian and New Zealand Standard Research Classifications (ANZSRC) ..................................... x

Fields of Research (FoR) Classification .............................................................................................. x

Chapter 1: Introduction ........................................................................................................................ 1

Introduction ...................................................................................................................................... 1

Rationale .......................................................................................................................................... 3

Research Questions .......................................................................................................................... 4

Thesis structure ................................................................................................................................ 6

Chapter Summary ............................................................................................................................ 6

References Cited .............................................................................................................................. 7

Chapter 2: Prehistoric human impacts to marine molluscs and intertidal ecosystems in

the Pacific Islands .............................................................................................................................. 14

Abstract .......................................................................................................................................... 15

Introduction .................................................................................................................................... 16

The Effects of Human Predation .................................................................................................... 17

An Historical Ecology Approach ................................................................................................... 19

Anthropogenic Extirpation of Mollusks in the Pacific Islands ...................................................... 20

Changes in the Size/Age Structure of Mollusk Populations .......................................................... 22

Trophic Alteration and Impacts to Species Richness, Abundance, and Diversity ......................... 25

Non-Anthropogenic Alterations to Mollusk Assemblages ............................................................ 30

Discussion ...................................................................................................................................... 30

Conclusion ..................................................................................................................................... 32

Acknowledgements ........................................................................................................................ 33

References Cited ............................................................................................................................ 34

Figures and tables ........................................................................................................................... 48

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Chapter 3: A refined protocol for calculating MNI in archaeological molluscan shell

assemblages: a Marshall Islands case study ....................................................................................... 49

Abstract .......................................................................................................................................... 50

Introduction .................................................................................................................................... 51

Current methods of MNI calculation in mollusc shell assemblages .............................................. 52

Site Description .............................................................................................................................. 53

Methods .......................................................................................................................................... 54

A refined protocol for calculating MNI ..................................................................................... 54

Gastropod and bivalve shell features ......................................................................................... 55

Additional NRE ......................................................................................................................... 56

Calculating gastropod MNI ........................................................................................................ 56

Calculating bivalve MNI ............................................................................................................ 58

MNI Calculation ........................................................................................................................ 60

Testing the influence of quantification protocol ........................................................................ 61

Results ............................................................................................................................................ 62

Total MNI .................................................................................................................................. 62

Rank order abundance ................................................................................................................ 62

Species richness and evenness ................................................................................................... 63

Element survivorship ................................................................................................................. 63

Discussion ...................................................................................................................................... 64

Conclusion ..................................................................................................................................... 66

Acknowledgements ........................................................................................................................ 67

References Cited ............................................................................................................................ 68

Figures and Tables ......................................................................................................................... 74

Chapter 4: Intertidal foraging on atolls: prehistoric forager decision making at Ebon

Atoll, Marshall Islands ....................................................................................................................... 94

Abstract .......................................................................................................................................... 95

Introduction .................................................................................................................................... 96

Previous archaeology in the Marshall Islands ................................................................................ 97

Mollusc assemblages from Marshall Islands archaeological sites ............................................. 98

Environmental Context .................................................................................................................. 99

Moniak islet ............................................................................................................................. 100

Ebon islet ................................................................................................................................. 101

Sites and Samples ......................................................................................................................... 102

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Methods of mollusc identification and quantification ................................................................. 102

Methodological framework .......................................................................................................... 103

Reconstructing foraging preferences ....................................................................................... 103

Hierarchical classification scheme ........................................................................................... 104

Data collection for molluscan zonation and ecology ............................................................... 105

Molluscan ecology and habitat classification scheme usage ................................................... 105

Results .......................................................................................................................................... 106

MLEB-1 ................................................................................................................................... 106

MLEB-31 ................................................................................................................................. 107

Discussion .................................................................................................................................... 108

Conclusion ................................................................................................................................... 110

Acknowledgements ...................................................................................................................... 110

References Cited .......................................................................................................................... 112

Figures and Tables ....................................................................................................................... 121

Chapter 5: Windward vs. leeward: Inter-site variation in marine resource exploitation on

Ebon Atoll, Republic of the Marshall Islands .................................................................................. 132

Abstract ........................................................................................................................................ 133

Introduction .................................................................................................................................. 134


MLEb-1 .................................................................................................................................... 137

MLEb-33 .................................................................................................................................. 138

MLEb-31 .................................................................................................................................. 138

Methods ........................................................................................................................................ 139

Identification and quantification protocols .............................................................................. 139

Statistical analyses ................................................................................................................... 139

Results .......................................................................................................................................... 141

Discussion .................................................................................................................................... 143

Conclusion ................................................................................................................................... 145




Chapter 6: Two millennia of mollusc foraging on Ebon Atoll, Marshall Islands:

sustained marine resource use on a Pacific atoll. ............................................................................. 158

Abstract ........................................................................................................................................ 159

xiv

Introduction .................................................................................................................................. 160

Traditional Marshall Islands Economy ........................................................................................ 161


Ebon Islet ................................................................................................................................. 162

Enekoion Islet .......................................................................................................................... 163

Moniak Islet ............................................................................................................................. 163

Habitat Mapping Methods and Description of Marine Habitats .................................................. 164

Methods of Mollusc Analysis ...................................................................................................... 165

Results .......................................................................................................................................... 167

MLEb-5 .................................................................................................................................... 168

MLEb-1 .................................................................................................................................... 168

MLEb-33 .................................................................................................................................. 170

MLEb-31 .................................................................................................................................. 171

Tests for human impact ............................................................................................................ 171

Discussion .................................................................................................................................... 172

Temporal and spatial trends in mollusc foraging ..................................................................... 172

Conclusion ................................................................................................................................... 177




Chapter 7: Conclusion ...................................................................................................................... 193

Introduction .................................................................................................................................. 193

Overview of thesis results ............................................................................................................ 193

RQ1: Has human foraging for molluscs impacted mollusc populations and

intertidal ecosystems in the Pacific Islands during the prehistoric period? ............................. 193

RQ2: Does the inclusion of an increased number of non-repetitive shell elements

(NREs) in quantification protocols influence measures of relative abundance and

taxonomic heterogeneity? ........................................................................................................ 194

RQ3: What methods can be generated to explore and understand forager decision-

making and habitat selection in atoll environments? ............................................................... 196

RQ4: What is the influence of spatial (settlement patterns and local habitat) and

temporal factors on the richness (number of species present), abundance (number

of individuals of each species present), and diversity (richness and relative

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distribution of individuals of each species within a population) of mollusc

assemblages on Ebon Atoll? .................................................................................................... 198

RQ5: Is there any indication that human foraging for molluscs directly impacted

mollusc populations or had secondary, indirect impacts on intertidal ecosystems on

Ebon Atoll over the two millennia of human occupation? ...................................................... 199

Future research objectives ............................................................................................................ 201

Concluding Remarks .................................................................................................................... 201


Appendix A ...................................................................................................................................... 206

Appendix B ...................................................................................................................................... 208

Appendix C ...................................................................................................................................... 211

Appendix D ...................................................................................................................................... 218

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Table of Figures

Chapter 2: Prehistoric human impacts to marine molluscs and intertidal ecosystems in the Pacific

Islands

Figure 1 Map of the Pacific Islands with sites mentioned in text ...................................................... 48

Chapter 3: A refined protocol for calculating MNI in archaeological molluscan shell assemblages:

a Marshall Islands case study

Figure 1 a. Stratigraphic section of MLEb-1, TP19 (left, 1 m wide) & TP18 (right, 1 m wide) south profile with a maximum depth of ~115cmbs. Scale is 1 m long.; b. North profile of TP7, with a maximum depth of 40cmbs at site MLEb-33 on Enekoion islet. The dense cultural deposit is ~35 cm thick. Scale is 1 m long. (Both photos, M. Weisler). ............................................................................................................................................. 84

Figure 2 Gastropod terminology. ....................................................................................................... 85

Figure 3 Examples of gastropod shapes. a. globoid b. involute c. tubular d. trochoid e. turbinate f. patelliform g. disjunct h. turriform. Note the substantial variation in spire height between shell forms. ............................................................................................................... 86

Figure 4 Bivalve terminology. ........................................................................................................... 87

Figure 5 Examples of bivalve shapes a. orbicular b. alate c. auriculate d. subquadrate e. trigonal f.fan-shaped g.ensiform h. elongate-elliptical. ..................................................................... 88

Figure 6 Gastropod NRE (1 = spire; 2 = anterior canal; 3 = posterior canal; 4 = outer lip; 5 = aperture; 6 = operculum; 7 = umbilicus). Hatched areas represent areas of shell included in quantification of MNI. Note the presence of NRE on some shell forms, but not others. ........................................................................................................................................... 89

Figure 7 The tMNI method of gastropod MNI calculation. Hatched areas represent a fragment of shell. (Sp = spire; OL = outer lip; Ap = aperture; AC = anterior canal/notch; PC = posterior canal/notch; Um = umbilicus; Op = Operculum) ...................................................... 90

Figure 8 Bivalve NRE (1 = umbo; 2 = posterior hinge; 3 = anterior hinge; 4 = posterior adductor muscle scar; 5 = anterior adductor muscle scar). Note the presence of only a single adductor muscle scar on the monomyarian shell valve of b. ................................................... 91

Figure 9 The tMNI method of bivalve MNI calculation. Hatched areas represent a shell fragment. (Um = umbo; AH = anterior hinge; PH = posterior hinge; AAMS = anterior adductor muscle scar; PAMS = posterior adductor muscle scar). ..................................................... 92

Figure 10 Additional NRE included in tMNI quantification. Hatched areas represent areas of shell included in quantification of MNI. a. view of Cypraeidae spp. aperture and base showing additional NRE; b. view of Neritidae spp. aperture and columellar deck showing location of additional NRE, I = anterior columellar deck/outer lip intersection II = posterior columellar deck/outer lip intersection. ..................................................... 93

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Chapter 4: Intertidal foraging on atolls: prehistoric forager decision making at Ebon

Atoll, Marshall Islands

Figure 1 Map of the Marshall Islands and Ebon Atoll, showing archaeological sites on leeward (Ebon) and windward (Moniak) islets. ............................................................................... 125

Figure 2 Schematic cross section of a. leeward Ebon islet and b. windward Moniak islet highlighting patterns of intertidal zonation on atolls, the molluscan fauna characterisitc of each habitat, the relative exposure of each islet to winds and waves and traditional human settlement patterns (after Kendall et al. 2012; Merlin et al. 1994; Weisler 1999b; Wiens 1962). c. Ebon islet oceanside reef flat (Photo: M. Harris), d. Ebon islet lagoonside (Photo: M. Weisler), e. Moniak islet lagoonside (Photo: M. Weisler) f. Moniak Islet oceanside (Photo: M. Weisler). .................................................................................. 126

Figure 3 Mollusc species from TP17-20, MLEb-1, represented by 15 or more individuals. ....................................................................................................................................... 127

Figure 4 Habitats accounting for more than 20% of MNI MLEb-1, TP17-20; a. all taxa b. Conus spp., Monetaria moneta and Cypraeidae spp. removed. See Table 1 for classification scheme key. ................................................................................................................ 128

Figure 5 Mollusc species from TP17-20, MLEb-1 assigned to D/1/15 or D/1/16, represented by 15 or more individuals. ............................................................................................ 129

Figure 6 Mollusc species from TP2-6, MLEb-31, represented by 15 or more individuals. ............ 130

Figure 7 Habitats accounting for more than 20% of MNI, TP2-6, MLEb-31 a. all taxa; b. Taxa assigned to D/1/18, represented by 15 or more individuals. See Table 1 for classification scheme key. ................................................................................................................ 131

Chapter 5: Windward vs. leeward: Inter-site variation in marine resource exploitation on Ebon

Atoll, Republic of the Marshall Islands

Figure 1 Map of the Republic of the Marshall Islands, with Ebon Atoll and the location of sites MLEb-1, MLEb-31 and MLEb-33, and photos depicting intertidal marine habitats characteristic of each islet (a) Ebon Islet oceanside, view northwest showing expansive reef flat (Photo: A. Lambrides), (b) Enekoion Islet lagoonside, view northeast showing seagrass beds in the intertidal (Photo: M. Harris), (c) Moniak Islet oceanside, view east of coral cobble and boulder intertidal (Photo: M. Weisler). ............................................ 155

Figure 2 The percent contribution to total MNI and NISP by taxon, site and screen for mollusc shell, 6.4 mm samples and fish bone 6.4 mm and 3.2 mm samples. Family level identifications, but note Selachii (modern sharks), which is a superorder/clade ............................. 156

Figure 3 Correspondence analysis of taxonomic abundance. (a) 6.4 mm bivalve shell, (b) 6.4 mm gastropod shell and (c) 6.4 mm fish bone samples are displayed on separate plots for clarity, (d) 3.2 mm fish bone samples. Key taxa are annotated and distinct taxa are not displayed due to minimal contribution to total MNI at each site. ........................................ 157

xviii

Chapter 6: Two millennia of mollusc foraging on Ebon Atoll, Marshall Islands: sustained marine

resource use on a Pacific atoll.

Figure 1 Map of the Republic of the Marshall Islands, with Ebon Atoll and the location of sites MLEb-1, MLEb-31 and MLEb-33 ...................................................................................... 186

Figure 2 Representative mollusc taxa from Ebon Atoll archaeological deposits ............................ 187

Figure 3 (a) Benthic Habitats mapped within a 2 km radius of MLEb-1 and MLEb-5 on Ebon Islet, MLEb-33 on Enekoion Islet, and MLEb-31 on Moniak Islet with photos depicting characteristic intertidal marine habitats (a) lagoonside, view north west showing seagrass beds north west of MLEb-1 (Photo: M. Weisler) (b) lagoonside, view north east of areas of coral growth adjacent to MLEb-5 (Photo: M. Harris) (c) oceanside, view northwest showing expansive reef flat (Photo: M. Harris) (d) lagoonside, view north east of seagrass beds (Photo: M. Harris) (e) oceanside, view north west showing rubble and boulder reef flat (Photo: M. Harris) (f) lagoonside, view south east showing coarse sands, Ebon Islet in background (Photo: M. Weisler) (g) oceanside, view east of areas of rubble and boulder dominated reef flat (Photo: M. Weisler) ............................................................................................................................................ 188

Figure 4 Summary of analysis for MLEb-1 TP6 showing a. evenness (E), dominance (1-D) and diversity (H’) b. relative abundance of top three ranked taxa overall c. predominant habitat categories, and d. feeding types. ..................................................................... 189

Figure 5 Summary of analysis for MLEb-1 TP 17-20 showing a. evenness (E), dominance (1-D) and diversity (H’) b. relative abundance of top three ranked taxa overall c. predominant habitat categories, and d. feeding types. ..................................................... 190

Figure 6 Summary of analysis for all analysed test pits at MLEb-33 showing a. evenness (E), dominance (1-D) and diversity (H’) b. relative abundance of top three ranked taxa overall c. predominant habitat categories, and d. feeding types. ..................................................... 191

Figure 7 Summary of analysis for MLEb-31 TP 2-6 showing a. evenness (E), dominance (1-D) and diversity (H’) b. relative abundance of top three ranked taxa overall c. predominant habitat categories, and d. feeding types. ..................................................... 192

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List of Tables

Chapter 3: A refined protocol for calculating MNI in archaeological molluscan shell assemblages:

a Marshall Islands case study

Table 1 Total MNI for all taxa, aggregated at test pit level ............................................................... 74

Table 2 Total MNI for the top ten ranked taxa only, aggregated at test pit level .............................. 75

Table 3 Unique family, genus and species counts for gastropods aggregated by test pit. For each test pit, the counts for all taxa and the top ten ranked taxa are presented. .......................... 76

Table 4 Evenness and dominance measures. D = Simpson’s Dominance, 1-D = Simpson’s Evenness, H’ = Shannon’s index, H’/lnS = Shannon’s evenness .................................... 77

Table 5 Eb-1 T18 & 19 NRE MNI and tMNI quantification results for gastropod taxa. * = change in rank order; ** = unique to rank order abundance for that method. ................................ 78

Table 6 Eb-33 TP7 NRE MNI and tMNI quantification results for gastropod taxa. * = change in rank order; ** = unique to rank order abundance for that method. ................................... 79

Table 7 Eb-33 TP7 NRE MNI and tMNI quantification results for bivalve taxa. ............................ 80

Table 8 Eb-1 TP18 and 19 NRE MNI and tMNI quantification results for bivalve taxa. ................. 81

Table 9 Contribution of the pre-selected bivalve counting character for all taxa. ............................. 82

Table 10 Contribution of the pre-selected gastropod counting character for all taxa. ...................... 83

Chapter 4: Intertidal foraging on atolls: prehistoric forager decision making at Ebon Atoll,

Marshall Islands

Table 1 Summary of previous analyses of molluscan assemblages from archaeological sites in the Marshall Islands from Majuro (Riley 1987), Arno (Dye 1987) and Utrōk (Weisler 2001) atolls. Habitat assignments from Baron (1992), Baron and Clavier (1992), Carpenter and Niem (1998), Demond (1957), Soemodihardjo and Matsukuma (1989), Thomas (2001), and Willan (1993). .................................................................................... 121

Table 2 List of zones, major geomorphological structures and detailed geomorphological structures used in the Ebon archaeological project hierarchical classification scheme (after Kendall et al. 2012:8-12). Zone J, dredged/excavated and Detailed Geomorphological structure 13, aggregated patch reefs was not used for the analysis presented here, as these classes relate to methods for mapping modern day atoll benthic habitats. Detailed Geomorphological structure 19, Algal Ridge, was added by the authors due to the distinctive range of molluscan taxa associated with this habitat (Morrison 1954). .............................................................................................................................. 123

Chapter 5: Windward vs. leeward: Inter-site variation in marine resource exploitation on Ebon

Atoll, Republic of the Marshall Islands

xx

Table 1 Chord distance values for mollusc shell and fish bone assemblages retained in the 6.4 mm

and 3.2 mm sieves for each site pair. 153

Table 2 Measures of taxonomic heterogeneity: NTAXA, Shannon's index of diversity (H') and evenness (E), Simpson's dominance (1-D) and Fisher’s α, as calculated for mollusc shell and fish bone assemblages retained in the 6.4 mm and 3.2 mm sieves for all sites (MLEb-1, MLEb-31 and MLEb-33). .................................................................................. 154

Chapter 6: Two millennia of mollusc foraging on Ebon Atoll, Marshall Islands: sustained marine

resource use on a Pacific atoll

Table 1 Summary data for mollusc assemblages from MLEb-1, MLEb-5, MLEb-31, and MLEb-33; Wt. = weight ................................................................................................................... 185

1

Chapter 1: Introduction

Introduction

Archaeomalacology, the study of mollusc remains from archaeological sites, has revealed that

humans have been foraging for molluscs for at least 165,000 years (Jerardino and Marean 2010).

Mollusc shells are excellent proxy records for human behaviour as they are ubiquitous in

archaeological deposits and preserve well compared with other marine fauna. Molluscs are also

critical components of tropical intertidal ecosystems and coral reefs and, as such, can be useful in

tracking long-term trajectories of change in marine environments. Molluscs are effective regulators

of algal cover (Hockey and Alison 1986), can filter water to improve quality (Hutchings et al. 2007;

Klumpp and Lucas 1994), and can increase habitat complexity through ecosystem engineering or

the accumulation of the shells of dead molluscs (Andréfouët et al. 2005; Gutiérrez et al. 2003).

Archaeomalacological analyses have elucidated patterns of forager behaviour (Thomas 1999, 2009),

exploitation and management of subsistence resources (Gutiérrez-Zugasti 2011a; Langejans et al.

2012; Milner et al. 2007; Whitaker 2008), human impacts, and the difficulties of disentangling

these processes from non-anthropogenic causes (Braje et al. 2007; Erlandson et al. 2008; Faulkner

2013; Giovas 2016; Giovas et al. 2013; Harris and Weisler in press-a and references therein; Jones

2007; Morrison and Hunt 2007; Spennemann 1989; Thakar 2011; Thakar et al. in press). Other

researchers have focussed on human responses to environmental or climatic changes (Amesbury

1999, 2007; Parkington et al. 2013) taphonomy (Faulkner 2010, 2011; Gutiérrez-Zugasti 2011b;

Sommerville-Ryan 1998), mollusc shells as raw material (Harris et al. 2017; Perrette 2011;

Spennemann 1993; Szabó and Koppel 2015) and tracking patterns in long-term human interaction

with the marine environment (Fitzpatrick et al. 2011; Szabó and Amesbury 2011). In addition,

given that molluscs are important for archaeologists and neo-ecologists alike, studies that combine

archaeological data with historical and neo-ecological data have proven utility for understanding

how coral reefs have changed over time, and might change in the future (Fitzpatrick and Intoh

2009; O'Dea et al. 2014; Thomas 2001, 2009, 2014; Wiley et al. 2013).

Atolls, consisting primarily of unconsolidated biogenic sediments atop a narrow reef platform

surrounding a lagoon, have long been considered marginal environments vulnerable to human

impacts and challenging landscapes for sustained habitation. This is due to a lack of standing fresh

water, nutrient poor soils for agriculture, and exposure to storms and extreme weather due to low

elevation.

2

The long-term survival of human populations in the atoll archipelago of the Marshall Islands was

underpinned by a system of pit-cultivation techniques for giant swamp taro (iraij, Cyrtosperma

chamissonis), rain-fed production of arrowroot (makmōk, Tacca leontopetaloides), and

arboriculture including pandanus (bōb, Pandanus tectorius), coconut (ni, Cocos nucifera), and

breadfruit (mā, Artocarpus altilis) (Weisler 1999a, b) and marine subsistence (Weisler 1999b,

2001b). Much of the reef platform is intertidal, and can be easily accessed for the exploitation of

finfish, molluscs and other marine resources that provided protein and other vitamins and minerals

not available or limited in terrestrial foods (Erlandson 1988, 2001; Weisler 2001b). The Marshallese

language has at least 64 words describing different fishing techniques, and about 45 words for

different kinds of mollusc, specific words that divide the intertidal into habitats and zones, and

sophisticated seafaring technology and navigation techniques attesting to a deep an intimate

knowledge of the ocean (Abo et al. 1976; Merlin et al. 1994). A single language spoken across the

entire archipelago, an area of nearly 2,000,000 km2, suggests continuous inter-atoll contact

throughout the prehistoric period (Sudo 1984).

For most of the 20th century Pacific atolls were relatively neglected compared to other island types

as it was thought that archaeological deposits would not survive in situ (Davidson 1968, 1971).

Archaeological survey and limited excavation of atolls in the Marshall Islands beginning in the

1970’s (Dye 1987a) revealed at least two millennia of human occupation. Subsequent work in the

archipelago has increased archaeological understanding of the lifeways of people living on atolls

during the precontract period (Christensen and Weisler 2013; Harris et al. 2016; Harris and Weisler

2016; Harris and Weisler in press-a, b; Harris et al. 2015; Horrocks and Weisler 2006; Lambrides

and Weisler in press; Pregill and Weisler 2007; Sommerville-Ryan 1998; Weisler 1999a, b, 2000,

2001a, b, 2002; Weisler et al. 2000; Weisler and Swindler 2002; Weisler et al. 2012; Weisler et al.

in prep.; Yamaguchi et al. 2009). Archaeological analyses have demonstrated that molluscs were a

consistent component of subsistence systems in the Marshall Islands from the time of initial

colonisation soon after atoll emergence (Kayanne et al. 2011; Weisler 1999b, 2001b). However,

these faunae have received little in-depth analysis in the archaeological discourses of the

archipelago. Broad syntheses of the place of molluscs in prehistoric period Marshallese economies

has been presented by Weisler (2001b), but there have been few dedicated studies of archaeological

molluscs from the archipelago prior to the research presented here. This thesis explores

quantification methods (Harris et al. 2015), analytical methods (Harris and Weisler 2016), and

conduct a spatio-temporal analysis of mollusc foraging during the prehistoric period on Ebon Atoll,

Republic of the Marshall Islands (RMI) (Harris et al. 2016; Harris and Weisler in press-b)

3

Rationale

Long-term patterns of mollusc foraging on atolls and the potential for human impacts to coral reefs

in the region are not well understood. Recently, archaeologists and neo-ecologists have

demonstrated the critical contribution of historical data for comprehensively understanding the state

of ecosystems due to the time-lag between disturbance and ecosystem change (Alleway and Connell

2015; Braje et al. 2005; Briggs et al. 2006; Hayashida 2005:45; Rick and Lockwood 2013). Recent

studies of finfish remains from sites in the RMI have demonstrated that Marshall Islanders have

exploited these resources for at least 2000 years (Weisler 1999a, 2000), potentially with little

negative impact (Lambrides and Weisler in press; Weisler 2001b). These studies have also

demonstrated some variability in patterns of mollusc exploitation across the windward-leeward

exposure gradient on atolls, and variation in foraging patterns between site type (i.e. village v.

ephemeral campsites) (Weisler 2001b).

On atolls, the configuration of intertidal environments and related faunal and floral communities are

strongly structured by the degree of exposure to wave action (Drumm 2005), and archaeological

studies in the Marshall Islands have demonstrated that larger, leeward islets that are sheltered from

the wind and waves are more likely to be permanently inhabited than smaller, windward islets (Dye

1987a; Weisler 1999b, 2001b, 2002). Small, often ephemeral windward islets are generally less

suitable for permanent settlement due to a smaller, often saline subterranean Ghyben-Herzberg

fresh water lens, making them generally unsuitable for agriculture. Variation in site use and the

taxonomic composition of mollusc assemblages relating to windward or leeward exposure has been

documented for other Pacific Islands (Bayman and Dye 2013; Bedford 2007; Kirch and Dye 1979;

Morrison and Hunt 2007; Szabó and Anderson 2012), but has not been systematically investigated

for the southern Marshall Islands (but see Weisler 2001b for a discussion of inter-islet variation on

Utrok Atoll, northern RMI). Broad syntheses of mollusc data from Utrok, Arno, Majuro and Ebon

Atolls (Dye 1987b; Riley 1987; Weisler 2001b), has revealed that most assemblages are rich

(consisting of many taxa), even (all taxa represented in relatively equal proportions) and diverse

(many taxa with many individuals from each taxon). Weisler (2001b:116) documented no

indications of human impacts to molluscs on Utrok, inferred to be the result of low human

populations and expansive reef flats. The mollusc assemblages recovered from Ebon Atoll provide

an opportunity to perform, for the first time in the RMI, a dedicated, fine-grained analysis of human

foraging for molluscs and human-environment interactions using high-resolution

archaeomalacological techniques.

4

It is critical that patterns of human behaviour and an elucidation of foraging practices must be based

on reliable, transparent identification and quantification protocols. Comprehensive and clearly

reported quantification protocols are critical to data quality, comparability and replicability. The

advantages and disadvantages of utilising Number of Individual Specimens (NISP) counts, shell

weight, or calculating Minimum Numbers of Individuals (MNI) has been widely debated in the

archaeomalacological and zooarchaeological literature (Driver 2011; Gutiérrez-Zugasti 2011b;

Jerardino et al. 2016; Popejoy et al. 2016). MNI values are commonly considered the most accurate

representation of taxonomic abundance in archaeological contexts, but previous quantification

protocols have relied on a very limited range of non-repetitive elements (NRE) to derive MNI

values, such as the apex or spire of gastropods and the umbo of bivalves (Claassen 1998, 2000;

Glassow 2000; Mason et al. 1998). Similarly, methods for investigating human foraging behaviour

have commonly utilised deterministic methods for reconstructing habitat selection based on the life

history of mollusc taxa (Allen 1992; Morrison and Addison 2008; Morrison and Hunt 2007;

Spennemann 1987; Szabó 2009; Thomas 2002; Weisler et al. 2010), where a single taxon is

assigned to a single habitat. This thesis explores an alternate probabilistic method for reconstructing

human foraging practices by assigning each taxon to multiple combinations of intertidal zone (reef

flat, shoreline, etc.), geomorphological structure (hard v. soft bottom) and benthic cover (sand,

rubble, coral, etc.). This method allows exploration of the most likely areas where molluscs were

collected, while acknowledging that particular taxa may be collected from multiple areas of the reef.

Research questions pertaining to these identified gaps in literature and observations of areas where

methods could be improved or altered are presented below.

Research Questions

The major goal of this research is to examine temporal and spatial variation in mollusc foraging on

Ebon Atoll, and whether prehistoric patterns of resource depression are visible in the archaeological

record. Five major questions will be addressed, broadly separated into two themes. First,

archaeomalacological methods for quantifying mollusc remains from archaeological sites will be

examined, a new method for investigating forager decision-making will be presented, and the

current state of knowledge of human impacts to molluscs in the prehistory of the Pacific Islands will

be explored. Second, these methods will be applied to archaeological datasets from Ebon Atoll to

investigate long-term human interaction with the marine environment, foraging behaviours, and

potential human impacts to coral reefs.

5

Research Question (RQ1) reviews literature pertaining to human impacts to molluscs during the

prehistoric period of the Pacific Islands. RQ1 also provides a broad, regional context for the

investigation of human impacts to molluscs and intertidal ecosystems on Ebon Atoll. RQ2 examines

current methods for quantifying mollusc remains from archaeological sites, and how the protocols

influence derived measures of relative abundance and taxonomic composition and heterogeneity.

Clear and transparent quantification protocols that do not inherently bias data towards one faunal

class over another are critical for developing high-resolution, replicable and reliable understandings

of past human behaviour (Driver 2011). RQ3 explores current methods for inferring human

foraging behaviour from mollusc remains, and proposes a new method that links

archaeomalacological data to a hierarchical classification scheme for benthic habitats in tropical

intertidal environments. RQ1, RQ2, and RQ3 are as follows:

RQ1: Has human foraging for molluscs impacted mollusc populations and intertidal ecosystems in

the Pacific Islands during the prehistoric period?

RQ2: Does the inclusion of an increased number of non-repetitive shell elements (NREs) in

quantification protocols influence measures of relative abundance and taxonomic heterogeneity?

RQ3: What methods can be generated to explore and understand forager decision-making and

habitat selection in atoll environments?

Archaeomalacological data has proven utility for enhancing understanding of past human

subsistence behaviours, and human-environment interactions in coastal and island archaeology.

Using the information gathered to address RQ1, and methods developed in addressing RQ2 and

RQ3, RQ4 and RQ5 examine human foraging patterns and potential human impacts to molluscs on

Ebon Atoll. RQ4 and RQ5 are as follows:

RQ4: What is the influence of spatial (settlement patterns and local marine habitats) and temporal

factors on the richness (number of species present), abundance (number of individuals of each

species present), and diversity (richness and relative distribution of individuals of each species

within a population) of mollusc assemblages on Ebon Atoll?

6

RQ5: Is there any indication that human foraging for molluscs directly impacted mollusc

populations or had secondary, indirect impacts on intertidal ecosystems on Ebon Atoll over the two

millennia of human occupation?

Thesis structure

This thesis consists of seven chapters: an Introduction, five published papers (Chapter 2 to Chapter

6), and a Conclusion. Chapter Two reviews the current state of knowledge regarding prehistoric

human impacts to molluscs, and potential secondary impacts to intertidal ecosystems in the Pacific

Islands resulting from human foraging for molluscs. Chapter Three reviews current methods for

calculating MNI for molluscs from archaeological sites, presenting a new method that uses a range

of non-repetitive shell elements to calculate MNI, rather than the few traditionally used. Chapter

Four presents an analysis of foraging behaviour by tracking the range of habitats likely accessed by

prehistoric foragers on Ebon Atoll. Chapter Five compares site-level data for mollusc and fishbone

assemblages from a windward and leeward islet on Ebon Atoll to understand the influence of site

location and site function on overall Ebon Atoll marine subsistence patterns. Chapter Six presents

the results of a comprehensive temporal and spatial analysis of mollusc remains from Ebon Atoll,

and investigates the potential for human impacts to molluscs and intertidal ecosystems in the

prehistoric period. Chapter Seven summarises the results of each published paper in relation to the

research aims and research questions, discusses future research objectives, and provides some

concluding remarks.

Chapter Summary

This chapter presented the primary aims of this thesis, which are to develop comprehensive

methods for quantifying archaeological mollusc shells from Ebon Atoll, Marshall Islands, which are

transparent, replicable and reliable. This thesis will also investigate long term patterns of human

interaction with molluscs in intertidal environments in the Pacific Islands, and focus intensively on

human foraging practices for molluscs on Ebon Atoll, RMI to understand the variation in foraging

across the windward-leeward atoll gradient, the influence of site function, and investigate potential

human impacts. Mollusc foraging on atolls is a relatively unexplored area of archaeological

research, and has the potential to contribute useful data to archaeological discourses on human

interaction with the ocean, human colonisation and long-term survival on small islands, and current

discourses on the global threats to coral reefs and marine ecosystems.

7

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14

Chapter 2: Prehistoric human impacts to marine molluscs and intertidal ecosystems in the

Pacific Islands

Note: This is the final version of a peer-reviewed article published in the Journal of Island and

Coastal Archaeology

Matthew Harris and Marshall I. Weisler

School of Social Science, The University of Queensland, St. Lucia, QLD 4072 Australia

Corresponding author: Matthew Harris, School of Social Science, The University of Queensland,

St. Lucia, QLD 4072 Australia. Email: [email protected]

15

Abstract

From long-term stratigraphic records in Pacific Island archaeological sites researchers have

documented alterations to molluskan species richness and abundance, decreases or increases in

mollusk shell size and, in rare cases, human foraging may have contributed to the extirpation of

mollusk taxa. Mollusks perform critical ecosystem functions in tropical intertidal environments,

including improving water quality through filtration, regulating algal cover, and increasing habitat

and substratum complexity through ecosystem engineering. These critical ecosystem functions can

be negatively affected by human foraging, possibly contributing to decreased resilience of coral

reefs to climatic alterations. We review modern ecological research on human impacts to mollusks

and intertidal ecosystems that illustrates the mechanisms and effects of human foraging. We then

examine centuries to millennial scale archaeological records from the Pacific Islands to understand

long-term, time-averaged trends in human impacts to intertidal ecosystems.

Keywords: archaeomalacology, anthropogenic impacts, coral reefs, prehistoric foraging,

zooarchaeology, marine subsistence

16

Introduction

The study of mollusk remains from archaeological sites, known as archaeomalacology, can reveal

important information on human foraging behavior (Harris and Weisler 2016; Szabó, 2009; Thomas

2009), management and exploitation of subsistence resources (Álvarez et al., 2011; Braje et al.

2007; Whitaker 2008), mobility and settlement patterns (Allen 2012), responses to climatic and

environmental fluctuations (Amesbury 2007), and can inform on long-term changes to coral reefs

and human interaction with the marine environment (Morrison and Addison 2008:16; Szabó and

Amesbury 2011). Mollusks are the most species rich class of marine invertebrates, and a critical

component of tropical intertidal ecosystems (Glynn and Enochs 2011). Active at all trophic levels,

mollusks perform important ecological functions, including increasing habitat complexity

(Andréfouët et al. 2005; Gutiérrez et al. 2003), improving water quality through filtration

(Hutchings et al. 2007), and regulating algal cover through herbivory (Hockey and Alison 1986).

The intertidal environments that mollusks inhabit are varied and ubiquitous, and despite decades of

dedicated research the ecological role of human foraging in these ecosystems is not well understood

(Allen 2003; Brander et al. 2010; Castilla 1999; Castilla and Duran 1985; Catterall and Poiner

1987; de Boer and Prins 2002; Erlandson and Rick 2010; Fitzpatrick and Donaldson 2007; Poiner

and Catterall 1988; Rick and Erlandson 2008; Rivadeneira et al. 2010). Measuring the impact of

human foraging is difficult given the rarity of cases where single stressors can account for

documented alterations to intertidal communities (McClanahan et al. 2014:459), and general lack of

modern ecological data necessary to measure the impact of humans on mollusks in the tropical

Pacific (Kinch 2003:5). However, studies of human interaction with marine mollusks report a range

of direct and indirect effects including, alterations to community structure and composition (Hockey

1987; Hockey and Alison 1986), change in the body size of exploited species (Giovas et al. 2010;

Spennemann 1987), or a lack of discernible impacts (de Boer and Longamane 1996; Morrison and

Addison 2008; Weisler 2001:116). The study of mollusks from archaeological sites in the Pacific

Islands has revealed that human foraging during the prehistoric period altered mollusk species

richness, abundance and diversity, physical size, and may have led to the extirpation of some taxa.

Data generated by archaeologists has also contributed valuable long-term historic records of human

interaction with the marine environments of the Pacific Islands (Dalzell 1998; Jones 2007).

Mollusk shells from archaeological contexts provide excellent proxy records for human interaction

with the intertidal zone as their shells preserve well, especially compared to other marine fauna, and

17

are ubiquitous in most coastal Pacific Island archaeological sites. Archaeologists often investigate

human disturbance to mollusks by assessing alterations to species abundance, diversity and

richness, and changes to body size. These data can be compared with archaeological,

paleontological and modern ecological data to identify local depletion and extirpation of marine

fauna (Dulvy et al. 2003; Edgar and Samson 2004:1579; Erlandson and Fitzpatrick 2006), and

contribute to modern conservation efforts (e.g., Aswani and Allen 2009; Jones 2009; Lauer and

Aswani 2010; Thomas 2009).

Human impacts to mollusks during Pacific Islands prehistory have been routinely documented, but

analytical and methodological variation hinder a regional synthesis of these studies. Issues with the

quantification of mollusk remains from archaeological sites have been discussed elsewhere (Giovas

2009; Harris et al. 2015; Mason et al. 1998), but variable or unclear reporting of quantification

protocols prevents rigorous comparison of assemblages quantified variably using weight, Number

of Individual Specimens (NISP), or Minimum Numbers of Individuals (MNI). As standards of

archaeological excavation have changed substantially throughout the development of Pacific Island

archaeology, variable screen size, sampling (not all excavated mollusks are retained for analysis),

and dating protocols hinder precise comparison of archaeomalacological datasets.

Rather than focus on quantitative comparison of datasets to discern regional or temporal patterning

in human foraging impacts, we discuss archaeological evidence for human impacts based on three

inferred outcomes of human foraging: (1) extirpation or extinction of mollusk species, (2) changes

in the size/age structure of mollusk populations, and (3) signatures of trophic alteration, most

commonly present as changes to species richness, diversity and abundance. We document

archaeological cases where human foraging has been reported as the primary driver for changes in

archaeological mollusk assemblages and suggest future research avenues for the region. Modern

ecological research on human impacts to mollusks is reviewed to elucidate the mechanisms of

change that may underpin long-term, time-averaged trends in archaeological datasets from the

Pacific Islands.

The Effects of Human Predation

Human predation directly reduces the abundance and biomass of mollusk populations (Green and

Craig 1999:210; Zhang et al. 2013:237), which can also alter the mean size of the prey population

(Castilla and Bustamante 1989; Fairweather 1990:453), and in cases of intensive and sustained

predation, local extirpation can occur (Dulvy et al. 2003). In addition to these direct effects,

18

predation can cause indirect effects on community structure as the targets of human predation are

often keystone species that have a disproportionate influence on associated flora and fauna relative

to their abundance or biomass (Paine 1995:962; Power et al. 1996:609). Predation of keystone

species can effect organisms at all trophic levels and decrease the ratio of predators to prey, thus

reducing interspecific competition and potentially increasing the abundance of subordinate, often r-

selected species (de Boer and Prins 2002; Fairweather 1990). Conversely, human predation can

increase diversity and richness by creating a mosaic of patches with different stages of succession

(de Boer et al. 2000), especially through the reduction of herbivorous taxa that regulate floral cover,

thus further impacting a range of ecological processes (Godoy and Moreno 1989; Hockey and

Alison 1986; Sagarin et al. 2007). Human predation at a number of locations along a coastline can

also cause faunal and floral communities to converge towards a common state of similar taxonomic

richness, diversity and abundance (Hockey and Alison 1986).

However, equifinality and the dynamic, unpredictable effects of predation can hinder precise

assignment of causation (Fairweather and Underwood 1991). As Fairweather (1990:453) surmised,

predation is a form of ecological interaction that can be “maddeningly idiosyncratic”. In modern

ecological studies, traditional subsistence harvesting is increasingly recognised as strongly

influencing invertebrate assemblages, though the outcomes of this type of predation are difficult to

measure and document due to the range of non-human stressors in the intertidal (Jimenez et al.

2012:90). The relationship between predation, recruitment, and change over time in the relative

abundance of marine invertebrates in intertidal areas is complex, and even simple studies of

predator-prey interaction have produced divergent results over a short period (Fairweather 1988).

Fecundity and growth rates, size at maturity, escape and avoidance mechanisms such as burying or

benthic mobility, the presence of adjacent populations for replenishment of stocks, and larval

phases (especially taxa with pelagic larva) can complicate understanding of the impacts of human

exploitation (Catterall and Poiner 1987:Table 7; de Boer et al. 2000:288). For archaeologists and

ecologists alike, the lack of ecological information on commonly exploited taxa, the response of

these populations to human predation in tropical intertidal settings, and limited understanding of the

human role in structuring intertidal populations reduces our confidence in isolating anthropogenic

influence (Castilla and Duran 1985; Catterall and Poiner 1987:119; McShane et al. 1994; Poiner

and Catterall 1988).

19

An Historical Ecology Approach

Pacific Island coral reefs are amongst the most structurally complex and taxonomically diverse

ecosystems in the world (Glynn and Enochs 2011; Jackson et al. 2001:631). The human

colonization and settlement of the Pacific Islands was the most expansive maritime migration in

history, and local adaptations reflect the diversity of island types (continental, high volcanic,

makatea and atolls) and time scales of occupation from many thousands of years to several

centuries (Fitzpatrick and Callaghan 2013; Irwin 1992; Kirch 2000; Weisler et al. 2016). Pre-

European human impacts to these ecosystems have been underestimated by ecologists (Erlandson

and Braje 2013; Smith and Zeder 2013), and so-called ‘pristine’ environments are commonly the

current representation of a deep history of anthropogenic influence (Alden Smith and Wishnie

2000:496; Myers and Worm 2003; Pinnegar and Engelhard 2008). If human occupation of Pacific

Islands, and mollusk foraging in these environments has decreased the resilience of tropical coastal

ecosystems to current climatic alterations (Jackson et al. 2001), the current state of coral reefs

cannot be fully understood, explained, conserved or restored without an historical perspective

(Hayashida 2005:45; McClanahan et al. 2014:59). Documenting human impacts across broad

temporal and spatial scales requires a multidisciplinary engagement with geological, biological,

ecological, archaeological and anthropological data (Baisre 2010:137; Erlandson and Fitzpatrick

2006:7). The unique long-term historical data provided by zooarchaeologists can help elucidate

proximate and ultimate causes of anthropogenic ecological change (Braje et al. 2005; Carder and

Crock 2012; Jackson et al. 2001; Wolverton and Lyman 2012). Zooarchaeological data alone

cannot provide the answers, and integrated research utilizing the methodological frameworks of

historical ecology to compare temporally disparate datasets has become increasingly common

(Briggs et al. 2006; Hayashida 2005; Pinnegar and Engelhard 2008).

We follow the broad definition of historical ecology as a multidisciplinary endeavor that uses

historic and prehistoric data to understand ancient and modern ecosystems, often with the goal of

providing context for contemporary conservation (Rick and Lockwood 2013:46-47). Rather than

treat humans and the environment as separate, historical ecologists investigate the dialogue between

them, and view the landscape as an outcome of these interactions (Balée 2006:77; Braje et al.

2005:6). Analyses based in historical ecology frameworks have eliminated the bias of the shifting

baselines syndrome identified by Pauly (1995), where each generation of fisheries scientists had

accepted the state of marine fisheries at the beginning of their careers as a baseline for future stock

assessments, an underestimation of pre-European environmental impacts (Erlandson and Braje

2013; Erlandson and Rick 2010), and a lack of time-depth in empirical records. Historical ecology

20

has facilitated deep historical analyses of current ecosystems (Baisre 2010; Bunce et al. 2008;

Carder and Crock 2012; Cramer et al 2015.; Morrison and Hunt 2007; Pauly 1995; Rick and

Lockwood 2013; Small and Nicholls 2003; Wake et al. 2013). Recent historic and ancient

archaeological records have been compared to assess fishing down food webs (Blick 2007; Pestle

2013), regime shifts, alternative stable states, trophic cascades and trophic level analyses,

extinctions (Dulvy et al. 2003; Seeto et al. 2012), and to establish baselines and reference states for

restoration ecology and conservation biology (Baisre 2010; Carder and Crock 2012). Historical

ecological research has revealed that even relatively minor artisanal or subsistence fisheries can

have long-term effects on marine environments (Briggs et al. 2006), and comparisons with

historical data have shown that current perceptions of ‘natural’ environments rarely match long-

term records (Alleway and Connell 2015).

While historical ecology has many potential benefits as an integrative framework for

multidisciplinary analyses, the comparison of datasets that might span days, decades, or up to tens

of thousands of years can be methodologically difficult. Integrating archaeological and

paleontological data with modern ecological data requires sacrificing the “apparent precision and

analytical elegance” of modern ecology (Jackson et al. 2001:630). Historical ecologists must be

aware of the limitations and strengths of the data, but the ability to observe time-averaged patterns

of change may offset the sacrifice in analytical precision that studies of extant environments alone

can provide (Rick and Lockwood 2013). Below, we review a range of modern case studies to

highlight the ways that human foraging can impact mollusk populations, and present archaeological

research from the Pacific Islands that has reported human impacts to mollusks.

Anthropogenic Extirpation of Mollusks in the Pacific Islands

Declines in the abundance of tridacnid clams (Cardiidae: Tridacninae) have been reported in both

archaeological and ecological studies in the Pacific Islands (Green and Craig 1999; Matthews et al.

2003; Morrison and Allen in press and references therein; Newman and Gomez 2002). In the late

20th century, extirpations were reported for a number of archipelagos, with Hippopus hippopus

(horse’s hoof clam) likely extinct in Guam (Paulay 1996), Fiji (Lewis et al. 1988) and Tonga

(McKoy 1980 in Lewis et al. 1988). Tridacna gigas (giant clam) has been extirpated from the

Caroline Islands and the Fiji archipelago (Lewis et al. 1988:67), and Tridacna spp. are rare in the

Gilbert Islands (Tebano and Paulay 2000). Tridacna are largely depleted from the Samoan

archipelago, with an inverse relationship between human population size and tridacnid abundance

21

(Green and Craig 1999:210). In Palau, Matthews et al. (2003:3) reported an overall decline in

tridacnids in areas where clam population density had traditionally been expected to be high.

While the causes of these declines are multi-faceted, and changes in tridacnid distribution are

dynamic over time and space (Copland and Lucas 1988; Newman and Gomez 2002), human

exploitation has been identified as a causal factor. Modern coastal development and alterations to

settlement patterns and agricultural activity during the prehistoric period increased terrigenous

runoff and water turbidity in the intertidal, negatively impacting the symbiotic relationship between

photosynthetic zooxanthellae and the tridacnid host (Kirch 1983; Morrison and Cochrane 2008;

Rolett 1992). Tridacnids may also be susceptible to overharvesting given their large, conspicuous

size, tendency to live in dense, spatially aggregated colonies, and slow growth rate (Catterall and

Poiner 1987; Morrison and Allen in press; Poiner and Catterall 1988; Whitaker 2008).

Documenting local or regional mollusk extirpation in archaeological contexts is difficult as the

presence or absence of a particular species is mediated by a range of stochastic and unpredictable

ecological phenomena that structure reef assemblages at any given time, many of which are

archaeologically intractable (Jones 2009:637; Sale 1980; Thomas 2009:580). Establishing island, or

archipelago wide archaeological evidence for the extirpation or extinction of mollusks requires

temporally controlled, regional archaeomalacological datasets suitable for comparative analyses,

which are rare in the Pacific Islands. Thus, anthropogenic extirpation and extinction of mollusks has

rarely been reported in Pacific archaeology (Allen 2003:324; Seeto et al. 2012). However, local

extirpation has been tentatively proposed for the northern Marshall Islands (Weisler 2001) and the

Fiji archipelago (Seeto et al. 2012). Weisler (2001:125) documented the presence of the bullmouth

helmet shell (Cypraecassis rufa) in archaeological sites at Utrōk Atoll, and the lack of modern

records for this taxon in the Marshall Islands as potentially indicative of anthropogenic extirpation

during the prehistoric period. Seeto et al. (2012:11-13) propose five non-mutually exclusive

explanations—overexploitation, introduced predators and diseases, increased sea surface turbidity,

and sea level fall—for the disappearance of Hippopus from the Boureawa and Qoqo (Fiji)

archaeological sites. While sea level fall and consequent habitat loss during the Lapita occupation

of the site (c. 2500 - 3050 BP) is inferred as the primary driver of the extirpation of Hippopus, a

general reduction in shell size over time may indicate that exploitation pushed local Hippopus

populations “beyond a threshold where the population could become re-established” (Seeto et al.

2012:11).

22

Changes in the Size/Age Structure of Mollusk Populations

The most common model for human-induced mollusk size reduction hypothesizes that foragers will

target the largest and oldest individuals, only selecting smaller and younger mollusks as larger

individuals are removed. Over time, the mean size of the population will decrease, with consistent

exploitation preventing growth to larger sizes, and prohibiting growth to sexual maturity (e.g., Allen

2012; Mannino and Thomas 2002; Swadling 1976). Often, physical size is used as a proxy for age,

however, changes in mollusk size can be induced by a range of non-anthropogenic factors, and

inferences of genuine human impact should ideally be demonstrated by both changes in size and in

ontogenetic development and age (Swadling 1976; Branch and Odendaal 2003). Reduction in size

can impact ecological functioning, including the regulation of subordinate prey species (Catterall

and Poiner 1987; de Boer et al. 2000) and macro-algal cover (Hockey and Alison 1986; Sagarin et

al. 2007). A reduction in mean body size and age can also alter sex ratios of populations and

decrease average reproductive output over the lifetime of the organism (Brander et al. 2010). These

changes can be critical to the long-term survival of mollusk populations, especially for sequentially

hermaphroditic taxa (individuals that change sex throughout life) (Branch and Odendaal 2003;

Fenberg and Kautstuv 2008).

Moreno et al. (1984) found that keyhole limpets (Fissurella spp.) were less abundant and smaller at

sites where human foraging was heaviest (Moreno et al. 1984:159). Human exclusion from the

intertidal over a 6000 km2 area of the Chilean coast resulted in increased densities and a larger

median size of Chilean abalone (Concholepas concholepas) (Castilla and Duran 1985) and a greater

size range of the owl limpet, Lottia gigantea (Sagarin et al. 2007). Human harvesting was also

correlated with a decline in reproductive potential of Cymbula oculus limpets in south-east South

Africa where sites protected from harvesting had 2.7 times as many adults as unprotected sites, and

a 182-fold increase in female reproductive output (Branch and Odendaal 2003:259-261).

Planes et al. (1993) documented the diminution of Tridacna maxima at sites in Bora-Bora Lagoon,

Society Islands, French Polynesia where tourists regularly consumed clam meat. While coastal

quarrying and land reclamation negatively affected clam habitats, which likely contributed to the

decline in mean shell size, T. maxima mean length was 12-16 % smaller at sites regularly exploited

by tourists (Planes et al. 1993:5; Table 1). Aswani et al. (2015) found that areas of Roviana Lagoon,

Solomon Islands, that were permanently closed or restricted for most of the year had larger Anadara

granosa (blood clams) and Polymesoda spp. (mud clams) individuals than areas that were

constantly accessed by foragers. Populations of both taxa from restricted areas had greater numbers

23

of sexually mature individuals and thus, a greater potential for clam reproduction than non-

restricted coastal areas (Aswani et al. 2015:226).

Pacific Islands archaeologists have routinely inferred a link between human harvesting and

reduction in mean shell size by measuring mollusks preserved whole, and/or establishing

morphometric relationships between shell features to generate formulae for predicting shell size

from fragmented remains (e.g., Kirch et al. 1995; Swadling 1976; Thangavelu et al. 2011). There is

ongoing debate as to the interpretive validity of predictive formulae that do not account for

allometric or ontogenetic growth and/or the influence of local ecological conditions on shell size

(Campbell 2015; Faulkner 2010; Jerardino and Navarro 2008). Singh et al. (2015) argued that rather

than using formulae for understanding mollusk ontogeny and evolutionary development,

archaeologists seek to describe changes over time; current methods for generating predictive

formulae based on morphometric data drawn from a wide geographic area are therefore appropriate

for archaeological inquiry.

Pamela Swadling first investigated shell size change in the Pacific Islands using a combination of

metric analyses and age determinations based on shell features to investigate the effects of human

exploitation on mollusk populations at prehistoric sites in New Zealand, Papua New Guinea and the

Solomon Islands (Swadling 1976, 1977 see also Green 1986). Grounded in molluskan biology and

ecology, Swadling investigated changes in mollusk size and recorded the presence or absence of

shell features indicating sexual maturity, such as the thickening of the apertural lip in the

Strombidae (Swadling 1976:158-159), fluting on the lower whorls of Trochidae (Swadling 1986),

and the spacing of annular growth striae in bivalves (Swadling 1976:158). Swadling sought to

determine if changes observed in mollusk body size were produced by “human or environmental

factors” (Swadling 1976:156, emphasis added), inferring that intensive human exploitation pressure

led to a decline in the size and age of Austrovenus stutchburyi (New Zealand little neck clam,

formerly Chione stuchburyi) populations at Maori pā sites in northern New Zealand. Swadling also

proposed that Lapita occupation of the Reef/Santa Cruz Islands in the Solomon Islands likely led to

a decline in the abundance of large top shells, Tectus niloticus (formerly Trochus niloticus), and

slight reductions in the means size and age of Tectus pyramis and the ark clam, Anadara antiquata.

Swadling (1986:145-146) used mollusks from Lapita period middens in the Reef/Santa Cruz sites,

and compared the assemblages to natural relative abundances of Indo-Pacific taxa to determine

foraging patterns. Swadling challenged Groube’s (1971) now outdated ‘Oceanic Strandlooper’

hypothesis, proposing instead that the inhabitants of the SE-RF-2 site likely relied on a mixed

24

horticultural and marine diet, rather than depleting marine resources prior to focusing on shifting

cultivation.

Swadling’s work provided a foundation for other Pacific archaeologists investigating prehistoric

human impacts to mollusks. Declines in shell size have been detected for Haliotis iris (Pāua),

Lunella smaragda and Cellana denticulata at Pallier Bay, New Zealand (Anderson 1981), Nerita in

Lakeba, Fiji (Best 1985), Gafrarium spp. at Tongatapu, Tonga (Spennemann 1987, 1989), Turbo

setosus at Mangaia, Cook Islands (Kirch et al. 1995) and Turbo smaragdus at the Haratonga Beach

Site, New Zealand (Allen 2012). Morphometric approaches have also been used to track decreases

in shell size in north-eastern Fiji (Thomas et al. 2004), Palau (Masse et al. 2006), the western coast

of New Zealand’s South Island (Jacomb et al. 2010), and Papua New Guinea (Thangavelu et al.

2011). These studies follow the model first employed in the Pacific Islands by Swadling (1976),

correlating increasing human exploitation pressure with decreases in shell size over time.

Inferring human impacts based on declining shell size over time has been criticized as many

archaeologists have associated size change with human predation without examining alternate

explanations such as environmental and climatic influences (Giovas et al. 2010:2797; Thakar et al.

in press). Assigning humans as primarily responsible for declining mollusk size in archaeological

contexts often lacks detailed consideration of the complex range of factors that would have shaped

these processes. While human impact can reduce mollusk shell size, the relationship between shell

size and human exploitation pressure is rarely clear. Molluskan body size is a dynamic process

influenced by a range of ecological processes, and causal links between human predation and body

size are difficult to conclusively establish over both short and long-term records (e.g McShane et al.

1994). Recent archaeological and ecological research has highlighted that solely attributing

decreasing shell size to human foraging lacks consideration of the range of non-anthropogenic

phenomena that can alter intertidal community structure. Equifinality in intertidal ecosystems has

traditionally received little attention in Pacific Island archaeomalacological literature (Giovas et al.

2010:2788; Jones 2009).

Influenced by historical ecological concepts and acknowledging the myriad factors influencing shell

size, Pacific Islands archaeologists are increasingly considering non-human explanations for

mollusk size change. Giovas et al. (2010) examined a mollusk assemblage from Chelechol ra Orrak,

in Palau’s Rock Islands, documenting that the humpbacked conch, Gibberulus gibberulus (formerly

Strombus gibberulus) increased 1 – 1.5 mm from c. 3000 BP to the present. Giovas et al.

25

(2010:2793-2796) hypothesize eight interrelated phenomena that may have contributed to this size

increase at the site, including trophic alteration through foraging, changes in local and regional

climatic and environmental conditions, and alterations to foraging patterns. Giovas et al.

(2010:2796) conclude that “there is insufficient evidence to support any one of these eight

hypotheses over all others” and stress the need for additional paleoenvironment data, and the use of

high-resolution techniques for determining ontogenetic development and age of mollusk shells,

rather than using size alone. Studies that consider the influence of human foraging, environment and

climatic factors, and consider the ecology and biology of mollusks demonstrate that humans are

only one of the complex factors that influence mollusk size through time. While alterations to

physical size of mollusks can inform on human impacts, there are a range of wider impacts that can

result from human foraging, such as alterations to trophic networks in tropical intertidal ecosystems.

Trophic Alteration and Impacts to Species Richness, Abundance, and Diversity

Human foraging can enact a range of top-down direct and indirect alterations to intertidal trophic

networks that reduce species abundance, diversity, and biomass. Intensive mollusk collecting can

enact long-lasting changes to intertidal ecosystems (e.g., Hockey 1987) given the many critical roles

mollusks play in trophic networks (Glynn and Enochs 2011; Odum and Odum 1955). Invertebrates,

including mollusks, are ubiquitous at low trophic levels, and elevate nutrients to higher trophic

levels (Klumpp and Pulfrich 1989). Large filter feeding mollusks improve water quality, with

Tridacninae recorded in Tonga filtering 600 ml of water per minute (Klumpp and Lucas 1994).

Aggregations of mollusk shells can also increase substratum heterogeneity and increase

sedimentation rates on the reef (Gutiérrez et al. 2003). In the Fangatau Atoll lagoon, T. maxima is

so hyper-abundant that it is the primary builder of lagoonal reef structures, creating large ridges and

mounds of hard, topographically complex substratum (Andréfouët et al. 2005:1039). The addition

of mollusk shell to reef habitats can also modulate the amount of substrate available for

colonization by other organisms, or create structures which provide refuge from predation

(Gutiérrez et al. 2003:81). Bivalves that bore into the substrate create refuges for fauna that live

deeply embedded in these habitats (Hutchings et al. 2007; Stier and Leray 2014) and bioeroding

mollusks create coral rubble and other carbonate sediments (Glynn and Enochs 2011:297).

Herbivorous grazing mollusks are effective regulators of algal cover in the intertidal (Klumpp and

Pulfrich 1989; Moreno et al. 1984). The removal of highly effective grazing fauna, such as limpets

and herbivorous fishes, can induce a phase-shift in habitats dominated by coral or rock to algae,

impacting a range of ecosystem functions and altering species composition (e.g., Hughes et al.

2007; Sagarin et al. 2007:400).

26

Humans are also effective ecosystem engineers (organisms that modify, create or maintain habitats),

and often physically alter habitats in the intertidal by constructing architectural sites and walled

fishponds along the coast (Castilla 1999:280; Jones et al. 1996; Weisler and Kirch 1985:Figure 3).

Kataoka (1996) noted an increase in the bivalves Tellina palatum, Anadara antiquata, and

Gafrarium pectinatum from mangrove habitats created by the construction of the Nan Madol

architectural complex on Pohnpei. The basalt columns and rubble fill from artificial islet

construction also created new habitats for the polished nerite, Nerita polita, which increased in

abundance in archaeological assemblages around 950 -1050 BP. Although not in the Pacific, during

the 19th and 20th centuries, a decline in agricultural productivity and an increasing human

population on Fuerteventura Island, Canary Islands has been linked to the extinction of the Canary

Island oystercatcher, Haemotopus meadewaldoi. Increased competition for food, restricting nesting

sites, and a progressive reduction in invertebrate stocks (primarily the limpet Patella candei and the

mussel Perna picta) due to human harvesting contributed to the extinction of H. meadewaldoi

(Hockey 1987:61).

Examining the impact of human foraging on interactions between mollusks and other intertidal

fauna is rare in Pacific Island archaeology. Masse et al. (2006) presents quantified predatory crab

attack scars on Gibberulus gibberulus shells from archaeological assemblages to assess interspecific

competition. Crab predation on mollusks can strongly structure gastropod populations (Tyler et al.

2014 and references therein) and Masse et al. (2006:124) proposed that as human foraging

increased in intensity, the number of crab attack scars on the shell should decrease as both mollusks

and crabs are targeted by human foragers (Masse et al. 2006:124). Masse reported a significant

decline in the number of crab attack scars in assemblages from Uchularois Cave and Tmasch in

Palau’s Rock Islands from the 9th century AD. Combined with the results of the analyzed fish

remains (Fitzpatrick et al. 2011; Fitzpatrick and Kataoka 2005), and morphometric analysis of the

G. gibberulus assemblage, significant evidence was presented for human induced resource

depression in the Rock Islands (Clark and Reepmeyer 2012).

The removal of keystone predators from intertidal environments can increase subordinate taxa

abundances, and reduce species diversity (Beauchamp and Gowing 1982). From modern

observations, Castilla and Duran (1985) reported that human foraging of Conchohlepas

conchohlepas in central Chile led to declines in mollusk species richness and an increase in the

abundance of the subordinate mussel Perumytilus purpuratus. When human predation of C.

27

concholepas ceased, species richness increased as multiple taxa were able to utilize the space

previously dominated by P. purpuratus. Hockey and Alison (1986:11) also reported that low-level

human exploitation targeting high-trophic level predators at several sites on the south-east coast of

South Africa led to increased richness, and similar taxonomic abundances and community structure

at exploited sites. These studies clearly demonstrate the short-term effects of human intertidal

foraging, while the archaeological record offers a unique long term perspective on the role of

humans in modifying the abundance, richness and diversity of mollusk communities.

Across the Pacific Islands, archaeologists have reported declines in the relative abundance of

targeted prey with a concurrent increase in the abundance of smaller taxa, taxonomic richness, or

both. While alterations to relative abundance and richness are not always attributed to foraging

pressure (see Best 1985), researchers in the region have routinely interpreted these patterns as the

result of human exploitation. Nichol (1986) proposed that humans overexploited Cellana

denticulata limpets and Amphibola at early-phase Hahei, New Zealand, driving foragers further

from the site to collect Perna mussels and smaller-bodied limpets, such as Cellana radians. Walter

(1998:86) proposed a similar outcome of human foraging for Turbo setosus from the algal ridge

offshore from the archaic Anai‘o site, Cook Islands. Within 200 years of the occupation of

Hanamiai Valley, Marquesas Islands beginning around 850 BP, the gastropod Trapezium oblongum

and the chiton, Chiton marquesanus disappear from the sequence (Rolett 1992), co-occurring with

increases in pig bone and anthropophilic land snails associated with Polynesian gardening. Weisler

(1995) reported the rapid decline in relative abundance of Cerithium tuberculiferum at HEN-10 on

Henderson Island (Pitcairn Group) around 520-670 BP as the result of human predation. Weisler

(1999 2001) also noted a decline in Tridacna and concurrent increase in Cerithium in the main

village site on Ujae Atoll, and documented a preference for large tridacnid clams at short-term camp

sites away from the main villages on both Utrōk and Ujae Atolls. Nunn et al. (2007:119) reported a

decline in the density (g/m3) of mollusk remains during the later phases of Lapita occupation of

Naitabale, Moturiki Island, Fiji (c. 2950-2600 cal. BP) as indicative of early human colonizing

populations depleting nearshore resources.

Other researchers have explored alterations to relative abundance using faunal abundance indices

(AIs) (Broughton 1994, 1997). Studies employing abundance indices use body size as a proxy for

foraging returns, positing that a decline in “large-bodied” relative to “small-bodied” taxa represents

a decline in foraging efficiency (Allen 2012), or to track alterations to habitat representation in

archaeological assemblages (Morrison and Cochrane 2008). AIs have been used to track changes in

28

mollusk deposits in New Zealand (Allen 2012), Fiji (Morrison and Cochrane 2008) and Hawaii

(Morrison and Hunt 2007). Allen (2012) grouped mollusk taxa from the Haratonga beach site, New

Zealand, based on average shell size and body weight into four classes (A-D), examining the

decline in classes A (>105 g or >100 mm) and B (105-15 g or 100-60 mm) relative to classes C (15-

1.5 g or 60-25 mm) and D (1.5 to < 1 g or <25 mm). A second index examined the relative

abundance of the larger-bodied trochid Cookia sulcata to the smaller-bodied nerite, Nerita

atramentosa. Taxa from size classes A and B, and C. sulcata decline in abundance, while N.

atramentosa abundance increases, was inferred to be the result of continuous harvesting pressures

(Allen 2012:304-306). Similarly, a decline in the abundance of Turbo sandwicensis and an increase

in Canarium maculatum (formerly Strombus maculatus), and stable abundances of other near-shore

mollusks was reported as evidence for anthropogenic impacts to coral reef habitats at Nu‘alolo Kai,

Kaua‘i, Hawaiian Islands (Morrison and Hunt 2007).

At the Natia Beach Site, Fiji, Morrison and Cochrane (2008) tracked declining relative abundances

of the sand-dwelling bivalves Gafrarium tumidum and Atactodea striata from the initial occupation

of the site around 2170 cal. BP, coincident with a decrease in “large-bodied” Trochus niloticus,

Anadara antiquata and Turbo crassus relative to the “small-bodied” gastropods Turbo cinerus,

Nerita sp., and Planaxis sulcatus. Overharvesting, the progradation of the Natia Beach terrace,

increased terrigenous runoff associated with use of the uplands in Fiji around 500 BP, and increased

ENSO activity post 650 BP all may have contributed to changing abundances of mollusks yet,

ultimately, more analysis is needed to establish broader, regional patterns and to fully comprehend

the role of humans in these changes (Morrison and Cochrane 2008:2397)

Researchers have justified the use of body size as a predictor of foraging returns based on a range of

factors, including a lack of evidence to indicate that processing and handling costs differed between

taxa (Morrison and Hunt 2007:339), and data from terrestrial foraging studies that show a

correlation between hunting efficiency and large-bodied prey are often cited (e.g., Broughton 1994;

Byers and Broughton 2004; Codding et al. 2010). Using body size to measure foraging returns has

been challenged based on the predictable aggregations of some marine animals, requiring little

technological investment, search time or risk for collection of large numbers of small individuals

(Erlandson and Fitzpatrick 2006:11; Whitaker 2008). Tracking changes in mollusk assemblages

using abundance indices can facilitate assessment of alteration to mollusk foraging when

comparative analytical units are carefully considered, and have proven utility for tracking changes

in habitat selection or processes of environmental or climatic alteration (Allen 2003:320; Morrison

29

and Cochrane 2008). However, researchers must be aware of the implications of defining “large”

and “small” bodied taxa as a proxy measure of foraging returns. While all models rely on

simplification, (Boyd and Richerson 1987 Railsback and Grimm 2011) tracking body size as a

primary indicator of foraging declines risks reducing complex human foraging behaviors to

“simplistic truisms such as the notion that large animals are more productive than smaller animals”,

regardless of the prey type, environment (Erlandson and Fitzpatrick 2006:11), and methods of

capture. In the Pacific Islands, the use of body size as an indicator of foraging returns has also

received criticism for denying those aspects of marine foraging and fishing that are not fitness-

maximizing, but mediated by human agency and/or cultural factors (e.g., Jones and Albarella 2009).

One method to more comprehensively model mollusk foraging is to utilize generative methods for

hypothesis testing, such as agent-based modelling (ABM). ABM can be used to simulate complex

social and ecological phenomena, for modelling outputs that are compared with archaeological data

(Gilbert 2008). Morrison and Addison (2008) developed two simple models of the role of climate

change impacts in human foraging. One model simulated mollusk resources that were replenished

quickly in coral habitats unaffected by climate change, and the second modelled forager response to

declining mollusks from coral reef habitats affected by climate-induced coral bleaching. When

compared to the Fatu-ma-Futi site, American Samoa, the taxonomically rich and even mollusk

assemblage deposited over c.1500 years correlated well with the stability model, indicating that

human foraging and climatic fluctuations did not affect nearshore mollusk populations. Using more

complex models, Morrison and Allen (in press) examined the influence of age at maturity,

reproductive output and energetic return, and of prey aggregation on human overexploitation. The

age at maturity/energetic return model is compared to several Polynesian archaeological sites that

exhibit a decline in Tridacna, or other large bodied taxa over the course of occupation (Allen 1992,

2012; Kirch and Yen 1982; Morrison and Addison 2008; Morrison and Hunt 2007). Humans were

considered the primary driver for the declining abundance of large-bodied taxa, but “conclusive

demonstration that ancient foragers were responsible [for reported declines in mollusk taxa] will

ultimately require evaluation of the contemporaneous paleoclimate conditions, and local reef

histories” (Morrison and Allen in press:9). By incorporating mollusk ecology, human foraging data,

and local ecological and palaeoclimatological data, ABM has the potential to test hypotheses of

human impacts in a high-resolution, explicit manner across space and through time. These models

also have the potential to model the impacts of the wide range of non-anthropogenic processes that

can impact mollusk populations.

30

Non-Anthropogenic Alterations to Mollusk Assemblages

There are a range of non-anthropogenic phenomena that can lead to changes in molluskan body

size, extirpation, extinction, and alterations to trophic networks. Mollusks are especially vulnerable

to non-anthropogenic stressors as they are generally sedentary, and unable to flee or relocate from

danger. Mollusks are subject to potentially lethal desiccation and thermal stress during diurnal low

tides (Kohn 1987:139; Petes et al. 2007; Yamaguchi 1975) and alterations to salinity due to rainfall,

especially in the tropics (Hancock and Simpson 1962:44; Yamaguchi 1975:229). Seasonally large

waves generated by storms and typhoons can lead to mortality of mollusks (Blumenstock 1958;

Kohn 1980) reducing species richness, and increasing dominance of those taxa which inhabit

physical refuges on intertidal platforms, often predators such as cone shells (Conidae) or Muricidae,

potentially leading to changes in trophic networks (Kobluk and Lysenko 1993; Leviten and Kohn

1980).

Sea-level fluctuations can lead to mass mortality of reef organisms and wide-scale mollusk

extirpations as recorded in the central Pacific during the late Cenozoic (Paulay 1990), and over

short time scales including recent evidence for almost complete mortality of macroscopic organisms

on the reef flat in Pago Bay, Guam following rapid sea level fall in 1972 (Yamaguchi 1975).

Holocene records for the Pacific Islands show several periods of sea level regression and tectonic

uplift that have been correlated with alterations to mollusk assemblages (Clark and Reepmeyer

2012; Dickinson 2003; Nunn 1990; Webb and Kench 2010; Woodroffe 2008). Amesbury (1999,

2007) proposed that sea level decline during the last 3000 – 4000 years correlated with alterations to

archaeological mollusk assemblages on Guam. Pre-Latte phase middens show a decline in the

mangrove adapted Anadara antiquata (c. 3500 – 1600 BP) and an increase in sand-dwelling

Tellinidae in the transitional phase (c. 1600 – 1000 BP). Latte phase middens (c. 1000 BP onwards)

are dominated by Strombus, ubiquitous on intertidal sand flats. Without consideration of the effects

of sea level, these patterns “might have been interpreted as overharvesting by the earliest

inhabitants of the Marianas” (Amesbury 2007:955). Similarly, Spennemann (1987) noted a decrease

in the abundance of Anadara in middens on Tongatapu, Tonga associated with sea level fall, with a

concurrent increase in Gafrarium as the lagoon became increasingly brackish.

Discussion

The analysis of mollusk assemblages from Pacific Islands archaeological sites has documented that

human foraging potentially impacted shell size, altered species richness and abundance, changed

trophic networks and, in some cases, may have extirpated mollusk species adjacent to

31

archaeological sites, or from whole islands. However, Pacific Islands archaeologists have linked

changes in mollusk assemblages with human foraging, especially changes in shell size, without

detailed consideration of other explanations. Current archaeomalacological research is presenting

more balanced approaches to investigating human foraging, better integrating the ecology of the

intertidal zone (Giovas et al. 2010) and utilizing multi-proxy environmental data on sea level and

other geological and climatic changes, as well as comparative zooarchaeological data from other

faunal classes, especially finfish (Fitzpatrick and Kanai 2001). These studies draw upon the

tradition of multi-disciplinary research in the Pacific Islands for understanding long-term patterns of

human interaction with the oceans (Aswani and Allen 2009; Fitzpatrick and Donaldson 2007; Jones

2009; Jones and Albarella 2009; Jones and Quinn 2009; Kataoka 1996; Kittinger et al. 2011). The

methodological frameworks of historical ecology have influenced the discourse on human impacts

to mollusks, and allowed archaeologists to contribute to current debates on the historic role of

humans and global reductions of marine fauna (Carder and Crock 2012).

There has been a bias towards analyzing large-bodied mollusks in Pacific Islands archaeology, but

recent integration of 3.2 mm and finer mesh screening for recovery protocols has yielded significant

data on smaller taxa in archaeological assemblages as by-catch useful for environmental

reconstruction, or as evidence for fine-grained or non-selective foraging strategies (Szabó 2001,

2009). These results should encourage archaeologists to examine entire assemblages, rather than

only analyzing those large-bodied taxa with the highest relative abundance. Quantification protocols

are more routinely and transparently reported, and the integration of multiple measures of relative

abundance (most commonly NISP, MNI, and weight) facilitates regional comparisons. The

archaeological study of human impacts to mollusks in the Pacific Islands is patchy (Figure 1),

especially for low coral islands (Thomas 2009; Weisler 1999, 2001). When human impacts to

mollusks are identified, it is often represented by isolated sites lacking supportive data at the island

or archipelago scale which deters elucidation of greater impacts.

While Pacific archaeologists have often assessed changes in individual marine resources, or

assemblages of resources, there has been less attention paid to how these collective impacts might

have fundamentally altered marine ecosystems through time (Allen 2003; Lambrides and Weisler

2016). However, researchers have begun to consider the broader ecological implications of human

impacts in the region (Aswani and Allen 2009; Jones 2009; Morrison and Hunt 2007). Future

archaeomalacology should ideally include fine-mesh screening, considering all taxa for

identification, rather than a suite of large-bodied, economically important taxa. Szabó (2009:186)

32

discussed the utility of identifying taxa which may have been incidentally collected for

understanding how humans interacted with the marine environment and also the risks of biasing

archaeological inferences regarding gathering strategies when all taxa are not considered for

identification. Quantification should be by NISP, MNI, and weight, with quantification protocols

explicitly reported. Land snails still remain relatively neglected, 20 years on from Kirch and

Weisler’s (1994) assessment of the lack of studies dealing with these fauna (but see Christensen and

Weisler 2013).

Researchers should collaborate with natural scientists for integrating the collection of

environmental data into archaeological research programs in order to generate data of wide

applicability. In order to confidently identify negative impacts due to human foraging researchers

must be able to evaluate the influence of climatic or environmental factors (Thakar et al. in press).

The ecology and biology of taxa in the archaeological assemblage must be considered, and the

complexities of an organism’s life history and local ecology must be critically evaluated before

assigning human impact as the primary mechanism for change. Metric analysis should only be

conducted on specimens identified to species level due to significant interspecific variation in

morphology for some Indo-Pacific mollusks, for example, Cellana limpets in Hawai‘i (Bird 2011;

Rogers 2015; Vermeij 1993, 2002). Schwerdtner Máñez et al. (2014:1-2) identified several key

areas for a global marine historic agenda: establishing the state of the oceans before human

exploitation, determining the key drivers of environmental change, the significance of marine

resources for human societies over time, the circumstances that have encouraged societies to exploit

or cease exploitation of the ocean, and the role of historical data in ocean governance and

management (see also Lambrides and Weisler 2016 for relevance to archaeoicthyological studies).

Archaeomalacology in the Pacific Islands is uniquely placed to provide historic data to engage these

global research agendas in the future.

Conclusion

Archaeomalacology in the Pacific Islands has provided historical data contributing to our

understanding of environmental, economic, and cultural processes in prehistory. Past researchers

developed a broad foundation of analytical techniques, methodological approaches and analyzed

datasets, and current pursuits are expanding archaeological discourses in the region, especially those

relating to historical ecology. The increasingly consistent reporting of quantification protocols,

using NISP, weight, and MNI, and the incorporation of fine-mesh screening into recovery methods

is facilitating new, comparative approaches providing novel data pertaining to the processes and

33

timing of human impacts to coastal marine ecosystems of the Pacific Islands, and thus enhancing

our understanding of long-term trends in human interactions with the ocean.

Acknowledgements

We appreciate the thoughtful comments from the two anonymous reviewers. Harris’s university

studies are supported by an Australian Government Research Training Program Scholarship.

34

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Figures and tables

Figure 1 Map of the Pacific Islands with sites mentioned in text

49

Chapter 3: A refined protocol for calculating MNI in archaeological molluscan shell

assemblages: a Marshall Islands case study

Note: This is the final version of a peer-reviewed article published in the Journal of Archaeological

Science

Matthew Harris1, Marshall I. Weisler1 and Patrick Faulkner2

1. School of Social Science, The University of Queensland, St Lucia, Queensland, 4072, Australia

2. School of Philosophical and Historical Inquiry, Faculty of Arts and Social Sciences, Department

of Archaeology, University of Sydney, Sydney, New South Wales, 2006, Australia




50

Abstract

Comprehensive and transparent protocols for calculating Minimum Number of Individuals (MNI)

for archaeological faunal assemblages are critical to data quality, comparability, and replicability.

MNI values for archaeological molluscan assemblages are routinely calculated by counting a select

range of Non-Repetitive Elements (NREs). Most commonly, only the frequency of the spire of

gastropods and the umbo or hinge of bivalves are recorded. Calculating MNI based only on the

frequency of these NREs can underestimate the relative abundance of particular molluscan shell

forms. Using archaeological mollusc assemblages from two sites in the Marshall Islands as a case

study, we outline a new protocol (tMNI) that incorporates a wider range of NRE and calculates

MNI based on the most frequently occurring NRE for each taxon. The principles that underlie the

tMNI method can be modified to be regionally or assemblage specific, rather than being a

universally applicable range of NRE for the calculation of MNI. For the Marshall Islands

assemblages, the inclusion of additional NRE in quantification measures led to (1) a 167% increase

in relative abundance of gastropods and 3% increase in bivalves (2) changes to rank order

abundance, and (3) alterations to measures of taxonomic richness and evenness. Given these results

for the Marshall Islands assemblages, tMNI provides more accurate taxonomic abundance measures

for these and other archaeological molluscan assemblages with similar taxa. These results have

implications for the quality of zooarchaeological data increasingly utilised by conservation

biologists, historical ecologists and policy makers.

Keywords: Mollusc quantification; Minimum Numbers of Individuals (MNI); Shell

middens; Marshall Islands; Analytical transparency

51

Introduction

Quantification is fundamental to zooarchaeological analyses, and comprehensive analytical

protocols are critical to ensure data quality, comparability, and replicability. As Wolverton

(2013:381) noted, it is essential that archaeologists undertake high-quality faunal analyses as

zooarchaeological data is increasingly utilised by conservation biologists, historical ecologists, and

policy makers (e.g. Augustine and Dearden 2014; Gobalet 2011; Carder and Crock 2012; Erlandson

and Fitzpatrick 2006; Groesbeck et al. 2014; Wake et al. 2013).

The relative merits of various faunal quantification methods and the analytical and interpretive

implications for using Minimum Numbers of Individuals (MNI), Number of Identifiable Specimens

(NISP) and/or weight have been widely discussed in the zooarchaeological literature, (Claassen

1998:106, 2000, Giovas 2009; Glassow 2000; Grayson 1979; Gutiérrez-Zugasti 2011; Lyman

2008:21–140, Mason et al. 1998; Reitz and Wing 2008:202–213). Post-depositional leaching of

calcium carbonate from molluscan shell and differential rates of fragmentation within and between

taxa can bias NISP values and weight measures of mollusc shell from archaeological deposits. As

such, many analysts working on assemblages of invertebrate taxa use MNI to potentially provide a

more accurate measure of taxonomic abundance (Ballbè 2005; Mannino and Thomas 2001; Nunn

et al. 2007; Poteate and Fitzpatrick 2013; Robb and Nunn 2013; Seeto et al. 2012).

MNI values for molluscan remains are most commonly calculated by counting the frequency of a

restricted number of Non-Repetitive Elements (NREs), such as the spire of gastropods or the umbo

and hinge of bivalves (Allen 2012; Ballbè 2005; Claassen 1998:106, Chicoine and Rojas 2013;

Mannino and Thomas 2001; Mason et al. 1998; Ono and Clark 2012; Poteate and Fitzpatrick 2013;

Seeto et al. 2012). This method, however, has the potential to consistently underrepresent some taxa

(Giovas 2009). Differential fragmentation resulting from inter-taxonomic variability in shell

architecture, morphology, and human processing of mollusc shell can lead to the under-

representation of particular shell forms; especially gastropods that lack robust, readily identifiable

spires.

We propose that current MNI calculation protocols utilising only a restricted range of NRE can

influence measures of taxonomic abundance, richness, evenness, and dominance, potentially

affecting reconstructions of human behaviour derived from archaeological material. This hypothesis

is tested using two assemblages of tropical Indo-Pacific mollusc shells from two prehistoric

habitation sites on Ebon Atoll, Marshall Islands. The assemblage was quantified using current MNI

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calculation protocols and a new, more comprehensive method for calculating molluscan MNI that

utilises a wider range of molluscan NREs and calculates MNI based on the most frequently

occurring NRE per taxon. Each quantification protocol is tested by comparing relative abundance

and rank order abundance. Alterations to taxonomic richness, evenness, and diversity are measured

using the number of taxa (NTAXA) Simpson's index of Diversity (1-D), Shannon's Evenness (E),

and The Shannon–Weiner index of Diversity (H′).

Results for the Marshall Islands assemblages analysed indicate that current methods for calculating

MNI routinely underrepresent gastropod abundance. Furthermore, the application of the new MNI

protocol resulted in increased richness and evenness values for all taxa. Given the importance of

molluscs for human subsistence and ecosystem maintenance, it is critical to consider the influence

of quantification measures on inferences of human behaviour and long-term impacts to the

environment. Analysts should employ quantification methods that result in the most precise and

accurate measures of relative abundance. Diversity indices, biomass estimates, and mean trophic

level are common measures used by zooarchaeologists and fisheries scientists for examining human

impacts to marine environments (Carder and Crock 2012; Cinner 2014; Morrison and Hunt 2007;

Perry et al. 2011; Wake et al. 2013), and the calculation of these indices using abundance data

derived from MNI protocols which utilise only a restricted number of NREs could be misleading or

erroneous. The compounding error introduced by such protocols could further bias interpretations

and reconstructions of changes in prehistoric subsistence practices and impact modern management

of marine resources.

Current methods of MNI calculation in mollusc shell assemblages

Common protocols for calculating MNI in molluscan assemblages are described in Mason et al.

(1998:308–309) and Claassen (1998:106). These protocols lack the sufficient descriptive detail

required (e.g., minimum criteria for determining NRE completeness) to ensure accuracy, precision,

and replicability of MNI calculations that would allow analysts to reliably compare datasets. The

quantification protocol outlined by Mason et al. (1998:309–309), calculates MNI by counting only a

limited range of predetermined shell features, emphasising the frequency of gastropod spires and

bivalve hinge and umbones. Moreover, Mason et al. (1998:308) assert that analysts should only

identify those fragments that contribute toward MNI. Claassen (1998:106) proposes similar

methods for MNI calculation including the quantification of gastropod umbilici. Only the pre-

selected NREs are identified and quantified for both methods, regardless of the presence of other

molluscan NREs that could increase MNI and influence diversity and richness measures. While

53

mollusc shell fractures in ways that are somewhat predictable (Harris 2011; Koppell 2010; Vermeij

1979; Zuschin et al. 2003), to determine the element or feature to be counted prior to analysis of the

archaeological material assumes that there is no variation in fragmentation or preservation at either

the assemblage or taxon level. Differential fragmentation or variation in processing techniques

could influence preservation of the pre-selected NRE across taxa, potentially under-representing

gastropod taxa that lack thick shells and durable spires, and bivalve shells lacking easily

identifiable, robust umbones and hinges (see also Giovas 2009; Glassow 2000).

An alternative method proposed by Giovas (2009: Fig. 3) calculates MNI using a part-scoring

system based on the presence or absence of portions of mollusc shell (see also Gutiérrez-Zugasti

2011). This method produced ‘no uniform pattern that holds across all taxa and samples’ (Giovas

2009:1560) and remains a valid alternative to NRE MNI. However, NRE based MNI may be less

subjective, as NRE are discrete, easily identified features compared to large zones of mollusc shell

(Lyman 2008:277). Furthermore, the identification of mollusc shell is often based on diagnostic

NRE, and the quantification method proposed here may expedite the quantification process

compared to part-scoring methods.

The method outlined below, referred to herein as tMNI, refines and extends upon the NRE MNI

method by: (1) including a wider range of NREs for counting, (2) recording element frequency by

taxon, and (3) calculating MNI after the highest frequency NRE is identified for each taxon. Ideally,

analysts should calculate MNI by stratigraphic layers, rather than arbitrary aggregates which inflate

MNI (Grayson 1984). This method is derived from “Traditional MNI” (Giovas 2009:1558),

described originally by White (1953) and elaborated by Grayson (1979, 1984), using a range of

well-defined molluscan NREs that often preserve in archaeological deposits rather than only hinges,

umbones, and spires. The utilisation of an expanded range of NREs reduces the inherent bias

towards particular forms (i.e. overall shape) of mollusc shell that occurs when the NRE for the

calculation of MNI is selected prior to analysis. While some researchers have implemented this

method, or similar methods, (e.g. Allen 2012; Kataoka 1996; Szabó 2009; Rosendahl 2012), no

formal protocol has been outlined in detail for the determination of MNI using a wide range of

NREs.

Site Description

The southernmost atoll in the Marshall Islands, Ebon Atoll (4°38′N, 168°42′E) consists of 22 islets

encircling a 104 km2 lagoon. Typical of Marshall Islands atolls, prehistoric villages are marked by

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concentrations of large marine molluscs (Tridacna spp., Conus spp., Spondylus spp.), shell

artefacts, and coral gravel spread to form pavements. Villages are situated parallel to and just inland

from the lagoon shore and often run most of the length of the larger islets. TP 18 and 19 (Fig. 1: a),

forming a 1 × 2 m unit, were excavated ∼25 m from the lagoon beach and ∼30 m west of the

council house on a small hill at site MLEb-1 (Rosendahl 1987:83; Weisler 1999: Fig. 4, 2002:20).

Continuous cultural deposits were encountered to a depth of 1.10 m. At the northeast portion of

Ebon Atoll, Enekoion islet (1 km long and 300 m wide) has one major village site (MLEb-33)

where TP7 (Fig. 1: b) (1 m2) was excavated 100 m from the lagoon shore just inland of a large

swampy gardening area. A cultural layer, ∼35 cm thick, was encountered.

Site deposits consist of coralline sands with a neutral pH; consequently, shell is well preserved and

minimal evidence of shell degradation via dissolution was noted during routine taxonomic

identification. Furthermore, in contrast to many mollusc shell assemblages from middens and

mounds (Perry and Hoppa 2011 cf. Weisler 2001:Table 7.7), the assemblages analysed here are

both taxonomically rich (many species present) and diverse (many taxa represented by many

individuals, rather than the assemblage dominated by a single taxon [e.g.Faulkner 2009]). The

richness and diversity of the samples will be discussed further in Section 5.2.

Methods

A refined protocol for calculating MNI

tMNI is calculated by the methods outlined below. All shell should be identified to the lowest

taxonomic level and quantified by NISP and/or weight to be broadly comparable with other studies

where MNI was not calculated (e.g.Amesbury 1999; Weisler 2001). Here, all specimens were

quantified by NISP and weight in grams to two decimal places. The use of a range of quantification

measures in concert can highlight the strengths and weaknesses of each method and are useful for

addressing additional questions, such as issues relating to taphonomy (see Faulkner 2013; Lyman

2008; Grayson 1984).

To ensure accurate identification, specimens that could not be confidently assigned to species were

only identified to genus or family, despite having similar morphology to dominant taxa (Szabó

2009:186). All identifications were completed to the lowest possible taxonomic level using modern

Indo-Pacific focussed comparative collections held at the University of Queensland archaeology

laboratory. Various reference manuals were also consulted, including: Abbott and Dance

(1990), Lamprell and Healy (2006), Poppe (2008), and Röckel et al. (1995). For consistency, all

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taxonomic names follow the World Register of Marine Species (http://www.marinespecies.org). A

review of gastropod and bivalve shell features is presented in the following section, followed by a

description of the NREs used to quantify archaeological mollusc remains from two prehistoric

habitation sites on Ebon Atoll, Marshall Islands.

Gastropod and bivalve shell features

There are five major classes of the Mollusca: the Gastropoda (e.g., whelks and winkles), Bivalvia

(e.g., clams and mussels), Cephalopoda (e.g., squid, cuttlefish, Nautilidae and octopuses),

Polyplacophora (chitons), and Scaphopoda (tusk shells). Only the Gastropoda and Bivalvia are

discussed in detail here, as along with the Polyplacophora, they are often the main classes of

molluscs recovered from archaeological sites.

Gastropod shells (Fig. 2) most commonly consist of a hollow cone coiled around a central axis,

known as the columella (Stachowitsch 2002, Vermeij 1993; Pechenik 2010). Each full revolution of

the shell around the columella is larger than the last as additional shell is secreted along the growth

margin (Ruppert et al. 2004). This combination of shell coiling and enlargement produces the

typical gastropod morphology of a coiled cone with a pointed top (posterior end) and a large

opening at the anterior end. Shell architecture (e.g. micro and macrostructure, teeth, nodes, spines,

and ribs) and morphology varies depending on shell growth rate, the overlap of whorls, tightness of

coiling, and angle of the aperture in relation to the horizontal plane (Vermeij 1993) (Fig. 3).

Additionally, environmental and ontogenetic factors can also influence shell architecture and form

(Rhoads and Lutz 1980).

Bivalve shells (Fig. 4) consist of two dorsally hinged, articulating valves that enclose the animal

(Gosling 2003:1). Shell shape can be classified broadly depending on the symmetry of valve pairs

and individual valve symmetry. The terms equivalve and inequivalve describe the symmetry of one

valve in relation to the other (Pechenik 2010). Lateral symmetry (equilateral or inequilateral)

describes the symmetry of the anterior and posterior portion of individual valves (Stachowitsch and

Proidl 1992). Bivalve form and architecture are determined by the way that the animal lays down

shell along the ventral margin and mantle surface, influenced during the life of the animal by a

range of ecological and ontogenetic factors (Gosling 2003:7, Rhoads and Lutz 1980) (Fig. 5).

A range of morphological elements are defined as NRE. The location of each NRE on the shell and

qualitative minimum criteria for counting fragmented NREs are described in the following sections.

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If multiple fragments can be refitted to form a complete NRE they should be counted as one NRE.

The location and descriptions of NREs are drawn from Stachowitsch and Proidl (1992)

Additional NRE

The NREs described below are useful for calculating MNI in archaeological assemblages of tropical

marine molluscs from the Marshall Islands. A wider range of NREs may be useful for quantifying

other Indo-Pacific molluscan shell assemblages. We recommend that all additional NREs be

reported in publication including a clear definition that includes minimum identification and

quantification criteria.

Calculating gastropod MNI

Gastropod NREs that were used in the quantification of Marshall Islands molluscan remains are the

(1) spire (2) anterior notch or canal (3) posterior notch or canal (4) outer lip (5) aperture (6)

operculum, and (7) umbilicus (Fig. 6). A quantification key is provided that illustrates examples of

our tMNI method for the quantification of gastropod fragments of different shell forms (Fig. 7).

The spire The spire consists of the protoconch and all shell whorls except the body whorl. The

protoconch is the shell laid down at the larval stage and can usually be differentiated from all other

whorls by a difference in sculpture and smaller size. In molluscan shell from archaeological

deposits—if present—the protoconch is generally eroded so that the suture lines at the intersection

of whorls are muted or diminished. For this NRE to be counted, greater than 50% of the apex—

consisting of the smallest whorls of the spire, and if preserved or present, the protoconch—must be

present.

The anterior notch or canal The anterior notch is located on the anterior side of the aperture, at the

base of the columella. Many taxa feature extended cylindrical forms of this NRE, known as canals

(e.g., the Muricidae subfamily, Muricinae). Anterior canals often fragment in archaeological

deposits. To account for post-depositional alteration, the minimum criterion for counting the

anterior canal or notch NRE is that the base of the columella is present. Additionally, some taxa

(such as the Neritidae) lack anterior notches, and additional NRE should be described and included

to account for this variability between taxa.

The posterior notch or canal In taxa where posterior notches occur, the NRE is morphologically

similar to the anterior notch, but occurs on the posterior margin of the aperture, rather than the

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anterior margin. Like anterior notches, these NRE can occur as extended cylindrical protrusions,

such as the posterior canals of the tropical frog shell, Bursa bufonia. More than 50% of the posterior

notch or canal must be present for this NRE to be counted.

The outer lip The outside edge of the aperture is known as the outer lip. The outer lip can be

ornamented with tooth-like protrusions known as denticles (e.g. some Neritidae) or thickened (e.g.,

Strombidae, Cassidae). The outer lip NRE can be counted if more than 50% is present. The location

and morphology of denticles that ornament the outer lip is useful for this determination.

The aperture The opening of the shell at the terminal margin (anterior end) of the coiled cone is the

aperture. Apertural morphology is variable, with some taxa (e.g., Trochidae, Turbinidae,

Architectonidae) lacking anterior notches or canals. An aperture is counted as whole when the

following elements are present: the outer lip, the inner lip (the edge of the aperture that is attached

to the columella, often ornamented with folds or plaits), and depending on the specific taxon

morphology, the anterior and posterior canals or notches. While this NRE duplicates counts of other

NRE noted above, recording aperture frequency contributes to studies of taphonomy (e.g. Szabó

2012) and meat extraction (e.g.Sommerville-Ryan 1998).

The operculum The aperture of most marine gastropods is capped by a flexible proteinaceous or

rigid calcified disk known as the operculum. In most cases proteinaceous opercula (e.g. the opercula

of Terebralia spp. and Strombus spp.) will not be preserved in archaeological deposits; however,

calcified opercula regularly preserve. The opercula of turban shells (Turbo spp.) are ubiquitous in

Pacific island archaeological sites (e.g. Allen 1992; Morrison and Hunt 2007; Walter 1998; Szabó

2009). An operculum may be counted if the nucleus can be confidently identified.

The umbilicus If the shell is loosely coiled around the columella an umbilicus (if open, rather than

closed) may be present as a small depression or cavity on the base of the columella side of the body

whorl. The umbilicus may contribute to MNI only if more than 50% of the element remains. The

umbilicus NRE limits the underrepresentation of taxa that lack anterior canals or notches, but may

be influenced by intraspecific variation in umbilicus form. For example, some members of the

genus Turbo exhibit individual variation in umbilicus form (Carpenter and Niem 1998:412–416),

which may influence MNI values based on this NRE.

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Gastropod NRE that are excluded from MNI There are several NRE that are excluded from

contributing to MNI calculations as they are highly variable across or within taxa, are strongly

influenced by shell age, or are too difficult to confidently identify in fragmented archaeological

remains. These NRE are the parietal lip and wall, the columella, and exterior shell sculpture. The

columella is excluded as a distinct NRE as this element is incorporated with the spire, anterior

canal, and inner lip NREs. Any exterior shell sculpture such as ribs, threads, nodules, and spines are

also not considered to be a robust and discrete NRE here. It is important to note that the

range of NREs outlined here are provided to demonstrate a range of NRE that were useful for the

Marshall Islands assemblage, and should be modified to suit the diverse assemblages, taxa, and

taphonomic processes which are encountered in the analysis of molluscan remains globally.

Calculating bivalve MNI

Bivalve NREs are the: (1) umbo and beak (2) anterior portion of the hinge (3) posterior portion of

the hinge (4) anterior adductor muscle scar, and (5) posterior adductor muscle scar (Fig. 8). A

quantification key is provided for the Bivalvia (Fig. 9).

All bivalve NREs must be sided in order to be quantified. There are several simple means of siding

valves. When teeth are present, they interdigitate on each opposing valve so that where there is a

projection on one valve, there will be a socket on the other. The valve side that contains the teeth or

sockets is regular and can be used to side valves for quantification. In addition, valve hinges of

inequilateral valves are often morphologically distinct on the anterior and posterior sides.

Adductor muscle scars (See Section 4.5.3) can also be used to side valves. These scars are either

equal (isomyarian) or of different sizes (anisomyarian). In some taxa, such as Spondylus spp., only

one muscle scar is present (monomyarian). For monomyarian taxa valves are sided according to the

presence or absence of a muscle scar. In isomyarian taxa, scar morphology can indicate valve side.

Anisomyarian taxa can be sided by comparing the relative size (accounting for shell growth) of

muscle scars. Additionally, valves can generally be sided by the prominent direction of the umbo.

For prosogyrate taxa where the umbo leans to the anterior, when the shell is placed with the dorsal

(exterior) surface facing upward, if the umbo points to the right the valve is from the right side of

the shell. A left-pointing umbo indicates a left valve. For opisthogyrate taxa where the umbo leans

toward the posterior, the siding procedure is reversed.

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The umbo and beak Like the spire of gastropods, the umbo and beak are formed during the earliest

growth stages of the animal. The beak is present as a small, outwardly protruding feature just above

the hinge. The strongly curved portion of the shell that is laid down after the beak is known as the

umbo. The umbo can be distinguished by tightly spaced concentric growth bands that can be muted

due to pre and post-depositional erosion. The distinctive morphology of the concavity inside the

umbo and beak, however, can be used to confidently identify this NRE which can be counted if

more than 50% of the beak is present.

The hinge The articulating surfaces which are ventral to the umbo on the interior of the shell valve

are known as the valve hinges or hinge. Along with the umbo, the hinge is most commonly

preserved in archaeological deposits. The hinge is divided into anterior and posterior NRE at the

ventral projection of the beak. By treating the hinge as two NRE in this way, the chances of

distinguishing a single individual from fragmented remains are increased and the bias towards taxa

with durable umbones is reduced.

The dentition generally present on the hinge of heterodont (complex hinges with a small number of

distinct teeth varying in size and shape) bivalves are classified as either cardinal or lateral teeth.

Cardinal teeth are found on the centre of the hinge, ventral to the umbo. Lateral teeth are generally

present in the form of ridges that lie anteriorly and posteriorly of the cardinal teeth. Cardinal and

lateral teeth can be used to determine if more than 50% of the NRE is present. A hinge NRE

(anterior or posterior portion) that is determined to be 50% complete can be counted. Inter-

taxonomic variation in the arrangement and number of teeth present on the hinge does occur (such

as the taxodont Arcidae, with many alternating teeth and sockets present on the hinge), and

quantification methods must be evaluated and refined based on the morphology of taxa using

similar methods to those described above.

The adductor muscle scars The parts of the live animal responsible for the opening and closing of

the shell valves are known as adductor muscles and hinge ligaments. Hinge ligaments rarely

preserve archaeologically, but the adductor muscles leave negative impressions or scars on the

interior of the shell valve that can be identified in archaeological remains and are considered NREs.

Each muscle scar (anterior and posterior) is counted as a single NRE. The minimum criteria for

identifying and counting the adductor muscle scar NRE is the presence of more than 50% of the

ventral margin of the scar.

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NRE excluded Cardinal teeth, lateral teeth, and marginal teeth are excluded as NRE due to their

inclusion in the hinge NREs. Marginal teeth are also excluded as it is problematic to determine

when more than 50% of these features are present in fragmented remains. The pallial line and sinus

are excluded as these features are often removed by post-depositional alteration of bivalve shell and

are difficult to confidently identify.

MNI Calculation

The frequency of each NRE is recorded as an integer for each taxon in the assemblage. The most

frequently occurring NRE for each gastropod taxon is the MNI. For bivalves, only NREs that can be

sided are used for quantification. The most frequently occurring NRE for the valve side (left or

right) with the highest count is used. Only bivalve NREs that can be confidently assigned a valve

side are counted toward MNI.

The quantification protocol outlined above highlights the range of distinct NRE that appear on

mollusc shells. Importantly for this study, a range of NRE other than the commonly used spire are

equally suitable for quantification, but not currently widely utilised in gastropod MNI calculation

protocols (e.g.Claassen 1998; Mason et al. 1998). For bivalves, the adductor muscle scars of

molluscs can be useful NREs, but are also not routinely used. The following case study highlights

the benefits of using these methods for the quantification of molluscan shell.

To compare quantification methods MNI was calculated based on the most frequently occurring

NRE for each taxon at each assemblage using the quantification method outlined above (tMNI) and

routine quantification protocols using the spire of gastropods and the umbo and hinge of bivalves

(NRE MNI), with the anterior and posterior portion counting as distinct NRE. All mollusc NRE

counts were aggregated at the test pit level prior to the calculation of MNI. All NRE described

above are used for tMNI calculations. Additionally, for the Cypraeidae, the base and labum adjacent

to the aperture were treated as separate NRE (Fig. 10: a) Similarly, for the nerites (Nerita spp.), an

additional NRE was utilised that counted the frequency of the distinctive whorls on the interior of

the shell where the columellar deck joins the outer lip, essentially replacing the posterior and

anterior canal NRE for these taxa (Fig. 10: b: I, I). While MNI is influenced by aggregation effects

(Grayson 1984, 1979), site level totals for all taxa highlight the influence of each calculation

method on overall abundance, richness, and diversity. In addition, by examining the values for

bivalves and gastropods separately, the influence of shell morphology on MNI value can be clearly

established.

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Testing the influence of quantification protocol

To assess the influence of MNI calculation protocols on relative abundance, MNI values derived

using NRE MNI was compared with MNI values calculated using tMNI. The resulting rank order

abundance of taxa for each quantification protocol is compared, and alterations to the top ten ranked

taxa are presented. Any observed differences in relative abundance and rank order depending on

quantification method highlight the potential influence of quantification measures on a range of

archaeological interpretations. Rank order abundance has important implications for examining

foraging practices (e.g.Szabó 2009), tracking and reconstructing environmental change (Amesbury

1999) and applying models of optimal foraging theory (Allen 2012; Bird and Bliege Bird 1997

2000; Stephens and Krebs 1986:17–24, Thomas 1999, 2002, 2007a, 2007b). To test the effect of

differential fragmentation, the fragmentation ratio for each taxon (NISP:MNI) was compared for

each method. This index allows the approximate calculation of the number of fragments per

individual (see Faulkner 2010:1946).

Species richness is the number of species present in the analytical unit of study and evenness is the

relative abundance of species (Magurran 2004:9). Species richness was calculated and compared for

each quantification protocol using NTAXA. NTAXA is a count of the number of distinct taxa in

each analytical unit calculated by collapsing taxa at the highest common taxonomic level. NTAXA

ensures that species richness is not artificially inflated by taxa which are more easily identified to

lower taxonomic levels. For example, if an analytical unit consisted of individuals from the

Cypraeidae family identified to Cypraea tigris, Lycina lynx and Cypraeidae spp., then the NTAXA

value would be one (1) rather than three (3), as fragments identified as Cypraeidae spp. might

possibly be unidentifiable fragments of C. tigris, L. lynx, or other cypraeids.

Assemblage diversity was calculated using multiple indices, the Simpson's index of Diversity (1-D)

and the Shannon–Weiner index of Diversity (H′) and Evenness (E), all common to

zooarchaeological analyses. 1-D values range from 0 to 1, with higher values indicating even

assemblages of many taxa with many individuals from each taxon (Magurran 2004:116). For the

Shannon–Weiner index of diversity (H′), theoretical values range between 0 and 5, however, values

between 1.5 and 3.5 are most common. Higher H′ values indicate greater diversity and richness.

Shannon's Evenness (E) values fall between 0 and 1, with values closer to 0 reflecting assemblages

dominated by a single taxon, and higher values reflecting assemblages with many taxa represented

by similar numbers of individuals (Lyman 2008:195, Reitz and Wing 2008:111). Random

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permutation tests of relative abundance data were carried out using the PAST Paleontological

Statistics Package, Version 3.04 (Hammer 2001), to test for significant difference between

Simpson's Index of Diversity (1-D), Shannon–Weiner Diversity (H′), and Evenness (E) values

reported for both quantification methods. As no alterations to taxonomic measures of dominance

and evenness were reported for bivalves, significant difference was tested for in gastropod samples

only.

Results

Total MNI

Site level totals demonstrate a marked difference in MNI for each quantification method (Table 1).

MNI calculated using tMNI for gastropods was three times larger (∼108%–207% increase in MNI)

than NRE MNI calculations. However, the tMNI for bivalves was at most 6% higher than NRE

MNI. The most notable distinction in MNI between quantification protocols was reported for

gastropods from TP18 and 19 (Table 1).

Differences in MNI depending on quantification method were also reported for the top ten

gastropod and bivalve taxa ranked by abundance (Table 2). MNI for gastropods calculated using the

tMNI method doubled (∼78%–115% increase) compared to NRE MNI. Bivalve MNI was similar

for both quantification protocols.

At the site level and for the top ten ranked taxa from each test pit, tMNI resulted in a marked

increase in the relative proportion of gastropods to bivalves compared with NRE MNI. Using NRE

MNI for TP18 and 19, bivalves accounted for 31% of total MNI, whereas using tMNI, bivalves

accounted for 13%. For TP 7, NRE MNI resulted in bivalves accounting for 38% of total MNI, but

tMNI reported 23% bivalves and 77% gastropods.

Rank order abundance

Each quantification method resulted in different rank order abundance for the top ten gastropod taxa

at both sites (Tables 3 and 4). Rank order was distinct for all gastropod taxa for both quantification

methods for TP18 and 19. In samples from TP18 and 19 (Table 3), Nerita plicata and Gutturnium

muricinum are not reported in the top ten ranked taxa for NRE MNI, but are rank one and two

respectively for tMNI. For bivalves, minor alterations to MNI were noted in both contexts and rank

order abundance was unaltered by quantification method (Tables 5 and 6).

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Species richness and evenness

For gastropods, richness at the site level was higher (∼17%–90% increase) in all cases at the family,

genus, and species level. NTAXA was slightly lower for TP18 and 19 using the tMNI method as a

result of the inclusion of NRE that could not be identified beyond the family level, such as the

distinctive siphonal notch of the Muricidae (Table 7). Species richness by NTAXA increased for

TP7. For the top ten ranked taxa tMNI calculations decreased richness (∼8%–54%) measured by

count of family, genus, and species, and also by NTAXA (Table 7).

Increased evenness and dominance measures for all gastropod taxa are also reported at both sites

(Table 8). A significant difference was also reported between Simpson's Evenness and Shannon's

Evenness values for the top ten ranked all gastropod taxa at TP18 and 19 (p = <0.001). For the top

ten ranked taxa only, evenness was increased for tMNI assemblages at TP18 and 19, but decreased

at TP7. A significant difference was also reported between Simpson's Evenness and Shannon's

Evenness values for the top ten ranked gastropod taxa at TP18 and 19 (p = <0.001). The majority

of MNI values for the top ten ranked taxa were derived from the apex, leading to similar or lower

values when additional elements are included using tMNI. No changes to species richness or

evenness due to quantification method were reported for bivalves.

Element survivorship

Bivalve MNI was not substantially altered by the application of the new protocol at either of the

tested sites. In only two cases were the adductor muscle scars the most frequent NRE. However

adductor muscles scars were the most frequent NRE only for those taxa with the highest NISP,

indicating increased fragmentation relative to other taxa. Furthermore, as many taxa were

represented by one or two whole individuals, often umbo, hinge and adductor muscle scar counts

were equal. This trend requires further investigation with a larger assemblage of bivalves, assessing

the influence of sample size and taphonomic alteration on MNI.

The contribution of the spire to the total MNI for gastropods was low compared to other elements

(Tables 9 and 10). These results reflect the differential survivorship and ease of identification of

elements across taxa. The taxa where the spire was the most frequently occurring element were

those with easily identifiable, high, (Cerithium nodulosum) or low dense spires (Conus spp.). Taxa

with low, fragile spires, but identifiable apertures and outer lips (such as the Neritidae) are

consistently underrepresented by the NRE MNI method utilising only spires. The MNI for these

taxa increased as a direct result of the inclusion of a wider range of NRE, reflected in decreased

64

mean fragmentation ratio values for all gastropod taxa (TP18 & 19: NRE MNI: 10.6/tMNI: 3.4,

TP7 NRE MNI: 4.2/tMNI: 2.5) and the top ten ranked gastropod taxa (TP18 & 19: NRE MNI:

9.7/tMNI: 2.3, TP7 NRE MNI: 4.2/tMNI: 2.9) when tMNI was implemented. The inclusion of taxa

specific NRE, such as the base and labum of the Cypraeidae, and the additional NRE for the

Neritidae increased MNI markedly, highlighting the utility of including additional NRE based on

the judgment of the analyst.

Discussion

The inclusion of a wider range of molluscan NRE has resulted in notable changes in abundance,

diversity and evenness. Studies of the quantification of fish bone from Pacific Island archaeological

sites have produced similar alterations to relative abundance and rank order when the range of

elements is increased (Lambrides and Weisler 2013). These results highlight the need for analysts to

carefully consider the potential loss of information which results from counting a restricted range of

NREs. The application of tMNI to an assemblage of mollusc shells from the Marshall Islands has

demonstrated that the morphological and architectural complexity of molluscan shell must be

considered in MNI quantification protocols. The tMNI and NRE MNI methods are both reliable; if

each method was tested multiple times for the same assemblage, results will be consistent (Nance

1987; Giovas 2009:1653). However, tMNI increases measurement validity and provides abundance

estimates that more closely estimate actual abundance of taxa within an assemblage (Carr 1987;

Mason et al. 1998:308).

Total MNI for the NRE MNI method and the tMNI method are markedly different and the relative

abundance of gastropods was increased substantially. Individuals were more likely to be quantified

when a wider range of NRE were utilised, indicated by decreased values for fragmentation ratio for

all gastropods and the top ten ranked taxa. The rank order abundance and element survivorship for

NRE MNI at MLEb-1 demonstrate a dominance of taxa with high, dense spires relative to overall

size, including Cerithium columna, C. nodulosum, and Planaxis sulcatus, and gastropods with

dense, low spires, such as Conus spp. and Vasum turbinellus. A more balanced range of shell forms

are represented when MNI is calculated using a wider range of NRE. The MNI and rank-order

abundance of globoid, weak spired taxa such as Nerita spp., and small taxa with apertural

thickening, such as Monoplex nicobaricus and Monetaria moneta, were increased. Overall, the spire

was rarely the most frequently occurring element when a range of NREs were quantified. Giovas

(2009:1563) stated that the NRE method can produce coarse grained estimates of abundance, but

65

the results outlined here indicate that the NRE MNI method provides MNI values that are inherently

biased towards particular gastropod shell forms.

Quantification results for all bivalves demonstrated that the umbo and hinge are the elements most

frequently preserved in this assemblage. It is possible that the NRE MNI method is adequate for

quantifying bivalves, but a larger sample of bivalves is needed for conclusive results. The counting

of adductor muscle scars is not a time consuming process. Moreover, the application of tMNI

allows the analyst to determine the relative contribution of each NRE to total MNI.

The application of the tMNI method resulted in variable alterations to richness, dominance and

evenness. By including a wider range of elements, richness, as measured by count of family,

genus, and species, was increased at both sites for all taxa. NTAXA was increased at TP7 for all

taxa, as taxa lacking spires which preserve well were represented in MNI calculations. NTAXA

decreased at TP18 and 19 for all taxa, as a result of family-level identifications. For example, the

Muricidae were represented by individuals from six genera and eight species, but family level

identification of the distinctive siphonal notches necessitated a collapsed value of 1 for

NTAXA. Quantification of additional NRE is resulted in increased family, genus, and species

counts. Family, genus, species and NTAXA values decreased for the top ten ranked taxa at both

sites. Using the NRE MNI method, many taxa are represented by single individuals, and many taxa

reported the same MNI value. The inclusion of additional NRE added more individuals of each

taxon as the bias toward taxa with robust spires was ameliorated. As a result, fewer taxa reported

equal MNI values.

For TP18 and 19, significant differences were noted for Simpson's Index values for all gastropod

taxa, and the top ten ranked taxa only. Simpson's Index is sensitive to changes in the most abundant

species in the sample, while less sensitive to species richness (Magurran 2004:115) The significant

difference between quantification methods is likely due to the dominance of Cerithidae (MNI = 64,

43.2% of total MNI) in NRE MNI calculations (Table 3), However, when MNI is calculated using

the tMNI method, no single taxon accounts for more than 20.6% of the total MNI. Shannon's index

is focussed on species richness and relative abundance (Magurran 2004:107), and the minimal

difference in NTAXA and differential distribution of individuals across taxa likely accounts for the

non-significant difference between quantification methods for all taxa, and the significant difference

between top-ten ranked gastropod taxa from TP18 and 19. For TP7, evenness is similar between

quantification methods (Table 4), reflected in the non-significant difference between Simpson's

66

index values derived from both the NRE MNI and tMNI methods. Changes in diet breadth and

evenness are critical measures for testing hypotheses relating to declines in foraging efficiency and

the long-term impacts of human extraction of molluscan resources (e.g. Broughton 1997; Nagaoka

2002). Measures of taxonomic abundance and heterogeneity are also crucial to understanding

forager decision making (e.g. Thomas 2007a), assisting in reconstructing environmental change

(Amesbury 1999; Faulkner 2013), and informing modern conservation efforts (e.g. Carder and

Crock 2012; Wake et al. 2013). While not all differences were statistically significant, alterations to

measures of taxonomic composition highlight the potential influence of quantification protocol on

archaeological inference.

Researchers are not able to directly compare the abundances of fish and molluscs using current

protocols. The NRE MNI method tends to measure the survival of the pre-selected counting

character, rather than the relative abundance of all taxa in the sample. The tMNI method allows

invertebrate abundance data to be compared to vertebrate abundance data (e.g. fishbone or

terrestrial animals) as the most frequently occurring NRE is used for both measures. In many

coastal sites, especially in the Pacific Islands, molluscan and finfish resources are important sources

of protein, often captured from the same habitats. Therefore, NRE MNI protocols may be masking

changes in subsistence systems that are reflected by shifting abundances of molluscs and finfish.

The preservation or lack thereof of particular NREs may also be a useful indicator of a range of

human behaviours, including off-site processing or shell-working.

Conclusion

The new protocol for the quantification of mollusc shell demonstrates the impact of increasing the

range of NRE included in MNI calculations. This new protocol has produced MNI values that more

closely match the actual abundance of taxa from an archaeological assemblage in the Marshall

Islands. Using this quantification protocol, alterations to richness, diversity, and rank order

abundance were reported. Existing quantification protocols for molluscan shell consistently

underrepresent the relative abundance of gastropods to bivalves and underrepresent the abundance

of particular shell forms. To enhance the study of prehistoric subsistence and provide data that are

increasingly used by conservation biologists, historical ecologists, and policy makers, it is critical

that the most accurate representation of richness, evenness, and diversity are provided. We

recommend that the implications of utilising tMNI quantification protocols be routinely considered.

We encourage analysts to locally adapt and refine the protocols outlined here for the analysis of

molluscan assemblages.

67

Acknowledgements

We thank the Vice Chancellor of the University of Queensland for strategic funding to the

archaeology programme. Marshall Islands fieldwork, conducted under permit from the Historic

Preservation Office (Republic of the Marshall Islands) was supported by a grant to Weisler from

the Office of the Deputy Vice Chancellor (Research). Harris' postgraduate studies are supported by

an Australian Postgraduate Award. The authors thank the three anonymous reviewers for their

useful comments on the manuscript.

68

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74

Figures and Tables

Table 1 Total MNI for all taxa, aggregated at test pit level

Site NRE

MNI tMNI

Gastropoda Eb-1 TP18 &19 188 577 Eb-33 TP7 125 260

Bivalvia Eb-1 TP18 &19 83 88 Eb-33 TP7 78 78

Total 474 1003

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Table 2 Total MNI for the top ten ranked taxa only, aggregated at test pit level

Site NRE MNI tMNI

Gastropoda Eb-1 TP18 &19 170 367 Eb-33 TP7 125 223

Bivalvia Eb-1 TP18 &19 83 88 Eb-33 TP7 78 78

Total 456 756

76

Table 3 Unique family, genus and species counts for gastropods aggregated by test pit. For each test pit, the counts for all taxa and the top ten ranked taxa are presented.

All taxa Top ten taxa

Eb-1 TP18 & 19 NRE MNI tMNI NRE MNI tMNI Families 18 21 13 6 Genera 24 32 14 8 Species 21 40 12 7 NTAXA 26 25 14 9

Eb33 TP7 NRE MNI tMNI NRE MNI tMNI Families 14 17 14 11 Genera 15 23 15 9 Species 14 21 14 11 NTAXA 15 19 15 12

77

Table 4 Evenness and dominance measures. D = Simpson’s Dominance, 1-D = Simpson’s Evenness, H’ = Shannon’s index, H’/lnS = Shannon’s evenness

All Taxa

TP18 & 19 TP7

NRE MNI tMNI NRE MNI tMNI 1-D 0.787 0.884 0.822 0.830 H’ 2.273 2.412 1.988 2.182

H’/lnS 0.698 0.749 0.734 0.741 Top ten ranked

TP18 & 19 TP7

NRE MNI tMNI NRE MNI tMNI 1-D 0.762 0.858 0.841 0.825 H’ 1.856 2.069 2.084 2.057

H’/lnS 0.724 0.942 0.770 0.828

78

Table 5 Eb-1 T18 & 19 NRE MNI and tMNI quantification results for gastropod taxa. * = change in rank order; ** = unique to rank order abundance for that method.

NRE MNI tMNI Rank Taxon MNI NISP Rank Taxon MNI NISP

1 Conus spp.* 36 190 1 Nerita plicata** 83 141 2 Cerithium columna* 32 45 2 Gutturnium muricinum** 70 132 3 Cerithidae spp.* 20 37 3 Conus spp.* 36 190 4 Vasum turbinellus** 11 73 4 Cerithium columna* 32 45 5 Cerithium nodulosum** 10 176 5 Monoplex intermedius** 31 41 6 Planaxs sulcatus** 10 16 6 Monoplex nicobaricus** 29 37 7 Drupa spp. ** 8 37 7 Nerita polita** 27 75 7 Canarium spp. ** 5 13 8 Monetaria moneta** 22 33 8 Turbo argyrostomus** 5 51 9 Cerithidae spp.* 20 37 8 Turbo spp. ** 5 85 10 Chicoreous spp.* 17 64 8 Mitra stictica** 4 18 9 Chicoreous spp.* 3 64 9 Trochus maculatus** 3 58 9 Monoplex spp. ** 3 46 9 Conus flavidus** 3 3 9 Nerita signata** 2 9 9 Melampus flavus** 2 6 9 Cerithium echinatum** 2 3 9 Pollia sp. ** 2 3 9 Trochidae spp. ** 2 8

10 Turbo setosus** 2 49

79

Table 6 Eb-33 TP7 NRE MNI and tMNI quantification results for gastropod taxa. * = change in rank order; ** = unique to rank order abundance for that method.

NRE MNI tMNI Rank Taxon MNI NISP Rank Taxon MNI NISP

1 Melampus flavus* 35 44 1 Nerita polita* 73 122 2 Conus spp. * 17 71 2 Melampus flavus* 39 44 3 Vasum turbinellus 16 90 3 Vasum turbinellus 28 90 4 Nerita polita* 15 122 4 Conus spp.* 23 71 5 Turbo argyrostomus* 7 60 5 Bursa spp.** 13 36 6 Cerithidae spp.* 6 8 6 Nerita plicata* 9 11 7 Nerita plicata 5 11 7 Turbo argyrostomus* 7 60 7 Cerithium nodulosum 5 48 8 Cerithidae spp.* 6 8 8 Canarium spp. 2 9 8 Monoplex nicobaricus** 6 6 8 Thais armigera** 2 8 9 Cerithium nodulosum* 5 48 8 Nerita spp. ** 2 7 9 Canarium spp.* 5 9 9 Drupa ricinus** 1 4 9 Gutturnium muricinum** 5 6 9 Mitra stictica** 1 8 10 Drupa ricinus* 4 4 9 Monetaria moneta** 1 2 9 Muricidae spp.** 1 6 9 Cerithium columna** 1 1 9 Sabia conica ** 1 2 9 Pterigya sp. ** 1 1 9 Drupa rubusidaeus** 1 2 9 Mamilla sp. ** 1 1 9 Nerita albicilla** 1 1 9 Terebra spp. ** 1 2 9 Trochidae spp. ** 1 2 9 Turbo spp. ** 1 17

10 - - -

80

Table 7 Eb-33 TP7 NRE MNI and tMNI quantification results for bivalve taxa. NRE MNI tMNI

Rank Taxon MNI NISP Rank Taxon MNI NISP 1 Fragum spp. 48 51 1 Fragum spp. 48 51 2 Asaphis violascens 10 27 2 Asaphis violascens 10 27 3 Chama spp. 10 11 3 Chama spp. 10 11 4 Corculum cardissa 4 4 4 Corculum cardissa 4 4 5 Spondylus sinensis 2 2 5 Spondylus sinensis 2 2 5 Ctena bella 2 2 5 Ctena bella 2 2 6 Arca sp. 1 1 6 Arca sp. 1 1 6 Spondylus sp. 1 1 6 Spondylus sp. 1 1

81

Table 8 Eb-1 TP18 and 19 NRE MNI and tMNI quantification results for bivalve taxa. NRE MNI tMNI

Rank Taxon MNI NISP Rank Taxon MNI NISP 1 Asaphis violascens 25 145 1 Asaphis violascens 26 145 2 Fragum spp. 10 11 2 Fragum spp. 10 11 2 Gafraium spp. 10 23 2 Gafrarium spp. 10 23 3 Ctena bella 6 6 3 Ctena bella 6 6 4 Tridacna spp. 3 4 4 Tridacna spp. 3 4 5 Arca spp. 2 3 5 Arca spp. 2 3 5 Barbatia spp. 2 5 5 Barbatia spp. 2 5 5 Tridacna maxima 2 5 5 Tridacna maxima 2 5 5 Chama spp. 2 7 5 Chama spp. 2 7 5 Codakia divergens 2 2 5 Codakia divergens 2 2 5 Lucinidae spp. 2 2 5 Lucinidae spp. 2 2 5 Spondylus spp. 2 4 5 Spondylus spp. 2 4 6 Tridacna crocea 1 2 6 Tridacna crocea 1 2 6 Tridacna cf. gigas 1 2 6 Tridacna cf. gigas 1 2 6 Vasticardium elongatum 1 1 6 Vasticardium elongatum 1 1 6 Codakia tigerina 1 1 6 Codakia tigerina 1 1 6 Pectinidae spp. 1 2 6 Pectinidae spp. 1 2 6 Pinctada spp. 1 20 6 Pinctada spp. 1 20

82

Table 9 Contribution of the pre-selected bivalve counting character for all taxa.

Most common element %umbo & hinge Umbo & hinge Other

Eb-1 TP18 & 19 19 2 90.5 Eb-33 TP7 8 0 100

83

Table 10 Contribution of the pre-selected gastropod counting character for all taxa.

Most common element % spire Spire Other Eb-1 TP18 & 19 27 37 42.2

Eb-33 TP7 14 24 36.8

84

Figure 1 a. Stratigraphic section of MLEb-1, TP19 (left, 1 m wide) & TP18 (right, 1 m wide) south profile with a maximum depth of ~115cmbs. Scale is 1 m long.; b. North profile of TP7, with a maximum depth of 40cmbs at site MLEb-33 on Enekoion islet. The dense cultural deposit is ~35 cm thick. Scale is 1 m long. (Both photos, M. Weisler).

85

Figure 2 Gastropod terminology.

86

Figure 3 Examples of gastropod shapes. a. globoid b. involute c. tubular d. trochoid e. turbinate f. patelliform g. disjunct h. turriform. Note the substantial variation in spire height between shell forms.

87

Figure 4 Bivalve terminology.

88

Figure 5 Examples of bivalve shapes a. orbicular b. alate c. auriculate d. subquadrate e. trigonal f.fan-shaped g.ensiform h. elongate-elliptical.

89

Figure 6 Gastropod NRE (1 = spire; 2 = anterior canal; 3 = posterior canal; 4 = outer lip; 5 = aperture; 6 = operculum; 7 = umbilicus). Hatched areas represent areas of shell included in quantification of MNI. Note the presence of NRE on some shell forms, but not others.

90

Figure 7 The tMNI method of gastropod MNI calculation. Hatched areas represent a fragment of shell. (Sp = spire; OL = outer lip; Ap = aperture; AC = anterior canal/notch; PC = posterior canal/notch; Um = umbilicus; Op = Operculum)

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Figure 8 Bivalve NRE (1 = umbo; 2 = posterior hinge; 3 = anterior hinge; 4 = posterior adductor muscle scar; 5 = anterior adductor muscle scar). Note the presence of only a single adductor muscle scar on the monomyarian shell valve of b.

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Figure 9 The tMNI method of bivalve MNI calculation. Hatched areas represent a shell fragment. (Um = umbo; AH = anterior hinge; PH = posterior hinge; AAMS = anterior adductor muscle scar; PAMS = posterior adductor muscle scar).

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Figure 10 Additional NRE included in tMNI quantification. Hatched areas represent areas of shell included in quantification of MNI. a. view of Cypraeidae spp. aperture and base showing additional NRE; b. view of Neritidae spp. aperture and columellar deck showing location of additional NRE, I = anterior columellar deck/outer lip intersection II = posterior columellar deck/outer lip intersection.

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Chapter 4: Intertidal foraging on atolls: prehistoric forager decision making at Ebon Atoll,

Marshall Islands

Note: This is the final version of a peer-reviewed article published in the Journal of Island and

Coastal Archaeology





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Abstract

Prehistoric molluscan assemblages provide insights into long-term patterns of human landscape use,

environmental change, and human impacts to marine resources. The investigation of forager

decision-making regarding the selection of certain mollusc taxa and/or the exploitation of particular

habitats is fundamental to understanding human-environment interactions in the past, and is

relevant for understanding trajectories of human impacts to the intertidal zone in coastal settings.

We document variability in the collection of molluscs at two archaeological sites on Ebon Atoll,

Republic of the Marshall Islands: one on a windward, intermittently occupied islet, and the other on

a permanently inhabited leeward islet. All molluscan taxa were assigned to a range of habitats

within a hierarchical classification scheme for intertidal marine environments. The relative

abundance of taxa from each habitat was used as a proxy for forager decision-making. We report a

generalized, non-selective, foraging strategy focused on gastropod taxa from the high intertidal and

supratidal. These results indicate that rather than focusing intensively on select taxa, intertidal

foragers targeted particular marine habitats, taking advantage of the predictable behaviors of the

molluscs that inhabit them.

Keywords: archaeomalacology, atoll archaeology, marine subsistence, Marshall Islands, shell

midden studies

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Introduction

Molluscs have formed a component of the human diet worldwide for at least 165,000 years

(Jerardino and Marean 2010), and remain essential to many coastal communities today (Aswani et

al. 2015). The analysis and interpretation of mollusc assemblages from archaeological sites have

revealed the complex relationship between humans, molluscs, and marine environments (e.g Bailey

and Milner 2008, Fitzpatrick et al 2009, Giovas et al. 2013, Hunt et al. 2011, Jerardino and Navarro

2008, Jiao 2007, Koike 1975, 1986, Poteate et al. 2014) which includes evidence for the formation

or construction of large shell mounds in Australia (Bailey 1975, Bailey et al. 1994) Brazil (Gaspar

et al. 2008) and North America (Nelson 1909, Uhle 1907), the intensive collection of particular taxa

(e.g., Erlandson et al. 2011, Faulkner 2013), size-selective harvesting (O’Dea et al. 2014, Whitaker

2008), and responses to resource depression, environmental and climatic change and human impacts

to ecosystems (e.g., Braje et al. 2007, Fitzpatrick and Keegan 2007, Parkington et al. 2013).

Furthermore, studies of contemporary forager behaviour have shown that human foraging for

molluscs in the intertidal is mediated by a range of factors including tidal movement, substrate type,

socio-economic and cultural factors, and other economic considerations explored primarily through

optimal foraging theory (e.g., Bird and Bliege Bird 1997, de Boer et al. 2002, Thomas 2001, 2002,

2007). While several studies have highlighted the importance of molluscan resources in prehistoric

subsistence strategies in the Marshall Islands (Dye 1987; Riley 1987; Weisler 1999b, 2001b),

intertidal foraging has not been investigated in detail.

Consisting primarily of unconsolidated sand and gravel atop a narrow reef platform surrounding a

lagoon, low coral atolls are challenging landscapes for sustained human habitation; yet the atoll

archipelago of the Marshall Islands has been occupied by humans for at least 2000 years (Kayanne

et al. 2011; Weisler 1999a, 2001b; Weisler et al. 2012). The intertidal zone of atolls is a complex

mosaic of benthic habitats that host a diverse range of flora and fauna exploited for subsistence by

prehistoric and present day Marshallese.

Reconstruction of human foraging preferences based on the habitat preferences of marine fauna has

proven utility in Pacific Islands archaeology (Allen 1992, 2012; Morrison and Addison 2008;

Morrison and Hunt 2007; Spennemann 1987; Szabó 2009; Thomas 2002; Weisler et al. 2010).

Changes or stability in the exploitation of marine resources from particular habitats may indicate

variation in foraging strategies relating to overexploitation (Morrison and Hunt 2007),

environmental change (Amesbury 2007; Spennemann 1987) or foraging preferences (Allen 2012;

Szabó 2009). A more comprehensive understanding of the foraging patterns of prehistoric

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Marshallese is fundamental to addressing questions of resource sustainability, human impacts to the

marine environment, and overall subsistence systems on oceanic atolls.

To investigate the relationship between prehistoric settlement patterns and human foraging for

molluscs, two assemblages from archaeological sites on Ebon Atoll, Marshall Islands are compared:

one from a small intermittently occupied habitation on a windward islet, and another from a

substantial permanent village on a leeward islet. All molluscan taxa were assigned a range of

habitats using a hierarchical classification scheme adapted from modern benthic habitat maps of

Majuro Atoll, Marshall Islands (Kendall et al. 2012), and the relative abundance of taxa from each

habitat is used to reconstruct time-averaged patterns of forager decision making (Allen 1992;

Nagaoka 2002; Szabó 2009). This method aimed to determine overall patterns of forager behaviour,

highlighting the habitats from which the majority of the assemblage could have been gathered and

providing new insights into prehistoric marine subsistence on Ebon Atoll.

Previous archaeology in the Marshall Islands

Visiting 12 Marshall Islands atolls in 1977, Rosendahl (1987) conducted brief archaeological

surveys, surface artefact collection and limited test excavations. In 1979, as part of a larger

programme of survey and excavation, Riley (1987) completed transect excavations at Laura village

on Majuro’s western rim to discover the depth and area of cultural deposits, establishing initial

occupation of the atoll at 1970 ± 110 BP (Riley 1987:Table 2.28). A year later, Dye (1987),

surveyed 132 of 133 islets on Arno Atoll, sampling 10 islets with transect excavations totalling

48.5m2. Three islets yielded prehistoric deposits indicating permanent habitation, with coral gravel

spreads, midden deposits and associated aroid pit agriculture (see Weisler 1999a).

The next major phase of archaeological research began in 1993, with Weisler’s interdisciplinary

project documenting variability in settlement and subsistence across the ~900 mm to 4000 mm

rainfall gradient from the dry north to the wet south of the archipelago. Ebon (4°N), Maleolap

(8°N), Ujae (9°N), and Utrōk (11°N) have been intensively surveyed and excavated as part of this

project (Weisler 1999a, b, 2001a, b, 2002; Weisler et al. 2012). The earliest habitation dates,

beginning about 2000BP, were consistently identified on the largest leeward islets associated with

aroid pit agriculture (Weisler 1999a; Weisler et al. 2012) , while smaller intermittently occupied

habitations were found on the windward islets.

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Various other projects have been conducted, some in response to modern development activities

(Shun and Athens 1990; Streck 1990), others focused on burial practices, human osteology and

prehistoric interaction (Spennemann 1999; Weisler 2000; Weisler et al. 2000; Weisler and Swindler

2002), material culture (Spennemann 1993; Weisler 2000; Widdicombe 1997), prehistoric

horticulture (Horrocks and Weisler 2006; Weisler 1999a), landscape history and the timing of initial

colonisation (Kayanne et al. 2011; Streck 1990; Weisler et al. 2012; Yamaguchi et al. 2009) as well

as the chronology for the human introduction of lizards (Pregill and Weisler 2007) and land snails

(Christensen and Weisler 2013). Only one study focused on molluscs from prehistoric middens

which considered primarily taphonomic issues (Sommerville-Ryan 1998).

Mollusc assemblages from Marshall Islands archaeological sites

A summary of previous excavations that include the identification and quantification of molluscan

remains from prehistoric-period archaeological sites in the Marshall Islands is provided (Table 1),

focusing on two components of the assemblages: taxonomic composition and the habitats from

which molluscs were likely collected (Dye 1987; Riley 1987; Weisler 2001b). Riley (1987) and

Weisler (2001b) utilised NISP (Number of Individual Specimens) counts and weight, whereas Dye

used presence/absence to characterise midden assemblages. Single quantification measures can be

problematic for assessing relative abundance when used independently of other measures (i.e.,

estimates of Minimum Numbers of Individuals [MNI]) and hinder precise comparison between the

assemblages and inferences regarding forager decision-making. The predominance of genus- or

family-level identifications, and variable recovery and analytical techniques, allow only broad

assessment of foraging practices for the assemblages discussed here. NISP rather than weight is

used to compare relative abundance where possible; NTAXA is used to compare species richness

and broad habitat assignments are based on the ecological review outlined below. NTAXA

quantifies the number of distinct taxa in the assemblage by collapsing taxa at the highest common

taxonomic level. For example, if an analytical unit consisted of Conomurex luhuanus, Gibberulus

gibberulus, Lambis sp. and Strombidae fragments, the NTAXA value would be collapsed to the

highest taxonomic level, in this case, family as all identified taxa belong to the family Strombidae.

Therefore, the NTAXA value would be one rather than four. This method avoids inflating species

richness when taxa are more easily identified to lower taxonomic levels, i.e., genus or species.

Molluscan remains were assessed at the site level to highlight broad patterns in mollusc

exploitation.

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Prehistoric mollusc assemblages from three atolls (Majuro, Arno and Utrōk) Marshall Islands are

generally rich and diverse. Major village sites on Arno and Utrōk atolls indicate a foraging strategy

focused primarily on a wide range of taxa from the lagoonside intertidal, and secondarily from the

oceanside reef flat and reef edge. Only Majuro sites indicate a focus on a single taxon, with

Conomurex luhuanus accounting for at least 80% of the total NISP from each Majuro site. Village

site assemblages are diverse and even, but are primarily composed of gastropods, aligning with

modern ecological surveys that report a ratio of 9:1 gastropod to bivalve species in the Marshall

Islands (Kay and Johnson 1987:133). Assemblages from small, intermittently occupied sites away

from the main village, are similarly rich, diverse and generalised, but somewhat reflect the relative

distance of the site from the oceanside or lagoonside. For example, at site MLUt-4, on Utrōk Atoll

(Weisler 2001b:24-26, 51-59) where the lagoonside environment is much less expansive and

occupation is adjacent to the oceanside reef flat, there is an increased emphasis on taxa occurring on

the lower intertidal of the oceanside reef.

Environmental Context

The southernmost atoll in the Marshall Islands, Ebon Atoll (4°38’N, 168°42’E) consists of 22 islets

encircling a 104km2 lagoon (Figure 1). The total land area of Ebon is ~5.4km2, but the reef platform

totals ~22km2 – >4:1 ratio of reef to land area. Ebon atoll is an ‘open’ atoll, with lagoon and ocean

waters exchanged regularly through a pass across the reef platform. The macrobenthic fauna of

‘open’ atolls are generally highly diverse, but with low overall abundance (Paulay 2000:28).

Around 1655 mollusc species occur in the Marshall Islands (Richmond et al. 2000:222), many of

which can be gleaned from the intertidal marine habitats, evidenced by diverse archaeological

mollusc assemblages from sites in the archipelago (Harris et al. 2015; Weisler 2001b). Finfish

formed an important component of the diet in prehistory (Lambrides and Weisler 2015; Weisler

2001b:106-113) and about 860 fish taxa occur in the Marshall Islands (Richmond et al. 2000:222).

Prehistoric terrestrial subsistence consisted of a mixed horticultural and arboricultural system of

coconut (ni, Cocos nucifera), giant swamp taro (iraij, Cyrtosperma chamissonis), pandanus (bōb,

Pandanus tectorius) arrowroot (makmōk, Tacca leontopetaloides) and breadfruit (mā, Artocarpus

altilis).

The configuration of intertidal habitats on atolls is mediated by geological history, exposure to

waves and currents, and the influence of the dominant north-east trade winds (Wiens 1962; Yamano

et al. 2005), leading to a distinction on Ebon Atoll between the marine environments of the

windward north-eastern extent and the sheltered south-eastern leeward areas (Figure 2). Further

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distinctions exist between portions of the reef that face the open ocean (oceanside, jablik) and those

which encircle the lagoon (lagoonside, jabar). Merlin et al. (1994) note that Marshallese divide the

marine environment into the reefs that face the open ocean (baal), reef flat (ioon-pedped-lik),

beachrocks at the subtidal fringe (pedpedilero), sandy shoreline (ioon-ippe-lik), lagoonside

shoreline referred to as ioon-ippe-iaar and the lagoonside intertidal and sublittoral called loiem. The

deep, interior portion of the lagoon is known as lokilmeejej. These areas correspond to the zones

defined in the habitat classification scheme discussed below and broadly follow zonation and

habitat conceptions of intertidal foragers on other Micronesian atolls (Thomas 2007). On Ebon, the

exposed, windward north-eastern islets are generally smaller and intertidal marine environments

facing the open ocean are composed of poorly sorted coral rubble washed from the subtidal reefs

with coarse, gravelly sands on the lagoonside. The larger leeward islets feature high-rugosity coral

reefs, inter-reefal sand flats and seagrass beds in the calm lagoonside waters and low relief,

expansive reef flat pavements on the oceanside.

Moniak islet

Moniak (~0.7 km2) lies on the north-eastern rim of Ebon Atoll (Figure 1). The long axis of the islet,

perpendicular to the north-easterly trade winds, is approximately 350m long and 230m wide at its

broadest point. The terrestrial zone of the islet reflects its exposed location, sloping upward from

the lagoonside to a natural rampart built of coral cobbles and boulders deposited by waves (Wiens

1962:333; Figure 2b). The Pisonia tree dominated interior zone hosts large colonies of terns

(Sternidae) and boobies (Sula spp.). Coconut crabs (Bigrus latro) and smaller crabs are found in

greater numbers on Moniak than on inhabited islets. It is likely that these attractive resources drew

prehistoric foragers to the islet as they continue to do today.

The oceanside reef edge of Moniak consists primarily of wave cut erosional channels known as spur

and groove formations. On oceanic atolls, the ridges of the channels host communities of corals,

crabs, urchins and molluscs such as Turbo, Drupa and large cypraeids (Morrison 1954; Odum and

Odum 1955). In the groove between the spurs finfish including hawkfish (Cirrithidae), blennies

(Blenniidae), parrotfish (Scaridae) and surgeonfish (Acanthuridae) are found, many of which can be

speared from the ridges at low tide, (Harry 1953:22; Morrison 1954; Wiens 1962:Plate 42). The

deeper, oceanward portions of the channels tend to be dangerous places for foraging and fishing due

to the presence of sharks and strong waves (Harry 1953:22).

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Shoreward of the spur and groove zone is a calcareous algal ridge that provides a habitat for

molluscs such as the rough turban (Turbo setosus), Trochus and Drupa. Exposed, wave-swept

pavements scattered with coral cobbles and reef rubble lie shoreward of the algal ridge. These

pavements are often colonised by macroalgae and host populations of molluscs including

herbivorous Cerithiidae, Cypraeidae and Trochidae and the predatory molluscs Conidae and

Muricidae, characteristic of windward reef pavements (Leviten and Kohn 1980). The shoreline and

supratidal zones of Moniak are primarily coral boulders and cobbles deposited during severe

storms. These environments are easily accessed at low and high tide and provide refuge from

desiccation for crabs and molluscs, such as Bursa spp, Thais spp., Vasum spp. and Nerita polita.

The lagoon-facing beach is composed of coarse grained sand, and is a habitat for the bivalves

Gafrarium spp. and Asaphis violascens.

Ebon islet

Ebon islet is situated on the south-eastern rim of Ebon Atoll, spanning a length of roughly 12km

from the north-eastern tip to the south-western Ruby Point. The land area of ~2.2km2 is over 40%

of the total land area of the atoll. The spur and groove zone on the leeward oceanside is sheltered

from exposure to waves, wind and storms and access to the reef edge for spearing, netting and

collection of large Cypraeids, Turbo and urchins is usually safe during low tide, even at night

(Personal observations, 12/29/2011). Reef flat pavements on Ebon islet are expansive and relatively

free of debris compared to Moniak. Large colonies of macroalgae and shallow sandy tide pools host

a wide range of mollusc species, hosting communities of Cypraeidae, Muricidae, Trochidae,

Conidae and Neritidae, among others. The oceanward shoreline is composed of comparatively finer

grained sand than Moniak, with beachrock outcrops demarcating previous shorelines. Gastropods

such as the nerites (Neritidae), littorinids (Littorinidae), hollow shelled snails (Ellobidae) and

clusterwinks (Planxinae) inhabit the shoreline fringe including the splash zone and upper intertidal.

The lagoonside is a mosaic of coral reefs, inter-reefal sand flats, turtle grass (Thalassia hemprichii)

beds, coral rubble, and smooth, eroded pavements. With an increase in habitat complexity

compared to Moniak islet, a general increase in the richness and diversity of mollusc communities

is predicted (Gratwicke and Speight 2005; Kohn and Leviten 1976). The lagoonside sands offer

habitat for the bivalves Asaphis violascens, Gafrarium spp., Vasticardium spp., Arca spp. and

Atactodea striata. Giant clams (Tridacna spp. and Hippopus sp.), spider conchs (Lambis spp. and

Harpago spp.) cone shells (Conus spp.), mitre shells and auger snails (Terebra spp. and members of

the family Mitridae) occur in the lagoonside habitats, though current abundance and distribution is

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not known. In addition to food, the shells were traditionally used as raw material for making a range

of tools and personal ornaments (Kramer and Nevermann 1938; Weisler 2000, 2001b).

Sites and Samples

MLEb-1 is located centrally within a ~2km long village system defined by seven sites along Ebon

islet, lagoonward of the largest horticultural pit system on the atoll (Weisler 1999a, 2002). TP17,

18, 19 and 20 were excavated into a low mound developed by successive coral pavements (living

floors), located 40m inland of the current lagoon shore and 20m northwest of the primary school.

Cultural deposits consisted of dense coral pebbles and coarse sand extending to a depth of 1.75m

(Weisler 1999a:Figure 4; 2002:20) including molluscan remains, fishbone and worked shell

artefacts. A total of 4953 fragments (6.39kg) of molluscan shell were retained and analysed from

the 6mm wet-screened material, with all but 217 fragments (4% total NISP) identifiable to family,

genus or species. The assemblage is dominated by gastropods—65% of NISP and 89% of MNI.

MLEb-31 is located ~65m from the current lagoon shore on the north-eastern islet of Moniak.

Cultural deposits consist of mixed coral cobbles and poorly sorted sand extending to a maximum

depth of 70cm. No coral living floors were encountered, suggesting prehistoric use of Moniak as a

temporary camp during sorties to the windward side of the atoll. A total of 1891 fragments (7.33kg)

of mollusc shell was retained and analysed from the 6mm wet-screened material, with all but 77

fragments (3%) identifiable to family, genus or species. The assemblage is dominated by gastropod

taxa in both NISP (78%) and MNI (85%).

Methods of mollusc identification and quantification

All molluscan remains were identified to the lowest possible taxon using books, identification

manuals (Carpenter and Niem 1998; Cernohorsky 1967; Poppe 2008) and Indo-Pacific molluscan

reference collections held at the University of Queensland. Due to the richness of atoll molluscan

fauna (Kay and Johnson 1987) and Indo-Pacific Mollusca generally (Bouchet et al. 2002:421), taxa

were identified based only on diagnostic features present on individual fragments, rather than

assuming fragments derive from dominant taxa (after Driver 2011; Szabó 2009; Wolverton 2013).

Taxonomic nomenclature was verified using the World Register of Marine Species online database

(WoRMS Editorial Board 2015). This approach to identification results in lower resolution foraging

reconstructions due to fewer species-level identifications, yet is preferable due to errors introduced

through over-identification.

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NISP was recorded for all taxa. Weight was recorded to the nearest 0.01g. MNI is used as the

primary measure of relative abundance, calculated according to the protocols outlined in Harris et

al. (2015). For MLEb-1, TP17-20, MNI was aggregated by stratigraphic layer. NRE (Non-

Repetitive Elements such as the spire or the siphonal notch of gastropods, or posterior and anterior

adductor muscle scars of bivalves) frequency was summed for each stratigraphic layer for all test

pits prior to the calculation of MNI. Due to the small sample size of molluscan assemblages from

individual test pits at MLEb-31, samples from TP2-6 (essentially from the same cultural layer) were

combined to increase sample size. NRE frequency was summed prior to calculation of MNI for

each taxon in each layer. The utility of MNI as a primary measure for archaeomalacological

analyses has been discussed in detail elsewhere (Claassen 1998; Giovas 2009; Harris et al. 2015;

Mason et al. 1998; Szabó 2009) and it is critical that any inferences based on MNI are considered in

light of NISP and weight data to assess the influence of post-depositional factors on measures of

relative abundance. The relative abundance (MNI) of molluscan taxa in the archaeological

assemblages is used here as a proxy for time-averaged patterning of forager decision making

regarding exploitation of molluscs from the intertidal reef habitats of Ebon Atoll.

Methodological framework

Reconstructing foraging preferences

Reconstructing marine mollusc foraging preferences can inform on subsistence systems, settlement

patterns and, perhaps, land tenure and broader socio-cultural relations. However, as Allen

(1992:331) notes, reconstructing foraging in this way reveals probabilistic (rather than

deterministic) relationships between the taxa in the assemblage and forager decision making. More

explicit, deterministic inferences can be made using oxygen isotopes and sclerochronology (e.g.,

Andrus and Thompson 2012); however, the methodology used here relies on ecological knowledge

of the preferences of particular molluscan taxa for configurations of water depth, tidal exposures,

substrate type and associated biological cover. These variables are fundamental when determining

the range of molluscan taxa foragers could have potentially exploited in a particular habitat.

Distinction in these factors between leeward and windward islets (Figure 2) make them useful for

investigating differences in forager decision making relating to local environment and settlement

patterns.

Allen (1992:331) cited three potential issues with investigating foraging in this manner: (1) the

specificity of faunal identifications, (2) the quality of ecological information available for each

taxon and (3) the depth of information pertaining to traditional or prehistoric extraction

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technologies and the articulation of this knowledge with the quality of information pertaining to

prey behaviour. Identification and quantification of faunal material has been discussed elsewhere

(Claassen 1998, 2000; Harris et al. 2015; Lyman 2008; Mason et al. 1998) and issues relating to the

quality of ecological data are covered below. However, little is known about mollusc foraging

technology during Marshall Islands prehistory. While there are at least 64 Marshallese words for

different fishing methods (Abo et al. 1976:361-362), there are no words specifically for the

collection of shellfish. However, there are at least 45 Marshallese words for particular shell taxa

(Abo et al. 1976:453-454), salted clams (jiookra), the meaty party of the clam (aḷaḷ), the rod-like

style from the digestive system of a Tridacna clam (lām), particular places where shells, fish, birds

or clams gather, (ajañ), or sickness resulting from consumption of surf clams (kọnet, Atactodea

striata) (Abo et al. 1976). Based on archaeological evidence from Pacific island archaeological sites

(e.g., Allen 2012; Morrison and Addison 2008; Szabó 2009; Szabó and Amesbury 2011), modern

studies of subsistence harvesting of shellfish and ethnographic data (e.g., Kinch 2003; Malm 2009;

Thomas 2001; Titcomb 1978), the ease of accessing the intertidal zone of the reef on the ocean and

lagoon sides of Ebon Atoll, and the authors’ observations of shellfish gathering in the Marshall

Islands, we hypothesise that most shellfish gathering would likely have occurred by hand while

walking or wading along the intertidal and shallow subtidal at low tide in the areas extending from

the shoreline, out across the reef flat, to the reef edge.

Hierarchical classification scheme

In order to assess forager decision making, a framework for assigning molluscan taxa to ecological

zones must be utilised. A hierarchical classification scheme is an objective, systematic approach to

benthic habitat classification and description (Mumby and Harborne 1999b:155) and is primarily

utilised by researchers mapping the spatial distribution of benthic habitats for conservation and

management of tropical marine environments (Kendall et al. 2012; Mumby and Harborne 1999a).

Hierarchical classification schemes partition the marine environment by describing and classifying

the location of discrete zones of the benthos. A habitat is defined in these schemes as a unique

configuration of: (1) location in relation to the shoreline, (2) geomorphological structure and (3)

benthic cover. This method of classifying the marine environment is adapted here to assign

molluscan taxa to particular combinations of these three environmental categories to use in

reconstructing forager decision making.

The habitat classification scheme used here was developed by Kendall et al. (2012) for mapping the

marine environment of Majuro Atoll, Marshall Islands. Kendall et al. (2012) employed a simple

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habitat classification scheme (in contrast to Mumby and Harborne 1999a) that omits detailed

attributes such as the percentage of hard bottom, relative patchiness of seagrass cover and the type

and/or species of coral cover. The modified classification scheme used here has only two

hierarchical attributes: Zone and Geomorphological Structure (Table 2). Geomorphological

structure consists of two levels of sub-attributes: Major Geomorphological Structure and Detailed

Geomorphological Structure. This classification scheme incorporates aspects of marine

environments critical to molluscs, including the relationship with the shoreline, tides and water

depth (Zone), substrate type (Major Geomorphological Structure) and associated biological cover

(Detailed Geomorphological Structure).

Data collection for molluscan zonation and ecology

A range of sources on Indo-Pacific molluscan fauna were consulted with a focus on atoll

environments, including field observations and surveys (e.g., Banner and Randall 1952; Bernstein

1974; Houk and Musburger 2013; Kay and Johnson 1987; Morrison 1954; Paulay 2000), reference

collections of molluscs from Micronesia (Demond 1957), studies of particular species (e.g., Abbott

1960; Kohn 1980; Taylor 1983, 1984) and identification guides (principal sources include: Burgess

1985; Carpenter and Niem 1998; Röckel et al. 1995).

All taxa recorded from the Ebon Atoll archaeological mollusc assemblages were assigned a number

of habitats using the hierarchical classification scheme outlined above. A total of 251 bivalve and

gastropod taxa from 42 families and 111 genera were assigned a combination of Zone, Major

Geomorphological Structure and Detailed Geomorphological Structure as determined by the habitat

preference(s) of each taxon. Reliable information relating to habitat preferences could not be

located for the following taxa: Pitar striatus, Ranularia testidunaria, Gyrineum pusillum, Chama

gryphoides, Plicopura spp., Nerita exuvia and Neritopsis radula. However, these taxa are

uncommon in archaeological sites on Ebon Atoll, totalling 8 NISP from both sites.

Molluscan ecology and habitat classification scheme usage

MNI values for taxa associated with a particular habitat were summed. The total MNI for all taxa

from each habitat was compared to total MNI for the assemblage and converted to a percentage.

These values are used as a proxy for human decision making, indicating those habitats from which

the taxa in the assemblage could have derived. By using site-level totals for each site, this method

allows a time-averaged assessment of the areas of the marine environment from which the majority

of the taxa present in the assemblage could have been collected. In the methodology adopted here

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no assumptions are made of the intentions of prehistoric foragers. Dominant taxa are given equal

analytical weight to non-dominant taxa. The analytical inclusion of these non-dominant taxa which

often together account for a large portion of total MNI, highlight broad trends in foraging practices

that may be masked when taxa are deemed non-economic or unimportant.

For specimens identified to family or genus, the relevant habitat information from species level

entries were aggregated and, where necessary, additional data was added for genera or species not

recorded in the assemblage (for example, the Conidae and Cypraeidae) based on the range of taxa

recorded for the Marshall Islands (Demond 1957; Kay and Johnson 1987). These aggregated

habitat designations capture the intrafamily variation in habitat preferences and the uncertainty

associated with family and genus level identifications. These lower level identifications hinder

high-resolution foraging reconstructions, but the sacrifice in analytical resolution minimises errors

introduced through over-identification.

Care was taken to assign taxa to all appropriate habitats, however, molluscan habitat preference is a

dynamic process influenced locally by a range of biological, ecological and climatic factors and can

alter markedly over short periods of time (Augustin et al. 1999:Table 2; Paulay 2000). Those taxa

which may have been processed off-site, or did not preserve will be invisible in foraging

reconstructions (Bird and Bliege Bird 1997). In many cases taxa are assigned to multiple habitats,

introducing the potential for over-representation of habitat types when numerically dominant taxa

are recorded for multiple habitats. However, the foraging patterns presented in the results should be

treated as probabilistic, rather than deterministic; this method highlights the habitats from which the

majority of the taxa in the assemblage could have been gathered, and can provide useful data for

testing hypotheses relating to the articulation of molluscan foraging with other aspects of human

behaviour.

Results

MLEB-1

The molluscan assemblage from MLEb-1 is both taxonomically rich and even, represented by 34

families, 62 genera and 63 species (NTAXA = 48, total MNI = 1258, Figure 3). Taxonomic

measures of heterogeneity reported an even assemblage as measured by Simpson's index of

diversity (1-D = 0.889), the Shannon-Weiner index of diversity (H’ = 2.668) and Shannon's

evenness (E = 0.689). The majority of taxa are epifaunal gastropods, with few infaunal bivalves in

the assemblage.

107

Most of the assemblage could have been gathered from the reef flat pavements (D/1/15, D/1/16),

which today are most prevalent on the oceanside of Ebon islet (Figure 4a).This single habitat

accounts for 58.1% of the individuals in the assemblage (Figure 5). Many of the top-ranked taxa in

the assemblage are highly associated with this habitat on Micronesian atolls, including N. plicata, V.

turbinellus, M. moneta, T. maculatus, M. intermedius and Drupa spp. (Demond 1957). Even when

the influence of taxa that can occur in multiple habitats are excluded from foraging reconstructions,

the oceanside reef flat pavement still accounts for 45.7% of MNI (Figure 4b). A large portion of the

assemblage could have also been gathered from rocky areas of the reef flat. This habitat accounts

for 41.8% of total MNI, represented primarily by N. polita and N. sinensis.

There is less evidence for foraging in the lagoonside coral reefs, sand flats and seagrass beds. G.

muricinum and Monoplex intermedius are common in the assemblage (15% of total MNI), and taxa

such as Tridacna spp., Lambis lambis and Harpago chiragra also indicate lagoonside collection,

although collection of these taxa is minimal (c.1% of total MNI).

MLEB-31

Some 31 families, 53 genera and 61 species (NTAXA = 37, MNI = 650) were recovered from

archaeological deposits at MLEb-31 (Figure 6). Simpson's index of diversity (1-D = 0.859), the

Shannon-Weiner index of diversity (H’ = 2.528) and Shannon's evenness (E = 0.7) reported an even

and diverse assemblage.

The greatest number of individuals in the assemblage could have been gathered from the reef flat

cobbles and boulders, currently circumscribing the northern, western and eastern sides of Moniak

islet and characteristic of windward islets (Wiens 1962; Figure 7a). Taxa characteristic of this

habitat on windward islets (N. polita, T. armigera) contribute 31% of total MNI. Reef flat rocks

account for 56.8% of the individuals in the assemblage. Once again, when the MNI of taxa that can

inhabit multiple habitats are removed from quantification, these trends still hold (Figure 7b). Reef

flat pavements are also highly ranked with V. turbinellus, C. nodulosum, T. maculatus and other

taxa found commonly on pavements in Micronesia, accounting for 36.3% of total MNI. Gathering

from sand flats and coral growth is also indicated primarily by the presence of A. violascens and G.

muricinum, with these two taxa accounting for 13% of total MNI.

108

Discussion

The molluscan assemblages from MLEb-1 and MLEb-31 indicate a generalist foraging strategy,

exhibiting rich and even assemblages with the major focus on collecting small gastropods from the

high intertidal and reef flat. Minor differences in taxonomic composition were noted, likely

reflecting local availability of taxa on windward and leeward islets. The taxonomic composition of

both assemblages suggests that foragers were not targeting particular taxa, but rather focusing

foraging efforts on particular habitats, exploiting the predictable behaviours the taxa hosted there.

The range of habitats, which is typically higher on leeward islets (Kendall et al. 2012), and taxa

exploited at both sites seems to reflect natural variation in the habitats adjacent to the archaeological

deposits. Both assemblages suggest an overall emphasis on gleaning, with the majority of the taxa

living epifaunally. However, most bivalves in both assemblages live infaunally, indicating that

foragers were also extracting molluscs by digging.

The predominance of Nerita at both sites suggests that these small taxa were an attractive resource

for prehistoric Marshallese. N. polita, the top ranked taxa at MLEb-31, burrows into the sand

between 5-10cm deep at the base of boulders and cobbles during high tides and diurnal low water.

The shallow burial depth characteristic of this species requires minimal effort from foragers

collecting this resource. During periods when the zone is free of water during nocturnal low tides,

N. polita emerges from the sand to mate and feed on macroalgae and returns to the sand before

inundation at high tide (Chelazzi 1982:453). Patterns of burrowing, foraging and emersion tend to

be highly predictable, with emersion following in the wake of the retreating tide and re-burial

occurring between 30 minutes and two hours prior to inundation from rising tides (Chelazzi

1982:454). N. polita also tend to re-bury close to the location of emersion. The relationship between

the activity of the tides, the behaviour of N. polita and predictable burial and emersion location,

would have allowed foragers easy access to this species for the entire low tide. Furthermore, large

concentrations of individuals can occur on single boulders or cobbles (Chelazzi 1982), facilitating

mass harvesting. Predictable patterns of behaviour are not unique to the nerites and may help to

explain the focus on oceanside reef flat environments on Ebon islet.

When atoll reef flats are aerially exposed during daytime low tides, surface temperatures commonly

reach as high as 38°C (Kohn 1987:139). Due to the surface temperature of the expansive reef flat at

Ebon islet during daytime aerial exposure, molluscs must take refuge in tide pools to avoid

desiccation (Russell and Phillips 2009:71). The vast majority of the gastropod taxa present in the

MLEb-1 assemblage, including the top-ranked N. plicata, live epifaunally, either grazing on algal

109

turfs or actively preying on other molluscan taxa. Like the predictable concentrations of N. polita

below and on the surface of cobbles and boulders, the predictable behaviours of molluscs sheltering

from desiccation, browsing on algae, or preying on other molluscs (Kohn 1983; Taylor 1978, 1983)

were likely targeted by prehistoric foragers.

While there is a strong indication of generalised gleaning from the oceanside intertidal at both

MLEb-1 and MLEb-31, it is likely that foragers at MLEb-1 also exploited lagoonside habitats. The

knobbly triton, G. muricinum, is the second highest ranked species at MLEb-1. While the behaviour

of this species is not well understood, Govan (1995) noted that G. muricinum occurs in almost all

lagoonside habitats, including sand flats, coral reefs and the inter-reefal sand flats. Furthermore, A.

violascens is ranked sixth by MNI at MLEb-1 and ranked two at MLEb-31. A. violascens burrows

relatively deep, with peak densities reported between 13 and 20cm (Soemodihardjo and Matsukuma

1989), preferring gravelly sands in sheltered lagoon habitats (Paulay 2000). Modern observations of

mollusc collecting on Tarawa, Kiribati have noted that due to A. violascens preference for the mid-

high intertidal beach slope, this species is accessible “even on the worst tides” (Paulay 2000:25).

This species is often the dominant bivalve in its habitat, located easily by the tell-tale siphonal

opening in the sand, and dug out (Paulay 2000:13). This combination of ecological factors likely

made A. violascens a dependable and attractive resource for prehistoric foragers.

It is difficult to draw inferences from presence/absence data alone, but comparisons with mollusc

assemblages from Arno Atoll (Dye 1987) seem to indicate exploitation of a similar range of taxa to

assemblages from Ebon Atoll. There is some indication that foragers on Arno were focusing efforts

on the lagoonside, but this assertion is tenuous given that the relative abundance of taxa cannot be

adequately assessed and many identifications were only to the family or genus level. Converse to

mollusc assemblages from Utrōk Atoll to the far north (Weisler 2001a, b), where lagoonside

gathering seems to be the focus, Ebon Atoll assemblages tend to be gathered primarily from

oceanside habitats, with a minor component of lagoonside foraging. These patterns may be

attributable to differences in quantification measures, but may indicate genuine variation in foraging

practices between northern and southern atolls.

A notable difference occurs between assemblages recovered from Transect 6 and 7 at Laura

Village, Majuro (Riley 1987) and MLEb-1 on Ebon islet. Both sites were major villages, with

permanent human populations and a well-developed zone of aroid pit horticulture. However, the

molluscan assemblages from sites at Laura village are dominated by the remains of the strawberry

110

conch, C. luhuanus. This species was not reported from deposits at MLEb-1 and the molluscan

assemblages from MLEb-1 or MLEb-31 do not indicate a pattern of intensive exploitation of any

single taxon, or reach the densities of Majuro deposits. The dominance and density of C. luhuanus

remains suggests that prehistoric foraging at Laura village was intensively focused on mass

collection of a single taxon, more similar to foraging patterns recorded for modern atoll dwellers

(Thomas 2014), than prehistoric assemblages from Ebon Atoll. A lack of suitable habitats or other

biotic or ecological factors may have inhibited the establishment of C. luhuanus colonies on Ebon

and Moniak islets. During the prehistoric period, the inhabitants of Ebon seem to have focused on

generalised gleaning of molluscs primarily from the oceanside reef flat and shoreline rocks.

Conclusion

An analysis of prehistoric foraging preferences of the inhabitants of two archaeological sites has

shown that on Ebon Atoll, Marshall Islands, foragers practiced a generalised collection strategy

focused on a rich assemblage of primarily gastropod taxa from the upper intertidal rocks, sand and

cobbles, and the oceanside reef flat pavement. Foragers likely relied on predictable patterns of

molluscan behaviour to harvest a wide range of taxa, rather than focusing foraging effort on any

individual taxon. Minor differences in taxonomic composition were noted, likely reflecting local

availability of taxa on windward and leeward islets. It is possible that this generalised foraging

pattern is related to other forms of marine subsistence, such as collecting edible seaweed or the

exploitation of inshore finfish. Further study will seek to understand how these patterns of

molluscan exploitation relate to the exploitation of finfish (Harris et al. 2016), shell working,

manufacture and curation of shell tools and atoll-wide settlement patterns. Ultimately, these data

will be used to investigate potential human impacts to the marine environments of Ebon Atoll that

may have been related to mollusc exploitation. The low-intensity, generalised collection strategy

inferred from an analysis of molluscan taxa in the assemblages may have allowed sustained yields

of molluscs from a range of environments for the entire period of human occupation, beginning

~2000 years ago.

Acknowledgements

Permission to conduct archaeological research in the Republic of the Marshall Islands was granted

to Weisler by the Historic Preservation Office (HPO), Ministry of Internal Affairs and on Ebon

Atoll, former mayor Lajan Kabua. Marshall Islands fieldwork was supported by a grant to Weisler

from the Office of the Deputy Vice Chancellor (Research), University of Queensland. Harris’

111

university studies are supported by an Australian Postgraduate Award. Marine molluscs collected

during field work have been returned to the HPO, Marshall Islands.

112

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Figures and Tables

Table 1 Summary of previous analyses of molluscan assemblages from archaeological sites in the Marshall Islands from Majuro (Riley 1987), Arno (Dye 1987) and Utrōk (Weisler 2001) atolls. Habitat assignments from Baron (1992), Baron and Clavier (1992), Carpenter and Niem (1998), Demond (1957), Soemodihardjo and Matsukuma (1989), Thomas (2001), and Willan (1993).

Atoll Islet Site type excavated area (m2) NTAXA NISP Representative taxa Predominant habitat(s)

Majuro Majuro (MiMLMj-1)

Village 7 25 35062

C. luhuanus Gafrarium spp. Naticidae spp. Harpa spp.

Quidnipagus palatum A. violascens Atactodea spp.

lagoon and ocean shoreline sands, lagoonside inter-reefal sand patches, areas of coral growth and seagrass

Majuro Majuro

(MiMLMj-10) Village 7 38 9460 C. luhuanus Gafrarium spp.

Atactodea spp. A. violascens ibid.

Arno Arno

(Ar-5-1, Ar-5-0, Islet 116)

Village 23 14 N/A Nerita polita Turbo spp. Cypraeidae

Tridacna sp. Quidnipagus sp. Lambis spp.

lagoonside shoreline, sand patches, coral growth seagrass, oceanside shoreline, reef flat pavement/ reef edge

Arno Bikareij (Islet 17)

Village 6 10 N/A

N. polita Turbo spp. Cypraeidae spp. Quidnipagus spp.

Tridacna spp. Cerithium spp. Trochus spp.

ibid.

Arno Jebu (112)

Village 1 12 N/A Tridacna spp. Cerithium spp. Nerita polita

Lambis spp. Cypraeidae Turbo spp.

ibid.

Utrōk Utrōk (MLUt-1) Village 26 35 8487 A. striata Tridacna spp.

Vasum spp. Codakia spp.

Lagoonside and oceanside reef flat, sands, shoreline, lagoonside coral, oceanside reef edge

Utrōk Aon (MLUt-5) Village 12 21 524 Tridacna spp. Asaphis sp. Turbo sp.

Conus spp. Trochidae C. nodulosum

ibid.

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Utrōk Aon (MLUt-4) Temporary

camp 12 27 1299 Turbo spp. Tridacna spp.

Vasum spp. Cypraea spp. Oceanside shoreline rocks, reef flat, and reef edge

Utrōk Allok (MLUt-2) Temporary camp

2 21 237 C. nodulosum Tridacna spp.

N. polita Fragum spp.

Lagoonside and oceanside reef flat, sands, shoreline, lagoonside coral

Utrōk Bikrak (MLUt-3) Temporary camp

10 32 1243 C. nodulosum Tridacna spp. Codakia spp.

Vasum spp. N. polita

ibid.

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Table 2 List of zones, major geomorphological structures and detailed geomorphological structures used in the Ebon archaeological project hierarchical classification scheme (after Kendall et al. 2012:8-12). Zone J, dredged/excavated and Detailed Geomorphological structure 13, aggregated patch reefs was not used for the analysis presented here, as these classes relate to methods for mapping modern day atoll benthic habitats. Detailed Geomorphological structure 19, Algal Ridge, was added by the authors due to the distinctive range of molluscan taxa associated with this habitat (Morrison 1954).

Zones code name description

A Land Terrestrial features at or above the high tide line. B Shoreline Intertidal Area between the spring high tide line and lowest spring tide level C Lagoon Area of water inside the atoll, surrounded by the Back Reef D Reef Flat Shallow, low relief area exposed at low tide between the Shoreline Intertidal and Fore Reef or Back

Reef E Back Reef Area on the lagoonside of an atoll sloping inward from the Shoreline Intertidal or Reef Flat down to the

seaward edge of the Lagoon floor. F Fore Reef Area along the seaward (oceanside) edge of the reef flat that slopes into deeper water to the landward

edge of the Bank/Shelf Escarpment G Bank/Shelf Deeper water extending offshore from the seaward edge of the Fore Reef to the beginning of the

escarpment where the insular shelf drops off into deep, oceanic water H Bank/Shelf Escarpment Begins on the seaward edge of the Fore Reef, where depth increases rapidly into deep, oceanic water. I Channel Naturally occurring channels in the seafloor that often cut across several other zones. K Pinnacle High-relief features occurring in the Lagoon that are separated from the Back Reef by the deeper waters

of the Lagoon. L Unknown Habitat proclivities could not be assessed.

Major geomorphological structures and detailed geomorphological structures 1 Coral Reef and Hard bottom Solid substrates, including bedrock, boulders and reef building organisms. A thin veneer of sediment

may be present. 11 Aggregate Reef Continuous, high-relief coral formation of variable shapes, lacking sand channels of Spur and Groove

formations. 13 Individual patch reef Coral formations that are isolated from other coral reef formations by bare sand, seagrass or other

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habitats. 14 Spur and Groove Alternating sand and coral formations that are oriented perpendicular to the Shoreline intertidal or

Fore Reef. The coral formations (spurs) of this feature typically have a high vertical relief and are separated by 1 to 5m of sand or hard bottom (grooves). Occurs only in the Fore reef or Bank/Shelf Escarpment zone.

15 Pavement Flat, low-relief, solid rock in broad areas, often with partial coverage of sand, algae, hard coral, Alcyonacea (sea whips or fans), zoozanthids or other sessile invertebrates.

16 Pavement with Sand Channels

Areas of pavement with alternating sand/surge channel formations that are oriented perpendicular to the Shoreline Intertidal or Bank/Shelf escarpment.

17 Reef Rubble Dead, unstable coral rubble often colonised with turf, filamentous, calcareous or encrusting macroalgae. Often occurs due to storm waves piling up dead coral.

18 Rock/Boulder Large, irregularly shaped carbonate blocks often extending from the island bedrock, indicating higher sea-levels, or aggregations of loose coral cobbles and boulders that have been detached and transported from their native beds. Individual cobbles and boulders often range in diameter from 0.25-3m

19 Algal Ridge Area of consolidated coral pavement colonised by calcareous algae occurring shoreward of the Bank/Shelf Escarpment or Fore Reef and demarcates the seaward margin of the Reef Flat. Often slightly higher elevation that the seaward and shoreward areas of the reef.

2 Unconsolidated Substrate Areas of the seafloor consisting of small, unattached or uncemeneted particles with less than 10% cover of large stable substrate.

21 Sand Areas of the seafloor consisting of small, unattached or unncemented particles. 22 Sand with Scattered Coral

and Rock Primarily sand bottom with scattered rocks or small, isolated coral heads.

23 Seagrass Primarily sand bottom colonised by seagrass. 3 Other Delineations Any other type of structure not classified as Coral Reef and Hard bottom or Unconsolidated Substrate. 31 Land Terrestrial features beyond the Shoreline Intertidal. 4 Unknown Habitat proclivities could not be assessed. 41 Unknown Habitat proclivities could not be assessed.

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Figure 1 Map of the Marshall Islands and Ebon Atoll, showing archaeological sites on leeward (Ebon) and windward (Moniak) islets.

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Figure 2 Schematic cross section of a. leeward Ebon islet and b. windward Moniak islet highlighting patterns of intertidal zonation on atolls, the molluscan fauna characterisitc of each habitat, the relative exposure of each islet to winds and waves and traditional human settlement patterns (after Kendall et al. 2012; Merlin et al. 1994; Weisler 1999b; Wiens 1962). c. Ebon islet oceanside reef flat (Photo: M. Harris), d. Ebon islet lagoonside (Photo: M. Weisler), e. Moniak islet lagoonside (Photo: M. Weisler) f. Moniak Islet oceanside (Photo: M. Weisler).

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Figure 3 Mollusc species from TP17-20, MLEb-1, represented by 15 or more individuals.

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Figure 4 Habitats accounting for more than 20% of MNI MLEb-1, TP17-20; a. all taxa b. Conus spp., Monetaria moneta and Cypraeidae spp. removed. See Table 1 for classification scheme key.

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Figure 5 Mollusc species from TP17-20, MLEb-1 assigned to D/1/15 or D/1/16, represented by 15 or more individuals.

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Figure 6 Mollusc species from TP2-6, MLEb-31, represented by 15 or more individuals.

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Figure 7 Habitats accounting for more than 20% of MNI, TP2-6, MLEb-31 a. all taxa; b. Taxa assigned to D/1/18, represented by 15 or more individuals. See Table 1 for classification scheme key.

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Chapter 5: Windward vs. leeward: Inter-site variation in marine resource exploitation on

Ebon Atoll, Republic of the Marshall Islands

Note: This is the final version of a peer-reviewed article published in the Journal of Archaeological

Science

Matthew Harris, Ariana B.J. Lambrides and Marshall I. Weisler

School of Social Science, The University of Queensland, St Lucia, Queensland, 4072, Australia



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Abstract

The variation in windward and leeward marine environments has been linked to distinctions in

marine subsistence on large, high volcanic Pacific Islands, but these patterns have not been explored

on low coral atolls. We document windward vs. leeward islet site variation in the taxonomic

composition of fish bone and mollusc shell assemblages from three archaeological sites at Ebon

Atoll, Republic of the Marshall Islands, to elucidate the relationship between local environment,

archaeological site type and the taxonomic composition of marine archaeofaunal assemblages.

While the representation of taxa at each site was broadly similar in terms of measures of taxonomic

heterogeneity (richness, evenness and dominance), chord distance and correspondence analysis

reported variation in taxonomic composition at each site. For mollusc shell assemblages, variation

in taxonomic abundance indicates the influence of the marine environments adjacent to each site

and the relative exposure of these coastlines to heavy surf, wind, waves and extreme weather

events. Fish bone assemblages recovered from 6.4 mm screens had less inter-site variation in

richness, evenness and rank order, but differences were noted in the rank order of fish taxa

recovered from selective 3.2 mm screening of archaeological deposits when compared between

sites. In contrast to patterns for molluscs, variation in the taxonomic composition of fish bone

assemblages likely relates to site function, rather than the marine environments adjacent to each

site. These trends highlight for the first time the complex range of factors that influenced the

prehistoric acquisition of marine resources between leeward and windward islets, and document

variation in prehistoric marine subsistence within one atoll.

Keywords: Atoll archaeology; marine subsistence; Marshall Islands; Micronesia; Pacific fishing;

shell midden studies; zooarchaeology; archaeomalacology; ichthyoarchaeology

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Introduction

Marine resources were a critical component of prehistoric subsistence systems across the Pacific

Islands (Allen 2012; Fitzpatrick et al. 2011; Jones 2009; Leach & Davidson 1988; Ono & Clark

2012; Szabó & Amesbury 2011; Thomas 1999; Weisler et al. 2010). Finfish and molluscan remains

are ubiquitous in Marshall Islands archaeological sites (Beardsley & Athens 1994; Dye 1987; Riley

1987; Rosendahl 1987; Shun & Athens 1990; Weisler 1999b, 2001b), and ethnographic and

linguistic evidence highlights the varied and complex ways that Marshallese interact with the

marine landscape (Abo et al. 1976; Erdland 1914; Kramer & Nevermann 1938; Spoehr et al. 1949;

Tobin 2002). The intertidal reef platforms of the Marshall Islands host at least 1000 species of

mollusc (Vander Velde & Vander Velde 2008), and over 800 fish taxa occur within 60 m ocean

depth (Myers 1999). These expansive reefs—often greater in area than the terrestrial zone of

atolls—provided predictable and possibly sustainable yields of marine subsistence resources

throughout prehistory (e.g., Ono & Addison 2013; Thomas 2014); indeed, on Utrōk Atoll situated at

the northern limit of permanently-inhabited atolls in the Marshall Islands, an 1800-year sequence

points to human populations, albeit in low numbers, with no indications of marine resource

depression (Weisler 2001b:128).

The degree of wave exposure has been recognised as a key factor influencing a range of important

ecological processes which are critical for structuring faunal composition in tropical intertidal

environments (Drumm 2005) and has been related to variation in human behaviour in

archaeological contexts. However, determining whether taxonomic composition of archaeofaunal

assemblages is driven by ecological conditions and/or human agency is undoubtedly a complex

endeavour. Patterned variation in site use and diet as it relates to site location (windward vs.

leeward) has been documented on large, high volcanic Pacific Islands (e.g., Bayman and Dye 2013;

Kirch & Dye 1979:58; Palmer et al. 2009; Weisler and Kirch 1985). In the Hawaiian archipelago

particular agricultural practices are more commonly associated with leeward or windward locations,

with rain-fed agriculture and sweet potato cultivation associated with dry, leeward landscapes, and

irrigated taro cultivation better suited to wetter windward regions (Palmer et al. 2009: 1444, Earle

1977:224, Weisler and Kirch 1985). The differences in windward and leeward environments have

also been recognised as influencing the exploitation of marine fauna. Ethno-archaeological research

into Niuan fishing strategies (Niuatoputapu, Polynesia) recognised the relationship between fishing

practices and distinctions in reef structure, tidal activities and faunal communities that were related

to windward or leeward location (Kirch and Dye 1979). Similarly, Kirch (1982) noted variation in

exploitation of fishes from three Hawaiian archaeological sites that was inferred to be driven by

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local environment. Also in Hawaiʻi, fishponds are more common on the leeward coasts than on the

exposed windward zone (Weisler and Kirch 1985). Distinctions in taxonomic composition between

two assemblages, Tangarutu (leeward) and Akatanui 3 (windward), from Rapa Island were

attributed to their windward/leeward location, and while similar species were identified at each site,

their rank-ordering was variable, with pomacentrids more common at the windward site of Akatanui

3 (Vogel and Anderson 2012).

Mollusc assemblages from large, high volcanic Pacific Islands also demonstrate a link between site

location and taxonomic composition. Assemblages from windward sites in Hawaiʻi are dominated

by limpets (Cellana spp.) and turban shells (Turbo spp.), characteristic of rocky shores, but are rare

in leeward sites (Kirch 1982, Morrison and Hunt 2007). Similarly, mollusc assemblages from

Vaunautu (Bedford 2007), Fiji (Szabó 2009) and Rapa (Szabó and Anderson 2012) reflect local

environmental conditions across the windward/leeward divide and have been interpreted as the

result of non-selective foraging strategies operating in varying environments. On atolls, the

configuration of marine environments and the distribution and relative abundance of fauna is

determined by geological history, exposure to wind, waves and currents as well as myriad

stochastic, local ecological, biological and abiotic factors and relates to the windward and leeward

exposure of each islet (Wiens 1962). However, atoll settlement patterns and subsistence practices

reflected in the variation between windward and leeward environments have not been investigated.

We explore inter-islet and inter-site variation in the taxonomic composition of fish bone and

mollusc shell assemblages from archaeological deposits on three islets on Ebon Atoll, Marshall

Islands to elucidate the relationship between human foraging behaviour, site function, site location

(windward v. leeward) and local environment. A range of statistical techniques are employed to

investigate whether differences in the taxonomic composition of the assemblages is a reflection of

ecological variability and site location (windward vs. leeward marine habitats) or site function

(village vs. camp site). Future research avenues for exploring spatial variation in atoll settlement

patterns and subsistence are then suggested.

Sites and Samples

Ebon Atoll is the southernmost atoll in the Marshall Islands. Consisting of 22 islets encircling a 104

km2 lagoon, the total land area is approximately 5.4 km2 (Figure 1). The reef platform totals over 22

km2, roughly a 4:1 ratio of reef to land area. Two field seasons (1995/1996 and 2011/2012) of

survey and excavation were conducted on Ebon Atoll as part of a larger project directed by Weisler

to investigate regional variation in Marshall Islands archaeology as it relates to the 700+ km north-

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south rainfall gradient, as well as documenting intra-atoll differences in settlement patterns and

subsistence (Weisler 1999a, b, 2000, 2001a, b, 2002; Weisler & Swindler 2002; Weisler et al.

2012). We report results from the analyses of the fish bone and mollusc shell remains retained in

6.4 mm and 3.2 mm screens at three sites excavated during the 2011/2012 Ebon Atoll field season.

A total of 68 m2 was excavated across seven archaeological sites on three islets, one situated on the

leeward rim (Ebon Islet), one with windward exposure (Moniak Islet) and Enekoion Islet located

between the two extremes. The archaeological sites chosen for analysis here include two lagoonside

villages (MLEb-1 and MLEb-33) (Weisler 2001b) and a much smaller, shorter-term occupation site

(MLEb-31) on Moniak (Weisler 2002). Lagoonside deposits were explicitly selected at all three

sites to minimise diachronic effects on these analyses as they all represent a later phase of

Marshallese prehistory in which habitation sites occur adjacent to the lagoon, in contrast to earlier

phases where deposits are in the interior and associated with horticultural pits (Weisler 2001a:129).

The following description of mollusc and finfish habitats on oceanic atolls derives from: Carpenter

and Niem (1998), Demond (1957), Hiatt and Strasberg (1960), Kohn (1987) and Weins (1962). The

largest islets and widest reef platforms are on the leeward south-eastern, western and north-western

rim of Ebon Atoll. MLEb-1 and MLEb-33 lie in this zone, relatively sheltered from waves, winds

and currents and feature high-rugosity coral reefs, and fine grained inter-reefal sand flats and

seagrass beds on the lagoonside, and expansive, low relief pavements on the oceanside. Habitat

complexity is highest on leeward islets, with a corresponding increase in faunal diversity predicted

(Gratwicke and Speight 2005; Kohn and Leviten 1976). While mollusc taxa are generally sessile,

and strongly associated with particular benthic habitats, finfish taxa are more difficult to associate

with windward or leeward environments. Fish often track across multiple habitats with day/night

cycles, tides, and during feeding. However, some taxa are strongly associated with certain substrate

types, which vary in predominance between leeward and windward reef habitats as described

below.

Leeward oceanside mollusc communities are highly diverse, with colonies of macroalgae and

shallow tide pools hosting large numbers of cowries (Cypraeidae) drupes and other murex shells

(Muricidae) top shells (Trochidae), cone shells (Conidae) and nerites (Neritidae). These reef

platforms are also associated with large schools of parrotfish (scarids), surgeonfish (acanthurids),

wrasse (labrids), goatfish (mullids), and small bodied sharks (carcharhinids), and algal turfs provide

grazing for rabbitfish (siganids), sea chubs (kyphosids), butterfly fish (chaetodontids), acanthurids,

damselfish (pomacentrids) and triggerfish (balistids).

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The lagoonside reefs, seagrass beds and sand flats host communities of giant clams (Tridacna spp.

and Hippopus spp.), spider conchs (Lambis spp. and Harpago spp.) Conidae, mitre shells and auger

snails (Terebra spp. and members of the family Mitridae). The upper intertidal sand flats provide

habitat for the easily accessible sand dwelling bivalves including the violet asaphis (Asaphis

violascens), venus clams (Gafrarium spp.), cockles (Vasticardium spp.), ark clams (Arca spp.) and

surf clams (Atactodea striata). Areas of coral growth on the lagoonside are associated with diverse

herbivorous, carnivorous, and omnivorous fish communities including scarids, balistids,

chaetodontids, pomacentrids, moray eel (muraenids), squirrelfish and soldierfish (holocentrids),

grouper (serranids), snapper (lutjanids), labrids, filefish (monacanthids), and pufferfish

(tetraodontids).

MLEb-31 is located on a windward islet, which is smaller and generally more exposed to winds,

waves and currents. The intertidal zone is primarily composed of poorly sorted coral rubble washed

from the ocean facing subtidal reefs, wave cut erosional channels, and coarse, gravelly sands on the

lagoonside. Habitat complexity is generally lower on windward islets, with a decrease in richness

and diversity of mollusc and fish communities predicted (Gratwicke and Speight 2005; Kohn and

Leviten 1976). Mollusc communities characterised by large and robust Turbo, drupes (Drupa spp.),

Cypraeidae, Conidae, vase shells (Vasum spp.), polished nerites (Nertia polita) and frog shells

(Bursa spp.). Finfish communities on windward islets are varied and complex, but taxa

characteristic of exposed surge channels include muraenids, carcharhinids, hawkfish (cirrhitids),

serranids, lutjanids, acanthurids, pomacentrids, labrids, scarids, combtooth blenny (blenniids), and

balistids.

The following analyses are based on all fish bone and mollusc shells retained in the 6.4 mm screens

from lagoonside deposits on Ebon Atoll; Test Pit (TP) 17 to 20 at site MLEb-1, TP 2 to 6 at site

MLEb-31 and TP 2 and 8 at site MLEb-33 (Figure 1). A single unit from each site—MLEb-1 (TP

17), MLEb-31 (TP 2) and MLEb-33 (TP 8)—was sieved with 3.2 mm screens during the 2011/12

fieldwork. All excavated sediments were wet-sieved. Hereafter, the single-unit sub-samples of fish

bones recovered from nested 3.2 mm and 6.4 mm screens are described as the 3.2 mm samples.

MLEb-1

MLEb-1 is located at the centre of a ~2 km long village system on Ebon Islet (Weisler 2002). Ebon

Islet is the largest islet of the atoll, featuring high-rugosity coral reefs and sand flats in the lagoon

intertidal and expansive, relatively calm intertidal reef flats on the oceanside (Figure 1a). Cultural

138

material, including molluscan remains, fish bone, charcoal, oven (um) stones and worked shell

artefacts were recovered from a 2 x 2 m unit (TP 17, 18, 19 and 20) excavated into a low mound,

built by the accumulation of successive coral pavements, located 40 m inland of the current lagoon

shore and 20 m northwest of the Primary School. Cultural deposits extend to a depth of 1.75 m.

Cultural material retained in the 6.4 mm screens yielded 3464 fragments of mollusc shell (MNI

[Minimum Number of Individuals] = 1258), and 4188 fish bones (MNI = 509), with 94.1% and

39.3% of fragments, respectively, identified to family, genus or species. The 3.2 mm fish bone

samples (TP 17) yielded a NISP (Number of Identified Specimens) of 2655 (MNI = 378), with

14.4% of fragments identified to family, genus or species.

MLEb-33

Situated on Enekoion Islet, MLEb-33 is a sparse to dense midden deposit surrounding a large aroid

pit situated from 100 m to 25m from the lagoon shore. A 1 x 2 m trench was excavated on the

lagoonward side of the aroid pit where cultural deposits extended to 40 cm below surface. The

oceanside reef flat is generally wider than at Ebon or Moniak, but is mainly composed of coral

rubble, boulders and eroded beachrock slabs, more similar to the exposed reef flat of Moniak than

Ebon Islet. The lagoonside environment features expansive seagrass meadows (Thalassia spp.,

Figure 1b) and sand flats, and some coral growth in the intertidal, similar to the lagoon

environments at Ebon Islet. Cultural material retained in the 6.4 mm screens yielded 617 fragments

of mollusc shell (MNI = 230), and 144 fish bones (total MNI = 67), with 96.8% and 60.5% of

fragments, respectively, identified to family, genus or species. The 3.2 mm fish bone samples (TP

8) yielded a NISP of 98 (MNI = 34), with 20.1% of fragments identified to family, genus or species.

MLEb-31

The small midden site MLEb-31 is located ~75 m from the lagoon shore on the windward islet of

Moniak (Weisler 2002). Cultural deposits extend to a maximum depth of 70 cm. The oceanside

intertidal is characterised by coral boulder ramparts and cobbles deposited by extreme weather

events (Figure 1c), in contrast to the relatively protected oceanside of Ebon and Enekoion Islets.

The lagoonside sands of Moniak are coarse and the shore declines steeply to the lagoon floor.

Cultural material retained in the 6.4 mm screens yielded 1740 fragments of mollusc shell (MNI =

650), and 1084 fish bones (MNI = 326), with 95% and 53.5% of fragments, respectively, identified

to family, genus or species. The 3.2 mm fish bone samples (TP 6) yielded a NISP of 648 (MNI =

192), with 20.4% of fragments identified to family, genus or species.

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Methods

Identification and quantification protocols

Fish remains were identified by Lambrides and mollusc remains by Harris; all identifications were

completed to the lowest taxonomic level using Indo-Pacific comparative reference collections

housed at The University of Queensland archaeology laboratory (see Lambrides & Weisler 2015: 5;

Weisler 2001b: appendix 3, for a description of the fish reference collection). Reference manuals

were also used for molluscan identification, including: Abbott and Dance (1990), Poppe (2008),

Röckel et al. (1995) and Burgess (1985). Due to the richness of Indo-Pacific marine fauna, all fish

bone (see Lambrides & Weisler 2013) and mollusc shell fragments were attempted for

identification, but lower order taxonomic identifications (e.g. genus and species) were assigned with

caution to avoid over-identification (Driver 1992; Wolverton 2013). Taxonomic abundance of

archaeological fish bone and mollusc shell were quantified by NISP and MNI. For fish remains,

MNI values were calculated following standard zooarchaeological protocols for vertebrate fauna

(Grayson 1984; Lyman 2008; Reitz & Wing 2008) and for molluscs following Harris et al. (2015).

The quantification methods used here allow comparison of fish and mollusc taxonomic abundance

as MNI values were consistently determined using the most frequently occurring Non-Repetitive

Element (NRE).

Statistical analyses

Both mollusc shell and fish bone samples were aggregated at the site level. The NRE frequency for

each taxon was summed by cultural layer for calculating MNI. Relative taxonomic abundance is

used here to examine differences in the taxonomic composition of fish bone and mollusc shell

assemblages from the three sites to explore the interaction between windward vs. leeward islets,

local environment and the extraction of marine fauna. A range of statistical tests were utilised

including taxonomic richness and diversity as measured by NTAXA, the Shannon-Weiner index of

diversity (H’), Shannon’s evenness (E), Simpson’s dominance (1-D), and Fisher’s α. Similarity and

difference in faunal composition was analysed using chord distance analysis, and correspondence

analysis (CA). These statistics have proven utility for examining similarities and differences in

taxonomic composition for archaeological assemblages, including faunal (Faith 2013) and

archaeobotanical samples (Wright et al. 2015). All statistical analyses reported below were carried

out using MNI values for comparability with other Pacific Island assemblages, but it should be

noted that statistical analyses of NISP values were tested and revealed similar trends (Grayson

1984; Lyman 2008). All statistical analyses were completed using PAST Paleontological Statistics

Package, version 3.06 (Hammer et al. 2001).

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Species richness (the number of species in an analytical unit) was assessed using NTAXA.

Evenness, being the relative abundance of species in the assemblage, was measured using the

Shannon-Weiner index of diversity (H’) and Shannon’s evenness (E). H’ values range between 0

and a theoretical maximum of 5, but values between 1.5 and 3.5 are most common. Higher H’

values indicate greater species diversity and richness. E values range between 0 and 1, with 0

indicating assemblages dominated by a single taxon, and values closer to 1 indicating rich, even

assemblages (Lyman 2008: 195; Reitz & Wing 2008: 111). The dominance of few species in the

assemblage was assessed using Simpson’s index of diversity (1-D). 1-D values range from 0 to 1,

with lower values indicating assemblages dominated by a single taxon (Magurran 2004: 116).

Fisher’s α, a measure of diversity, was also utilised as Shannon’s indices and NTAXA can be

influenced by sample size (Faith 2013). Fisher’s α values are considered to be relatively

independent of sample size (Hayek & Buzas 2010: 295-296). Fisher’s α tracks the occurrence of

taxa represented by single individuals as a measure of overall diversity (Karlson et al. 2004).

Significant difference between diversity indices calculated for each sample were also carried out

using random permutation tests of relative abundance data.

Chord distance and exploratory CA analyses were conducted using non-aggregated (i.e. not

collapsed by NTAXA) relative abundance data. NTAXA quantifies richness by collapsing taxa at

the highest common taxonomic level for each assemblage. NTAXA values are generally correlated

with sample size and can be influenced by identification protocols, but do ensure richness values are

not inflated by species that are more easily identified to lower taxonomic levels. Chord distance

analysis is a scaled measure of Euclidean distance for examining the dissimilarity between samples

in relative abundance of species, such as sites or cultural units (Faith et al. 1987; Legendre &

Gallagher 2001). Chord distance values range from 0, indicating samples with no difference in

relative abundance, up to indicating no species in common between samples. Chord distance

values are useful measures of dissimilarity for the assemblages examined here, as species

represented by single individuals are not highly weighted.

This suite of statistical tests allows an exploration of the role of site location (windward vs. leeward

marine habitats) and site function (village vs. camp site) on the taxonomic composition of the

assemblages. Taxonomic measures of heterogeneity and chord distance are complementary analyses

which can be used to assess human collection strategies (i.e. non-selective or selective behaviours)

141

that are linked to local faunal community structure (i.e. number of species, dominance of particular

taxa, etc.) and site function. Correspondence analysis is used to further explore the relationship

between particular taxa, ecological variables, and site function, and provides useful data for

comparison with the results of the other statistical analyses used here.

Results

Figure 2 presents the relative abundance of mollusc and fish taxa identified from the 6.4 mm and

3.2 mm screened assemblages at sites MLEb-1, MLEb-31 and MLEb-33. To highlight broad trends

in taxonomic composition at each site, quantification data are aggregated at the family level.

Characteristic of Indo-Pacific marine archaeofaunas, many species are represented (e.g., Morrison

& Addison 2009; Ono & Intoh 2011; Riley 1987; Szabó 2009; Weisler 2001b). The molluscan

assemblage is dominated by gastropods (x = 84.2% MNI / 81.7% NISP), with bivalves

contributing minimally to MNI and NISP. Both 6.4 mm and 3.2 mm fish bone assemblages are

dominated by piscivores and omnivores/benthic carnivores, which account for 75.2 % and 84.4 %

of total MNI, respectively.

Taxonomic measures of heterogeneity for all samples report high richness and evenness and low

dominance overall (Table 2). Random permutation tests for significant difference between index

values at each site reported significant values only for 1-D values for molluscs between MLEb-1

and MLEb-31 (p = 0.0002) and E values for 3.2 mm fish bone samples from MLEb-1 and MLEb-31

(p = 0.0264). 1-D values are sensitive to differences in the relative abundance of the top ranked

taxa, explaining the significant result for mollusc samples. E values are sensitive to alterations in

the relative abundance of all taxa, once again explaining the significant difference reported for 3.2

mm fish samples from MLEb-1 and MLEb-31.

Chord distance was used to measure the dissimilarity between the relative abundance of taxa in

each assemblage. The greatest faunal dissimilarity as measured by chord distance was reported for

molluscan assemblages from site pairs MLEb-1/MLEb-31 and MLEb-1/MLEb-33. Minimal

dissimilarity was reported for the mollusc assemblage from MLEb-31/MLEb-33, 6.4 mm fish bone

assemblages from all site pairs and 3.2 mm fish bone assemblage from site pair MLEb-1/MLEb-31.

Moderate dissimilarity was noted for 3.2 mm fishbone assemblages from site pairs MLEb-1/MLEb-

33 and MLEb-31/MLEb-33. Chord distance analysis indicates that molluscan assemblages tend to

be more taxonomically dissimilar than fish bone assemblages across all site pairs, except for MLEb-

142

31/MLEb-33. Both taxonomic measures of heterogeneity and chord distance analysis indicate that

all assemblages were relatively similar in terms of richness, evenness, and relative abundance of

taxa, with the most pronounced differences generally between mollusc assemblages from MLEb-1

and MLEb-31.

CA of taxonomic abundance (6.4 mm data) was used to investigate whether differences in the

taxonomic composition of the assemblages as initially determined by the results of the diversity

measures, and chord distance, was better explained by local ecological variability (windward vs.

leeward marine habitats) or site function (village vs. camp site). Figure 3a-c plots CA axis 1 and 2

for all samples, which account for 77.8% and 22.2% of the variance in taxonomic abundance,

respectively. Axis 1 discriminates between windward and leeward islets, with MLEb-1, on the most

leeward islet, reporting the lowest axis 1 score and MLEb-31, on the most windward islet, reporting

the highest axis 1 score. MLEb-33, which is moderately exposed to windward waves, currents and

wind, reports an intermediate axis 1 score. The negative axis 1 score that characterises MLEb-1 is

associated with 43 mollusc taxa and six fish taxa (Carcharhinus spp., Decapterus spp., Elagatis

bipinnulata, Ostraciidae, Sphyraena spp., and Thunnus spp.) that occur only at that site, and account

for 11% and 4.3% of total site MNI, respectively. MLEb-31 is characterised by positive axis 1

scores, and is associated with 34 mollusc taxa and a single fish taxon (Zebrasoma sp.) that occur

only at that site, and account for 7.7% and 0.3% of total site MNI, respectively. MLEb-33 is

characterised by negative axis 2 scores, and is associated with five molluscan taxa (Conus

leopardus, C. lividus, Corculum cardissa, Harpa spp., Periglypta spp.) that occur only at that site

(2.5% of total site MNI), but no distinct fish species. Axis 1 scores are negatively loaded by reef flat

pavement dwelling gastropod taxa, the most common habitat exploited for mollusc gathering at

MLEb-1 (Harris and Weisler 2016). Conversely, axis 2 scores are negatively loaded by sand-

dwelling gastropod and bivalve taxa. Interestingly, the extant lagoon environment adjacent to

MLEb-33 is predominately turtle grass (Thalassia spp.) beds and sand flats. Habitat proclivities are

more difficult to assess for the non-sessile fish but, generally, the representation of feeding

behaviours (piscivores, omnivores/benthic carnivores and herbivores) for non-distinct taxa were

broadly similar at each site. In contrast, the CA of 3.2 mm fish bone taxonomic abundance data

(Figure 3d) report similar levels of variance for both axis 1 and axis 2, 58.2 % and 41.8 %,

respectively. This suggests that there is less taxonomic similarity between sites than represented by

the 6.4 mm data, which is also reflected by the chord distance scores (Table 1). Similar to the 6.4

mm fish bone CA, distinct taxa from all sites only accounted for a small percentage of the

143

assemblage, specifically 5.6 % of total MNI. CA results reflect the substantially different rank

ordering of taxa at each site as represented by the 3.2 mm data.

Discussion

Spatial variation in marine subsistence as it relates to windward and leeward settlement patterns on

a single atoll has not previously been assessed in Pacific Island archaeology. A range of statistical

analyses were implemented using mollusc shell and fish bone relative taxonomic abundance data

reported from three habitation deposits on Ebon Atoll. All sites were located adjacent to the extant

lagoon shore, with one a temporary habitation site (MLEb-31), and the other two large villages

(MLEb-1 and MLEb-33).

The taxonomic composition of archaeological mollusc and fish bone assemblages from each site

evidenced a similar suite of families with assemblages characterised by highly rich and even

measures of taxonomic diversity, and no strongly dominant taxa, despite probable differences in

habitat complexity at each site. All mollusc assemblages are dominated by gastropods, with

bivalves contributing minimally to MNI. The dominance of gastropods is characteristic of

macrobenthic mollusc communities recorded for other atolls in the Marshall Islands (Kay &

Johnson 1987), potentially indicating a generalised molluscan foraging strategy at all sites (Harris &

Weisler 2016, Szabó 2009, Kirch 1982). Richness was generally greatest at MLEb-1, which is

unsurprising as this is both the largest sample, and from the most complex habitat (Gratwicke and

Speight 2005).

Mollusc assemblages at each site have relatively high ranks for nerites, muricids (Drupa spp. and

Thais spp.), Conus spp., Cerithidae, Cypraeidae, Turbo spp. and Asaphis violascens. Fish bone

assemblages recovered from the 6.4 mm screens are generally dominated by piscivorous species

(e.g., serranids, lutjanids and carangids) followed in rank order by omnivorous/benthic carnivorous

species (e.g., holocentrids, lethrinids and balistids) and herbivorous species (e.g. acanthurids and

scarids). Fish bone assemblages recovered from the 3.2 mm screens showed increased dominance

of omnivores/benthic carnivores (e.g., holocentrids, exocoetids and mullids) which may be related

to average fish bone size for these taxa, bone density and taphonomy. For fish bone assemblages

from the 6.4 mm screens, scarids and serranids are rank 1 and 2, respectively, at MLEb-1 and

MLEb-31, and rank 2 and 3 at MLEb-33. However, the 3.2 mm samples, while similar in

taxonomic composition, showed greater variation in the rank ordering of these taxa when compared

144

to the 6.4 mm samples, similar trends were noted from Rapa Islands archaeological sites, where 2

mm screens were utilised (Vogel and Anderson 2012).

Mollusc assemblages reported generally greater inter-site variation in taxonomic abundance than

fish bone assemblages. The statistical analyses utilised here indicate variation in relative taxonomic

abundance of mollusc assemblages is due to differences in the local environment at each site. At

MLEb-1, the majority of the molluscan assemblage could have been gathered from the oceanside

reef flat and coral reefs (Harris & Weisler 2016). Conversely, CA shows that those molluscan taxa

that prefer sandy lagoon substrates are most strongly associated with MLEb-33, a marine

environment today which is characterised by large lagoonal sand flats and turtle grass beds.

Furthermore, assemblages at MLEb-31 consist principally of those taxa which either inhabit the

boulder ramparts, typical of windward islets (i.e., Nerita polita), or those taxa which are suitably

adapted to constant exposure to wind, waves and currents on the reef edge (i.e., Mauritia

mauritiana, Vasum turbinellus, and Thais armigera). The variability in the relative abundance of

Nerita plicata, Nerita polita and the ranellids (Monoplex intermedius, Monoplex nicobaricus and

Gutturnium muricinum) likely explains the significant difference in measures of dominance

between molluscan assemblages from MLEb-1 and MLEb-31. This result also potentially indicates

the influence of local environment, as Ranellidae are most common in areas of coral growth (Govan

1995), which are characteristic of Ebon Islet (MLEb-1), but are rare at Moniak (MLEb-31). The

correlation between local environment and the molluscan taxa in the assemblage, in addition to the

even, rich and diverse taxonomic composition indicates that a non-selective foraging strategy,

mediated by local environment, operated at each site. These patterns are broadly similar to mollusc

assemblages from other oceanic islands where richness and evenness are high, and taxonomic

composition varies predominately with changes in site location and local environment (e.g. Szabó

2009).

Fish bone assemblages, however, generally have lower values of dissimilarity between sites and are

harder to link to marine environments adjacent to each site because fish track across different

habitats while foraging, unlike molluscs that are generally sessile. For example, Katsuwonus

pelamis, a pelagic-oceanic dwelling species, is dominant at the largest village site, MLEb-1 but rare

at the campsite, MLEb-31 indicating that variation in fish bone assemblages may be related to site

function rather than the marine environments adjacent to the sites. This trend requires further

analysis (e.g. assessment of temporal variation and inclusion of additional sites), but could relate to

a number of variables, including settlement patterns and fish capture strategies operating at each

145

site. Variability in inter-site taxonomic composition for 3.2 mm samples was generally greater than

6.4 mm fish bone assemblages. Mesh size has been linked to alterations in species richness and

diversity (e.g., Nagaoka 2005; Ono & Clark 2012) and inferences made regarding capture methods,

morphometric reconstructions of fish size, ontogenetic growth and associated live fish behaviour

can be useful for predicting fishing technology (Bertrando & McKenzie 2011).

Conclusion

Exploratory data analyses were implemented to determine whether there are differences and/or

similarities in the taxonomic composition of mollusc shell and fish bone assemblages from three

archaeological sites situated on windward and leeward islets at Ebon Atoll, Marshall Islands.

Results indicate broad similarity in assemblage composition, reflected in similar richness, evenness

and dominance scores at each site, regardless if the sites were small intermittently occupied

habitations on windward islets or large villages on leeward islets. Where variation in taxonomic

composition occurs, the configuration of marine environments at each site may account for much of

the differences in the mollusc assemblages, while fishing technology (capture techniques) and site

function (i.e. village sites v. campsites) could account, in part, for the variation in fish bone

assemblages at each site. Intra-islet variation in taxonomic abundance, metric analysis of fish bone

to assess body size over time and possible effects of human impacts to marine fisheries, studies of

associated material culture and temporal analysis of alterations to foraging strategies will provide

additional datasets for testing the influence of local marine environments and human settlement

patterns on relative taxonomic abundance of mollusc shell and fish bone assemblages from Ebon

Atoll.

This study has shown that even within a single atoll, human foraging patterns can differ over small

spatial scales. The observed patterns follow documented evidence from other Pacific Islands where

molluscan assemblages broadly reflect local environmental conditions. In contrast, fishbone

assemblages possibly reflect capture methods and site function. The results presented here highlight

the importance of atolls for examining the dialogue between human behaviour and local marine

environments when investigating long-term trajectories of human-environment interaction.

Assessing variation in the composition of archaeofaunal assemblages from windward and leeward

islets can yield useful information for understanding variation in settlement patterns and intra-atoll

subsistence practices—the latter previously not recognised. These intra-atoll analyses are critical for

assessing variability in marine subsistence practices and are applicable to other island types across

the Pacific.

146

Acknowledgements


to Weisler by the Historic Preservation Office, Ministry of Internal Affairs and on Ebon Atoll,

former mayor Lajan Kabua. Marshall Islands fieldwork was supported by a grant to Weisler from

the Office of the Deputy Vice Chancellor (Research), University of Queensland. Harris’ and

Lambrides’ postgraduate studies are supported by an Australian Postgraduate Award.

147

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Figures and Tables

Table 1 Chord distance values for mollusc shell and fish bone assemblages retained in the 6.4 mm and 3.2 mm sieves for each site pair.

6.4 mm samples 3.2 mm samples

Site Pair molluscs fish bone fish bone

MLEb-1/MLEb-31 1.085 0.463 0.481 MLEb-1/MLEb-33 1.045 0.538 0.732 MLEb-31/MLEb-33 0.373 0.566 0.741

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Table 2 Measures of taxonomic heterogeneity: NTAXA, Shannon's index of diversity (H') and evenness (E), Simpson's dominance (1-D) and Fisher’s α, as calculated for mollusc shell and fish bone assemblages retained in the 6.4 mm and 3.2 mm sieves for all sites (MLEb-1, MLEb-31 and MLEb-33). 6.4 mm samples 3.2 mm samples

Index molluscs fish bone fish bone MLEb-1 MLEb-31 MLEb-33 MLEb-1 MLEb-31 MLEb-33 MLEb-1 MLEb-31 MLEb-33

NTAXA 47 37 26 27 25 18 29 25 18 1-D 0.887 0.859 0.869 0.921 0.926 0.909 0.936 0.940 0.919 H’ 2.648 2.528 2.512 2.780 2.822 2.605 2.968 2.972 2.705 E 0.687 0.700 0.711 0.844 0.877 0.901 0.881 0.923 0.936 Fisher’s α 9.631 8.508 7.534 6.803 6.306 8.071 7.316 7.670 15.51

155

Figure 1 Map of the Republic of the Marshall Islands, with Ebon Atoll and the location of sites MLEb-1, MLEb-31 and MLEb-33, and photos depicting intertidal marine habitats characteristic of each islet (a) Ebon Islet oceanside, view northwest showing expansive reef flat (Photo: A. Lambrides), (b) Enekoion Islet lagoonside, view northeast showing seagrass beds in the intertidal (Photo: M. Harris), (c) Moniak Islet oceanside, view east of coral cobble and boulder intertidal (Photo: M. Weisler).

156

Figure 2 The percent contribution to total MNI and NISP by taxon, site and screen for mollusc shell, 6.4 mm samples and fish bone 6.4 mm and 3.2 mm samples. Family level identifications, but note Selachii (modern sharks), which is a superorder/clade

157

Figure 3 Correspondence analysis of taxonomic abundance. (a) 6.4 mm bivalve shell, (b) 6.4 mm gastropod shell and (c) 6.4 mm fish bone samples are displayed on separate plots for clarity, (d) 3.2 mm fish bone samples. Key taxa are annotated and distinct taxa are not displayed due to minimal contribution to total MNI at each site.

158

Chapter 6: Two millennia of mollusc foraging on Ebon Atoll, Marshall Islands: sustained

marine resource use on a Pacific atoll.

Note: This is the final version of a peer-reviewed article published in Archaeology in Oceania





159

Abstract

Small, remote islands, such as low coral atolls, with nutrient-poor, biogenic soils for food crops and

vulnerability to extreme weather, have long been considered marginal environments for human

habitation. Yet, four decades of archaeological research in the atoll archipelago of the Marshall

Islands, eastern Micronesia have demonstrated sustained human occupation there for over two

millennia. Here, we present a fine-grained analysis of mollusc remains from four recently excavated

archaeological sites (4476 total MNI/ 14843 total NISP) combined with mapping and analysis of

extant benthic habitats, on Ebon Atoll, Marshall Islands. We examine spatial and temporal

variability in mollusc foraging practices from prehistoric village sites and ephemeral campsites

across the windward-leeward exposure gradient. Our analysis demonstrates that foragers targeted a

rich assemblage of taxa from different habitats, reflecting a foraging strategy that was adapted to

local environmental conditions. Human foraging over 2000 years documented no observable human

impacts to molluscs or nearshore intertidal marine ecosystems, challenging previous notions of

atolls as marginal, exceptionally difficult settings for human habitation.

Keywords: archaeomalacology, shell midden, human impacts, Pacific Islands archaeology,

intertidal ecosystems.

160

Introduction

Coral reefs provided critical resources to the inhabitants of the Marshall Islands during the

prehistoric period, but the long-term patterns of human behaviour and potential impacts to these

environments as a result of mollusc foraging has not been well studied. The coral reefs of the

Republic of the Marshall Islands (RMI) were considered to be in good condition about 10 years ago

relative to global patterns of reef decline (Beger et al. 2008:412; Hughes et al. 2003;), but a range

of anthropogenic stressors threaten these ecosystems (Houk and Musburger 2013). Rapid growth in

human populations along coastlines during the last century has resulted in substantial impacts to

intertidal marine environments, especially coral reefs (Brander et al. 2010). These stresses reduce

biodiversity and cause substantial negative impacts to the communities that depend on coastal

environments for subsistence, shoreline protection, water quality, lifestyle, and personal and

cultural identity (Brander et al. 2010:65; Cinner 2014). The reefs of the Marshall Islands host at

least 1655 mollusc species, and ~860 fish taxa (Richmond et al. 2000) that provide critical

economic resources. Archaeological research has demonstrated that Marshall Islanders exploited

marine resources for subsistence and raw materials since colonisation about 2000 years ago (Dye

1987a; Kayanne et al. 2011; Weisler 1999a, 2000), with little negative impact (Lambrides and

Weisler in press; Weisler 2001b). However, the long-term patterns of mollusc foraging in these reef

habitats is not well understood, especially as it relates to potential human impacts to coral reef

ecosystems. Hayashida (2005:45) and other researchers have stressed the importance of historical

data for understanding the current state of ecosystems due to the time-lag between disturbance and

ecosystem change (Alleway and Connell 2015; Rick and Lockwood 2013).

Nearly four decades of archaeological research in the Marshall Islands has revealed a sequence of

occupation that begins soon after atoll emergence, likely some time just before 2000 BP (Dye

1987a; Riley 1987: Table 2.28, Kayanne et al. 2011; Weisler 1999a, 2001a, 2001b; Weisler et al.

2012). In 1993, Weisler commenced an interdisciplinary project documenting the variability in

colonisation dates, marine and terrestrial subsistence practices, and human impacts across the north-

south rainfall gradient in the archipelago. As part of this project, Weisler (2001b) synthesised data

on mollusc foraging in Marshallese palaeoeconomies, and broad foraging preferences and the

differences in faunal assemblage composition at windward and leeward sites have also been

explored (Harris et al. 2016; Harris and Weisler 2016). For the first time, we present a fine-grained

spatio-temporal analysis of mollusc remains from recent archaeological excavations on Ebon Atoll,

Marshall Islands. We examine mollusc assemblages from four archaeological sites representative of

the major environmental and settlement types on atolls (windward/leeward and

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permanent/ephemeral occupation). Our diachronic analysis, spanning two millennia of human

occupation, examines long term human interaction with the marine environment and also

investigates potential human impacts to the intertidal zone.

Traditional Marshall Islands Economy

Atolls consist primarily of unconsolidated sediments forming atop a narrow reef platform that

surrounds a lagoon formed through the development of fringing reefs around a subsiding volcanic

island. These landscapes have been considered marginal and difficult for sustained human

habitation due to a lack of standing fresh water and only nutrient-poor biogenic soils for the

cultivation of food crops (Fosberg 1954). However, the subterranean Ghyben-Herzberg freshwater

lens has been utilised for pit-cultivation of giant swamp taro (iraij, Cyrtosperma chamissonis) since

colonisation (Weisler 1999a). Arboriculture including varieties of pandanus (bob, Pandanus

tectorius), as well as coconut (ni, Cocos nucifera), breadfruit (ma, Artocarpus altilis), and the low-

lying arrowroot (makmok, Tacca leontopetaloides) were also cultivated during the prehistoric

period and continues to the present.

Marshall Islanders are accomplished seafarers, with frequent prehistoric interisland contact

suggested by a single language spoken across the entire archipelago encompassing 2 million km2,

with only minor, mutually intelligible dialect differences in the Ratak (eastern) and Ralik (western)

island chains (Bender 1969:xii-xiii). There are more than 100 different Marshallese words

describing fishing techniques, shell taxa, and the intertidal zone (Merlin et al. 1994) attesting to a

deep and intimate knowledge of marine ecosystems (Abo et al. 1976:361-362, 453-454). The iroj

(chief) sometimes restricted access to the reef, known locally as mo, which may have been invoked

to conserve resources (Sudo 1984:208). Although birds and dogs contributed to the diet, the major

source of protein was from the sea, with the intertidal zone utilised for , fishing and mollusc

foraging. Archaeological deposits in the RMI indicate continuous exploitation of molluscs and

finfish over the course of human occupation on Utrok, Ujae, Arno, Majuro and Ebon Atolls (Dye

1987b; Harris and Weisler 2016; Riley 1987; Weisler 1999b, 2001b), with most assemblages

consisting of a rich, even, and diverse range of taxa. Weisler (2001b:116) documented no

indications of human impacts to molluscs on Utrok Atoll, inferred to be the result of low human

populations and expansive reef flats. There is also no evidence for adverse prehistoric human

impacts to finfish resources (Lambrides and Weisler in press; Weisler 2001b).

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Sites and Samples

We focus on excavations from four archaeological sites on Ebon Atoll: prehistoric village sites

MLEb-1 and MLEb-5 on Ebon Islet, MLEb-33 on Enekoion Islet, and an ephemeral campsite,

MLEb-31, on Moniak Islet (Figure 1). All deposits were excavated in arbitrary 10 cm spits within

stratigraphic layers. Although sediments of selected units were wet-sieved through 3.2 mm mesh,

mollusc remains analysed here were wet screened through 6.4 mm mesh. Water worn shell, samples

with evidence of clionid sponge adherence to the interior of the shell, or samples exhibiting other

forms of damage indicating secondary deposition were not retained for analysis. The few gastropod

specimens (< 1%) showing evidence of hermitting were excluded from analysis. All samples were

cleaned of sediment prior to identification and quantification. Smaller taxa such as Melampus

flavus, Planaxis sulcatus, and Ctena bella are included in the following analyses as they may

represent areas of the littoral environment that were accessed by foragers while collecting other

taxa, and are useful for characterising the assemblage.

Archaeological deposits on Ebon Atoll villages generally consist of gravelly sand layers, the

product of reworked coral gravel pavements, deposited atop sterile sands representing the original

ground surface prior to human habitation. Ephemeral or short-term occupation campsites lack coral

gravel pavements, while agricultural trenches have sparse midden and occasional combustion

features. Agricultural trenches sometimes revealed a buried A horizon that was covered with spoil

during the initial excavation of aroid pits (Weisler 1999a). Cultural material at all sites consisted

primarily of fish bones, mollusc shells, shell artefacts, and combustion features. We present five

AMS radiocarbon age determinations on coconut endocarp and Pandanus drupe that were

calibrated to two standard deviations using the IntCal09 curve and the OxCal program (Reimer et

al. 2009). The details of all chronometric dates from Ebon Atoll will be presented elsewhere

(Weisler et al. in prep.).

Ebon Islet

MLEb-1 is located centrally within the ~2 km long prehistoric village near the lagoonside of Ebon

Islet. This village system consists of several archaeological sites and associated aroid pits, and is

currently the major population centre of the atoll. A single test pit (TP 6) and three larger

excavations (TP 17 – 20, TP 8 – 12, TP 13 – 16) totalling 14 m2 were conducted along a transect

from the lagoon shore to the interior aroid pits. A 2 m × 2 m area excavation (TP 17 – 20) was

positioned 20 m north-west of the primary school and 40 m inland of the lagoon shore on a low

mound primarily built from successive coral gravel pavements. Cultural deposits extended to 1.75

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m. Radiocarbon age determinations from Layer IIIA on coconut endocarp from the base of the

lowest cultural deposits in TP17 and TP 19 indicate initial occupation here sometime after 925-790

cal BP ( 940 ± 25 BP OZP-927). TP 6 is located 150 m inland of the lagoon, within an area

previously identified as an early occupation site (Weisler et al. in prep.). Cultural deposits extended

to 1 m and included mollusc remains, charcoal, um or oven stones, and prehistoric artefacts. A

single radiocarbon date from TP 6, Layer IIIA revealed a basal age of 1895 – 1730 cal BP (1890 ±

30 BP, OZP925). Additional excavations of two trenches excavated across the spoil heap of aroid

pits, with a 1 × 5 m trench (TP 8 – 12) located 185 m inland of the lagoon and TP13 – 16 located

250 m from the lagoon. Cultural deposits were relatively shallow, with material located to 0.23 m

deep in TP 8 – 12 and 0.30 m at TP13 – 16. A radiocarbon date from the base of TP 15 yielded a

date of 460 – 295 cal BP (300 ± 25 BP, OZP926).

MLEb-5 is located ~650 m southeast of MLEb-1. A 3 m × 5 m unit (TP 1, 13, and 15-27) was

excavated into a low mound 120 m from the lagoon shore. Cultural deposits extended to a depth of

0.5 m, totalling 8.25 m3. The earliest dates for the atoll were encountered at MLEb-5, with initial

occupation of the mound at 2295 - 1995 cal BP (2115 ± 30 BP, OZP932). Cultural material

included coral gravel spreads, charcoal, um stones, primarily fish and molluscs, but also human

remains, and shell artefacts.

Enekoion Islet

A prehistoric village site (MLEb-33) was located on Enekoion Islet. We analysed mollusc

assemblages from six test pits excavated around a large (~236 m2) aroid pit between 25 m and 100

m from the lagoon shore. Here, TP 1, 6, and 7 are aggregated due to proximity and to maximise

sample size. Units 2 and 8 form a contiguous 1 m × 2 m trench, but TP 3 is analysed individually.

Cultural material from MLEb-33 consisted of mollusc remains, fish bone, worked shell artefacts,

coral gravel spreads, and um stones. Cultural deposits were relatively shallow, extending to a

maximum depth of 0.4 m in TP 2 and 8. A single radiocarbon age determination from an oven, 27

cmbs (centimetres below surface) in TP1 yielded a date of 505 - 315 cal BP (370 ± 30BP, OZP318

BP).

Moniak Islet

Previous excavations by Weisler had located cultural deposits at MLEb-31 indicating a relatively

small site occupied for short periods of time for acquiring seabirds, intertidal foraging for molluscs,

and as a place for staging fishing sorties (Weisler 2002). During the 2011-2012 field season, four

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test pits (TP 2 – 6) were excavated over an area between 55 m and 125 m from the current lagoon

shore. Cultural deposits extended to 0.70 m, interrupted between 20 – 45 cmbs by a culturally

sterile storm deposit. Large storm events are historically recorded for the atoll, with a large typhoon

that occurred during the 1850s causing widespread food shortages and damage to horticulture

(Mason 1950).

Habitat Mapping Methods and Description of Marine Habitats

Atoll environments are dynamic and the configuration of intertidal habitats can vary over short time

scales, but modern marine habitats adjacent to archaeological sites on Ebon (MLEb-1 and 5),

Enekoion (MLEb-33), and Moniak (MLEb-31) islets provide useful comparative data for

understanding prehistoric subsistence practices. Benthic habitat maps were generated using

protocols outlined in Kendall et al. (2012). The minimum mapping unit (MMU) is the minimum

size of a single feature (e.g. area of sandy bottom, patch of coral) for delineation. The MMU size

can influence landscape metrics as well as indices of heterogeneity and diversity (Kendall and

Miller 2008;). Broadly, a smaller MMU will more effectively capture diminutive and rarer habitats,

where larger MMU will merge these smaller habitats into broader categories, sacrificing some

analytical resolution (Kendall & Miller 2008). We adopted a minimum mapping unit (MMU) of

1000 m2 to align with existing maps of Majuro Atoll (Kendall 2012, Kendall & Miller 2008) and to

account for the lack of in situ calibration data. High-resolution (e.g. 100 m2 MMU) differences in

habitat structure are not necessary when broad characterisation of extant marine environments is the

aim for archaeological hypothesis testing. All maps were digitised at 1:2500 scale, providing a

balance between map detail and expediency (Kendall et al. 2001:38). Orthorectification for all

satellite imagery was fixed as imagery was generated by the Arc2Earth plugin for ArcGIS. Village

structures and paths present in the 1995-1996 and 2011-2012 field seasons were used as ground

control points for site and test pit locations. The relative areas of each habitat mapped within a 2 km

radius of each study site are presented in Appendix A. Below we summarise the major differences

between islets, noting common mollusc taxa and report the Shannon-Wiener index of diversity (H’)

for each mapped area.

Habitats on each islet broadly reflect the degree of exposure to winds, waves, and currents (Figure

2). Habitats adjacent to MLEb-1 and MLEb-5 on the largest islet (~2.2 km2) of Ebon were the most

diverse (MLEb-1, H = 2.663; MLEb-5, H = 2.557) of the mapped sites. Diversity was marginally

lower at MLEb-33 on Enekoion Islet (H = 2.165) and least diverse at MLEb-31 on Moniak Islet (H

= 0.693). Ebon islet features relatively calm, expansive reef flat pavements that host a range of

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molluscs on the oceanside, characteristic of large, leeward islets (Kendall et al. 2012; Wiens 1962).

These pavements are colonised by macroalgae and feature shallow tide pools and sand channels that

commonly host Cypraeidae, Muricidae, Trochidae, Conidae, and Neritidae (Figure 2C). Enekoion

(MLEb-33), to the north, is moderately more exposed than Ebon, reflected in a large area of reef flat

rubble on the oceanside (Figure 2E). Moniak also features an expansive reef flat pavement, but

these habitats are more exposed to high-energy waves and are consequently scattered with coral

cobble and reef rubble. These habitats characteristically host predatory molluscs such as Conidae

and Muricidae, and Cerithiidae, Cypraeidae, and Trochidae. The spur and groove zone that occurs

oceanward of the reef flat habitats is expansive on Ebon, Moniak and Enekoion islets. These

habitats characteristically host Turbinidae, Drupa spp., and large Cypraeidae. An algal ridge is also

present on all three islets, just shoreward of the spur and groove topography, hosting Trochidae,

Turbinidae, and Drupa spp.

The lagoonside habitats of Ebon and Enekoion islets are a complex mosaic of large areas of live

coral, sand flats, and seagrass beds (Figure 2A-E). Patch reefs and aggregate reef account for a large

portion of mapped area for these islets, but were not present in mapped areas of Moniak Islet

(Supplementary Appendices A, B). The less complex habitats on Moniak are likely correlated with

a decrease in richness and diversity of mollusc communities compared with Ebon and Enekoion

(Gratwicke and Speight 2005; Kohn and Leviten 1976). Expansive seagrass (cf. Thalassia

hemprichii) beds are present in the upper- and mid-intertidal of Ebon and Enekoion lagoonside, but

are absent at Moniak. These habitats provide contemporary inhabitants of Enekoion Islet with

strombs, indicated by the frequency of discarded Conomurex luhuanus shells around the modern

village. Modern studies of I-Kiribati atoll dwellers have highlighted the importance of seagrass beds

for modern foraging activity and archaeological deposits from Palau and Majuro demonstrate that

this taxon was exploited prehistorically (Giovas et al. 2010; Riley 1987). The shoreline and high-

intertidal of Ebon and Enekoion is generally sand, where Moniak is primarily rocks and boulders

that slope upwards from the reef flat to the islet surface (Figure 2G). The sandy habitats of Ebon

and Enekoion host Asaphis violascens and Gafrarium spp., where the rocky shoreline of Moniak

offers habitat for Cerithiidae, Cypraeidae, Trochidae, Turbinidae, and Neritidae.

Methods of Mollusc Analysis

Molluscs were identified to the lowest possible taxonomic level using Indo-Pacific molluscan

reference collections housed at the University of Queensland Pacific Archaeology Lab, and

reference books and manuals (Carpenter and Niem 1998; Cernohorsky 1967; Poppe 2008).

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Identifications were based only on diagnostic features on individual fragments, rather than

assuming fragments derive from common taxa (Driver 2011; Szabó 2009; Woo et al. 2015). All

taxonomic nomenclature was verified following the World Register of Marine Species online

database (WoRMS Editorial Board 2015). The Number of Identified Specimens (NISP), weight

(recorded to the nearest 0.01g), and Minimum Numbers of Individuals (MNI) were recorded for all

taxa. MNI is used as the primary measure of relative abundance, with NISP and weight providing

comparative data for assessing taphonomic factors such as fragmentation and post-depositional

leaching of carbonate (Faulkner 2011; Giovas 2009; Szabó 2009). Metric analysis of major taxa and

meat-weight reconstructions (e.g. Allen 2012) were not undertaken as MNI, NISP and weights were

more appropriate measures for our analytical purposes. MNI was calculated according to the

protocols outlined in Harris et al. (2015). Non-repetitive element (NRE) frequency for each taxon

was summed from 10 cm spits aggregated to cultural layer prior to the calculation of MNI. As

stratigraphy was broadly continuous across MLEb-31 deposits, TP 2-6 were treated as a single

cultural deposit to increase sample size. All other test pits were analysed individually or as

aggregated deposits where units were contiguous.

Assemblage richness (the number of species in an analytical unit) was measured by collapsing

taxonomic categories to the highest common level (NTAXA) to avoid duplicate counts of

categories and to provide conservative estimates of richness. Taxonomic diversity and evenness was

measured using the Shannon-Wiener index of diversity (H’), Shannon’s evenness (E), Simpson’s

dominance (1-D), and Fisher’s α. H’ and E provide a measure of the number of individuals per

species in an analytical unit (taxonomic evenness). H’ values generally fall below a theoretical

maximum of 5, between 1.5 and 3.5, with higher values indicating greater species richness and

diversity. E values range between 0 and 1, with values closer to 1 indicating assemblages with a

rich and even composition (Lyman 2008:195). Dominance was measured using 1-D, where values

range between 0 and 1, with low values indicating dominance of a single taxon (Magurran

2004:116). Due to the sensitivity of H’ and E to sample size, Fisher’s α was used as values are

relatively sample size independent, tracking the number of taxa represented by only single

individuals to measure overall diversity. Statistical significance of alterations to these measures of

taxonomic heterogeneity was assessed using random permutation tests of relative abundance data.

Chord distance, a scaled measure of Euclidean distance, was used to analyse similarity and

difference in taxonomic composition between cultural layers (Legendre and Gallagher 2001). Chord

values range between 0 and , with higher values indicating increasing distance, or dissimilarity

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between samples. All statistical analyses were conducted using PAST Palaentological Statistics

Package, Version 3.14 (Hammer 2001).

Habitat preferences were explored using the methods outlined in Harris and Weisler (2016). This is

a probabilistic method for reconstructing forager behaviour that assigns mollusc taxa to habitat

categories using a hierarchical classification scheme for benthic habitats (Appendix B). We also

included an analysis of potential alterations to trophic networks and other indirect effects of human

foraging by assigning mollusc taxa feeding-habit and behavioural characteristics (Appendix C,

Tables 1- 5). All ecological data were drawn originally from the Neogene Marine Biota of Tropical

America Molluscan Life Habits Database (Todd 2001) and verified with appropriate literature if

necessary. Gastropod taxa are assigned to one of seven categories (Appendix C, Table 1) and as

either epifaunal or infaunal based on dominant mode of life. Bivalve taxa were assigned an

organism/substrate relationship, feeding type, mobility, and shell fixation method (Appendix C,

Table 2 - 5). Analysis of alterations to the relative abundance of taxa assigned to these categories

allows assessment of potential alteration to trophic networks due to human exploitation or other

factors. Only genus-level identifications were used for these analyses. Family-level identifications

were rare (3 % of total MNI), but introduce considerable uncertainty in foraging reconstructions

that potentially mask variation.

These statistical tests are used to assess the relationship between site location (e.g. windward v.

leeward, near lagoon v. interior), inferred site function (e.g. village or campsite), and the taxonomic

composition of mollusc assemblages from our four study sites on Ebon Atoll, Marshall Islands. For

the first time, these methods will also be used to assess temporal changes in human foraging of

molluscs in the southern Marshall Islands to assess long term patterning in human interaction with

the intertidal zone. Taxonomic measures of heterogeneity (H’, E, 1-D, Fisher’s α), chord distance,

and habitat representation are complementary analyses that allow a comprehensive characterisation

of assemblage variation (Faith 2013; Harris et al. 2016) and potential human impacts to mollusc

fauna and intertidal environments on Ebon Atoll over the last 2000 years.

Results

The Ebon Atoll mollusc assemblage (Table 1) is well preserved. Minimal chemical dissolution and

burning (< 1 %) of shell were noted for the sites analysed. Fragmentation measured by MNI/NISP

was moderate at 0.31, with many diagnostic fragments or complete mollusc shells recovered. A

total MNI of 4476 (14843 NISP) was reported from 199 taxonomic categories, with 119 to species,

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60 to genus, and 20 to family or subfamily (Appendix D). Gastropod taxa dominate, accounting for

81.8 % of total MNI (MNI 3822). Gastropod taxa are predominately epifaunal (80.1 % MNI)

predatory carnivores (33 % MNI) or herbivores on rock and rubble substrates (40.5 %). Bivalve

taxa are largely unattached (16 % MNI) infaunal siphonate taxa (13.7 % MNI). Archaeological

molluscs (Figure 3) are mostly taxa that inhabit the reef flat rocks and boulders (e.g. Nerita spp.,

Vasum turbinellus, Thais armigera), pavements (e.g. Nerita spp., Cerithium nodulosum, Conus

spp., Drupa spp., Monetaria moneta), and sand flats (e.g. Guturnium muricinum, A. violascens)

(Supplementary 4), but previous analyses have demonstrated that locally available habitats mediate

human selection on Ebon Atoll and that there is evidence of collection from a wide range of habitats

(Harris et al. 2016; Harris and Weisler 2016). Measures of taxonomic heterogeneity reported a

diverse and even assemblage overall (NTAXA = 49, H’ = 2.660, E = 0.683, 1-D = 8.914). Richness

is significantly correlated with sample size (rs = 0.67, p = <0.001). We present analytical summaries

of trends in measures of taxonomic heterogeneity, relative abundance of feeding types and mode of

life, and the habitats from which most of the taxa in the assemblage could have been collected.

MLEb-5

3m × 5m area excavation A large sample of 4401 NISP yielded an MNI of 988 from the only

cultural layer, Layer I. The assemblage was rich (NTAXA = 45), but reported low evenness for

Ebon Atoll deposits (Table 1) with low density overall (136.75 MNI/m3). The assemblage was

dominated by gastropods (72.1 % MNI), primarily Nerita plicata and N. polita (33 % of total MNI).

Major taxa aside from the nerites include A. violascens (MNI 108), Gafrarium spp. (MNI 65),

Conus spp. (MNI 62), and Cypraeidae (MNI 29). The range of taxa present indicate an emphasis on

collection of epifaunal, primarily herbivorous gastropod taxa from mid-intertidal and upper

intertidal habitats, including reef flat and shoreline rocks and boulders, reef flat pavements, sand

and rubble. The largest sample of Tridacna (primarily T. maxima) was recovered from this deposit

(MNI 42, NISP 698), accounting for 39 % of total MNI for Tridacna across all sites. This sample

was the most heavily fragmented of any Tridacna assemblage on the atoll (MNI/NISP = 0.04). The

only other deposit with comparably high fragmentation was from the other early period deposit on

Ebon Islet, MLEb-1, TP 6 (MNI/NISP = 0.11).

MLEb-1

TP 6 Molluscan samples from early deposits (Layers IIB – IIA) are small, with a total MNI of 25

and taxonomically even with low richness (Figure 4). In contrast with most Ebon assemblages that

are dominated by gastropods, most individuals from Layers IIB and IIA are infaunal bivalves

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derived from reef flat sands, with A. violascens and Gafrarium spp. accounting for 64 % of MNI.

The assemblage from Layer IB is similar, with a continued dominance (53.7 % MNI) of molluscs

from sand habitats, Gafrarium spp. and A. violascens. NTAXA and evenness increase with sample

size. Chord distance reported high dissimilarity (chord = 1.235) between Layer IB and the

uppermost cultural layer, IA. This is correlated with an increase in the relative abundance of Conus

spp., Nerita polita and V. turbinellus in Layer IA, with an overall increased abundance of taxa

derived from the reef flat pavement (52.3 % of MNI). Concurrently, there is an increase in the

abundance of carnivorous gastropods, accounting for 53.6 % of MNI compared with 20-36 % in

Layers IIB-IB.

TP 17-20 The largest sample of molluscs on Ebon Islet was recovered from TP 17-20 (Figure 5),

with a total MNI of 1273 (NISP 3597). Lower deposits (Layers IIB-IIA) are typically diverse, but

somewhat less even than most Ebon assemblages (Table 1). Three taxa, N. plicata, N. polita and A.

violascens account for 43.7 % of MNI in IIB and 40.7 % of MNI in IIA. Taxa from these relatively

early layers could have been gathered from the reef flat pavements (IIB: 57 % of MNI, IIA: 54.5

%), rocks and boulders on the reef flat (IIB: 53.5 %, IIA: 49.1 %) and shoreline (IIB: 41.9 %, IIA:

40.8 %), and reef flat rubble (IIB: 44.2 %, IIA: 49.9 %).

While reef flat pavements are highly represented in all layers, and N. plicata, N. polita, and A.

violascens are also highly ranked throughout, Layer IB to IA have an increased abundance of taxa

from coral habitats. In Layers IIB and IIA coral habitats account for 2.7 – 17. 4 % of MNI. In Layer

IB, reef flat coral habitats account for 32.8 % of MNI and peak in abundance in Layer IA,

accounting for 44.3 %. Across the four cultural layers, molluscs from shoreline rocks and rubble

decline from 41.9 % in IIB to 14.7 % in IA and taxa from seagrass beds increase from 11.6 % in

Layer IIB to 30.5 % in Layer IA, potentially indicating a development or expansion of these

habitats on the lagoonside, or a shift in foraging behaviour. A concurrent increase in predatory

carnivores driven by increasing abundance of Monoplex spp. and G. muricinum, marks layers IA

and IB as taxonomically quite different to earlier layers. Chord distance reported high dissimilarity

between Layer IIA and IB, and paired diversity permutation tests reported significant difference for

1-D, H and E between IIA/IB (1-D: p = < 0.01; H: p = < 0.01; E: p = 0.02) and IB/IA (1-D: p = <

0.01; H: p = 0.02; E: p = < 0.01). A chi-square test indicated a significant association between layer

and feeding type X2 (9, n = 1415) = 93.234, p = < 0.001, Monte-Carlo p = 0.0001, V = 0.14781.

Cramer’s V showed that the effect size was small to medium (Cohen 1988). Examination of

adjusted residuals showed that there were significantly greater numbers of predatory carnivores

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(CP) in IA and significantly more herbivorous (HR/HM) individuals in Layers IIA and IIB. These

trends also hold when herbivores and carnivores are collapsed to a binary carnivore or herbivore,

rather than the more detailed categories of CP, HO, HR, and HM.

Agricultural trenches (TP 8-16) Mollusc assemblages from the two agricultural trenches on Ebon

Islet had relatively small samples (TP 8-12: 47 MNI/141 NISP, TP13-16: 130 MNI/257 NISP) that

were rich, even, and diverse. Fragum fragum, N. polita, and A. violascens were top ranked in the

single cultural layer in TP 8-12, with 61.4 % of total MNI derived from reef flat sands. TP 13-16,

oceanward of TP 8-12, had increased abundances of taxa that could have been collected from reef

flat pavements in Layers A to I, with M. moneta, Conus spp., N. plicata, and Engina mendicaria

accounting for 17 % of MNI in Layer I and Bursa spp., V. turbinellus, Tridacna maxima, and C.

nodulosum accounting for 20 % of total MNI Layer A. The differences in taxonomic composition

are reflected in high dissimilarity as measured by chord distance (TP 8-12/A – TP 13-16/I = 1.122,

TP 8-12/A – TP 13-16/A = 0.910). Both trenches reported high abundances of epifaunal gastropods,

with bivalves more abundant in TP 8-12 than in TP 13-16, possibly due to the increased proximity

to the lagoonside sands.

MLEb-33

TP 1,6-7 The mollusc assemblage from the single cultural layer (Layer I) within TP 1, 6, and 7 was

dense (447.2 MNI/m3), rich, diverse, and even (Table 1, Figure 6). A total NISP of 1392 yielded

559 MNI. The five highest ranked taxa are N. polita (MNI 121), Fragum sp. (MNI 67), V.

turbinellus (MNI 45), N. plicata (MNI 43), and M. flavus (MNI 32). Most taxa in the assemblage

likely derive from rocks and boulders on the reef flat (57.4 % MNI) and shoreline (38.9 % MNI),

and reef flat pavements (38.2 % MNI). The majority of individuals are herbivorous gastropods

(50.3 % MNI) that live epifaunally. Predatory carnivores account for 25.8 % of MNI, primarily V.

turbinellus and Conus spp., characteristic of the rocky, exposed shorelines of the oceanside reef flat

of Enekoion Islet.

TP 2 and 8 N. polita, V. turbinellus, Conus spp., Turbo argyrostomus, and C. nodulosum constitute

62.3 % of MNI from TP 2 and 8 cultural deposits. The assemblage was generally rich and even

(Figure 6) with most taxa derived from reef flat and shoreline rocks and boulders, and reef flat

pavements (34.2 % – 44.2 % of MNI). Epifaunal herbivorous (48.5 % of MNI) and carnivorous

(35.9 % of MNI) gastropod taxa were typically most common.

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TP 3 A total of 331 MNI was recovered from only 0.2 m3, making this assemblage the densest

recovered from Ebon Atoll (1655 MNI/m3). Four gastropod taxa (C. nodulosum, Conus spp., V.

turbinellus, and N. polita) comprise 56.5 % of total MNI, reflected in relatively low evenness values

compared with other Ebon Atoll mollusc assemblages (H’ =2.4330, E = 0.756). Reef flat pavements

(67.1 % MNI) and shoreline rocks and boulders (49.2 % MNI) are the two highest-ranked habitats

(Figure 6).

MLEb-31

TP 2-6 The cultural layers of MLEb-31 (Figure 7) are divided by a storm deposit (Layers IC and

SD) that is delineated by large coral cobbles and coarse biogenic gravel dividing Layers IA and IB

from IIA and IIB. Assemblage composition was relatively static, with all cultural layers primarily

composed of epifaunal gastropods, with a generally even contribution of both herbivorous and

carnivorous taxa. Layers IIB and IIA report high relative abundance of N. polita, V. turbinellus,

Conus spp., A. violascens, and C. nodulosum, with these taxa accounting for 65 % of total MNI in

Layer IIA. These taxa are highly abundant in the layers proceeding the storm event, with the same

taxa accounting for 51.5 % of total MNI in IA, and 45.2 % in IB. Moniak assemblages reported

some of the lowest evenness scores for Ebon Atoll, but still represent a non-selective foraging

strategy as reflected in Fisher’s α and overall richness. The majority of taxa across all cultural layers

could have been gathered from the shoreline rocks and boulders and the reef flat pavement,

consistent with the results of previous analysis of this assemblage (Harris et al. 2016; Harris and

Weisler 2016).

Tests for human impact

Diversity permutation tests reported non-significant differences between cultural layers in all

contexts except for MLEb-1, TP 17-20, and MLEb-31, TP 2-6. Significant differences were

reported for MLEb-31 between layers with and without evidence of storm deposited molluscs.

Fisher’s α reported significant difference from cultural layers both above (Layer IB) and below

(IIA) the storm deposit layers (SD/IC). These differences in Fisher’s α reflect that almost all taxa in

the storm deposit layers are represented by only a single individual. Results from MLEb-1 indicate

significant differences between cultural layers for 1-D, H and E between Layers IA-IB (1-D: p = <

0.01; H: p = 0.02; E: p = < 0.01) and Layers IB-IIA (1-D: p = < 0.01; H: p = < 0.01; E: p = 0.02).

Overall, chord distance reported moderate dissimilarity between cultural layers (x = 0.924). The

greatest dissimilarity between cultural layers were reported for MLEb-1, TP 17-20 between Layers

172

IIA and IB (Chord = 1.187), MLEb-1 TP 6 IIA-IB / IB – IA (Chord = 1.236 / 1.235). The high

chord distance values for TP 17-20 correlate with the general shift in species abundances and

assemblage composition between upper and lower strata. At MLEb-31, high chord distance values

were reported for layers above and below the storm deposits, but this is likely due to sample size

changes between layers, rather than reflecting assemblage composition overall. In addition, a chi-

square test indicated a significant association between layer and feeding type at both MLEb-1 (X2

(9, n = 1415) = 93.234, p = < 0.001, Monte-Carlo p = 0.0001, V = 0.14781) and MLEb-31 (X2 (15,

n = 829) = 32.86, p = 0.005, Monte-Carlo p = 0.007, V = 0.11495). Cramer’s V showed that the

effect size was small to medium in both cases (Cohen 1988). For MLEb-1, examination of adjusted

residuals showed that there were significantly greater numbers of predatory carnivores in IA and

significantly less in Layers IIA and IIB. Additionally, in Layers IIA and IIB there were significantly

more herbivores on rock, rubble or coral substrates, and more herbivores on fine-grained substrates.

At MLEb-31, examination of residuals showed that there were significantly greater numbers of

herbivorous omnivores in IB, just after the storm deposits and significant numbers of greater

predatory carnivores in Layer IIB, the earliest cultural layer prior to the storm event.

Discussion

Temporal and spatial trends in mollusc foraging

Previous analyses (Harris et al. 2016; Harris and Weisler 2016) have demonstrated that site-level

taxonomic composition of mollusc assemblages on Ebon Atoll is broadly reflective of a fine

grained, non-selective foraging strategy mediated by the availability of taxa in marine habitats

adjacent to archaeological sites and differences in local habitat according to the windward-leeward

exposure gradient. The analysis presented here supports these results, demonstrating that these

foraging practices can be inferred for most of the sequence. Ebon assemblages from early period

through late deposits are rich, even, and diverse. The taxa broadly represent local habitats, though

additional palaeoenvironmental and geomorphological data are necessary to reconstruct the

configuration of marine habitats at the time of initial colonisation. Here, analysis of the extant

marine environment with benthic habitat maps has demonstrated broad similarities between

intertidal configuration on each islet and the molluscs represented in archaeological assemblages.

While there are minor alterations to relative abundance through time, five taxa (Nerita polita, N.

plicata, Conus spp., Vasum turbinellus, and A. violascens) are highly ranked at all sites, with N.

plicata most common in leeward Ebon deposits and N. polita and V. turbinellus more common from

assemblages on windward islets, likely due to local environment. Small-bodied gastropod taxa seem

173

to have been the major focus, with bivalves only a minor component of most assemblages.

Gastropods are mostly epifaunal, herbivorous taxa that could have been collected by gleaning.

Where bivalve taxa were present, infaunal siphon-feeding taxa were most common, suggesting,

unsurprisingly, digging for bivalves from the intertidal and shoreline sands. However, the majority

of prehistoric collecting activity seems to have occurred on the reef flat pavement and reef flat

boulders, with these habitats consistently ranked first at all sites.

Variation in mollusc assemblages relates to the windward-leeward exposure gradient (Harris et al.

2016; Harris and Weisler 2016). There is some evidence for intra-islet variation in assemblage

composition that may be related to site function (i.e. village sites v. midden deposits associated with

aroid pits) and distance to the ocean or lagoon shore. Minor differences in taxonomic composition

were noted between lagoonside and interior deposits at MLEb-1 and MLEb-33. Lagoonside

deposits tend to be richer and evenness values for interior deposits was generally higher.

Lagoonside deposits at MLEb-1 and MLEb-5 reported some of the lowest evenness scores for the

atoll, with the majority of MNI contributed by few taxa, notably nerites, ranellids, and psammobids.

Interior deposits also have a higher relative abundance of taxa from the oceanside reef edge,

including V. turbinellus, T. argyrostomus, and T. maculatus. In other Marshall Islands assemblages,

distance to the oceanside is correlated with higher abundances of these and other lower

intertidal/reef edge gastropod taxa (Weisler 2001b). This is in line with expectations, as taxonomic

composition at other sites on Ebon Atoll tend to reflect adjacent local habitats.

There were minor differences from these non-selective foraging patterns, both from early deposits

on Ebon Islet. Early deposits at MLEb-1, TP 6 reported the highest relative abundance of bivalves

of any cultural deposit, suggesting the possibility of an early focus on A. violascens and Gafrarium

spp. soon after Ebon was colonised. However, sample sizes were small and these conclusions

remain tentative as other, larger early deposits at MLEb-5 are dominated by gastropods. At MLEb-

5, however, the largest assemblage of Tridacna (primarily T. maxima) was recovered. Several

worked Tridacna fragments appear to be tool-making debitage. This site has also previously been

identified as the location of the largest assemblage of skipjack tuna (Katsuwonis pelamis) on Ebon

Atoll (Lambrides and Weisler in press) and the early date in addition to the substantial K. pelamis

and Tridacna spp. assemblage point towards a site of some importance in the early period

occupation on Ebon Atoll.

174

Assemblages from late period village sites on Ebon and Enekoion islets have similar taxonomic

composition and are consistent with mollusc assemblages from village sites on other Marshall

Islands atolls, being rich, diverse, and even (Dye 1987b; Riley 1987; Weisler 2001b). While there

was some variation in taxonomic composition between deposits at MLEb-1 and MLEb-33, with

rocky, oceanside taxa such as V. turbinellus more common at Enekoion, and coral dwelling taxa

more common on Ebon, both sites reflect a similar foraging strategy focused on the intertidal reef

flat and gleaning. Riley (1987) reports assemblages from sites at Laura Village, Majuro Atoll,

composed of as much as 80 % C. luhuanus, but no such focus on a single taxon was reported for

any Ebon site. The seagrass beds that currently dominate the lagoonside habitats of Enekoion Islet

were either not accessed by foragers in prehistory, or more likely, given the exploitation of these

habitats in the region throughout prehistory (e.g. Giovas et al. 2010), were not present on Enekoion

until recently, perhaps only historically. While late-period village sites reported relatively low

evenness scores for Ebon Atoll assemblages, no taxa accounted for greater than 25 % of MNI. Even

early village site assemblages at MLEb-5, where evenness was relatively low, no single taxon

accounted for greater than 22 % of MNI. Ephemeral village sites showed a similarly wide range of

taxa exploited, with taxonomic composition reflective of local environment, but still no taxa

accounts for greater than 32 % of MNI for any cultural layer. The non-selective foraging strategy

inferred here was mediated strongly by the richness and diversity of local marine environments.

Thus, the low scores for evenness at Moniak may also relate to wave exposure, local habitat

complexity, and substrate rugosity as taxonomic richness and diversity are generally lower in less

complex marine environments, such as pavements on windward islets, compared with, for example,

areas of coral growth on leeward islets (Gratwicke and Speight 2005; Kohn and Leviten 1976).

However, a focus on a wide range of taxa, spread relatively equally across functional groups and

feeding guilds, likely mitigated long-term human impacts on mollusc populations on Ebon Atoll

(Giovas 2016).

A range of archaeological and neo-ecological studies have demonstrated that human foraging for

molluscs can lead to alterations in species richness, abundance, and diversity contributing to wider

scale ecosystem impacts (Allen 2003; de Boer and Prins 2002; Erlandson et al. 2011; Giovas et al.

2013; Giovas et al. 2010; Harris and Weisler in press;). However, the overall picture from Ebon

Atoll is one of molluscs as a minor and sustainable contributor to diet during the prehistoric period,

similar to Utrok Atoll to the far north (Weisler 2001b) and other small islands occupied during the

Holocene both within and beyond the Pacific Ocean (Giovas 2016; Thomas 2014). There is scant

evidence for major ecological alteration resulting from human foraging of molluscs, with little

175

evidence for changes in habitat selection, richness, evenness or diversity, and little indication of

impacts to particular trophic groups based on feeding type or mode of life analysis. Archaeologists

exploring small islands and historical ecology have posited that conservation was not necessary in

these contexts as small population size and abundant marine resources limited human impacts

(Thomas 2014; Weisler 2001b). Additionally, foragers on small islands practicing generalised

collection strategies or ‘reef-sweeping’ may have mitigated impacts by taking a range of taxa from

similar feeding guilds or functional groups (Giovas 2016; Szabó 2009, cf. Szabó and Anderson

2012). A similar foraging strategy on Ebon Atoll, focused on relatively equal proportions of taxa

from a range of functional groups from the reef flat pavements and reef flat boulders, may have

limited human impacts to a degree that they are not visible in the archaeological record.

While significant differences were noted between measures of heterogeneity, chord distance

reported high dissimilarity and a chi-square test showed association between layer (midden versus

storm deposit) and feeding type at MLEb-31. The cultural deposits at MLEb-31 are interrupted by

storm-deposited coral rubble and the alterations in mollusc composition are likely related to this

event rather than human impacts. Kohn (1980) surveyed populations of predatory intertidal

gastropods before and after a typhoon on Eniwetok Atoll in the northern Marshall Islands, reporting

that taxa that inhabit refuges such as cracks, crevices, and depressions in the reef flat will be

adequately protected during storm events. Shell architecture was also an important determinant in

mortality rates, with Muricidae, especially Drupa spp., suffering lower mortality rates due to a shell

and foot that are well adapted to resist damage and dislodgement from wave action. However, taxa

that inhabit algal turfs were significantly impacted and suffered high mortality. Trends in the

assemblage generally correlate well with these findings, with the storm event coinciding with a

decline in Conidae relative abundance and an increase in Muricidae, especially Drupa and Thais. In

Layer IB, the increase in herbivorous taxa is driven primarily by an increase in N. plicata that

inhabit refuges in the upper intertidal and reproduce and disperse via planktonic larvae (Chelazzi

and Vannini 1980; Crandall et al. 2008; Demond 1957). It is possible that N. plicata resisted high

storm mortality rates through a combination of reproductive strategies and being adapted to high-

energy environments led to increased abundances. Therefore, high chord values and significant

difference between measures of heterogeneity in this layer likely result from these factors, rather

than an anthropogenic cause.

Only a single context had any alterations to assemblage composition that could represent human

impact: TP 17-20 at MLEb-1. Significant differences were noted for 1-D, H, E, rank order, and

176

feeding categories between cultural layers, concurrent with a shift in sub-dominant habitats and an

increase in richness and density. From Layer IIB-IA, the proportion of carnivorous gastropods

increased, peaking to 52.5 % of assemblage MNI in IA. At the same time, evenness declines sharply

due to the increase in the abundance of G. muricinum, from 0.4 % of MNI in IIB to 16.3 % of MNI

in IA. This shift is concomitant with a decrease in evidence for foraging among shoreline rocks and

boulders and an increase in evidence for both seagrass and coral habitats on the reef flat. The

predominance of reef flat pavements remains steady, accounting for around 50 % of MNI for all

layers. Despite these alterations, it is unlikely that these changes reflect human impacts to the

marine environments adjacent to MLEb-1. G. muricinum is dominant in Layer IA, but there is no

evidence to suggest a decline in predominant taxa from earlier layers. N. plicata, Conus spp.,

ranellids, and A. violascens continue to be highly ranked in Layer IA. There is little evidence from

an analysis of habitats that these changes reflect degradation of the intertidal zone due to trophic

cascade or other alterations to trophic networks. While an increase in macroalgal cover may signal

loss of hardbottom habitats that have been associated with human foraging in other studies (Castilla

and Duran 1985; Godoy and Moreno 1989;), at MLEb-1, these changes are concurrent with both an

increase in predatory carnivores and proportional representation of coral habitats, opposing

evidence for a phase shift. The increase in predatory carnivores, coral habitats, and seagrass habitats

is concurrent with an increase in shell density (MNI/m3) and species richness. These changes may

be more adequately explained by an increase in foraging activity at the site, possibly due to human

population increase and the establishment of the large village site at MLEb-1. An increase in

population may have correlated with an increase in foraging activity and the number of different

habitats encountered or accessed by foragers practising a non-selective foraging strategy. While

more data are needed to confirm this hypothesis for TP 17-20, at this stage there is little to no

indication that human foraging for molluscs on Ebon Atoll resulted in negative impacts to the

intertidal ecosystem that are visible in the archaeological record.

Weisler (2001b) and Thomas (2014) argued that atolls, with a high ratio reef to land area and

relatively low population sizes, are unlikely to present evidence for long-term impacts from human

foraging for molluscs. On Ebon Atoll, a total of ~22 km2 of reef area surrounds ~5.4 km2 of land

area. The reefs of the Marshall Islands are considered to be ‘in excellent condition’, especially on

atolls distant from the urban centres of Majuro and Kwajalein (Beger et al. 2008:388). Though there

are many modern threats to RMI reefs, the fine-grained, broad, and non-selective prehistoric

mollusc foraging likely practiced on Ebon Atoll does not appear to have generated long-term

negative impacts. Giovas (2016) has recently argued that fine-grained, non-selective foraging for

177

molluscs on small islands is unlikely to result in human impacts to molluscs or the wider marine

environment, primarily through a lack of intense disturbance to any particular functional group.

Indeed, many cases where both modern and archaeological studies have demonstrated that human

foraging for molluscs has resulted in negative impacts have been due to an intensive focus on a

single taxon, or members of the same functional group (often, large predatory gastropods or

efficient herbivorous regulators of algae) (Braje and Erlandson 2013; Castilla and Duran 1985;

Erlandson et al. 2008; Jerardino and Navarro 2008; O'Dea et al. 2014). We presented

archaeological evidence from Ebon Atoll to support these assertions in parallel with other studies

from Grand Bay and Sabazan in the West Indies (Giovas 2016, Poteate et al. 2014), Fiji (Szabó

2009), and Atafu Atoll, Tokelau (Ono and Addison 2013). At Utrok atoll in the north (Weisler

2001b), foragers targeted a wide array of taxa, with major differences in assemblage composition

related to flexible foraging strategies that reflect the configuration of the local environment adjacent

to archaeological sites, with no discernible human impacts. It seems likely that foraging for

molluscs on Ebon Atoll provided a predictable resource to supplement the products of extensive

horticultural and arboricultural activity, fishing, and capturing seabirds and crustaceans.

Conclusion

A temporal and spatial analysis of the mollusc assemblage from three major village sites and one

ephemeral campsite has revealed little evidence for human impacts to molluscs during prehistory on

Ebon Atoll. While small islands, and especially atolls, have long been considered marginal, fragile

environments difficult for sustained human occupation, we presented evidence for long-term

continuity in foraging practices spanning two millennia from colonisation through to the historic

period. We also highlight that in contrast to other island types in the Pacific region, the differences

in mollusc assemblage composition between windward and leeward locations on atolls are subtle

and that a gradient, rather than a dichotomy, exists between mollusc assemblages from windward

and leeward habitats (Kirch 1982; Morrison and Hunt 2007; Wiens 1962). However, all mollusc

assemblages from Ebon Atoll were consistently rich, even, and diverse, with the major source of

variation between archaeological sites related to the configuration of adjacent marine habitats.

Other authors working in Micronesia have noted the remarkable productivity of the nearshore

habitats on atolls, positing that low population density and abundant marine resources mitigated

long-term impacts to the reef (Thomas 2014; Weisler 2001b). These results are also consistent with

current discourses on the role of small islands in the human story, with Fitzpatrick et al. (2016)

among a number of researchers challenging traditional conceptions of small islands as remote,

marginal, and isolated (Giovas 2016), a position developed early on by Weisler (1995, 1996, 1997)

178

for the geographically isolated but socially connected Pitcairn Group. Linguistic evidence clearly

points to consistent and continuous contact between atolls across the Marshall Islands throughout

prehistory (Rehg 1995). Ethnographic evidence and storage pits from archaeological sites

demonstrate that Marshall Islanders developed effective methods for preserving terrestrial foods in

preparation for times of scarcity (Horrocks and Weisler 2006; Pollock 1984; Spoehr et al. 1949;

Weisler 2001b). Studies of marine resource extraction in the archipelago, including Weisler (2001b)

and Lambrides and Weisler (in press), have not identified evidence for human impacts to finfish

resources in archaeological contexts, despite rich and dense fishbone assemblages. This analysis

demonstrates that foraging on Ebon Atoll focussed on a broad range of taxa from different habitats,

with most foraging occurring on reef flat pavements on leeward islets, with windward islets

reporting higher abundances of taxa from rocks and boulders. These patterns reflect a foraging

strategy that was adapted to local environmental conditions, with molluscs providing sustained

returns throughout prehistory. Our evidence challenges previous conceptions of atolls as

environmentally marginal for human habitation and document that human populations had no

discernible negative impacts on molluscs for at least two millennia on Ebon Atoll.

Acknowledgements


to Weisler by the Historic Preservation Office (HPO), Ministry of Internal Affairs, and on Ebon

Atoll, former mayor Lajan Kabua. Marshall Islands fieldwork was supported by a grant to Weisler

from the Office of the Deputy Vice Chancellor (Research), University of Queensland. An

Australian Institute of Nuclear Science and Engineering grant (ALNGRA 12004) to Weisler funded

the radiocarbon age determinations. Harris’s university studies are supported by an Australian

Research Training Scheme award. Molluscs collected during fieldwork have been returned to the

HPO, Marshall Islands. We thank the two anonymous reviewers for their comments on the

manuscript.

179

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---. 1999a. The antiquity of aroid pit agriculture and significance of buried A horizons on Pacific

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51.










Woo, K., P. Faulkner and A. Ross. 2015. The effects of sampling on the analysis of archaeological

molluscan remains: A quantitative approach. Journal of Archaeological Science: Reports

7:730-740.

WoRMS Editorial Board 2015 World Register of Marine Species. Retrieved from

<http://www.marinespecies.org at VLIZ>.

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Figures and Tables

Table 1 Summary data for mollusc assemblages from MLEb-1, MLEb-5, MLEb-31, and MLEb-33; Wt. = weight

MLEb-1 and MLEb-5, Ebon Islet

Unit Layer MNI NISP Wt. (g) MNI/m3 NTAXA H′ E 1-D Fisher's α 6 IA 115 347 831.5 287.50 32 2.998 0.865 0.929 14.69 IB 59 215 207.78 306.49 27 3.036 0.921 0.939 19.26 IIA 41 115 126.32 230.99 7 1.671 0.859 0.766 3.677

17-20 IA 804 2330 3923.83 525.49 43 2.609 0.694 0.873 9.71 IB 247 735 1014.62 251.40 32 2.877 0.83 0.923 9.797 IIA 118 277 315.54 232.51 24 2.408 0.758 0.836 9.104 IIB 87 223 442.68 122.97 27 2.528 0.767 0.832 13.41

8-12 A 47 141 305.75 61.84 23 2.921 0.932 0.934 17.8

13-16 A 85 174 497.22 244.60 32 3.187 0.920 0.948 18.66 13-16 I 45 83 233.74 230.77 21 2.767 0.909 0.92 15.33

3 x 5 I 988 4401 19469.7 119.83 45 2.509 0.659 0.843 9.716

MLEb-31, Moniak Islet

Unit Layer MNI NISP Wt. (g) MNI/m3 NTAXA H′ E 1-D Fisher's α 2-6 IA 171 494 2973.21 2988.12 23 2.38 0.759 0.864 7.154

IB 261 742 1535.38 1553.41 35 2.558 0.719 0.819 10.87 SD 32 66 281.35 281.87 13 2.157 0.841 0.83 8.155 IC 18 29 63.78 63.78 13 2.447 0.954 0.901 21 IIA 176 449 1666.62 1673.26 26 2.449 0.752 0.841 8.425 IIB 42 130 404.27 407.4 20 2.676 0.893 0.905 14.96

MLEb-33, Enekoion Islet

Unit Layer MNI NISP Wt. (g) MNI/m3 NTAXA H′ E 1-D Fisher's α 1, 6, 7 I 559 1392 2685.71 2699.21 35 2.589 0.728 0.869 8.28

2 IA 96 243 1007.96 1012.01 17 2.272 0.802 0.854 6 IB 39 81 393.74 398.52 16 2.287 0.825 0.847 10.14 8 I 96 315 1076.91 1093.93 27 2.793 0.847 0.905 12.49 3 I 331 1807 4388.48 4398.68 25 2.433 0.756 0.876 6.274

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Figure 1 Map of the Republic of the Marshall Islands, with Ebon Atoll and the location of sites MLEb-1, MLEb-31 and MLEb-33

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Figure 2 Representative mollusc taxa from Ebon Atoll archaeological deposits

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Figure 3 (a) Benthic Habitats mapped within a 2 km radius of MLEb-1 and MLEb-5 on Ebon Islet, MLEb-33 on Enekoion Islet, and MLEb-31 on Moniak Islet with photos depicting characteristic intertidal marine habitats (a) lagoonside, view north west showing seagrass beds north west of MLEb-1 (Photo: M. Weisler) (b) lagoonside, view north east of areas of coral growth adjacent to MLEb-5 (Photo: M. Harris) (c) oceanside, view northwest showing expansive reef flat (Photo: M. Harris) (d) lagoonside, view north east of seagrass beds (Photo: M. Harris) (e) oceanside, view north west showing rubble and boulder reef flat (Photo: M. Harris) (f) lagoonside, view south east showing coarse sands, Ebon Islet in background (Photo: M. Weisler) (g) oceanside, view east of areas of rubble and boulder dominated reef flat (Photo: M. Weisler)

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Figure 4 Summary of analysis for MLEb-1 TP6 showing a. evenness (E), dominance (1-D) and diversity (H’) b. relative abundance of top three ranked taxa overall c. predominant habitat categories, and d. feeding types.

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Figure 5 Summary of analysis for MLEb-1 TP 17-20 showing a. evenness (E), dominance (1-D) and diversity (H’) b. relative abundance of top three ranked taxa overall c. predominant habitat categories, and d. feeding types.

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Figure 6 Summary of analysis for all analysed test pits at MLEb-33 showing a. evenness (E), dominance (1-D) and diversity (H’) b. relative abundance of top three ranked taxa overall c. predominant habitat categories, and d. feeding types.

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Figure 7 Summary of analysis for MLEb-31 TP 2-6 showing a. evenness (E), dominance (1-D) and diversity (H’) b. relative abundance of top three ranked taxa overall c. predominant habitat categories, and d. feeding types.

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Chapter 7: Conclusion

Introduction

This chapter presents a discussion of the main research findings of this thesis. Each research

question (RQ1 – RQ5) is addressed individually. Future research objectives, and concluding

remarks are also provided.

Overview of thesis results

RQ1: Has human foraging for molluscs impacted mollusc populations and intertidal ecosystems in

the Pacific Islands during the prehistoric period?

A number of neo-ecological and archaeological studies have demonstrated the potential for human

foraging for molluscs to have strong direct (reductions in abundance and biomass of targeted

species, reduction in body-size over time) and indirect (alterations to trophic networks, interspecific

competition, community structure) effects. These impacts are routinely investigated by

archaeologists working in the Pacific Islands, and outcomes ranging from changes in shell size,

trophic alteration and possibly extirpation of particular taxa have been linked to human foraging.

This thesis presented three key findings from a literature review of archaeomalacological studies in

the Pacific Islands.

First, previous studies commonly linked changes in mollusc assemblages to human foraging,

primarily via a decrease in mean shell size or a decline in the abundance of large-bodied taxa,

without fully exploring other explanations. Human foraging can result in a decline in shell size, but

there is rarely a clear link between the two, even in controlled studies (e.g. McShane et al. 1994).

These interpretations are less frequently presented in current literature, with researchers routinely

considering the ecology of the intertidal zone and incorporating multi-proxy datasets including

climate, sea-level, geological and other faunal data into analyses. Historical ecological analyses of

archaeological data sets have demonstrated the complex link between human foraging and shell size

or the abundance of particular taxa in the intertidal (Faulkner 2009; Giovas 2016; Giovas et al.

2013; Giovas et al. 2010; Thomas 2014) within and outside the Pacific Islands.

Second, large-bodied gastropod taxa have received disproportionate representation in

archaeomalacological analyses due to a lack of fine-mesh screening or exclusion of small taxa from

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identification or analysis. However, recovery methods that include < 3.2 mm screening or attempt

identification on the total assemblage have demonstrated, for example, the importance of small-

bodied taxa for environmental reconstruction or as resulting from non-selective foraging strategies.

In addition, researchers in the Pacific Islands are more commonly presenting clear, detailed

identification and quantification protocols. The continued reporting of these methods will facilitate

comparison of archaeological datasets across the region to understand long-term human interaction

with the marine environment, and possible impacts to intertidal ecosystems.

Third, in concert with other researchers (Allen 2003; Aswani and Allen 2009; Jones 2009; Jones

and Quinn 2009), this thesis stressed the importance of analysing impacts to individual faunal

classes as well as wider ecological impacts of marine subsistence on intertidal ecosystems in the

Pacific Islands. Analyses aimed at generating these data will allow broad assessment of the role of

long-term human interaction with the marine environment in structuring intertidal ecosystems in the

region, and the resilience of coral reefs to future impacts including climate change. These studies

would ideally include collaborative research with other disciplines including ecology, marine

biology, and geology.

RQ2: Does the inclusion of an increased number of non-repetitive shell elements (NREs) in

quantification protocols influence measures of relative abundance and taxonomic heterogeneity?

Ebon Atoll assemblages were used to test a new quantification protocol for Indo-Pacific mollusc

taxa that incorporates an increased number of non-repetitive shell elements (NREs). Commonly

utilised quantification protocols in archaeomalacology count only a select number of NREs. For

example, for gastropods, the spire is most common, and the umbo and/or hinge for bivalves (e.g.

Allen 2012; Claassen 1998; Mannino and Thomas 2001). This thesis presented the hypothesis that

commonly utilised quantification protocols may systematically over-represent taxa with well-

preserved spires, umbones or hinges. Measures of taxonomic heterogeneity and assemblage

characteristics (richness, evenness, and diversity) derived from these quantification protocols would

also be influenced by these biases, and as such these quantification methods may be altering

inferences of past human behaviour relating to the collection of molluscs in the Pacific.

In order to test this hypothesis, two mollusc assemblages from Ebon Atoll, Marshall Islands were

quantified using common quantification methods (referred to as NRE MNI), and a new

quantification protocol, referred to as tMNI. The new MNI method, tMNI, uses an expanded

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number of NREs for the quantification of mollusc shells, records element frequency per taxon, and

MNI is calculated based on the most frequently occurring NRE for each taxon per analytical unit,

rather than the total number of a single or restricted range of NRE. A formal protocol for this

quantification method was outlined, to assure transparency, clarity and replicability of results

(Driver 2011; Wolverton 2013; Woo et al. 2015). Each quantification protocol was assessed by

comparing MNI values calculated using the NRE MNI protocol with the new, tMNI protocol. The

influence on rank-order abundance, and derived measures of taxonomic heterogeneity including

richness (NTAXA), and diversity and evenness (Simpson’s index of diversity, and the Shannon-

Weiner indices of diversity and evenness). The influence of differential fragmentation was assessed

by comparing a ratio of NISP to MNI for each protocol.

This comparison yielded several key findings related to shell form and the influence of

quantification protocols. Principally, common methods of MNI quantification (NRE MNI) using a

restricted range of elements systematically underrepresent gastropod abundance for Indo-Pacific

taxa. As much as a two-fold increase in gastropod MNI was noted for the same assemblage

quantified using the tMNI protocol. Turrifom taxa with high, dense spires such as Cerithium

nodulosum were over-represented using NRE MNI, while globoid-form taxa with weak spires, such

as Nerita spp. were consistently under-represented. The tMNI method did not produce lowered

MNI values for these turriform taxa, but instead more accurately represented the relative abundance

of these taxa to the total assemblage. Conversely, tMNI protocols resulted in only modest increases

in bivalve MNI, however, the inclusion of additional NRE did increase MNI and count individuals

that would not have been represented by NRE MNI protocols.

Divergent results were also reported for measures of taxonomic richness and heterogeneity for each

quantification method. In all cases, expanding the number of NRE included for quantification

resulted in an increase in richness as measured by NTAXA. As with the results for abundance,

richness was increased due to the inclusion of taxa with spires that do not preserve well in

archaeological deposits. Measures of evenness and diversity were also influenced by quantification

protocol. Assemblage evenness was also impacted, with significant difference for Simpson’s index

of diversity results for TP18 and 19 at MLEb-1 due to the over-representation of the turriform

Cerithiidae when the NRE MNI protocol was used. While no other significant differences were

reported, the variation in results for derived measures of assemblage composition highlight the

potential influence of quantification protocol on inferences of human foraging behaviour.

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Finally, the tMNI method allows a more comprehensive comparison of archaeomalacological data

with other faunal datasets. Because both tMNI and common methods for the analysis of vertebrate

fauna use the most commonly occurring NRE as the basis for calculating MNI, raw abundance data

can be compared. For many coastal sites, mollusc shells and fishbones are ubiquitous components

of the assemblage, and the major classes of subsistence remains.

This comparative study demonstrated that the inclusion of an increased number of non-repetitive

shell elements (NREs) in quantification protocols has a marked impact on measures of relative

abundance, and species richness, diversity, and evenness. Quantification protocols for mollusc

shells that incorporate a wide range of NREs were demonstrated to provide a more valid

measurement of relative abundance, avoiding biasing any type of shell architecture over another.

Furthermore, these methods can be adapted for use in a wide range of regions and

archaeomalacological contexts, allow comparison with other faunal data, and establish a clear,

replicable quantification protocol for use in future research.

RQ3: What methods can be generated to explore and understand forager decision-making and

habitat selection in atoll environments?

Patterns of human foraging for molluscs, and the decisions made by foragers to collect from

particular areas of the intertidal zone, are mediated by a range of physical (e.g., tidal movements,

reef structure, ease of access, substrate type) and sociocultural (e.g., individual preferences, cultural

taboos, gender roles, age) factors. The influence of these factors on the accumulation of mollusc

assemblages in archaeological sites has traditionally been explored in archaeology through optimal

foraging theory, or by reconstructing foraging preferences by assigning mollusc taxa to single,

relatively broad habitat types (Bedford 2007; Morrison and Addison 2008; Morrison and Hunt

2007), or a range of detailed classes (Allen 2012; Clark et al. 2001; Szabó 2009). These methods of

reconstructing habitat selection are referred to by Allen (1992:331) as defining probabilistic

relationships between foraging patterns and the taxa in the assemblage. These methods rely on

linking knowledge of the ecology of the intertidal zone and the molluscs that are hosted there with

mollusc taxa recovered from archaeological sites. However, by assigning each taxon to only a

single habitat, the complex relationship between molluscs and the complex variation in water depth,

tidal exposures, substrate type, and associated biological cover in the intertidal zone is highly

simplified.

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Hierarchical classification schemes are a robust framework for assigning mollusc taxa to habitat

categories to assess forager decision making. This method for classifying the marine environment is

commonly used to map the distribution of benthic habitats and assign a combination of location in

relation to the shoreline, geomorphological structure, and benthic cover to define a habitat class.

However, this scheme can be adapted to assign mollusc taxa to areas of the intertidal zone where

they would most likely be encountered by foragers. Using a classification scheme developed by

Kendall et al. (2012) for Majuro Atoll, all mollusc taxa in the assemblage were assigned to one or

more habitats based on a literature review of Indo-Pacific mollusc ecology. With each taxon

assigned to an area of the intertidal zone, forager decision making as it relates to both site location

(windward v. leeward) and site function (village v. campsites) was investigated for two

archaeological sites on Ebon Atoll.

An analysis of the range of habitats represented at each site demonstrated that a broad-based,

generalist foraging strategy was employed during the prehistoric period. All assemblages were rich,

and even, with many habitat classes represented. Gastropods from the high intertidal and reef flat

were the most common component of both windward and leeward assemblages, with differences in

the taxa exploited likely reflecting local habitat variation. Though there were some taxa that were

more common than others, foraging seems to have targeted habitats, and the predictable

aggregations of taxa that inhabit them, rather than any specific focus on a single species. Only

minor differences were noted between assemblages from the major village site on Ebon Islet and

the ephemeral campsite on Moniak Islet. The source of this variation likely relates to be the

configuration of intertidal habitats adjacent to each site, as the more exposed Moniak Islet featured

greater numbers of taxa adapted to strong waves and currents (e.g. Vasum turbinellus), while Ebon

assemblages featured greater numbers of taxa that inhabit the high-rugosity reefs of the leeward

lagoon. These findings relate to RQ4, and are discussed in more detail below, however, this thesis

has presented a new method for detecting these differences in mollusc assemblages from Indo-

Pacific archaeological sites. This thesis also includes a clear and transparent description of the

method that can be adapted to investigate other archaeological sites within and beyond the Indo-

Pacific for comparative studies. The foraging preferences of human foragers for molluscs can yield

data regarding long-term interactions of humans with coastal environments, and how these may

have changed through time. These findings can be related to other archaeological datasets, and

compared with ancillary datasets including climate records, geological datasets, and modern studies

of forager behaviour.

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RQ4: What is the influence of spatial (settlement patterns and local habitat) and temporal factors

on the richness (number of species present), abundance (number of individuals of each species

present), and diversity (richness and relative distribution of individuals of each species within a

population) of mollusc assemblages on Ebon Atoll?

As stated above, a study of mollusc assemblages from the leeward Ebon Islet and windward Moniak

Islet demonstrated that variation in assemblage composition most likely relates to the configuration

of intertidal habitats adjacent to each site. Variation in the patterning of archaeological data

depending on windward or leeward coastal exposure have been noted for other Pacific Islands.

Subsistence practices differed between windward and leeward exposed sites in Hawaii (Bayman

and Dye 2013 ; Earle 1977; Kirch and Dye 1979; Palmer et al. 2009; Weisler and Kirch 1985), and

different reef configurations on other high islands (Kirch and Dye 1979; Morrison and Hunt 2007;

Szabó 2009; Szabó and Anderson 2012). The configuration of intertidal habitats and mollusc-

bearing environments on atolls are heavily influenced by the relative exposure to winds, waves, and

currents, geological history and other stochastic factors.

In addition to these local ecological factors, archaeological and geographical investigations indicate

that human settlement patterns of Marshall Islands atolls tend to be patterned in a predictable

manner. Permanent villages that are the population centres of atolls tend to be located on islets with

large land area and a well-developed Ghyben-Herzberg freshwater lens that are sheltered from

waves, winds and currents. Islets that are exposed to strong waves, winds and currents on the

windward side of atolls are generally smaller, with insufficient freshwater lenses to support

permanent habitation. These windward islets are typically associated with ephemeral occupation

sites, and were likely used during the prehistoric period for staging fishing sorties and collecting

seabirds and molluscs. This thesis presented both a way to investigate these differences by

presenting a new method for analysing human foraging preferences, and for the first time on atolls,

an analysis of the role of local ecological variation in mollusc foraging. Additionally, this thesis

examined the role of human settlement patterns on mollusc foraging, which has been explored

primarily for northern atolls in the Marshall Islands, but not in a dedicated study.

An analysis of mollusc assemblages from four archaeological sites on Ebon Atoll including

leeward, village sites (MLEb-1, MLEb5), a windward ephemeral occupation site (MLEb-31), and a

moderately exposed village site (MLEb-33) has demonstrated three key findings (1) regardless of

site location or site type, mollusc assemblages are rich, even and diverse (2) foragers seem to have

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practiced a fine grained, non-selective foraging strategy; and (3) differences in assemblage

composition seems to have been most strongly mediated by the configuration of intertidal habitats

adjacent to archaeological sites, rather than site function. However, for leeward islets there was a

tendency for increased proximity to the lagoon (and therefore to permanent village sites) to be

associated with relatively low evenness scores, and higher abundance of nerites, ranellids and

psammobids. Increased proximity to the oceanside was associated with an increased evenness and

abundance of taxa that prefer the reef edge.

A comparative analysis of mollusc and fish bone assemblages from MLEb-1 and MLEb-31

demonstrated that unlike molluscs, taxonomic composition of fishbone assemblages tends to be

more strongly structured by site type, rather than location. Dissimilarity scores for fishbone

assemblages were generally lower than molluscs. Though requiring further analysis, this thesis

proposed that while mollusc assemblages are strongly mediated by local environment, variation in

fish bone likely relates to the range of fish capture strategies practiced at different site types.

RQ5: Is there any indication that human foraging for molluscs directly impacted mollusc

populations or had secondary, indirect impacts on intertidal ecosystems on Ebon Atoll over the two

millennia of human occupation?

Atolls have traditionally been considered especially difficult settings for long-term human

habitation. A lack of standing fresh water, poor soils, and vulnerability to extreme weather have

been cited as challenges to survival. However, archaeological research in the Marshall Islands has

demonstrated that human populations have persisted since initial colonisation soon after atoll

emergence. Marine resources are key to this survival, and the literature review presented in Chapter

2 demonstrated the potential for long-term exploitation of marine fauna to alter intertidal

ecosystems. This thesis investigated 2000 years of foraging for molluscs on Ebon Atoll for the first

time to both understand long-term human interaction with the marine environment, and also to

investigate potential impacts. Two new methods, one for calculating MNI (Chapter 3), and one for

tracking foraging preferences (Chapters 4 and 5) for investigating human foraging preferences, and

modern benthic habitat maps were generated and incorporated into a temporo-spatial analysis of

mollusc assemblages from four archaeological sites on Ebon Atoll.

The variability in mollusc assemblages relating to the windward-leeward exposure gradient on

atolls has been discussed in this chapter, and extensively in Chapters 4 and 5. Temporal analysis of

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mollusc assemblages demonstrated three key findings: (1) a suite of five taxa, (Nerita polita, N.

plicata, Conus spp., Vasum turbinellus and A. violascens) are highly ranked at all sites through

time, but all assemblages are rich, even and diverse; (2) molluscs formed a minor, stable component

of the human diet, likely from initial colonisation to the historic period; and (3) there is little

indication of negative impacts to molluscs or intertidal ecosystems as a result of human foraging for

molluscs based on these analyses.

The five most common taxa in Ebon assemblages are typical Indo-Pacific fauna that are abundant in

intertidal atoll environments, and reflect the non-selective foraging strategy employed throughout

the sequence. Minor alterations to rank-order abundance was noted, but there was no indication of

over-exploitation of any particular taxon at any analysed site. The only evidence for focused

targeting of a single taxon was reported from early deposits at the village site at MLEb-5, Ebon

Islet. This site had the highest relative and absolute abundance of Tridacna and may be associated

with the production of shell tools. While other archaeological sites in the Marshall Islands have

yielded evidence for focussed exploitation of a single taxon, this was not the case for any Ebon

assemblage. In addition, densities of mollusc remains from Ebon Atoll assemblages were generally

low, especially compared to other Micronesian assemblages (Giovas et al. 2010), indicating that

molluscs were a minor and predictable component of the diet.

The intertidal zone of atolls is remarkably productive, and expansive compared to the small land

area available for habitation. This marine productivity and generally low human populations have

been suggested by other researchers to be key to the lack of observable long-term impacts to

molluscs in these ecosystems (Thomas 2014; Weisler 2001). The broad-based, generalised foraging

strategy practiced during the prehistoric period on Ebon Atoll also likely spread direct and indirect

impacts across multiple trophic levels and functional groups. In archaeological and ecological

studies that have demonstrated human impacts, foraging is usually centred on intensively harvesting

a single, or narrow range of taxa. This thesis presents results to support those of other small-island

researchers both within and outside the Pacific Islands (Giovas 2016; Thomas 2014; Weisler 2001)

that assert that a lack of disturbance to any particular functional group, high marine productivity and

low human population density did not result in observable impacts to molluscs. These results also

support current discourses on small islands in the human story, challenging traditional notions of

these landscapes as harsh, remote, marginal and isolated settings for human habitation. The foraging

strategy inferred here provided sustained yields of molluscs for at least two millennia on Ebon

Atoll, Marshall Islands.

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Future research objectives

This thesis has demonstrated the utility of employing a suite of transparent and robust quantification

protocols to accurately and reliably measure the relative abundance of taxa in archaeomalacological

assemblages. The advantages of utilising a wide range of NRE for quantification have been

demonstrated, especially for gastropod taxa. Further studies on a larger, more diverse assemblage of

bivalve taxa would elucidate the role of NRE selection on this class of molluscs more clearly.

However, gastropod taxa were consistently underrepresented, and future research should endeavour

to consider NRE selection, and the influence these analytical decisions can have on reconstructions

of the past. Researchers should clearly and transparently report quantification protocols, and seek to

build comparative datasets, especially for low coral atolls, where data is patchy.

Furthermore, the development of novel methods for understanding foraging decision-making

presented here have highlighted the utility of probabilistic reconstructions of habitat selection. With

this new method, this thesis presented for the first time a detailed analysis of foraging practices

during the prehistoric period on Ebon Atoll. While no indications of human impact were observed

here, the generation of multi-proxy data to assess the condition of atoll reefs throughout the

sequence of human occupation would greatly enhance understanding of long-term human

interaction with these ecosystems. At present, there is limited geomorphological data on atoll islet

development for the atolls of the Marshall Islands, and other high-resolution proxy data for climate

in the region is lacking. These datasets would be useful for a range of archaeological and historical

ecological studies, and should be incorporated into future research objectives.

Concluding Remarks

This thesis presented new quantification and analytical methods for understanding human foraging

for molluscs in tropical Indo-Pacific settings, and reviewed archaeological evidence for human

impacts to molluscs in the Pacific Islands. A new quantification protocol was presented that

considered a wide range of NRE for the calculation of MNI, more accurately representing the

relative abundance of taxa in mollusc assemblages from Ebon Atoll, Marshall Islands. The new

MNI method presented here can be adapted for use with any assemblage, not only those from the

Indo-Pacific region. This method allows a more reliable comparison of mollusc relative abundance

with other faunal classes as both methods use the most frequently occurring NRE to calculate MNI.

Researchers in other regions have highlighted the utility of this method for both

archaeomalacological analyses, and broader analyses of multiple faunal classes (Jerardino et al.

202

2016; Morin et al. in press; Popejoy et al. in press; Popejoy et al. 2016). The method for

reconstructing forager-descision presented in this thesis facilitates understanding of long-term

patterning in foraging behaviour. These data are critical to further elucidation of the role of humans

in structuring marine environments through time, and the impacts of foraging on intertidal

ecosystems worldwide.

This thesis also undertook a high-resolution study of the archaeomalacological record of Ebon

Atoll, demonstrating that molluscs had been a stable component of the diet for two millennia. Braje

et al. (in press) recently emphasised the critical importance of the archaeology of islands for both

understanding the role of humans in altering or adapting to these environments, but also as critical

to enhancing future global sustainability. This thesis presents new methods and high-resolution data

to contribute to these research aims. Mollusc assemblages from Ebon were rich, even and diverse,

incorporating a broad range of taxa from different habitats. Variation in assemblage composition is

likely related to the configuration of intertidal habitats on windward and leeward exposed islets,

rather than site function. No discernible human impacts were noted, indicating that this generalised

foraging strategy, low human populations and a productive marine environment produced sustained

yields for molluscs by spreading impact across trophic levels and functional groups. These data

contest traditional perceptions of atolls as marginal, and are in line with current discourses that

challenge notions of small islands, and especially atolls as remote, isolated and marginal settings for

human habitation.

203

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206

Appendix A

Summary of extant marine habitats mapped within a 2km radius of archaeological sites on Ebon Islet (MLEb-1, MLEb-5) Enekoion Islet (MLEb-33) and Moniak Islet (MLEb-31)

207

Habitats km2 %

Code Name

ML

Eb-1

ML

Eb-5

MlE

b-33

ML

Eb-31

ML

Eb-1

ML

Eb-5

MlE

b-33

ML

Eb-31

B Shoreline Intertidal

B/1 Coral Reef and Hardbottom

B/1/18 Rock/Boulder 0.016 0.006 0.023 0.052 0.80 0.35 0.79 2.41

B/2 Unconsolidated Substrate

B/2/21 Sand 0.081 0.070 0.037 0.010 4.16 4.18 1.28 0.47

D Reef Flat

D/1 Coral Reef and Hardbottom

D/1/11 Aggregate Reef 0.106 0.133 0.336 5.48 7.90 11.68 0.00

D/1/12 Aggregated Patch Reef 0.092 0.125 0.122 4.75 7.41 4.25 0.00

D/1/13 Individual Patch Reef 0.007 0.007 0.34 0.39 2.23 0.00

D/1/15 Pavement 0.294 0.144 0.974 1.214 15.12 8.56 33.83 55.90

D/1/16 Pavement with Sand Channels

0.283 0.354 14.60 21.01 0.00 0.00

D/1/17 Reef Rubble 0.122 0.034 0.511 6.30 2.00 17.74 0.00

D/1/18 Rock/Boulder 0.012 0.012 0.109 0.070 0.60 0.72 3.78 3.21

D/2 Unconsolidated Substrate

D/2/21 Sand 0.078 0.030 0.011 0.007 4.04 1.78 0.38 0.31

D/2/22 Sand with Scattered Coral and Rock

0.047 0.047 0.065 0.000 2.43 2.80 2.27 0.00

D/2/23 Seagrass 0.186 0.114 0.125 0.000 9.57 6.79 4.34 0.00

E Back Reef

B/1 Coral Reef and Hardbottom

E/1/11 Aggregate Reef 0.057 0.052 0.022 2.92 3.12 0.75 0.00

E/1/12 Aggregated Patch Reef 0.093 0.121 0.060 4.79 7.18 2.10 0.00

E/1/17 Reef Rubble 0.030 0.138 1.55 0.00 0.00 6.35

E/2 Unconsolidated Substrate

E/2/21 Sand 0.000 0.000 0.000 0.167 0.00 0.00 0.00 7.70

E/2/22 Sand with Scattered Coral and Rock

0.144 0.146 0.115 0.092 7.42 8.69 3.98 4.25

H Bank/Shelf Escarpment

H/1 Coral Reef and Hardbottom

H/1/14 Spur and Groove 0.211 0.192 0.144 0.238 10.85 11.38 5.01 10.95

H/1/19 Algal Ridge 0.083 0.097 0.159 0.184 4.28 5.74 5.51 8.45

L Unknown

L/1 Coral Reef and Hardbottom

L/1/18 Rock/Boulder 0.000 0.000 0.002 0.000 0.00 0.00 0.07 0.00

208

Appendix B

List of zones, major geomorphological structures and detailed geomorphological structures used in the Ebon archaeological project hierarchical classification scheme (after Kendall et al. 2012:8-12). Zone J, dredged/excavated and Detailed Geomorphological structure 13, aggregated patch reefs was not used for the analysis presented here, as these classes relate to methods for mapping modern day atoll benthic habitats. Detailed Geomorphological structure 19, Algal Ridge, was added by the authors due to the distinctive range of molluscan taxa associated with this habitat (Morrison 1954).

209

Zones

code name description A Land Terrestrial features at or above the high tide line. B Shoreline Intertidal Area between the spring high tide line and lowest spring tide level C Lagoon Area of water inside the atoll, surrounded by the Back Reef D Reef Flat Shallow, low relief area exposed at low tide between the Shoreline Intertidal and Fore Reef or Back Reef E Back Reef Area on the lagoonside of an atoll sloping inward from the Shoreline Intertidal or Reef Flat down to the seaward

edge of the Lagoon floor. F Fore Reef Area along the seaward (oceanside) edge of the reef flat that slopes into deeper water to the landward edge of the

Bank/Shelf Escarpment G Bank/Shelf Deeper water extending offshore from the seaward edge of the Fore Reef to the beginning of the escarpment

where the insular shelf drops off into deep, oceanic water H Bank/Shelf Escarpment Begins on the seaward edge of the Fore Reef, where depth increases rapidly into deep, oceanic water. I Channel Naturally occurring channels in the seafloor that often cut across several other zones. K Pinnacle High-relief features occurring in the Lagoon that are separated from the Back Reef by the deeper waters of the

Lagoon. L Unknown Habitat proclivities could not be assessed.

Major geomorphological structures and detailed geomorphological structures 1 Coral Reef and Hard bottom Solid substrates, including bedrock, boulders and reef building organisms. A thin veneer of sediment may be

present. 11 Aggregate Reef Continuous, high-relief coral formation of variable shapes, lacking sand channels of Spur and Groove

formations. 13 Individual patch reef Coral formations that are isolated from other coral reef formations by bare sand, seagrass or other habitats. 14 Spur and Groove Alternating sand and coral formations that are oriented perpendicular to the Shoreline intertidal or Fore Reef.

The coral formations (spurs) of this feature typically have a high vertical relief and are separated by 1 to 5m of sand or hard bottom (grooves). Occurs only in the Fore reef or Bank/Shelf Escarpment zone.

15 Pavement Flat, low-relief, solid rock in broad areas, often with partial coverage of sand, algae, hard coral, Alcyonacea (sea whips or fans), zoozanthids or other sessile invertebrates.

16 Pavement with Sand Channels

Areas of pavement with alternating sand/surge channel formations that are oriented perpendicular to the Shoreline Intertidal or Bank/Shelf escarpment.

210

17 Reef Rubble Dead, unstable coral rubble often colonised with turf, filamentous, calcareous or encrusting macroalgae. Often occurs due to storm waves piling up dead coral.

18 Rock/Boulder Large, irregularly shaped carbonate blocks often extending from the island bedrock, indicating higher sea-levels, or aggregations of loose coral cobbles and boulders that have been detached and transported from their native beds. Individual cobbles and boulders often range in diameter from 0.25-3m

19 Algal Ridge Area of consolidated coral pavement colonised by calcareous algae occurring shoreward of the Bank/Shelf Escarpment or Fore Reef and demarcates the seaward margin of the Reef Flat. Often slightly higher elevation that the seaward and shoreward areas of the reef.

2 Unconsolidated Substrate Areas of the seafloor consisting of small, unattached or uncemeneted particles with less than 10% cover of large stable substrate.

21 Sand Areas of the seafloor consisting of small, unattached or unncemented particles. 22 Sand with Scattered Coral

and Rock Primarily sand bottom with scattered rocks or small, isolated coral heads.

23 Seagrass Primarily sand bottom colonised by seagrass. 3 Other Delineations Any other type of structure not classified as Coral Reef and Hard bottom or Unconsolidated Substrate.

31 Land Terrestrial features beyond the Shoreline Intertidal. 4 Unknown Habitat proclivities could not be assessed.

41 Unknown Habitat proclivities could not be assessed.

211

Appendix C

Neogene Marine Biota of Tropical America Molluscan Life Habits Database (NmiTA) categories (after Todd 2001)

212

Table A Gastropod feeding type categories Code Feeding Category Description

CP Predatory carnivores

Predators feeding on and killing whole sedentary and mobile macro-organisms and also selective ingesters of foraminifera (foraminiferivores). Included here are scavengers, which with just a few known exceptions, are also predators, shifting facultatively when carrion is present (Britton and Morton 1994)

CB Browsing carnivores

Predators which feed on sedentary, and typically clonal, animals (e.g. corals and other cnidarians, sponges, ascidians) without killing them. This also includes those ‘parasites’, which are ectoparasitic upon mostly relatively larger sedentary or mobile prey.

HO Herbivorous omnivores Browsing macroherbivores with unselective omnivory, typically of epifauna attached to macroalgae

HM Herbivores on fine-grained Substrates

Microalgivores, detritivores, microphages and unselective deposit feeder. Also included here is a miscellany of herbivorous Non HR and HP categories, including those living on wood or mangrove substrates.

HR Herbivores on rock, rubble or coral

substrates Microalgivores

HP Herbivores on plant or algal substrates Micro and macroalgivores and detritivores on macroalgal and seagrass substrates.

SU Suspension feeders Includes taxa feeding solely or dominantly upon suspended particles, including mucociliary feeders.

213

Table B Bivalve organism/substrate relationship categories Code Organism/Substrate Relationship Notes

ER Epifaunal recliner

EP Epifaunal

On a range of substrates; including sediment; consolidated substrates including biogenic substrates (e.g. coral), and macroalgal and seagrass substrates

SI Semi-infaunal

IS Infaunal siphonate

IA Infaunal asiphonate

WN Nestler on or within hard substrates Excluding active borers

WB Borer, nestling in hard substrate Includes taxa feeding solely or dominantly upon suspended particles, including mucociliary feeders.

WU Nestler within burrow of another organism in unconsolidated substrate

214

Table C Bivalve feeding type categories Code Feeding Type Description

SU Suspension feeder

DU Subsurface deposit feeder

DS Surface deposit feeder

Surface and subsurface deposit feeders food sources and strategies have been compared and contrasted by Jumars et al. (1990). Suspension feeders may ingest deposited material and surface deposit feeders may suck in material from the water column (Kamermans 1994). Despite this, the two groups reflect distinct feeding strategies with often very different food sources. There is growing evidence that some tellinid species, among surface deposit feeders, may facultatively suspension feed. This swop between suspension and deposit feeding may occur as a response to food quality and quantity, hydrodynamics and predation pressure. Nevertheless, this ability may vary between congeners (Levinton 1991). To help resolve ecological patterns, for the present I have simply coded all tellinoids as surface deposit feeders except those taxa which have been examined and are only known to suspension feed.

DC Chemosymbiotic deposit feeder

CAR microcarnivore

215

Table D Bivalve mobility categories Code Feeding Category Notes

IM Immobile

Includes cemented, boring, nestling and reclining taxa with no means of repositioning, apart from that which may result from growth

SE Sedentary Sluggish forms which have at least some capacity to reposition in response to disturbance

MA Actively mobile Including active crawlers and burrowers.

SW Swimming Those which have the ability to swim and which are believed to do so not solely as an escape response.

216

Table E Bivalve attachment type categories Code Attachment type

UN Unattached

BA Bysally attached

CE Cemented

217

References Cited Britton, J.C. and B. Morton. 1994. Marine carrion and scavengers. Oceanography and Marine

Biology: an annual review 32.

Jumars, P.A., L.M. Mayer, J.W. Deming, J.A. Baross and R.A. Wheatcroft. 1990. Deep-sea deposit-

feeding strategies suggested by environmental and feeding constraints. Philosophical

Transactions of the Royal Society of London A: Mathematical, Physical and Engineering

Sciences 331(1616):85-101.

Kamermans, P. 1994. Similarity in food source and timing of feeding in deposit-and suspension-

feeding bivalves. Marine Ecology-Progress Series 104:63-63.

Levinton, J. 1991. Variable feeding behavior in three species ofMacoma (Bivalvia: Tellinacea) as a

response to water flow and sediment transport. Marine Biology 110(3):375-383.

Todd, J.A. 2001. Neogene Marine Biota of Tropical America Molluscan Life Habits Database London: Smithsonian Tropical Research Institute Panama, Natural History Museum Basel Switzerland.

218

Appendix D

Relative abundance data for molluscs from Ebon Archaeological sites

219

MLEb-1, Ebon Islet Table A Relative abundance of all taxonomic categories for MLEb-1, TP 17-20 by MNI, NISP and Weight in grams.

IA IB IIA IIB

MNI. NISPP.

Weight (g) MNI. NISP

P. Weight

(g) MNI. NISPP.

Weight (g) MNI. NISP

P. Weight

(g) Bivalvia

Arcidae Arca spp. 2 3 2.96 1 2 1.06 Barbatia spp. 2 5 2.64 1 1 1.15

Cardiidae Acrosterigma spp. 1 1 0.21 1 2 2.79 Fragum fragum 3 7 1.18 6 11 3.02 1 2 0.69 Fragum spp. 1 1 0.12 1 1 0.33 Hippopus spp. 1 1 2.46 Tridacna crocea 1 7 27.18 1 1 2.45 Tridacna gigas 1 1 5.24 1 1 3.59 Tridacna maxima 1 10 223.89 1 2 17.35 Tridacna spp. 3 29 119.25 1 3 5.97 1 2 5.29 Tridacna squamosa 1 3 27.83 Vasticardium elongatum 1 1 4.66 Vasticardium spp. 1 1 5 1 2 13.48

Chamidae Chama pacifica 3 11 18.43 Chama spp. 6 23 49.34 2 5 42.99

Lucinidae Lucinidae 1 1 0.22 Ctena bella 2 4 1.3 2 5 2.58 2 3 0.81 2 2 0.36

Mesodesmatidae Atactodea striata 1 1 0.18 Psammobiidae Asaphis violascens 27 219 173.63 10 97 59.41 10 67 37.06 7 50 53.61

Gari spp. 1 3 6.42 Pteriidae Isognomon spp. 1 1 0.49

Pinctada spp. 1 3 1.48 Spondylidae Spondylus spp. 1 4 2.36 1 2 31.3 1 1 0.64

Tellinidae Tellina palatum 1 1 0.4

220

Tellina scobinata 1 1 0.16 Veneridae Gafrarium spp. 6 18 11.79 8 29 19.11 5 14 11.65 2 4 2.74

Periglypta puerpera 1 1 2.1 Gastropoda

Buccinidae Pollia spp. 1 1 2.65

Pollia undosa 3 9 7.94 1 1 0.32 Bursidae Bursa spp. 13 74 130.85 4 8 25.29 1 1 0.53 3 4 26.46 Cassidae Cassis cornuta 1 1 9.66

Cerithidae Cerithium columna 33 54 25.8 5 11 4.3 3 3 1.44 2 2 1.6

Cerithium echinatum 3 4 3.86 2 2 0.79

Cerithium nodulosum 8 211 580.32 4 57 114.69 4 16 60.31 2 14 53.38

Cerithium spp. 17 29 9.6 3 6 1.45 4 7 2.79 1 1 0.73

Clypeomorus spp. 1 1 0.93 Conidae Conus araneosus 1 1 0.93

Conus ebraeus 2 3 3.33

Conus flavidus 1 1 9.11 1 1 20.93

Conus marmoreus 1 1 4.07

Conus miliaris 1 1 2.11

Conus spp. 57 254 405.57 13 58 94.83 1 5 9.54 2 5 11.56 Cypraeidae Cypraeidae 21 52 60.96 5 26 19.26 2 4 3.02

Cypraea spp. 7 6 13.74 2 5 7.84

Cypraea tigris 1 1 0.72 1 1 2.62 1 1 5.28

Erosaria erosa 1 1 3.33

Luria spp. 1 1 0.48 1 1 2.12

Lyncina spp. 2 3 12.52

Mauritia maculifera 1 2 3.57

Mauritia spp. 14 15 55.2 2 4 11.77 1 1 2.43 1 1 3.11

Moneta annulus 2 2 0.98

Monetaria caputserpentis 1 1 1.61

Monetaria moneta 25 34 27.29 12 21 15.65 2 2 1.4 1 1 0.71

221

Monetaria spp. 2 2 4.64 Ellobiidae Melampus flavus 8 12 4.23 2 2 0.8

Melampus spp. 1 5 0.25 1 1 0.15 Fasciolariidae Fasciolariidae 1 1 0.88 Hipponicidae Sabia conica 2 3 1.18

Mitridae Mitra mitra 1 1 0.52

Mitra stictica 4 16 19.31 1 3 2.47 Muricidae Muricidae 3 8 26.5 1 3 17.73 1 1 1.85

Chicoreus spp. 15 57 266.56 5 28 81.08 2 6 20.78 1 2 15.26

Drupa aperta 1 1 0.52

Drupa clathrata 1 2 15.95 1 1 1.12

Drupa grossularia 6 6 10.07

Drupa morum 17 22 36.12 2 3 10.53

Drupa ricinus 22 25 29.85 4 4 7.46

Drupa spp. 8 43 44.38 6 15 16.7 2 5 5.71 1 1 1.93

Mancinella alouina 1 2 9.31

Morula granulata 3 7 5.85 1 1 0.52

Morula spp. 2 3 2.34 4 6 4.35 1 1 0.75 2 2 1.06

Morula uva 4 4 3.73 1 1 0.99 Plicopurpura spp. 1 1 0.33

Thais armigera 5 17 200.88 1 3 15.04 1 2 12.74

Thais spp. 1 1 13.18 Naticidae Mammilla spp. 1 1 0.56

Polinices spp. 2 3 2.18 1 3 2.65 Neritidae Nerita exuvia 2 2 1.16

Nerita plicata 77 97 52.62 32 49 24.06 31 43 23.09 24 52 28.72

Nerita polita 13 34 18.22 15 42 24.03 7 20 11.32001 7 17 11.35

Nerita signata 4 4 1.43 2 2 0.53 3 6 1.85 1 1 0.14

Nerita spp. 1 2 0.48 1 1 0.58 Neritopsidae Neritopsis radula 1 1 0.56 2 2 1.72 1 1 0.38

222

Planaxinae Planaxis sulcatus 11 14 4.23 1 3 0.7 2 3 1.16 1 1 0.23 Ranellidae Ranellidae 3 5 2.79 1 1 0.25 1 3 3.09

Cymatium spp. 1 1 0.55

Guturnium muricinum 131 195 87.92 5 6 2.21 2 3 1.45 1 1 0.45

Monoplex intermedius 38 46 40.45 15 18 13.4 6 6 4.21 2 2 1.84

Monoplex nicobaricus 40 50 47.42 14 16 12.66 3 3 1.06 1 1 0.22

Monoplex spp. 15 56 24.03 1 9 5.52 1 2 1.22 1 2 0.83 Strombidae Strombidae 1 1 0.72 1 3 1.84 1 1 6.39

Canarium spp. 5 8 5.19 2 4 1.37 1 1 1.98 Canarium microurceus 2 2 1.67

Harpago chiragra 1 1 0.67

Lambis lambis 1 9 17.28 1 2 2.02

Lambis spp. 1 5 7.42 1 8 12.89 1 2 1.46 1 10 14.71

Strombus maculatus 2 2 0.74 1 1 0.92

Strombus spp. 1 1 0.3 Terebridae Terebridae 1 1 0.38 1 1 1.07

Myurella spp. 3 10 7.57

Oxymeris areolata 1 1 2.12

Oxymeris crenulata 2 12 14.37 1 2 11.8

Oxymeris spp. 1 1 0.64

Terebra spp. 2 6 2.07 1 1 0.47 Tonnidae Tonnidae 1 1 0.42

Tonna spp. 1 2 0.75 Triviidae Trivirostra spp. 2 2 1.19 1 1 0.6

Trochidae Trochus maculatus 19 56 95.09 9 26 47.01 3 9 12.08 1 3 14

Trochus spp. 2 6 5.96 1 5 2.36 1 1 0.5 Turbinellidae Vasum turbinellus 14 83 218.09 5 23 56.74 2 5 12.91 2 4 78.21

Vasum spp. 2 4 13.05 1 1 2.86 Turbinidae Turbo argyrostomus 9 72 272.43 1 12 36.35 1 1 3.56 1 5 46.4

Turbo setosus 2 55 183.47 1 10 19.48 1 4 31.19 1 3 17.08

223

Turbo spp. 7 83 60.27 2 14 15.92 1 7 7.15 1 3 5.67 Vermetidae Vermetidae 1 1 2.43 1 1 0.65

Unidentified 68 27.12 23 11.02 4 0.68 8 1.17

224

Table B Relative abundance of all taxonomic categories for MLEb-1, TP 6 by MNI, NISP and Weight in grams.

IA IB IIA IIB MNI. NISPP. Weight

(g) MNI. NISPP. Weight (g) MNI. NISPP. Weight

(g) MNI. NISPP. Weight (g)

Bivalvia Arcidae Barbatia spp. 1 1 0.31

Cardiidae Cardiidae 1 2 1.84 Acrosterigma spp. 1 1 6.82 Fragum fragum 2 4 0.77 2 4 0.99 1 1 0.49

Fragum spp. 1 2 0.27 Hippopus hippopus 1 1 19.97 Hippopus spp. 1 1 0.39 Tridacna crocea 1 6 43.92 1 2 20.81 Tridacna maxima 1 9 115.56 1 1 11.92 Tridacna spp. 1 22 55.61 1 18 56.35 1 5 17.72 1 11 19.37

Vasticardium

elongatum 1 1 1.36 1 1 14.62

Vasticardium spp. 1 2 3.84 Chamidae Chama spp. 1 1 1.33 Lucinidae Codakia spp. 1 1 0.79

Ctena bella 2 5 6.31 1 2 0.64 Mesodesmatidae Atactodea striata 2 2 0.42 1 10 3.1

Psammobiidae Asaphis violascens 5 38 29.35 3 31 12.83 8 33 41.1 2 10 1.95 Pteriidae Pteriidae 1 2 0.53

Pinctada spp. 1 3 3.82 1 2 0.52 Spondylidae Spondylus spp. 1 3 3.82

Tellinidae Tellinidae 1 1 0.83 Tellina palatum 2 15 12.63 2 14 7.41 1 2 0.6 1 2 0.81 Tellina spp. 1 1 0.48 1 5 2.67

Veneridae Veneridae 1 2 1.21

225

Antigona spp. 1 1 24.89 Gafrarium pectinatum 1 2 1.17 Gafrarium spp. 2 9 3.24 5 31 22.13 5 13 11.37 1 3 2.39 Periglypta puerpera 1 1 1.06 Periglypta spp. 1 3 1.98

Gastropoda Bursidae Bursa rhodostoma 1 1 8.03

Bursa spp. 1 1 0.43 Cassidae Cassis cornuta 1 1 53.45

Cerithidae Cerithium columna 2 4 1.21 1 1 0.77 Cerithium nodulosum 2 38 110.43 1 4 4.95 Cerithium spp. 3 4 1.22 1 1 0.31

Conidae Conus distans 1 1 1.81 Conus marmoreus 1 1 5 Conus spp. 14 25 37.41 4 14 8 3 4 2.65

Cypraeidae Cypraeidae 1 1 0.68 1 1 1.97 Cypraea spp. 1 3 1.25

Cypraea tigris 1 1 16.22 1 1 1.48 Erosaria helvola 1 2 0.82 Mauritia spp. 1 1 3.85 Monetaria moneta 2 3 1.3 1 3 1.42 1 1 0.5 Monetaria obvelata 1 1 0.35

Ellobiidae Melampus flavus 1 1 0.11 Haliotidae Haliotidae 1 1 0.16

Littorinidae Littoraria coccinea 1 1 0.4 Mitridae Mitra spp. 1 1 1.07 1 1 0.16

Mitra stictica 1 3 5.96 1 1 0.66 Muricidae Drupa morum 3 4 5.47

Drupa ricinus 2 2 1.49 Drupa spp. 1 1 0.47 1 1 0.77

226

Morula granulata 1 2 0.4 1 1 0.57 Thais armigera 2 2 29.22

Naticidae Naticidae 2 3 2.82 Neritidae Nerita plicata 5 10 3.99 1 3 0.87 3 5 1.1 3 4 0.82

Nerita polita 11 11 5.97 8 25 9.78 3 7 3.26 1 2 0.52

Nerita spp. 1 8 2.51 Nerita undata 1 1 0.31

Planaxinae Planaxis sulcatus 1 1 0.26 1 1 0.55 Ranellidae Ranellidae 1 2 9.36

Cymatium spp. 1 1 1.15

Guturnium muricinum 1 2 0.71 1 1 0.52 Monoplex intermedius 3 3 4.15 1 1 0.67 Monoplex nicobaricus 2 2 0.71 1 1 0.2

Monoplex spp. 1 1 0.31 1 1 0.21 Strombidae Harpago chiragra 1 1 7.28

Lambis lambis 1 1 0.72 Lambis spp. 1 10 27.76 1 2 1.7 1 1 0.95

Terebridae Terebra spp. 1 1 0.38 Trochidae Trochus maculatus 1 2 3.57

Trochus spp. 1 1 0.46 1 1 0.57 Turbinellidae Vasum turbinellus 10 28 89.82 1 2 12.58

Turbinidae Turbo spp. 1 2 1.03 1 5 1.25 1 2 1.61 Turbo argyrostomus 1 12 50.63 1 2 10.6

Turbo setosus 1 1 0.81 1 1 1.76 Turbo stenogyrus 1 3 5.11

Unidentified 21 8.8 21 8.56 13 5.54 7 0.38

227

Table C Relative abundance of all taxonomic categories for MLEb-1, TP 8-12 by MNI, NISP and Weight in grams

A

MNI. NISPP. Weight (g)

Bivalvia

Arcidae Barbatia (Savignyarca) spp. 1 1 0.09 Cardiidae Acrosterigma spp. 1 2 8.88

Fragum fragum 6 21 6.51 Tridacna crocea 1 1 18.5 Tridacna maxima 1 4 50.61 Tridacna spp. 1 10 62.13

Mesodesmatidae Atactodea striata 1 39 11.25 Fragum fragum 6 21 6.51

Psammobiidae Asaphis violascens 5 8 4.11 Veneridae Gafrarium spp. 2 5 3.09

Gastropoda Buccinidae Engina mendicaria 1 1 1 Cerithidae Cerithium columna 1 1 0.28

Cerithium nodulosum 1 3 4.64 Conidae Conus spp. 3 3 19.14

Cypraeidae Monetaria moneta 2 2 0.95 Naticidae Naticidae 3 3 0.77 Neritidae Nerita plicata 2 2 0.44

Nerita polita 5 8 9.07 Ranellidae Monoplex spp. 1 1 0.47

Strombidae Harpago chiragra 1 1 0.73

Lambis lambis 1 1 40.87

Lambis spp. 1 2 4.6 Terebridae Oxymeris crenulata 1 2 0.78 Trochidae Trochus maculatus 1 1 0.3

Trochus spp. 1 3 3.89 Turbinellidae Vasum turbinellus 1 1 2.06

Turbinidae Turbo argyrostomus 1 3 41.69

Turbo stenogyrus 1 1 1.68 Unidentified - 11 7.22

228

Table D Relative abundance of all taxonomic categories for MLEb-1, TP 13-16 by MNI, NISP and Weight in grams A I



Bivalvia Arcidae Barbatia spp. 2 2 0.34

Cardiidae Fragum fragum 8 16 4.55 1 1 0.44 Trachycardium spp. 1 1 0.18 Tridacna crocea 1 2 10.53 Tridacna maxima 1 3 42.47 1 1 30.31 Tridacna spp. 1 1 0.44 1 2 5.31

Cardiidae Fragum fragum 8 16 4.55 1 1 0.44 Trachycardium spp. 1 1 0.18

Chamidae Chama spp. 1 1 1.09 Lucinidae Ctena bella 2 2 0.45

Mesodesmatidae Atactodea striata 1 3 0.68 1 16 3.97 Psammobiidae Asaphis violascens 2 10 5.83 2 3 7.34

Veneridae Antigona spp. 1 2 6.05 Gafrarium spp. 1 1 0.4 1 1 1.21

Gastropoda Bursidae Bursa spp. 5 5 11.2 2 2 4.38

Cerithidae Cerithium columna 1 1 0.72 1 1 0.27

Cerithium nodulosum 3 11 114.56 1 4 9.19

Cerithium spp. 1 3 0.87 Conidae Conus ebraeus 1 1 4.83

Conus spp. 1 4 3.92 3 4 6.62 Cypraeidae Cypraeidae 3 8 9.18 2 2 2.13

Cypraea tigris 1 1 1.95

Lyncina spp. 1 1 4.56 Mauritia mauritiana 1 1 4.69

Monetaria

caputserpentis 1 1 4.86

Monetaria moneta 3 3 1.65 Janthinidae Janthinidae 1 1 0.36 Muricidae Muricidae 1 1 2

Chicoreus spp. 2 3 15.7 Drupa morum 1 1 1.41 Drupa ricinus 2 2 1.98 Drupa spp. 1 3 2.51 1 2 1.49

Morula granulata 1 1 0.72 Morula uva 1 1 0.71

Neritidae Nerita exuvia 1 1 2.99

Nerita plicata 2 2 1.56 Nerita polita 10 20 13.46 1 2 0.43

229

Planaxinae Planaxis sulcatus 3 3 0.88 1 1 0.24 Ranellidae Guturnium muricinum 1 1 0.4

Monoplex intermedius 2 2 1.95

Monoplex nicobaricus 3 3 4.5 2 3 3.11

Monoplex spp. 1 1 0.61 Strombidae Harpago chiragra 1 2 40.09

Lambis lambis 1 1 34.18 Lambis spp. 1 1 0.63

Strombus spp. 1 2 1.28 Terebridae Oxymeris crenulata 1 1 1.61 1 2 21.38

Tonnidae Malea spp. 1 1 2.18 Trochidae Trochus maculatus 4 8 18.79 2 4 11.74

Trochus spp. 1 1 0.19 Turbinellidae Vasum turbinellus 5 9 31.13 1 4 6.26

Vasum ceramicum 1 2 5.11 Turbinidae Turbo argyrostomus 3 6 101.04 2 3 34.55

Turbo setosus 1 1 4.5

Turbo spp. 1 10 13.73 2 6 13.27

Turbo stenogyrus 1 1 13.72 Vermetidae Vermetidae 1 3 2.9

Unidentified 12 7.79 2 0.71

230

MLEb-5, Ebon Islet

Table E Relative abundance of all taxonomic categories for MLEb-1, 3 x 5m area excavation by MNI, NISP and Weight in grams

A


Bivalvia Arcidae Arca spp. 1 1 0.96

Arca ventricosa 1 1 0.6

Barbatia (Savignyarca) spp. 5 11 24.07 Cardiidae Acrosterigma spp. 2 10 13.41

Fragum fragum 4 21 10.77 Fragum spp. 5 13 5.59 Hippopus hippopus 2 15 225.24 Trachycardium spp. 1 1 0.51 Tridacna crocea 2 5 312.27 Tridacna maxima 39 211 6953.26 Tridacna spp. 1 752 3976.55 Tridacna squamosa 3 4 30.98 Vasticardium elongatum 6 43 230.35 Vasticardium spp. 1 11 116.89 Vasticardium angulatum 1 1 0.77

Chamidae Chama pacifica 1 1 4.05 Chama spp. 2 20 50.45

Lucinidae Codakia punctata 2 2 24.07 Ctena bella 6 16 5.92

Mesodesmatidae Atactodea striata 1 1 0.14 Spondylidae Spondylus spp. 1 5 11.9

Spondylus squamosus 1 1 35.52 Pectinidae 1 1 0.1

Psammobiidae Asaphis violascens 108 786 810.19 Tellinidae Tellina palatum 8 56 59.57

Tellina scobinata 1 5 7.53 Tellina spp. 1 3 6.13

Veneridae Gafrarium spp. 65 269 221.11 Periglypta puerpera 1 21 54.43

Gastropoda Buccinidae Pollia undosa 2 3 4.36

Bursidae Bursa bufonia 1 1 11.32

Bursa spp. 4 17 73.62 Cassidae Cypraecassis rufa 1 1 0.65

Cerithidae Cerithium columna 5 6 2.79

Cerithium echinatum 2 2 1.24

Cerithium nodulosum 13 64 295.59

Cerithium spp. 2 9 4.78

231

Conidae Conus chaldeus 1 2 5.85

Conus distans 1 9 90.15 Conus ebraeus 2 2 10.46 Conus marmoreus 2 4 35.43 Conus miliaris 1 1 18.52 Conus spp. 62 159 553.04

Cypraeidae Cypraeidae 29 130 189.04 Erosaria helvola 1 1 0.42 Erosaria spp. 2 2 0.95 Lyncina lynx 1 1 7.68 Lyncina spp. 8 26 53.91 Mauritia spp. 10 13 26.91 Moneta annulus 4 4 2.74 Monetaria caputserpentis 7 7 41.07 Monetaria moneta 15 21 22.63 Talparia talpa 1 1 1.83

Ellobiidae Melampus flavus 4 8 3.36 Fasciolariidae Fasciolariidae 1 1 1.07

Harpidae Harpa amouretta 1 1 1.54 Harpa spp. 1 3 1.44

Hipponicidae Sabia conica 2 2 1.02 Mitridae Mitridae 1 1 0.43

Mitra spp. 1 1 2.81 Mitra stictica 2 6 6.48

Muricidae Muricidae 5 44 28.56 Chicoreus spp. 1 2 3.56 Drupa grossularia 1 1 1.16 Drupa morum 7 14 21.16 Drupa ricinus 7 9 6.57 Drupa spp. 3 14 9.12 Morula granulata 1 1 0.57 Morula spp. 1 1 0.49 Morula uva 5 5 3.01 Plicopurpura spp. 1 1 0.37 Thais armigera 3 10 110.45 Thais spp. 1 2 1.17 Thalessa virgata 4 9 13.73

Naticidae Naticidae 1 1 0.3 Mammilla spp. 1 2 1.2 Notocochlis spp. 26 33 31.55

Neritidae Nerita exuvia 1 1 0.64 Nerita plicata 212 320 247.11 Nerita polita 112 219 149.45 Nerita signata 6 8 2.78 Nerita spp. 13 45 8.96 Nerita undata 1 1 0.26

Patellidae Scutellastra flexuosa 3 3 0.8

232

Planaxinae Planaxis sulcatus 4 6 1.08 Pteriidae Isognomon spp. 1 7 27.23

Pinctada spp. 2 46 67.56 Ranellidae Ranellidae 1 2 0.31

Guturnium muricinum 6 8 3.97 Monoplex intermedius 7 9 5.19 Monoplex nicobaricus 3 4 1.68 Monoplex spp. 3 8 3.1

Strombidae Strombidae 1 1 0.27 Canarium maculatum 1 1 1.98 Canarium spp. 5 7 10.69 Canarium wilsonorum 1 1 3.05 Harpago chiragra 16 117 2399.84 Lambis lambis 1 10 65.68 Lambis spp. 1 25 86.88 Strombus spp. 1 1 0.21

Terebridae Terebridae 1 3 2.15 Oxymeris crenulata 1 1 0.32 Oxymeris spp. 1 1 6.92

Triviidae Trivirostra spp. 2 2 0.83 Trochidae Trochus maculatus 6 55 63.55

Trochus spp. 1 8 5.48 Turbinellidae Vasum turbinellus 6 30 134.2

Turbinidae Turbo argyrostomus 9 84 241.49 Turbo setosus 22 43 714.79 Turbo spp. 5 77 107.88

Vermetidae Vermetidae 1 3 1.17 Unidentified 299 202.84

233

MLEb-31, Moniak Islet Table F Relative abundance of all taxonomic categories for MLEb-31, TP 2 - 6 by MNI, NISP and Weight in grams

IA IB IIA IIB IC SD

MNI NISP Wt. (g) MNI NISP Wt.

(g) MNI NISP Wt. (g) MNI NISP Wt.

(g) MNI NISP Wt. (g) MNI NISP Wt.

(g)

Bivalvia

Arcidae Barbatia spp. 1 1 0.31

Cardiidae Cardiidae 1 6 0.66

Fragum spp. 1 1 0.02 4 5 0.34 1 1 0.69

Hippopus hippopus 1 1 87.42

Tridacna crocea

2 2 136.68

Tridacna maxima 4 7 988.12 1 3 64.8 1 5 127.4 1 6 102.28

Tridacna spp. 1 15 90.5 1 6 16.06 1 3 37.55 1 1 0.09

Tridacna squamosa 1 1 7.71 1 1 1.73

Vasticardium spp. 1 1 1.56 1 1 2.33

Carditidae Beguina

semiorbiculata 1 1 0.51

Chamidae Chama spp. 1 1 4.14 3 4 12.47

Lucinidae Ctena bella 1 1 0.1

Psammo-biidae

Asaphis violascens

32 139 150.5 15 105 103.11 10 41 61.15 2 11 13.49 3 10 9.52 2 6 7.1

234

Spondylidae Spondylus

sinensis 1 2 49.41 1 2 34.37

Spondylus spp. 1 2 9.09 1 1 0.28

Veneridae Periglypta

puerpera 1 3 3.54 1 1 1.92

Pitar striatus 1 1 2.55

Gastropoda

Buccinidae Pollia undosa 2 3 3.95 Bursidae Bursa spp. 2 3 9.01 3 9 7.03 2 10 11.19 1 4 3.6

Cerithidae Cerithium

columna 1 1 0.43

Cerithium nodulosum 6 23 128.39 2 28 68.57 10 74 318.21 1 6 15.3 1 2 3.27 1 4 10.19

Cerithium spp. 1 1 0.25

Conidae Conus catus 1 2 1.45 1 1 0.96 1 2 3.74

Conus miles 2 2 45.21 1 2 6.9

Conus miliaris 1 1 32.21 1 1 2.66

Conus spp. 5 19 103.04 10 38 119.96 12 49 137.27 1 9 75.09 1 3 8.76 2 3 30.2

Cypraeidae Cypraeidae 4 9 7.87 2 6 4.24 1 2 1.32 1 2 1.66 1 1 2.44

Cypraea spp. 1 1 2.1 1 2 4.75

Erosaria

helvola 1 1 0.47

235

Luria isabella 1 1 14.38

Luria spp. 1 1 1.56

Mauritia eglantina 1 2 5.7 1 1 0.55

Mauritia spp. 2 2 6.46 5 10 16.23 3 3 5.33 1 1 1.68

Monetaria

caputserpentis 2 2 9.26 1 1 6.45

Monetaria

moneta 4 4 3.97 1 1 0.66

Monetaria

spp. 1 1 2.16

Lyncina

leviathan

Ellobiidae Melampus

flavus 2 2 1.14

Fascio- lariidae

Latirus maculatus 1 1 6.02

Harpidae Harpa

amouretta 1 1 0.95

Hippon-icidae Sabia conica

2 3 0.62

Mitridae Mitra imperialis 1 1 1.6

Muricidae Muricidae 1 1 1.27

Chicoreus brunneus 1 1 2.71

Chicoreus

1 2 4.28 2 3 18.23

236

spp.

Drupa aperta 1 1 0.73 3 3 7.29

Drupa

clathrata 1 1 10.45

Drupa

grossularia 1 1 1.45 1 1 2.09

Drupa morum 3 3 9.98 1 2 1.7

Drupa ricinus 2 2 3.24 1 1 0.56 1 2 3.42

Drupa spp. 5 11 7.87

Mancinella

alouina 1 1 3.11

Morula

granulata 1 1 1.55

Morula spp. 1 2 0.49 1 1 0.47 1 1 1.02

Naquetia cumingii 1 1 1.79

Thais

armigera 24 88 568.99 4 35 142.4 2 10 99.78 1 6 21.19 1 1 12.13 1 1 3.61

Thalessa

virgata 1 2 2.44 1 2 15.81

Nassariidae Nassarius papillosus 1 1 1.55 1 1 2.12

Nassarius

spp. 1 1 0.08

Naticidae Polinices spp. 1 1 0.85

Mammilla

237

simiae

Neritidae Nerita albicilla 1 1 0.87

Nerita plicata 2 2 1.79 8 8 3.48 2 2 0.88 1 1 0.6

Nerita polita 36 48 51.79 82 130 103.87 57 75 78.86 1 26 26.67 1 1 1 11 16 20.2

Nerita signata

4 6 4.77

1 1 1.58

Nerita spp. 1 2 0.96 2 14 5.76 1 4 1.73 1 1 0.72

Nerita undata 1 2 1.1 9 12 10.96 1 0 0

Olividae Oliva annulata 1 1 3

Oliva minicea 1 1 3.23 1 1 0.74

Patellidae Scutellastra

flexuosa 1 1 0.37

Pteriidae Isognomon spp.

1 1 0.53

Ranellidae Charonia

tritonis 1 3 5.51 1 1 3.24

Guturnium muricinum 5 5 1.71 14 17 7.4 7 6 3.74 1 1 0.33

Gyrineum

pusillum 1 1 0.79

Monoplex

intermedius 2 2 1.86 4 5 4.4 1 2 1.57 2 2 2.21

Monoplex

nicobaricus 6 6 5.15 2 3 6.15 1 1 0.88

Monoplex 1 1 0.8 1 3 0.82 1 1 0.31 1 1 0

238

spp.

Ranularia

testudinaria 1 1 2.17

Strombidae Strombidae 1 2 2.7 1 7 2.16 1 1 0.97

Canarium spp. 5 10 4.44 1 1 3.28

Harpago chiragra 1 2 31.99

Lambis lambis

1 1 11.34

1 2 14.07

Lambis spp. 1 1 0.37

Lentigo

lentiginosus 1 1 3.23

Strombus luhuanus 2 2 5.01

Strombus spp.

1 6 2.31 1 2 1.57

Terebridae Terebridae 1 3 0.77

Hastula

solida 1 1 0.63

Oxymeris crenulata 1 5 9.82 1 1 3.19 1 1 0.5

Oxymeris spp. 1 1 1.59 Tonnidae Malea pomum 1 2 1.71 1 3 3.87 1 1 1.25

Tonna perdix

Trochidae Trochus maculatus

3 10 495.2 7 31 42.81 4 5 21.34 1 3 6.49

239

Turbinellidae Vasum

turbinellus 9 19 113.95 9 49 118.64 19 66 389.91 9 22 118.36 3 12 34.05

Turbinidae Turbo

argyrostomus 2 26 99.19 4 22 98.05 4 15 74.66 5 10 51.81 3 4 20.71 2 8 55.09

Turbo setosus 3 6 31.53 3 13 125.17 1 4 35.09 1 1 1.62 2 2 9.57

Turbo spp. 1 19 32.04 3 39 71.1 1 11 38.76 1 6 10.44 1 1 3.59

Turritellidae Turritella spp. 1 1 0.87 Vermetidae Vermetidae 1 2 1.02

Turridae Turridae 1 1 1.72

Unidentified 15 14.91 37 18.03 20 6.64 3 3.13 1 0.52

240

MLEb-33, Enekoion Islet

Table G Relative abundance of all taxonomic categories for MLEb-3, TP 1, 6, and 7 by MNI, NISP and Weight in grams

I MNI. NISPP. Weight (g) Bivalvia

Arcidae Barbatia spp. 1 1 0.24 Cardiidae Acrosterigma spp. 1 1 0.4

Corculum cardissa 5 9 2.32 Fragum spp. 67 162 54.09 Tridacna maxima 2 3 263.23 Tridacna spp. 1 2 9.91

Chamidae Chama spp. 11 28 263.34 Lucinidae Ctena bella 2 3 0.87

Psammobiidae Asaphis violascens 19 125 106.15 Tellinidae Tellina palatum 1 1 0.05 Veneridae Veneridae 1 1 0.15

Gafrarium spp. 1 1 0.45 Gastropoda

Buccinidae Pollia undosa 2 2 1.54 Bursidae Bursa spp. 15 42 78.71

Cerithidae Cerithidae 1 4 0.87 Cerithium columna 1 1 0.28

Cerithium nodulosum 7 85 253.8

Cerithium spp. 23 26 7.66 Conidae Conus marmoreus 1 1 6.81

Conus spp. 29 89 320.82 Cypraeidae Cypraeidae 6 8 14.19

Erosaria helvola 1 2 0.82 Mauritia spp. 1 1 7.8 Monetaria moneta 2 5 1.78

Ellobiidae Melampus flavus 32 41 15.91 Melampus spp. 1 1 0.08

Harpidae Harpa amouretta 1 1 0.34 Harpa spp. 1 1 0.4

Hipponicidae Sabia conica 1 2 0.71 Mitridae 1 3 1.02

Mitridae Mitra spp. 1 1 0.93

Mitra stictica 3 8 10.03 Pterygia spp. 1 1 1.27

Muricidae Muricidae 3 8 12.16 Chicoreus spp. 1 1 1.59 Drupa aperta 1 1 2.8 Drupa morum 2 3 8.14 Drupa ricinus 5 5 4.36

241

Drupa rubusidaeus 1 5 25.42 Drupa spp. 1 1 0.4 Morula uva 2 2 1.88 Thais armigera 3 11 49.44 Thais spp. 1 1 1.1 Thalessa virgata 1 2 1.99

Nassariidae Nassarius papillosus 1 1 0.26 Naticidae Mammilla spp. 2 2 0.33 Neritidae Nerita albicilla 2 2 2.45

Nerita plicata 43 65 42.7 Nerita polita 121 225 160.41 Nerita signata 1 1 0.6 Nerita spp. 3 9 1.83

Patellidae Scutellastra flexuosa 1 1 0.06 Planaxinae Planaxis sulcatus 8 9 2.42 Ranellidae Ranellidae 1 1 0.4

Guturnium muricinum 11 12 4.51 Monoplex intermedius 3 3 4.15 Monoplex nicobaricus 8 8 4 Monoplex spp. 1 7 2.7 Spondylidae 1 2 1.72

Spondylidae Spondylus sinensis 2 3 60.7 Spondylus spp. 1 1 0.63

Strombidae Canarium spp. 5 11 4.94 Lambis spp. 1 6 4.55

Terebridae Terebridae 1 2 1.16 Tonnidae Tonnidae 1 12 0.49

Malea spp. 1 1 2.34 Tonna pennata 1 2 0.7

Trochidae Trochus maculatus 3 8 12.66 Trochus spp. 1 1 0.28

Turbinellidae Vasum turbinellus 45 137 438.75 Turbinidae Turbo argyrostomus 16 80 290.59

Turbo setosus 6 14 57.4 Turbo spp. 3 34 45.33

Vermetidae Vermetidae 1 2 0.40 Unidentified 28 13.5

242

Table H Relative abundance of all taxonomic categories for MLEb-33, TP 2 by MNI, NISP and Weight in grams IA IB

MNI. NISPP. Weight (g) MNI. NISPP. Weight

(g) Bivalvia

Cardiidae Fragum spp. 5 5 11.2 2 2 4.38 Tridacna maxima 8 16 4.55 1 1 0.44 Tridacna spp. 1 1 0.18

Chamidae Chama spp. 1 1 0.44 1 2 5.31 Psammobiidae Asaphis violascens 1 1 4.86

Spondylidae Spondylus sinensis 1 3 0.68 1 16 3.97 Tellinidae Tellina palatum 1 3 2.51 1 2 1.49

Gastropoda Bursidae Bursa spp. 2 2 0.34

Vasticardium elongatum 1 2 10.53 Cerithidae Cerithium nodulosum 1 3 42.47 1 1 30.31

Conidae Conus spp. 1 1 0.72 1 1 0.27

Cypraeidae Cypraeidae 3 11 114.56 1 4 9.19 Muricidae Chicoreus spp. 1 1 1.09

Drupa spp. 1 1 4.83

Naquetia cumingii 1 4 3.92 3 4 6.62 Neritidae Nerita plicata 1 1 1.95

Nerita polita 3 8 9.18 2 2 2.13

Nerita signata 1 1 4.56 Nerita spp. 1 1 4.69

Ranellidae Guturnium muricinum 3 3 1.65

Monoplex intermedius 1 1 0.36 Monoplex spp. 2 2 0.45

Strombidae Strombidae 2 2 1.98 Harpago chiragra 12 7.79 2 0.71


Trochidae Trochus maculatus 1 1 0.72 Turbinellidae Vasum turbinellus 1 1 0.71

Turbinidae Turbo argyrostomus 1 1 2

Turbo setosus 1 1 2.99

Turbo spp. 2 2 1.56 Unidentified 1 3 0.87

243

Table I Relative abundance of all taxonomic categories for MLEb-33, TP 8 by MNI, NISP and Weight in grams


Cardiidae Fragum spp. 2 2 1.54 Tridacna maxima 15 42 78.71 Tridacna spp. 1 1 0.4 Vasticardium elongatum 5 9 2.32

Chamidae Chama spp. 2 3 263.23 Psammobiidae Asaphis violascens 1 1 0.93

Pteriidae Pinctada spp. 3 8 10.03 Spondylidae Spondylus spp. 1 1 1.59

Veneridae Gafrarium spp. 1 2 1.99 Periglypta spp. 1 1 0.26

Gastropoda Bursidae Bursa spp. 1 1 0.24

Cerithidae Cerithium nodulosum 67 162 54.09 Conidae Conus distans 1 2 9.91

Conus leopardus 1 1 0.28

Conus lividus 7 85 253.8

Conus spp. 23 26 7.66

Cypraeidae Cypraeidae 1 4 0.87

Monetaria moneta 11 28 263.34

Fasciolariidae Fasciolariidae 1 1 6.81 Harpidae Harpa spp. 29 89 320.82 Mitridae Mitra mitra 6 8 14.19

Muricidae Muricidae 1 1 0.08 Chicoreus spp. 1 1 7.8

Drupa ricinus 2 5 1.78

Drupa spp. 32 41 15.91

Thais armigera 1 1 0.34

Neritidae Nerita plicata 1 1 0.4

Nerita polita 1 2 0.71

Nerita signata 2 3 0.87

Ranellidae Guturnium muricinum 1 1 1.27 Monoplex nicobaricus 1 3 1.02 Monoplex spp. 28 13.5

Strombidae Strombidae 2 3 8.14 Lambis spp. 1 1 2.8

Terebridae Terebridae 1 5 25.42 Oxymeris crenulata 5 5 4.36

Trochidae Trochus maculatus 1 1 0.4 Turbinellidae Vasum turbinellus 2 2 1.88

244

Turbinidae Turbo argyrostomus 3 8 12.16 Turbo setosus 3 11 49.44 Turbo spp. 1 1 1.1

Unidentified 1 2 0.82

245

Table J Relative abundance of all taxonomic categories for MLEb-33, TP 3 by MNI, NISP and Weight in grams


Arcidae Arca spp. 1 1 1.18 Barbatia spp. 1 1 0.31

Cardiidae Fragum spp. 7 20 0.58 Tridacna spp. 1 2 11.16

Chamidae Chama spp. 1 1 1.56 Psammobiidae Asaphis violascens 6 52 27.03

Veneridae Antigona spp. 1 1 1.2 Gastropoda

Bursidae Bursa spp. 8 54 100.25 Cerithidae Cerithium nodulosum 67 769 1763.65

Cerithium spp. 5 5 1.14 Conidae Conus distans 2 6 70.9

Conus leopardus 1 2 4.74

Conus marmoreus 2 7 33.21

Conus spp. 55 216 675.57 Cypraeidae Cypraeidae 2 17 12.64

Erosaria helvola 1 2 2.58

Monetaria moneta 3 3 2.58 Harpidae Harpa spp. 1 1 0.17

Hipponicidae Sabia conica 1 1 0.52 Mitridae Mitra stictica 1 3 4.07

Muricidae Muricidae 1 1 0.47 Chicoreus spp. 2 15 72.11

Drupa morum 1 1 0.78

Drupa ricinus 1 1 0.64

Drupa rubusidaeus 2 9 42.88

Morula spp. 1 1 0.64 Thais armigera 2 10 124.43

Naticidae Naticidae 1 1 0.35 Neritidae Nerita plicata 14 20 11.48

Nerita polita 30 44 35.16 Nerita signata 2 3 1.36 Nerita spp. 1 14 1.14

Planaxinae Planaxis sulcatus 5 5 1.82 Ranellidae Guturnium muricinum 23 24 14.7

Monoplex intermedius 1 1 1.98 Monoplex nicobaricus 11 12 9.09 Monoplex spp. 1 10 3.99

Strombidae Strombidae 1 5 5.01 Harpago chiragra 2 4 4.06

246


Terebridae Terebridae 1 3 3.49 Trochidae Trochus maculatus 7 44 45.46

Turbinellidae Vasum turbinellus 35 322 1046.46 Turbinidae Turbo argyrostomus 11 33 141.48

Turbo setosus 3 6 12.32 Turbo spp. 1 37 11.49

Unidentified 13 10.2

a thesis submitted for the degree of doctor of …688962/s...archaeomalocological methods, forager...

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