spatial ecology of reef fishes justin welsh and david bellwood

Spatial Ecology of Reef Fishes

Justin Welsh and David Bellwood

Roles on reefs: Herbivory

Introduction

•Transport sediment

•Maintain algal turfs

•Remove macroalgae

•Overall, support resilience

Importance of resilience

Introduction

?

Who and what... We think we know. But where and why?

Introduction

Introduction

Haremic versus Schooling

What is the spatial ecology of roving herbivores and is there an influence of social systems?

Introduction

Chlorurus microrhinos

•Haremic

•Roving herbivore

•Active telemetry

Case study: the parrotfishes

Scarus rivulatus

•Schooling

•Roving herbivore

•Passive telemetry

•Algal removal

•Leave deep, long-lasting grazing scars

•Haremic

Introduction

Chlorurus microrhinos

Objectives:

•Quantify home range size

•Determine the influence of physical factors

•Implications for ecosystem role

Introduction

Study site: Orpheus Island, Pioneer Bay

Methods

Capture

•Barrier netting

Methods

Capture

Tagging

•Anesthetic

MS-222

•Tag

(V9T-2H, Vemco)

•Suture

Methods

Tracking

•Tracking from Kayak

for 3 - 5 days(Meyer and Holland 2005)

•Receiver

(VR100, Vemco)

•Directional hydrophone

(VH1110, Vemco)

Methods

Home range: 8,100 m2

Core area: 1,690 m2

Results

Welsh and Bellwood 2012, Coral Reefs Vol: 31

Core vs non-core: Physical characteristics:

Results

Results:

*

*

Core area Non-core area *

*

•Core areas centered on topographic complexity

•Limited mobility in haremic parrotfish

•What about schooling species?

Summary

Herbivores

• So far, highly site attached

• Social species?

• e.g. schooling?

Introduction

Scarus rivulatus• Highly abundant

• Important herbivores

• Schooling species

• Roving herbivore?

Introduction

Introduction

Objectives:

•Evaluate the foraging range of S. rivulatus

•Understand the foraging range of their schools

Passive acoustic telemetry

Introduction

Heupel et al 2006

• VR2W receivers

• V9 transmitters

• 60 m detection rangeWelsh et al. 2012, Coral Reefs

Orpheus island array

Methods

Capture

• 3 schools captured using barrier nets

Methods

Tagging

• Same tagging procedure as per active tracking

• Monitor individuals for 7 months

Spatial data analysis

• Maximum potential foraging range

Chapter 2

>5%>5% >5%>5%

<5%<5%

>5%>5% >5%>5%

<5%<5%

Spatial range

Results

• Average area occupied: 0.244 km2

Welsh and Bellwood 2012, Coral Reefs

Results

• Average area occupied by the school: 0.238 km2

Spatial range

Conclusion

• Site attached

• Facultative schooling

• Limited school fidelity

Conclusion

Introduction

Chlorurus microrhinos

•Haremic

•Site attached

Scarus rivulatus

•Schooling

•Site attached

Herbivores from a different perspective:Regardless of social system, functional role occurs

on small spatial scales

Credits

David Bellwood, Roberta Bonaldo, Simon Brandl, Rebecca Fox. Chris Goatley, Andy Hoey, Jess Hopf, Charlotte Johansson, Michael Kramer, Susannah Leahy, Carine Lefèvre, Jenn Tanner, OIRS and LIRS staff and Vemco.Photos by Joao Paulo KrajewskiFunding provided by: ARC center of excellent for coral reef studies, Australian museum, James Cook University

Schooling and feeding

• Feeding observations:

‣ 160 individuals, 1 min each, 4 times of the day, 2 sites

Results

Significance of schooling

Results