global patterns of freshwater fish communities in mediterrannean

GLOBAL PATTERNS OF FRESHWATER FISH COMMUNITIES IN MEDITERRANNEAN BIOMES

Elif Esther Fehm-Sullivan

B.S., California State University, Sacramento, 2003

THESIS

Submitted in partial satisfaction of the requirements for the degree of

MASTER OF SCIENE

in

BIOLOGICAL SCIENCES

at

CALIFORNIA STATE UNIVERSITY, SACRAMENTO

FALL 2010

ii

GLOBAL PATTERNS OF FESHWATER FISH COMMUNITIES IN MEDITERRANNEAN BIOMES

A Thesis

by

Elif Esther Fehm-Sullivan Approved by: __________________________________, Committee Chair Jamie Kneitel, Ph.D. __________________________________, Second Reader Brett Holland, Ph.D. __________________________________, Third Reader Patrick Foley, Ph.D. __________________________________ Date

iii

Student: Elif Esther Fehm-Sullivan

I certify that this student has met the requirements for format contained in the University

format manual, and that this thesis is suitable for shelving in the Library and credit is to

be awarded for the thesis.

__________________________, Graduate Coordinator ___________________ Susanne Lindgren, Ph.D. Date Department of Biological Sciences

iv

Abstract

of

GLOBAL PATTERNS OF FRESHWATER FISH COMMUNITIES IN MEDITERRANNEAN BIOMES

by

Elif Esther Fehm-Sullivan

Explaining patterns of species richness is a central theme in community ecology.

Ecologists have focused on local (within a site), regional (among sites in a given region),

or geographical (among regions) explanations of diversity patterns. In the case of

freshwater fish, studies illustrate that biological factors (competition and predation),

along with physical factors (habitat diversity, water chemistry, flow regime, temperature

and channel morphology), interact to influence species richness within and among

communities and that both operate within a range of spatial scales.

This study identified global patterns of species richness and trophic diversity in

twelve Mediterranean biome freshwater fish communities located on six continents.

Differences were found in both species richness and trophic diversity between continental

river basins. This study also examined energetic, ecological, and historical factors that

may explain freshwater fish species richness and trophic diversity among Mediterranean

biome river basins. The energetic factor, average annual discharge, was found to explain

species richness; and that none of the seven factors measured explained trophic diversity.

This result is contrary to studies that have shown net primary productivity as explaining

species richness in global freshwater fish communities. The difference presented in this

v

study states that all basin studies were in one habitat type, the Mediterranean biome,

whereas other studies examined several varying habitat types. The resulting specific

knowledge can help conserve species richness and manage river basins altered by human

activity.

___________________________, Committee Chair Jamie Kneitel, Ph.D.

___________________________ Date

vi

DEDICATION

In loving memory of Sherwood Anthony Fehm Jr. and Saba Phyllis Fehm-Sullivan.

vii

ACKNOWLEDGMENTS

Completing a Masters is truly a marathon event, and I would not have

been able to complete this journey without the aid and support of countless people

over the past seven and a half years. I would like to express my gratitude to my

supervisor, Dr. Jamie Kneitel, whose expertise, understanding, and patience added

considerably to my graduate experience. I appreciate his vast knowledge and skill

in many areas (e.g., statistical analysis, community ecology, and dry humor), and

his assistance in writing. I also want to thank him for his calm reserve during

times of stress. I would like to thank the other members of my committee, Dr.

Bret Holland, and Dr. Patrick Foley for the assistance they provided at all levels

of my thesis project. Finally, I would like to thank Dr. Susanne Lindgren, the

Graduate Student Advisor, for giving me the opportunity to finish my thesis.

I would like to give my eternal gratitude to my father James E. Sullivan

for the guidance and wisdom that he has given me throughout my life. I have

been able to develop and grow as an individual as a result. He provided me with

moral, emotional, and writing support during this entire process. I doubt I will

ever be able to convey my appreciation fully. I must also acknowledge the quiet,

constant, intense and enduring support of my mother Sadie Çançar Sullivan. A

very special thank you goes to Dr. Barbara Cordonii, who years ago diagnosed

my learning disabilities, and with whose tutelage enabled me to reach this level of

viii

education. Without her motivation and encouragement, I would not have

considered a graduate career.

ix

TABLE OF CONTENTS Page

Dedication .......................................................................................................................... vi

Acknowledgments............................................................................................................. vii

List of Tables .......................................................................................................................x

List of Figures .................................................................................................................... xi

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

Methods................................................................................................................................9

Results ................................................................................................................................11

Discussion ..........................................................................................................................24

Conclusion .........................................................................................................................29

Appendix A. Trophic level richness per drainage basin. ...................................................32

Appendix B. Data sources ..................................................................................................33

Appendix C. Species lists and trophic level .......................................................................34

Appendix D. Table of environmental factor values per drainage basin ............................42

Appendix E. Calculation table for NPP .............................................................................43

Literature Cited ..................................................................................................................44

x

LIST OF TABLES Page Table 1. Trophic Level ANOVA ......................................................................................14 Table 2. Species Richness ANOVA .................................................................................16 Table 3. Continental Trophic Richness ANOVA. ............................................................18 Table 4. Multiple Regression on Species Richness and Trophic Diversity. .....................21

xi

LIST OF FIGURES Page Figure 1. Global map of Mediterranean Biome Locations .................................................8 Figure 2. Trophic Level Histogram. .................................................................................15 Figure 3. Species Richness Histogram. .............................................................................17 Figure 4. Continental Trophic Species Richness Histogram. ...........................................19 Figure 5. Continental Community Composition Chart. ....................................................20 Figure 6. Species Richness Regression with the San Joaquin River. ...............................22 Figure 7. Species Richness Regression without the San Joaquin River. ..........................23

1

INTRODUCTION

A central issue in both biogeography and community ecology is to understand the

factors that shape species richness patterns across different spatial scales (Cody and

Mooney, 1978; Griffiths, 2006). Among vertebrates, fish have been one of the most

intensely studied groups for local (within river), regional (among rivers), and

geographical (among regions) community structure. Numerous common patterns in fish

community organization have been identified among distinct river basins at several

different spatial scales. For example, at a local scale, physical factors appear to

determine species richness in variable environments (Capone and Kushlan, 1991). On

larger spatial scales (regional and geographical), physical factors such as area, total

discharge, and primary productivity, along with historical factors such as speciation rates

and dispersal are the major determinant of species richness and regulate the importance

of local-scale factors (Lamoureux et al., 2002).

To better understand freshwater fish communities, ecologists have studied several

aspects of community structure. These include biogeographic histories and their relation

to the distribution of freshwater fishes (Novacek, 1976; Bernatchez and Wilson, 1998;

McDowall, 2002; Landini and Sorbini, 2005; Goren and Ortal, 1998), diversity of

trophic categories (feeding patterns) (Tonn, 1990; Winemiller, 1991; Behrens and

Lafferty, 2007; Daufresne and Boёt, 2007; Erös, 2007; Mittelbach et al., 2007; Lévêque

et al., 2008), and species richness (Hawkins et al., 2003; Oberdorff et al., 1995; Guégan

et al., 1998; Oberdorff et al., 2001; Griffiths, 2006; Reyjol et al., 2007).

2

The inland water fishes of the Mediterranean have been studied since the first

description of Tilapia galieae by Peter Artedi, considered the father of Ichthyology, more

than 200 years ago (Goren and Ortal, 1998). Some biogeographers have recognized the

importance of the isolation of fishes, and distinct drainages in shaping species richness

and diversity. For example, Lyons and Willig (2002) noted that isolation preserved the

products of speciation events which occurred either within single bodies of water, or

when waters became fragmented and rejoined. Each isolated lake or river system tends to

have its own characteristics and a substantial number of endemic species. In some cases,

the present distribution of freshwater fishes has been shaped by millions of years of

change in global water cycles (Lèvêque et al., 2008). Due to these constantly changing

global water cycles (i.e. glaciation, water availability and temperature variation due to

climate change), the nature and dynamics of freshwater systems have evolved

continuously, at various spatial and temporal scales (Lèvêque et al., 2008). Although

clearly there can be important differences among the fish species present in tributaries

within any basin, species are typically more similar in any location within a river basin

than they are among locations in neighboring basins (Griffiths, 2006). These basins and

waterways can provide natural laboratories for the study of community structure and the

processes that influence them. The similarities among some of the fishes in these

historically isolated systems suggest broad-scale parallelism or convergence (Dyer, 2000;

Cussac et al., 2004; Landini and Sorbini, 2005).

Most studies of assemblage organization in stream fish address the effects of

inter-specific interactions and environmental variation on assemblage structure and

3

resource use (Moyle and Light, 1996). Some effort has been devoted to quantifying

large-scale variation and the multi-scale determinants of assemblage patterns and

processes (Bernatchez and Wilson, 1998). As a result, it is uncertain whether

determinants of local structure and function can be extrapolated to explain assemblage

patterns over broad regional scales (Bernatchez and Wilson, 1998). Moreover,

knowledge of the influence of regional constraints and historical processes on species

distribution, abundance, and assemblage composition remain general, although this

knowledge has been considered critical for advancement in stream fish ecology and

conservation (Poff, 1997). Because as a general rule fish only move by swimming, no

other single factor is more important in regional biogeography of freshwater fishes and

drainage basin limits and affinities (Koleff et al., 2003).

Spatial variability in species diversity patterns are primarily explained by three

hypotheses. These include the (1) species-area theory (Preston, 1962), which predicts

that species richness increases as a power function of surface area; (2) species-energy

theory (Wright, 1983), which predicts that species variation is correlated with energy

availability in the system; and (3) historical theory (Whittaker, 1977), which explains

richness gradients, on a global scale, by patterns of recolonization and maturation of

ecosystems after glaciation (Guégan et al., 1998). This study undertakes an exploration

to determine if any of these hypotheses for freshwater vertebrates (fishes) in similar

climates holds true. Much research on the community ecology of temperate freshwater

streams has been conducted in North America, and some researchers have assumed that

the patterns observed in North America should be applicable elsewhere (Reyjol et al.,

4

2007; Rühland et al., 2008). Notably, this assumption has recently been called into

question (Hendry and Stearns, 2004). In the circum-Mediterranean region, there is a

dearth of information about factors causing the large-scale spatial structuring of fish

assemblages. It is also doubtful whether the frameworks developed for temperate streams

can be directly translated to such semiarid systems (Reyjol et al., 2007).

Mediterranean ecosystems largely occur along the western edges of continents

between the 30° and 40° parallels in both northern and southern hemispheres. The

world’s five Mediterranean-climate ecosystems are limited to: the region bordering the

Mediterranean Sea; central Chile; the Cape region of South Africa; southwestern and

southern Australia; and all of California south to upper Baja California (Illes, 1978;

Moyle, 2002; Morgan, 2003; Figure 1). Moderated by cold ocean currents offshore, the

Mediterranean climate is characterized by mild, rainy winters and warm, dry summers

(Underwood et al., 2009). ). This favorable climate has made the Mediterranean Biome

densely populated by humans (Clavero et al., 2004).

Consequently, these regions suffer from multiple threats, including deforestation

and desertification that result from urbanization, agriculture, recreation and other human

activities. Invasive plants and animals are also drastically altering the ecosystem and its

biodiversity in all of the five Mediterranean regions of the world. As a result, the

Mediterranean biome, occurring on three percent of the earth’s total land area, is one of

the most highly altered and imperiled ecosystems on the planet, with the most disturbed

area of any biome (Underwood et al., 2009). In concert with high biodiversity and

5

endemism, this has resulted in all Mediterranean biome locations considered biodiversity

hotspots (Myers et al., 2000).

Several studies have focused on comparisons of physical characteristics of

species, species richness, and composition of Mediterranean biome communities within

one continental location, or between two different continental locations. These studies

have focused on the status of the high level of species richness and endemism in plant

communities (Mooney and Dunn, 1970; Cody and Mooney, 1978; Arroyo and Cavieres,

1991; Heywood, 1993; Cowling et al., 199; and Underwood et al., 2009). They have also

included avian communities (Kark and Sol, 2005) and freshwater fish communities

(Bernardo et al., 2003; Clavero at al., 2004; Darwall and Smith, 2006; Pascual et al.,

2007). Very few studies have focused on the communities or organisms found within the

Mediterranean biome and compared them across continents. These studies include those

done by Mooney and Dunn (1970) on Mediterranean plant species, which focused on the

physical similarities of plants illustrating instances of convergent evolution due to

similarities in climate, despite separate distinct evolutionary histories. Additionally,

Cody and Mooney (1978) found similar occurrences of convergent evolution due to

similar climates in their review of Mediterranean plant communities, in addition to other

similar studies that focused on bird and lizard communities (Kark and Sol, 2005;

Ioannidis, 2008).

No studies have looked specifically at freshwater fish trophic diversity within a

similar but isolated biome and compared them across continents, including the

Mediterranean biomes. Most fish assemblage comparisons are done across varying

6

latitudinal gradients of differing biotic regions such as Arctic, Nearctic, Tropical, and

Temperate regions (Winemiller, 1991), or are used to identify ichthyological “provinces”

of the world (Lèvêque et al., 2008). In addition, studies have been done to investigate

the freshwater icthyofauna of several Mediterranean streams (Goren and Ortal, 1999;

Kleynhans, 1999; Dyer, 2000; Kadye and Marshall, 2007). Many of these have been

conducted to establish a baseline of species present after urbanization and/or to monitor

restoration measures (Corbacho and Sanchez, 2001; Bernardo et al., 2003; Clavero et al.,

2004; Clavero et al., 2005; Habit et al., 2006; Magalhães et al., 2007). There are

however, no comparative studies of global freshwater fish community patterns within a

similar biome or latitudinal location. What makes the study of patterns in the

Mediterranean biome so uniquely compelling is its location. Being equidistant to the

Equator, this location minimizes or even eliminates any latitudinal gradient effects on

species richness and trophic diversity (Winemiller, 1991; Mittelbach et al., 2007).

The purpose of this study was to compare freshwater fish community richness and

structure among Mediterranean biomes, which have similar climatic conditions and

minimal latitudinal gradient effects. Differences of community trophic diversity and

species richness were tested between the biome locations, and related to measurable

physical parameters. These parameters were hydrology, geology, ecology, and climate.

The hydrological parameters included total drainage basin area in square kilometers and

mean annual discharge at the river mouth in cubic meters per second. The geological

parameters were total surface area of the continent and area of glaciation. The ecological

7

parameter was net primary productivity. Finally, the climactic parameters were mean

annual temperature and mean annual rain fall in the basin area.

8

Figure 1. Figure 1. Global Map of Mediterranean Biome Locations. California Mediterranean Research Learning Center (2009).

.

9

METHODS

The twelve rivers studied were distributed as follows: two river basins from each of

the continents of Europe, Asia, North and South America, Africa and Australia

(Appendix A). Species richness was obtained by recording presence data from published

sources of fish assemblages (Appendix B), which were then counted and totaled

(Appendix A and C). Fish species found in drainages located within the six continents

were categorized into feeding guilds: insectivores, piscivores, herbivores, omnivores,

and planktivores using diet information from www.fishdatabase.org (Appendix C).

These five feeding guilds are commonly used for trophic level classification of fish in

North America (Karr, 1986) and Europe (Griffiths, 2006). Only adult forms were taken

into consideration as feeding behavior changes during ontogeny (Brown and Matthews,

1995). The number of species found in each of the five feeding guilds were counted and

totaled to determine species richness within trophic levels (Appendix A).

Values for fish species richness were subject to several sources of error. First, the

number of fish species may be underestimated due to inadequate sampling effort or

extinctions due to human activity occurring before collections were made (Oberdorff et

al., 1995). Secondly, the number of fish species may be overestimated if some species

have been recently introduced in rivers (Moyle 2002). To minimize these potential

adverse effects upon the accuracy of the study, only the most recent references were

selected, and only fish currently found within these basins were used. Extinct fishes were

not included in this study.

10

For each drainage system the following variables were determined from the

literature (Appendix D) : (1) total surface area of the drainage basin in square kilometer

(km2), (2) mean annual discharge at the river mouth in cubic meters per second (m3/s),

(3) total surface area of the continent (km2), (4) mean annual temperate (C˚), (5) mean

annual rain fall in the area (mm), (6) glaciated area within the study basin (km2), and (7)

net primary productivity (kg2/yr) as can be seen in Table 2.

The seventh variable of net primary productivity was calculated using Lieth’s

(1975) model as applied by Golubyatnikov and Denisenko (2001) (Appendix E). As net

aquatic productivity data was difficult to obtain, mean annual air temperature and mean

annual rainfall were used to estimate average mass of terrestrial primary productivity

from Lieth’s (1975) model as demonstrated by Oberdorff et al. (1995). Terrestrial

primary productivity and aquatic primary productivity co-vary (Livingstone et al., 1982;

Oberdorff et al., 1995; Hugueny, 1989) and were used as a surrogate in this study; as seen

in previous studies (Livingstone et al., 1982; Oberdorff et al., 1995; Hugueny, 1989).

Statistical Analysis

One-way analysis of variance (ANOVA), the two-way ANOVA, the chi-squared

test, and multiple regressions were all used to assess hypotheses. One-way ANOVAs

were used to determine whether the number of trophic levels present and species richness

differed among continents. A two-way ANOVA was used to determine whether the

species richness within each trophic level differed among continents. A chi-square test

was conducted to determine if there was an association between number of species per

11

trophic level and continent. Finally, two backward elimination multiple regressions were

used to determine if there were any relationships between the independent variables total

surface area, mean annual discharge, total surface area of the continent, mean annual

temperature, mean annual rain fall in the area, and the dependent variables of species

richness and number of trophic levels present. The variable, total basin area of historical

glaciation was removed from the multiple regressions because none of these basins had

any history of glaciation (Mercer, 1983; Moyle and Herbold, 1987). After running the

multiple regressions, the San Joaquin River became an outlier. Upon further

investigation, as this river is a highly disturbed system and in fact is intermittently dry for

over 132 miles (Pereira et al., 1996), it was removed from the data set.

Species richness (total and within trophic levels) data was not normally distributed.

All attempts at transformation of these data sets were unsuccessful at obtaining normal

distribution, including squaring, taking the square root, taking the natural log, and

multiplying the data set. As a result, non-parametric tests were used and caution should

be used when interpreting the results. Data was analyzed using SPSS 17.0 software.

RESULTS

Numbers of trophic levels (trophic diversity) were statistically different among

continental locations (Table 1, Figure 2). The continents of Asia, Europe, North

America, Africa and South America had somewhat similar trophic diversity. Trophic

levels from all continents were significantly different from Australia (Figure 2). Rivers

in Africa, Asia, Europe, North America, and South America supported almost twice as

12

many trophic levels as Australia (Figure 2). Total species richness was also significantly

different among continents (Table 2, Figure 3). North America, Australia, and South

America had greater species richness then that of Asia, Europe and Africa. Across trophic

levels and continents, there were significant differences in species richness (Table 3,

Figure 4). The omnivore trophic level had the greatest number of species than any other

group (Figure 4 and 5).

The chi-square test conducted to determine a possible association between species

richness of trophic levels and continent revealed a significant difference between trophic

richness levels in the southern hemisphere and the northern hemisphere (X2 = 34.59,

df=4, P<0.001 (Figure 5).

Ecological and Historical Factors on Species Richness

Among all six factors (total surface area of the drainage basin, mean annual

discharge at the river mouth, total surface area of the continent, mean annual temperate,

mean annual rain fall, and glaciated area within the study basin) there were no

statistically significant relationships with species richness except for a weak positive

relationship with annual average discharge (Table 3, Figure 6). The San Joaquin River

was found to be the only outlier. With this outlier removed, there was a very strong

positive relationship between species richness and annual average discharge (Table 4) as

seen in Figure 7.

13

Ecological and Historical Factors on Number of Tropic Levels Present

Among all six factors of total surface area of the drainage basin, mean annual

discharge at the river mouth, total surface area of the continent, mean annual temperate,

and mean annual rain fall, there were no statistically significant relationships within

tropic levels (Table 4).

14

Trophic Level SS df MS F-value P-value

Between

Continents 5.417 5 1.083 4.333 0.051

Within

Continents 1.500 6 0.250

Total 6.917 11 229.9

Table 1. Trophic Level ANOVA. Statistical summary of a one-way ANOVA results for between continent effects for number of trophic levels present. This table illustrates that there is a statistically significant difference between the numbers of trophic levels between continental locations. All statistically significant P-values are italicized.

15

Figure 2. Trophic Level Histogram. Mean trophic level diversity of Mediterranean fresh water fish for each continent location. Asia, Europe, North America, South America and Africa have twice as many trophic levels occupied as Australia.

16

Species Richness SS Df MS F-value P-value

Between

continents 4916.667 5 983.33 5.717 0.028

Within

Continents 1032.000 6 172.00

Total 5948.667 11

Table 2. Species Richness ANOVA. Statistical summary of a one-way ANOVA results for between continent effects for species richness. This table illustrates that there is a statistically significant difference between the numbers of trophic levels between continental locations. All statistically significant P-values are italicized.

17

Figure 3. Species Richness Histogram. Mean species richness of Mediterranean fresh water fish for each continent location. North America has the greatest number of species. Australia and South America are the second most specious and have similar species richness. Asia, Europe, and Africa are similar and have the least amount of species richness.

18

Source SS Df MS F-value P-value

Trophic Level 4038.90 4 1009.725 49.335 P <0.001

Continent 983.33 5 196.667 9.609 P<0.001

Trophic Level*Continent 2511.50 20 125.575 6.136 P<0.001

Error 614.00 30 20.467

Total (Corr) 8147.73 59

Table 3. Continental Trophic Richness ANOVA. Statistical summary of a two-way ANOVA testing possible interactions between tropic level, species richness and continent. This table illustrates that there is a significant difference in species richness among both trophic levels and continents. Additionally, there is a significant interaction between trophic level and content on species richness. All significant P-values are italicized.

19

Figure 4. Continental Trophic Species Richness Histogram. This represents all of the species present within the trophic levels present at each continental location.

20

Figure 5. Continental Community Composition Chart. This chart breaks down each continent into its representative trophic levels and their contribution to total species richness.

21

Table 4. Multiple Regression on Species Richness and Trophic Diversity. This table consists of the most descriptive factors on species richness and trophic diversity found when conducting a backwards multiple regression on the hydrological, geological, ecological, and climactic factors. Included are annual average discharge both with and without the San Joaquin River on species richness, and drainages area on trophic diversity. These values had the lowest P-value of all 7 factors measured against. Significant P values are italicized.

Dependent variable

Parameter R F-value P-value Df Model

Species Richness (SR)

Annual Average Discharge with San Joaquin River (AAD)

0.478 2.965 0.116 11 SR=0.035(AAD)+15.524

Species Richness (SR)

Annual Average Discharge without San Joaquin River (AAD)

0.852 23.847 0.001 10 SR=0.058(AAD)+0.571

Trophic Diversity (TD)

Drainage Area (AREA)

0.45 2.533 0.143 11 TD=4.065-1.197e^-6(AREA)

22

Figure 6. Species Richness Regression with the San Joaquin River. Species Richness of Mediterranean freshwater fish for each river as a function of annual average discharge at river mouth. This regression is illustrated with the San Joaquin River included.

23

Figure 7. Species Richness Regression without the San Joaquin River. Species richness of Mediterranean freshwater fish for each river excluding the San Joaquin River, as a function of annual average discharge at river mouth.

24

DISCUSSION

Freshwater fish community structure (trophic level diversity, trophic level

richness, and species richness) differed across each of the six Mediterranean biomes.

North America supported the highest levels of species richness followed by Australia and

South America; Asia, Europe, and Africa were similar and had lower species richness

(Figure 3). Australia had the least amount of species richness present (Figure 2).

Continental trophic richness differed significantly with omnivory consistently

having the highest species richness (Figure 4). Further observation revealed significant

differences between types of trophic levels present among the continental locations

specifically regarding the richness of both insectivores and piscivores between the

northern and southern hemispheres (Figure 5). The northern hemisphere had

significantly fewer insectivores than the southern hemisphere. Conversely, the northern

hemisphere had significantly more piscivores then the southern hemisphere.

The second investigation comprising this study examined differences of

community trophic diversity and species richness between the biome locations, in

addition to seeing if these differences could be explained by measurable physical

parameters such as hydrology, geology, ecology, and climate. Among all seven factors

measured, only the hydrological parameters of annual average discharge demonstrated a

positive effect upon species richness (Figure 7). No significant effects of the seven

factors on trophic diversity were found.

Historically, biogeography is the science of studying and observing patterns in

ecosystems at different spatial and temporal scales (Lamouroux, 2002). Previous studies

25

have done so by using various community properties, such as species richness and

proportional composition of trophic levels (Moyle and Herbold, 1987; Lamouroux,

2002). Such patterns expressed in community convergence are an aspect of the

hypothesis that characteristics of communities are predictable from their environment

(Schluter, 1986), and that communities are structured rather than random entities.

Models predicting similarities in community traits from independent systems having

similar environmental features suggest the existence of key repeated mechanisms

underlying community organization (Lamouroux, 2002). Therefore, while predictive

tools in ecology often site specific and poorly transferable across ecosystems (Peters and

Myers, 1991), convergence studies can provide general models for predicting

fundamental community patterns in multiple sites (Mooney and Dunn, 1970; Cody and

Mooney, 1978). This study investigated community structure across the broadly separate

geographic regions in the Mediterranean biome and then compared this structure in terms

of trophic level diversity.

The concept of trophic levels is one of the oldest ideas in ecology and helps us to

understand assemblage composition and energy flow within communities (Thompson et

al., 2007). The results of the trophic diversity analysis of this study illustrate a

prevalence of omnivory within all of the continental locations. This is not the only case

where omnivory dominates communities, a fact that has been documented in several

aquatic systems (e.g., marine, reservoirs, and estuarine) and is thought to stabilize food

webs (Emmerson and Yearsley, 2004). The importance and prevalence of omnivory for

the structure and dynamics of food webs is a long-standing controversy (Cousins, 1987;

26

Burns, 1989; Polis, 1991; Holt and Polis, 1997; Vandermeer, 2006; Thompson et al.,

2007). Omnivory is key to the fundamental understanding of food web dynamics, and

as a result much debate has occurred over this subject (Polis and Strong, 1996; Hairston

and Hairston, 1997; Thompson et al., 2007). Current theoretical models suggest that

omnivory may in fact stabilize food webs (Emmerson and Yearsley, 2004; Thompson et

al., 2007), and that larger food webs support higher levels of omnivory (Woodward and

Hildrew, 2002; Thompson et al., 2007). This theory was evident in this study, as there

were greater numbers of species within continental locations that had higher levels of

omnivory (Figure 4 and 5). Further analysis would be required to confirm this

possibility.

The inverse proportion of piscivorous and insectivorous species richness between

the northern and southern hemisphere is not surprising as both of these families evolved

separately approximately 160 to 150 million years ago; salmonids evolved in Laurasia

while the galaxiid family evolved in Gondwanaland (Waters et al., 2000; McDowall,

2002; Clavero et al., 2005; Lévêque et al., 2008). This finding supports both the well-

documented biogeographical colonization histories of the southern and northern

hemispheres (McDowall, 2002) and the positive relationship between body size and

trophic level in fishes (see Data collected in Appendix C). Body size determines the

range of prey species a predator can consume, allowing larger individuals with larger

anatomy to feed at higher trophic levels (Winemiller, 1991; Jennings et al., 2001). The

salmonid family dominates northern hemisphere freshwater fish communities in

temperate locations, which tend to be large piscivorous fish (Jennings et al., 2001).

27

Meanwhile, in the southern hemisphere the galaxiid family dominates these same

communities, which tend to be small insectivorous fish (Reyjol et al., 2007).

While these two historical explanations of trophic level composition contribute to

understating the observed patterns, other ecological processes such as extinction,

invasion, competition, and disturbance, may also play a role in shaping these

communities.

As previously discussed, the difference in the predictive ability of varying factors

is based on the size scale of the community patterns. On the local scale, physical factors

appear to determine species richness in variable environments (Capone and Kushlan,

1991). On larger spatial scales (regional and geographical), physical factors such as area,

total discharge, and primary productivity, along with historical factors such as speciation

rates and dispersal are the major determinant of species richness, and regulate the

importance of local-scale factors (Lamoureux et al., 2002). These differences in spatial

variability in species diversity patterns are primarily explained by the three previously

introduced theories: the species-area theory (Preston, 1962), the species-energy theory

(Wright, 1983), and the historical theory (Whittaker, 1977). This study sought to try and

branch these two differing spatial scales by comparing similar a similar type of

environment across a broad geographical area, in addition to trying to determine if any of

the three aforementioned hypotheses held true for freshwater vertebrates (fishes) in

similar climates.

The results of this study indicated that annual average discharge is the most

important factor influencing freshwater fish species richness patterns globally across the

28

entire Mediterranean biome, illustrating for the Mediterranean biome that the species-

area theory and historical theory do not explain species richness patterns. This finding is

consistent with those of Poff and Allan (1995), Oberdorff et al. (2001) and Cattanéo

(2005). These studies show that changes in annual average discharge influence the

functional organization of fish assemblages and/or demonstrated effects on species

richness. While the species-energy theory does help explain species richness across the

Mediterranean biome, additional consideration is in order since several previous studies

looking at freshwater species richness patterns have found that area, average annual

discharge, and primary productivity explained species richness (Oberdorff et al., 1995;

Guégan, 1998; Hawkins et al., 2003; Clavero et al., 2004). Nevertheless, a general

understanding of the degree of similarity of fish communities across geographical distinct

basins is lacking. This is primarily because quantitative descriptors can sometimes

become intercorreleated across basins, making it difficult to identify which factors are

responsible for community structure (Lamaroux, 2002). Using these species richness

theories as general predicative tools of community characteristics seem to initially require

precise measurements of the factors defining the community’s habitat (Lamaroux, 2002).

A better understanding of Mediterranean biome communities could be achieved by

further studies into the hydraulic nature of these basins, the effect of high disturbance of

flow regime on primary productivity, and the effect of invasive species on the native

community.

In this study, primary productivity not being a predictor of species richness could

be due to the highly disturbed nature of the riparian habitat of the Mediterranean biome.

29

As previously stated, the Mediterranean biome is one of the most altered systems in the

world. Several studies have illustrated that changes in natural stream regime affect

primary productivity (Mallin et al., 1993). All rivers in this study, as with most

Mediterranean biome rivers, have been dammed and have several water diversions. The

primary reasons for these dams are flood control, to regulate the fluctuation of water flow

throughout the year, and agricultural purposes. As in all Mediterranean biome locations,

agriculture has been a dominant feature of the terrestrial environment. This has led to the

degradation of riparian habitats and diversion of water from the rivers themselves to

irrigate vast croplands (Underwood et al., 2009). Due to the installation of these dams,

the natural hydrology of these rivers has also been altered to reflect more of a constant

flow regime rather than the cyclical flood regime that defines the Mediterranean biome

(Junk et al., 1989). The damming of a river has been called a cataclysmic event in the

life of a riverine ecosystem (Ligon et al., 1995). By changing the flow of water,

sediment, nutrients, energy, and biota, dams interrupt and alter most of a river’s

important ecological processes (Ligon et al., 1995). This could be the reason that

primary productivity in the basins studied does not reflect species richness.

CONCLUSION

The data and analysis presented here have led to the surprising conclusion that

annual average discharge is the most important factor influencing fish species richness

patterns globally across the entire Mediterranean biome. This illustrates that for the

Mediterranean biome the species-area theory and historical theory do not explain species

30

richness patterns. While the species-energy theory does help explain species richness in

the Mediterranean biome, additional consideration is in order; since several previous

studies looking at freshwater species richness patterns have found that area, average

annual discharge and primary productivity explained species richness (Oberdorff et al.,

1995; Guégan, 1998; Hawkins et al., 2003).

The Mediterranean-climate regions of the world are renowned for high levels of

richness and endemism in both flora and fauna. However, it is one of the most imperiled

ecosystems in the world, and has the highest density of human population and

agricultural practices. A fuller understanding of these freshwater Mediterranean

communities, their composition, and the factors that contribute to their survival and

enhancement will help formulate the required strategies to rehabilitate, conserve, and

protect them in the future. Armed with the knowledge that annual average discharge of

these highly endangered river basins directly influences species diversity, dam discharge

regimes can be monitored and modified to result in the desired level of species richness.

31

APPENDICES

32

Appendix B. Data sources.

33

Location Drainage

Drainage Area in Square

Kilometers

Average Annual Discharge in Cubic Meters per Second

Area of Continent in

Square Kilometers

Average Annual Rain

Fall in millimeters

Average Annual

Temperature in Degrees Celsius

Average Area of

Historical Glaciation

Species Richness in Number of

Species

Europe

Mira Antunes,

2008

Global Runoff Data Center,

2010

Encyclopedia Britannica,

2008

Magalhaes, 2002

Magalhaes, 2002

Illes, 1978;

Griffiths, 2006

Bernardo et al., 2003

Guadiana Clavero et al., 2004


2010


2008

Corbacho and Sanchez,

2001

Corbacho and Sanchez, 2001

Illes, 1978;

Griffiths, 2006

Clavero et al., 2005

Asia

Bilga Sari et al.,

2006


2010


2008

World Weather

Information Service,2000

World Weather Information

Service, 2000

Illes, 1978;

Griffiths, 2006

Sari et al., 2006

Qishon Bar-Or,

2000

Oren et al., 1973; Global Runoff Data Center, 2010


2008

World Weather

Information Service, 2000

Bar-Or, 2000 Goren and

Ortal, 1999

Oren et al., 1973; Goren and Ortal,

1999

North America

Sacramento Moyle, 2002


2010


2008

World Weather



Service ,2000

May and Brown, 2002

May and Brown, 2002

San Joaquin

Moyle, 2002


2010


2008

World Weather



Service, 2000

Moyle, 2002

Moyle, 2002

South America

Biobío

Gobierno De Chile, Direccion

General De Aguas, 2004

Oyarzun, 1995; Feige et al.,

2009; Global Runoff Data Center, 2010


2008

Oyarzun, 1995;

Gobierno De Chile,

Direccion General De Aguas, 2004


Service, 2000

Cussac et al., 2004

Dyer, 2000

Itata

Gobierno De Chile, Direccion

General De Aguas, 2004

Feige et al., 2009; Global Runoff Data Center, 2010


2008

World Weather

Information Service,

2000


Service, 2000

Cussac et al., 2004

Dyer, 2000; Figueroa et al.,

2010

Africa

Berg Kalejta and

Hockey, 1991


2010


2008

Flügel, 1995; World

Weather Information

Service, 2000

Flügel, 1995; World Weather

Information Service., 2000

Cussac et al., 2004

Livingstone et al., 1982

Orange Kleynhans,

1999


2010


2008

Swanevelder, 1981; World

Weather Information

Service, 2000

Flügel, 1995; World Weather


Cussac et al., 2004

Livingstone et al., 1982

Australia

Murray Walker et al., 1993


2010


2008

World Weather

Simpson et al., 1993;



Service, 2000

Unmack, 2001;

Cussac et al., 2004

Allen et al., 2002; Morgan, 2003; Morgan et al.,

2005; Australian Department of Fisheries, 2009

Swan Morgan,

2004


2010


2008

World Weather

Information Service,

2000; Viney and

Sivapalan, 2001


Service, 2000

Unmack, 2001;

Cussac et al., 2004

Allen et al., 2002; Morgan, 2003; Morgan,, 2004; Morgan et al.,

2005; Australia Department of Fisheries, 2009

Appendix C. Species lists and trophic level.

34

Continent Europe

Location Iberian Peninsula

Drainage Guadiana Mira

Continent Asia

Location Turkey Israel

Drainage Bigla Qishon

Species Trophic level Species

Trophic Level

Anguilla anguilla Piscivore Anguilla anguilla Piscivore

Salmo trutta macrostigma Omnivore Acantghobrama lissneri Omnivore

Oncorhynchus mykiss Omnivore Garra rufa Herbivore

Leuciscus cephalus Omnivore Hemigrammocapoeta nana Herbivore

Petroleuciscus borysthenicus Omnivore Clarias gariepinus Omnivore

Rhodeus amarus Herbivore Aphanius mento Omnivore

Phoxinus phoxinus Omnivore Mugil cephalus Planktivore

Vimba vimba Omnivore Liza ramada Planktivore

Chalcalburnus chalcoides Omnivore Orecochromis aureus Planktivore

Barbus tauricus escherichi Planktivore Tilapia zillii Herbivore

Capoeta capoeta bergamae Planktivore Tristamella sacra Omnivore

Gobio gobio Omnivore Mugil cephalus Omnivore

Cobitis fahirae Omnivore

Neogobius fluviatilis Omnivore

Mugil cephalus Omnivore

35

Species Trophic level Species Trophic level

Petromyzon marinus Piscivore Anguilla anguilla Piscivore

Anguilla anguills Piscivore Chondrostoma lemmingii Omnivore

Alosa alosa Omnivore Barbus sclateri Omnivore

Anaecypris hispanica Planktivore Barbus bocagei Omnivore

Barbus comiza Piscivore Chondrostoma polylepis Planktivore

Luciobarbus microcephalus Omnivore Rutilus alburonides Omnivore

Barbus sclateri Omnivore Mugil cephalus Omnivore

Chondrostoma polylepis Omnivore

Leuciscux pyrenaicus Omnivore

Rutilus lemmingii Omnivore

Tinca tinca Omnivore

Tropidophoxinellus alurnoides Omnivore

Coitis paludica Omnivore

Gasterosteus aculeatus Omnivore

Blennius fluviatilis Omnivore

Oncorhynchus mykiss Omnivore

Esox lucius Piscivore

Carassius auratus Herbivore

Cyprinus carpio Omnivore

Gobio gobio Omnivore

Lepomis gibbossus Omnivore

Micropterus salmoides Piscivore

Gambusia holbrooki Insectivore


Continent North America

Location California

Drainage Sacramento San Joaquin

Species Trophic level Species

Trophic level

Lampetra tridentata Piscivore Lampetra tridentata Piscivore

36

Lampetra fluviatilis Piscivore Lampetra fluviatilis Piscivore

Lampetra pacifica Piscivore Entosphenus hubbsi Piscivore

Acipenser transmontanus Omnivore Acipenser transmontanus Omnivore

Acipenser medirostris Omnivore Acipenser medirostris Omnivore

Alosa sapidissima Omnivore Alosa sapidissima Omnivore

Dorosoma petenese Herbivore Dorosoma petenese Herbivore

Cyprinus carpio Omnivore Cyprinus carpio Omnivore

Carassius auratus Herbivore Carassius auratus Herbivore

Notemigonus crysoleucas Omnivore Notemigonus crysoleucas Omnivore

Orthodon microlepidotus Omnivore Orthodon microlepidotus Omnivore

Mylopharodon conocephalus Omnivore Mylopharodon conocephalus Omnivore

Lavinia exilicauda Omnivore Lavinia exilicauda Omnivore

Ptychocheilus grandis Piscivore Ptychocheilus grandis Piscivore

Gila bicolor Omnivore Pogonichthys macrolepidotus Omnivore

Pogonichthys macrolepidotus Omnivore Hesperoleucus symmetricus Omnivore

Hesperoleucus symmetricus Omnivore Hesperoleucus symmetricus Omnivore

Rhinichthys osculus Omnivore Rhinichthys osculus Omnivore

Richardsonius egregius Omnivore Notemigonus crysoleucas Omnivore

Notemigonus crysoleucas Omnivore Pimephales promelas Herbivore

Pimephales promelas Herbivore Catostomus occidentalis Herbivore

Catostomus planyrhynchus Herbivore Ictalurus furcatus Omnivore

Catostomus occidentalis Herbivore Ictalurus punctatus Omnivore

Ictalurus furcatus Omnivore Ictalurus catus Piscivore

Ictalurus punctatus Omnivore Ictalurus nebulosus Omnivore

Ictalurus catus Piscivore Ictalurus melas Omnivore

Ictalurus nebulosus Omnivore Hypomesus transpacificus Planktivore

Ictalurus melas Omnivore Hypomesus nipponensis Omnivore

Hypomesus transpacificus Planktivore Spirinchus thaleichthys Omnivore

Hypomesus nipponensis Omnivore Oncorhynchus kisutch Planktivore

Spirinchus thaleichthys Omnivore Oncorhynchus tshawytscha Omnivore

Oncorhynchus kisutch Planktivore Oncorhynchus mykiss Omnivore

Oncorhynchus tshawytscha Omnivore Oncorhynchus keta Omnivore

Oncorhynchus mykiss Omnivore Oncorhynchus gorbuscha Omnivore

Oncorhynchus keta Omnivore Oncorhynchus nerka Planktivore

Oncorhynchus gorbuscha Omnivore Salmo trutta Omnivore

Oncorhynchus nerka Planktivore Salvelinus fontinalis Omnivore

Salmo trutta Omnivore Salvelinus namaycush Omnivore

Continent North America con’t

Location California

Drainage Sacramento San Joaquin

Salvelinus namaycush Omnivore Lucania parva Omnivore

Salvelinus fontinalis Omnivore Salvelinus confluentus Omnivore

Lucania parva Omnivore Menidia beryllina Planktivore

Gambusia affinis Omnivore Gasterosteus aculeatus Omnivore

37

Menidia beryllina Planktivore Morone saxatilis Omnivore

Gasterosteus aculeatus Omnivore Morone chrysops Piscivore

Morone saxatilis Omnivore Archoplites interruptus Omnivore

Morone chrysops Piscivore Pomoxis nigromaculatus Omnivore

Archoplites interruptus Omnivore Pomoxis annularis Piscivore

Pomoxis nigromaculatus Omnivore Lepomis gulosus Omnivore

Pomoxis annularis Piscivore Lepomis cyanellus Omnivore

Lepomis gulosus Omnivore Lepomis macrochirus Omnivore

Lepomis cyanellus Omnivore Lepomis gibbosus Omnivore

Lepomis macrochirus Omnivore Lepomis microlophus Omnivore

Lepomis gibbosus Omnivore Micropterus salmoides Omnivore

Lepomis microlophus Omnivore Micropterus punctulatus Omnivore

Micropterus salmoides Omnivore Micropterus dolomieui Omnivore

Micropterus punctulatus Omnivore Micropterus coosae Omnivore

Micropterus dolomieui Omnivore Perca flavescens Omnivore

Micropterus coosae Omnivore Percina macrolepida Omnivore

Perca flavescens Omnivore Hysterocarpus traski Omnivore

Percina macrolepida Omnivore Eucyclogobius newberryi Omnivore

Hysterocarpus traski Omnivore Acanthogobius flavimanus Omnivore

Eucyclogobius newberryi Omnivore Tridentiger bifasciatus Omnivore

Acanthogobius flavimanus Omnivore Leptocottus armatus Omnivore

Tridentiger bifasciatus Omnivore Cottus asperrimus Omnivore

Leptocottus armatus Omnivore Cottus gulosus Omnivore

Cottus asperrimus Omnivore Planktivoretichthys stellatus Omnivore

Cottus gulosus Omnivore Mugil cephalus Omnivore

Planktivoretichthys stellatus Omnivore


Continent South America

Location Central Chile Central Chile

Drainage Biobio Itata


Ameiurus melas Omnivore Ameiurus melas Omnivore

Ameiurus nebulosus Omnivore Ameiurus nebulosus Omnivore

Ancistrus erinaceus Herbivore Ancistrus erinaceus Herbivore

Australoheros facetus Omnivore AustraloHerbivoreos facetus Omnivore

Basilichthys australis Omnivore Basilichthys australis Omnivore

38

Basilichthys microlepidotus Omnivore Basilichthys microlepidotus Omnivore

Brachygalaxias bullocki Omnivore Brachygalaxias bullocki Omnivore

Brachygalaxias gothei Omnivore Brachygalaxias gothei Omnivore

Bullockia maldonadoi Omnivore Bullockia maldonadoi Omnivore

Carassius auratus auratus Omnivore Carassius auratus auratus Omnivore

Carassius carassius Omnivore Carassius carassius Omnivore

Cheirodon australe Herbivore Cheirodon australe Herbivore

Cheirodon galusdai Herbivore Cheirodon galusdai Herbivore

Cheirodon interruptus Planktivore Cheirodon interruptus Planktivore

Cheirodon kiliani Omnivore Cheirodon kiliani Omnivore

Cheirodon Piscivoreiculus Herbivore Cheirodon iculus Herbivore

Cnesterodon decemmaculatus Omnivore Cnesterodn decemmaculatus Omnivore

Cyprinus carpio carpio Omnivore Cyprinus carpio carpio Omnivore

Diplomystes camposensis Omnivore Diplomystes camposensis Omnivore

Diplomystes chilensis Omnivore Diplomystes chilensis Omnivore

Diplomystes nahuelbutaensis Herbivore Diplomystes nahuelbutaensis Herbivore

Galaxias globiceps Omnivore Galaxias globiceps Omnivore

Gambusia affinis Omnivore Gambusia affinis Omnivore

Lepomis gibbosus Omnivore Lepomis gibbosus Omnivore

Nematogenys inermis Omnivore Nematogenys inermis Omnivore

Odontesthes brevianalis Omnivore Odontesthes brevianalis Omnivore

Odontesthes gracilis Omnivore Odontesthes gracilis Omnivore

Odontesthes hatcHerbivorei Omnivore Odontesthes hatcHerbivorei Omnivore

Odontesthes mauleanum Omnivore Odontesthes mauleanum Omnivore

Odontesthes wiebrichi Omnivore Odontesthes wiebrichi Omnivore

Orestias agassizii Herbivore Orestias agassizii Herbivore

Orestias ascotanensis Omnivore Orestias ascotanensis Omnivore

Orestias chungarensis Omnivore Orestias chungarensis Omnivore

Orestias laucaensis Omnivore Orestias laucaensis Omnivore

Orestias parinacotensis Omnivore Orestias parinacotensis Omnivore

Orestias piacotensis Planktivore Orestias piacotensis Planktivore

39

Continent Australia

Location Southern Australia South Western Australia

Continent Africa

Location South Africa South Africa

Drainage Orange Berg


Austroglanis sclateri Omnivore Pseudobarbus phlegethon Insectivore

Barbus aeneus Omnivore Oncorhynchus mykiss Omnivore

Barbus anoplus Omnivore Pseudobarbus burgi Omnivore

Barbus hospes Omnivore Sandelia capensis Omnivore

Barbus kimberleyensis Piscivore Calaxias zebratus Planktivore

Barbus pallidus Omnivore Micropterus dolomieu Omnivore

Barbus trimaculatus Omnivore Lepomis macrochirus Omnivore

Clarias gariepinus Omnivore Labeo umbratus Herbivore

Labeo capensis Herbivore Liza richardsonii Planktivore

Labeo umbratus Herbivore Mugil cephalus Omnivore

Liza richardsonii Planktivore

Mesobola brevianalis Planktivore


Pseudobarbus quathlambae Insectivore

Tilapia rendalli Herbivore

Tilapia sparrmanii Herbivore


Oreochromis mossambicus Herbivore

Pseudobarbus quathlambae Insectivore

40

Drainage Darling-Murray Swan-Avon


Retropinna semoni Omnivore Lepidogalaxias salamandroides Omnivore

Mugil cephalus Omnivore Galaxias occidentalis Omnivore

Percichthys chilensis Omnivore Percichthys chilensis Omnivore

Percichthys melanops Omnivore Percichthys melanops Omnivore

Galaxias fuscus Insectivore Galaxiella munda Insectivore

Nematalosa erebi Omnivore Galaxiella nigrostriata Insectivore

Hypseleotris spp Omnivore Tandanus bostocki Omnivore

Galaxias brevipinnis Omnivore Bostockia porosa Omnivore

Galaxias maculatus Insectivore Nannatherina balstoni Omnivore

Pseudaphritis urvillii Omnivore Nannatherina vittata Omnivore

Craterocephalus amniculus Omnivore Mugil cephalus Omnivore

Melanotaenia splendida tatei Omnivore Pseudogobius olorum Omnivore

Philypnodon macrostomus Insectivore

Macquaria colonorum Omnivore

Galaxias rostratus Insectivore

Philypnodon grandiceps Omnivore

Tandanus tandanus Omnivore

Macquaria ambigua ambigua Piscivore

Neosilurus hyrtlii Omnivore

Tasmanogobius lasti Omnivore

Anguilla reinhardtii Omnivore

Macquaria australasica Omnivore

Galaxias olidus Omnivore

Maccullochella peelii peelii Omnivore

Melanotaenia fluviatilis Insectivore

Craterocephalus fluviatilis Omnivore

Gadopsis marmoratus Omnivore

Anguilla australis Insectivore

Afurcagobius tamarensis Omnivore

Mordacia mordax Piscivore

Bidyanus bidyanus Omnivore

Herbivoreinosoma microstoma Omnivore

Mogurnda adspersa Piscivore

Nannoperca australis Omnivore

Leiopotherapon unicolor Omnivore

Continent Australia con’t

Location Southern Australia

Drainage Darling-Murray

Species Trophic level

41


Salvelinus confluentus Omnivore

Carassius auratus Omnivore

Misgurnus anguillicaudatus Omnivore

Oncorhynchus mykiss Omnivore

Perca fluviatilis Omnivore

Rutilis rutilis Omnivore

Tinca tinca Omnivore

44

LITERATURE CITED

Allen, G.R., Midgley, S.H. & Allen, M. (2002) Field guide to the freshwater fishes of Australia. Western Australian Museum, Perth.

Antunes, C. (2008) Report on the eel stock and fishery in Portugal 2008. Technical

Report. Centre for Marine and Environmental Research, University of Porto, Porto, Portugal.

Arroyo, M and L. Cavieres. (1991) The Mediterranean type climate flora of central

Chile-what do we know and how can we assure its protection? Noticiero de Biologica, 5: 48-56.

Australian Department of Fisheries. (2009) Fishes of Australia. Accessed March

17, 2009. http://www.fish.wa.gov.au/docs/pub/NativeFreshwaterFish/ index.php?0501

Bar-Or, Y. (2000) Restoration of the rivers in Israel’s coastal plain. Water, Air, and Soil Pollution. 123, 311-321. Behrens, M. and K. Lafferty. (2007) Temperature and diet affects on omnivorous fish performance: implications for the latitudinal diversity gradient in herbivorous fishes. Canadian Journal of Aquatic Science. 64: 867-873. Bernardo, J., Ilheu, M., Matono, P., and Costa, A. (2003) Interannual variations of fish assemblage structure in a Mediterranean river: implications of stream

flow on the dominance of native or exotic species. River Research and Application. 19: 521-532.

Bernatchez, L. and Wilson, C. (1998) Comparative phylogeography of Nearctic and Palearctic fishes. Molecular Ecology. 7: 431-452. Brown, A. V. and W. J. Mathews. (1995) Stream ecosystems of the central United States, in Ecosystems of the World, Vol. 22. River and Stream Ecosystems (eds. C. E. Cushing, K. W. Cummings, and G. W. Marshall). Elsevier, Amsterdam, pp. 89-116. Burns, T. (1989) Lindemen’s contradiction and the trophic structure of ecosystems. Ecology. 70:1355-1362. Capone, T.A. and J. A. Kushlan. (1991) Fish community structure in dry-season stream pools. Ecology. 72: 983-992.

45

Cattanéo, F. (2005) Does hydrology constrain the structure of fish assemblages in French streams? Regional scale analysis. Archives für Hydrobiologie. 164: 367-385. Clavero, M., Blanco-Garrido, F., and J. Prenda. (2004) Fish fauna in Iberian Mediterranean river basins: biodiversity, introduced species and damming impacts. Aquatic Conservation: Marine and Freshwater Ecosystems. 14: 575-585. Clavero, M., Blanco-Garrido, F., and J. Prenda. (2005) Fish-habitat relationships and fish conservation in small coastal streams in southern Spain. Aquatic Conservation: Marine and Freshwater Ecosystems. 15: 415-426. Cody, M. and H. Mooney. (1978) Convergence versus nonconvergence in

Mediterranean-climate ecosystems. Annual Review of Ecology and Systematics. 9: 265-321.

Corbacho, C. and J. Sánchez. (2001) Patterns of species richness and introduced species in native freshwater fish faunas of a Mediterranean-type basin: The Guadiana river (Southwest Iberian peninsula). Regul. River. Res. Mgmt. 17: 699-707. Cousins, S. (1987) The decline of the trophic level concept. Trends in Ecology and Evolution. 2: 312-316. Cowling, R., Rundel, P., Lamont, B., Arroyo, M. and M. Arianoutsou. (1996) Plant diversity in Mediterranean climate regions. Trends in Ecology and Evolution. 11: 362-366. Cussac, V., Ortubay, S., Iglesias, G., Milano, D., Lattuca, M., Barriga, J., Battini, M, and Gross, M. (2004) The distribution of South American galaxiid fishes: the role of biological traits and post-glacial history. Journal of Biogeography. 31: 103-121. Darwall, W. and K. Smith. (2006) The status and distribution of freshwater fish endemic to the Mediterranean basin. The World Conservation Union (IUCN) Cambridge, UK. Daufresne, M. and P. Boët. (2007) Climate change impacts on structure and diversity of fish communities in rivers. Global Change Biology. 13: 2467- 2478. Dyer, Brian. (2000) Systematic review and biogeography of the freshwater fishes of Chile. Oceanological Studies. 19:77-98.

46

Emmerson, M and J. Yearsley, (2004) Weak interactions, omnivory and emergent food- web properties. Proceedings of the Royal Society B: Biological Sciences. 271: 397-405. Encyclopedia Britannica. (2008) Encyclopedia Britannica Online. Accessed June 15,

2009. Area of continents. http://www.Britannica.com. Erös, T. (2007) Partitioning the diversity of riverine fish: the roles of habitat types and non-native species. Freshwater Biology. 52: 1400-1415. Feige, K., Miller, C., Robinson, L., Figueroa, R., and B. Peucker-Ehrenbrink. (2009) Strontium isotopes in Chilean rivers: the flux of unradiogenic continental Sr to seawater. Technical Document. Laboratoire d’Etudes en Géophysique et Océanographie Spatiale (LEGOS). Figueroa, R., Ruiz, V. H., Berrios, R., Palma, A., Villegas, P., Andreu-Soler,A. (2010) Trophic ecology of native and introduced fish species from the Chillán river, south-central Chile. Journal of Applied Ichthyology, 26:1, 78-83. Fish Base. (2008) Used to collect presence, absence, and trophic level data for fish

species in all biome locations. Accessed May 18th, 2008. http://www.fishbase.org/search.php

Flügel, W. (1995) River salination due to dryland agriculture in the Western Cape

Province, Republic of South Africa. Environment International. 21:5, 679- 686.

Global Runoff Data Center(GRDC). (2007) From the World Climate Research

Programme. River discharge data. Retrieved October 19, 2007. http://www.bafg.de/nn_267044/GRDC/EN/02__Services/02__DataProducts/MajorRiverBasins/riverbasins__node.html?__nnn=true

Griffiths, David. (2006) Patter and process in the ecological biogeography of European freshwater fish. Journal of Animal Ecology. 75: 734 – 751. Gobinero De Chile, Ministerio De Obras Publicas, Direccion General De Aguas. (2004) Informe Tecnico. Departmento De Administraction De Recursos Hidricos. Santiago, Chile. Golubyatnikov, L. and E. Denisenko. (2001) Modeling the values of net primary production for the zonal vegetation of European Russia. Biology Bulletin. 28: 293–300. Translated from Izvestiya Akademii Nauk, Seriya Biologicheskaya, No. 3, 2001, pp. 353–361.

47

Goren, M. and R. Ortal. (1999) Biogeography, diversity and conservation of the inland water fish communities in Israel. Biological Conservation. 89: 1-9. Guégan, J., Lek, S., and T. Oberdorff. (1998) Energy availability and habitat heterogeneity predict global riverine fish diversity. Nature. 391: 382- 384. Habit, E., Belk, M., Tuckfield, R., and O. Parra. (2006) Response of the fish community to human-induced changed in the Biobío River in Chile. Freshwater Biology. 51: 1-11. Hairston, N. Jr., and H. Hairston, Sr. (1997) Does food web complexity elimination trophic-level dynamics? American Naturalist. 149: 1001-1007. Hawkins, B., R Field, H. Cornell, D. Currie, J Guégan, D Kaufman, J. Kerr, G. Mittelbach, T. Oberdorff, E O’Brien, E. Porter, and J. Turner. (2003) Energy, water, and broad-scale geographic patterns of species richness. Ecology, 84: 12, 3105-3117. Hendry, A., S. Stearns. (2004) Evolution illuminated salmon and their relatives. Oxford University Press. Oxford, U.K. Heywood, H. (1993) Mediterranean floras and their significant in relation to world

biodiversity. In Connassance et conservation de la flore des iles de la Méditerranée. Colloque Internaional, Parc Naturel Régional de la Corse and Conservatoire Botanique National de Porquerolles. 5-8 October 1993, Porticcio Corse Sud, France.

Holt, R. and G. Polis. (1997) A theoretical framework for intraguild predation. American Naturalist. 149: 745-764.

Hugueny, B. (1989) West African rivers as biogeographic islands. Oecologia. 79: 235- 243. Illes, J., ed. (1978) Limnofauna Europaea, 2nd edn. Gustav Fishcher Verlad,

Stuttgart. Ioannidis, Y. (2008) Comparison of reptile communities in three types of thermophilous Mediterranean forest in southern Greece. Journal of natural history. 42: 421 -433 Jennings, S., Pinner, J., Polunin, N. and T. Boon. (2001) Weak cross-species

relationships between body size and trophic level belie powerful size based trophic structuring in fish communities. Journal of Animal Ecology. 70: 934-944.

48

Junk, W., Bayley, P. and R. Sparks. (1989) The flood pulse concept in river-floodplain systems, p. 110-127. In D. P. [ed.] Proceedings of the International Large River Symposium. Special Publication Canadian Fisheries and Aquatic Science. 106. Kalejta, B., and P. Hockey. (1991) Distribution, abundance, and productivity of benthic invertebrates at the Berg River estuary, South Africa. Estuarine, Costal and Shelf Science. 33:2, 175-191. Kark, S. and D. Sol. (2005) Establishment success across convergent Mediterranean

ecosystems: an analysis of bird introductions. Conservation Biology. 19: 1519- 1527. Kadye, W. and B. Marshall. (2007) Habitat diversity and fish assemblages in an African river basin (Nyagui River, Zimbabwe). African Journal of Ecology. 45: 374-381. Karr, J. (1986) Assessing biological integrity in running waters: a method and its rational. Special Publication/Illinois Natural History Survey. 5:20-22. Kleynhans, CJ. (1999) The development of a fish index to assess the biological integrity of South African rivers. Water South Africa. 25:3, 265-278. Koleff, P., K. Gaston, and J. Lennon. (2002) Measuring beta diversity for presence absence data. The Journal of Animal Ecology. 72: 3, 367-382. Lamouroux, N., N. Poff, P. Angermeier. (2002) Intercontinental convergence of stream fish community traits along geomorphic and hydraulic gradients. Ecology, 83:7, 1792-1807. Landini, W. and Sorbini, C. (2005) Evolutionary dynamics in the fish faunas of the Mediterranean basin during the Plio-Pleistocene. Quaternary International 140-141: 64-89. Lèvêque, C., T. Oberdorff, and D. Paugy. (2008) Global diversity of fish (Pisces) in freshwater. Hydrobiologia, 595: 545-567. Lieth, C. E. (1975) Climate response and fluctuation dissipation. Journal of Atmospheric Sciences. 32: 2022-2026. Ligon, F., Dietrich, W., and W. Trush. (1995) Downstream ecological effects of dams. 1995. BioScience, Ecology of Large Rivers. 45: 183-192.

49

Livingstone, D., A. Rowland, and P.E. Bailey. (1982) On the size of African riverine fish faunas. American Zoology. 22: 361-369. Lyons, S. C. and M. R. Willig. (2002) Species richness, latitude, and scale- sensitivity. Ecology. 83:1, 47-58. Magalhães, M. Beja, P., Schlosser, I., and M. Collares-Pereira. (2007) Effects of multi-year droughts on fish assemblages of seasonally drying Mediterranean streams. Freshwater Biology. 52: 1494-1510. Mallin, M., Parel, H., Rudeck, J., and P. Bates. (1993) Regulation of estuarine primary production by watershed rainfall and river flow. Marine Ecology Progress Series. 93: 199-203. May, J. and L. Brown. (2002) Fish communities of the Sacramento River Basin:

Implications for conservation of native fishes in the Central Valley, California. Environmental Biology of Fishes. 63:373-388.

McDowall, R. (2002) Accumulating evidence for a dispersal biogeography of southern cool temperate freshwater fishes. Journal of Biogeography. 29: 207-219. Mediterranean Research Learning Center. National Park Service (2009) Used for figure

1. Accessed (February 3, 2009). http://www.researchlearningcenter.com/ media/abo_map.gif

Mercer, J. (1983) Cenozoic glaciation in the Southern Hemisphere. Annual Review of

Earth and Planetary Science. 11: 99-132.

Mittelbach, G., Schemske, D., Cornell, H., Allen, A., Brown, J., Bush, B., Harrison, S., Hurlbert, A., Knowlton, N., Lessios, H., McCain, C., McCune, A., McDade,

L., McPeek, M., Near, T., Price, T., Richlefs, R., Roy, K., Sax, D., Schluter, D., Sobel, J. and M. Turelli. (2007) Evolution and the latitudinal diversity gradient: speciation, extinction, and biogeography. Ecology Letters. 10: 315-331.

Mooney, H. and E. Dunn. (1970) Convergent evolution of Mediterranean-climate

evergreen sclerophyll shrubs. Evolution. 24: 292-303. Morgan, D. (2003) Distribution and biology of Galaxias truttaceus (Galaxiidae) in south-western Australia, including first evidence of parasitism of fishes in Western Australia by Ligula intestinalis (Cestoda). Environmental Biology of Fishes. 66: 155-167.

50

Morgan, D. (2004) Distribution and impacts of introduced freshwater fishes in Western Australia. New Zealand Journal of Marine and Freshwater Research. 38: 511-523. Morgan, D., Hambleton, S., Gill, H., and S. Beatty. (2005. Distribution, biology, and likely impacts of the introduced redfin perch (Perca fluiatilis) (Percidae) in Western Australia. Marine and Freshwater Research. 53:8, 1211-1221. Moyle, P. (2002) Inland fishes of California. University of California Press, Berkley USA. Moyle, P. and B. Herbold. (1987) Life-history patterns and community structure in

stream fishes of Western North American. Comparisons with Eastern North America and Europe, in Community and Evolutionary Ecology of North American Stream Fishes, (eds. W. J. Mathews and D. C. Heins). University of Oklahoma Press, Norman, pp. 25-32.

Moyle, P. and Light, T. (1996) Biological invasions of freshwater: empirical rules and assembly theory. Biological Conservation 78: 149-161. Myers, N., Mittermeier, R., Mittermeier, C., da Forseca, G. and J. Kent. (2000) Biodiversity hotspots for conservation priorities. Nature 403: 853-858. Novacek, M. and Marshal, L. (1976) Early biogeographic history of Ostariophysan fishes. Copeia. 1:1-12. Oberdorff, T., Guégan, J., and B. Hugueny. (1995) Global patterns of fish species richness in rivers. Ecography. 18: 345-352. Oberdorff, T., Hugueny, B., and T. Vigneron. (2001) Is assemblage variability related to environmental variability? An answer for riverine fish. Oikos. 93: 419-418. Oren, O., Zismann, and H. Hornung. (1973) The hydrography and distribution of fishes along the shore of Dor, Israel: Part I. The hydrography of the shore of Dor. Aquaculture. 2, 343-367. Oyarzun, C. (1995) Land use, hydrological properties, and soil erodibilities in the Bio-

Bio basin, central Chile. Mountain Research and Development. 15:331-338.

51

Pascual, M., Cussac, V., Dyer, B., Soto, D., Vegliano, P. Ortuby, S. And P. Macchi. (2007) Freshwater fishes of Patagonia in the 21st Century after a hundred years of human settlement, species introductions, and environmental change. Aquatic Ecosystem Health & Management. 10:212-227. Pereira, W., Domagalski, J., Hostettler, F., Brown, L. and J Rapp. (1996) Occurrence and accumulation of pesticides and organic contaminants in river sediment, water and clam tissues from the san Joaquin River and tributaries. Environmental Toxicology and Chemistry. 15: 172–180. Peters, P. and J. Myers. (1991) Preserving biodiversity in a changing climate. Issues in Science & Technology. 91: 66-72. Poff, N. and J. Allan. (1995) Functional organization of stream fish assemblages in relation to hydrological variability. Ecology. 76: 606-627. Poff, N.L. (1997) Landscape filters and species trait: towards mechanistic understanding and prediction in stream ecology. Journal of the North American Benthological Society. 16: 391-409. Polis, G. (1991) Complex trophic interactions in desserts: an empirical critique of food- web theory. American Naturalist. 138: 123-155. Polis, G and D. Strong. (1996) Food web complexity and community dynamics. American Naturalist. 147: 813-847. Preston, F. (1962) The canonical distribution of commonness and rarity I and II. Ecology. 43: 185-215 and 410-432. Reyjol, Y., Hugueny, B., Bianco, P. and D. Pont. (2007) Patterns in species richness and endemism of European freshwater fish. Global Ecology and Biogeography. 16: 65-75. Rühland, K., Paterson, A., and J. Smol. (2008) Hemispheric-scale patterns of climate-

related shifts in planktonic diatoms from North American and European lakes. Global Change Biology. 14: 2740-2754.

Sari, H., S. Balik, M. Ustaoğlu, A. Ilhan. (2006) Distribution and ecology of freshwater ichtyofauna of the Biga Peninsula, North-western Anatolia, Turkey. Turkish Journal of Zoology. 30: 35-45.

52

Simpson, H., Cane, M., Herczeg, A., and S. Zebiak. (1993) Annual river discharge in southeastern Australia related to El Nino-southern oscillation forecasts of sea surface temperatures. Water Resources Research. 29:11, 3671-3680. Schluter, D. (1986) Tests for similarity and convergence of finch communities. Ecology. 67: 1073-1085. Swanevelder, C. (1981) Utilizing South Africa’s largest river: The physiographic background to the Orange River scheme. GeoJournal. 2:2, 29-40. Thompson, J., Gautheir, R., Amiot, J., Ehlers, B., Collin, C., Fossat, J., Barrios, V., Arnaud-Miramont F., Keefover-Ring. K. and Y. Linhart. (2007) Ongoing adaptation to Mediterranean climate extremes in a chemically polymorphic plant. Ecological Monographs. 77: 421-439. Tonn, W. (1990) Climate change and fish communities: a conceptual framework. Transactions of the American Fisheries Society. 119: 337-352. Unmack, P. (2001) Biogeography of Australian freshwater fishes. Journal of Biogeography. 28:9, 1053-1089. Underwood, E., Viers, J., Klausmeyer, K., Cox. and M. Shaw. (2009) Threats and

biodiversity in the Mediterranean biome. Diversity and Distributions. 15:188-197. Vandermeer, J. (2006) Omnivory and the stability of food webs. Journal of Theoretical Biology. 238: 497-504 Viney, N. and M. Sivapalan. (2001) Modeling catchment processes in the Swan- Avon river basin. Hydrological Processes. 15: 2671-2685. Waters, M.J., Dijkstra, H. and P. G. Wallis. (2000) Biogeography of a Southern Hemisphere freshwater fish: how important is marine dispersal? Molecular Ecology 9:1815-1821 Winemiller, Kirk O. (1991) Ecomorphological diversification in lowland freshwater fish assemblages from five biotic regions. Ecological Monographs. 61:4, 343-365. Whittaker, R. (1977) Evolution of species diversity in land communities. Evolution Biology. 10: 1-67. Woodward, G. and A. Hildrew. (2001) Invasion of a stream food web by a new top predator. Journal of Animal Ecology. 70: 273-288.

53

World Weather Information Service. (2000). The Commission of Basic Systems of the World Meteorological Organization Mandated. Hong Kong. Temperature and Rainfall Data World Wide. Retrieved February 18th, 2009. From http://worldweather.wmo.int/

Wright, E. (1983) Species energy theory: an extension of species-area theory. Oikos. 41: 495-506.

global patterns of freshwater fish communities in mediterrannean

Documents