WHlldm J. mdtt~ews Professor, Department of Zoology Curator of Flshes, Oklahoma Museum of Natural History

The University of Oklahoma

Norman, OK

SPRINGER-SCIENCE+BUSINESS MEDIA, B.V.

Library of Congress Cataloging-in-Publication Data

Matthews, William J. (William John) Patterns in freshwater fish ecology / William J. Matthews.

p. cm. Includes bibliographical references and index. ISBN 978-1-4613-6821-2 ISBN 978-1-4615-4066-3 (eBook) DOI 10.1007/978-1-4615-4066-3 I. Freshwater fishes--Ecology. I. Title.

QL624.M38 1998 597. 176--dc21 97-21339

Cover Drawing: Coral McCallister, Norman, OK Cover design: Curtis Tow Graphics

CIP

Copyright © 1998 by Springer Science+Business Media Dordrecht Originally published by Chapman & Hall in 1998 Softcover reprint of the hardcover 1st edition 1998

Copyright © Second Printing 1998 by Kluwer Academic Publishers

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, mechanical, photo­copying, recording, or otherwise, without the prior written permission of the publisher, Springer-Science+Business Media, B.V.

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For my family

Contents

Introduction

1. Overview of Fishes and Fish Assemblages 1.1 Problems and Approaches in Fish Ecology

"Reighard's Lament" 1.2 Diversity of Fishes and Their Habitats

Fish Versus Tetrapod Diversity Examples of Diverse Fish Faunas Diversity of Fishes by Geographic Region Diversity Within Taxonomic Groups Morphological Diversification Habitats of Fishes

1.3 Questions about Fish Assemblages Focus of This Book Factors Potentially Influencing Assemblage Structure Macroecology Classes of Explanations for Fish Assemblage Structure Effects of Fish Species and Assemblages in Ecosystems

1.4 Explanations? Correlative Versus Mechanistic Explanations for Observed Patterns Time Scales for Evolutionary and Ecological Thought Influence of Phylogeny on Ecology Classification and Evolutionary Systematics

1.5 Guideposts

2. Structure of Fish Assemblages 2.1 Introduction

What Is a Fish "Assemblage" in the Context of a "Locality"? What Is Fish Assemblage "Structure"?

vii

XVll

2 3 5 5 6 7

10 11 11 12 15 15 19 22 22 24 25 26 28

30 30 30 32

viii / Patterns in Freshwater Fish Ecology

2.2 Number of Species, Families, and Species per Family 33 Numbers of Fish Species in an Assemblage 33 The Empirical Evidence: Numbers of Species per Locality 38 Local Assemblages in Individual Stream Pools? 44 Number of Families in Local Assemblages, and Species per Family 45

2.3 Trophic and Functional Groups, and PredatorlPrey Species 54 Composition of Assemblages by Trophic Groups 54 Relative Abundance of Piscivore to Prey Species in Assemblages 60 Functional Groups of Fish in Assemblages 66

2.4 Abundance, Body Size, and Mouth Size 73 Distribution of Abundance of Species Within Assemblages 73 Body and Mouth Size Structure Within Whole Assemblages 77

2.5 Summary 84

3. Discrete Versus Overlapping Assemblages and Assemblage Stability 86 3.1 Discrete Versus Overlapping Assemblages 86

Background 86 Fish Assemblages-Discrete Versus Overlapping? 88 Distinct Fish Assemblages in Streams? 90 Distinct Fish Assemblages Among Lakes? 91 Random Versus Discrete Groupings of Fish Species-

A Multivariate Model 93 Detecting Discrete Fish Assemblages in Streams and Lakes-A

Statistical Test of the Evidence 99 3.2 Stability of Fish Assemblages 104

Background 107 Classical and Descriptive Studies 108 Qualitative Changes in Fish Assemblages 109 Quantitative Studies-Temperate Streams 110 Assessment of Long-Term Samples by Similarity Indices and

Coefficients of Variation 120 Multivariate Assessment of Temporal Variation in Fish Assemblages 122 Stability Across Combined Spatial and Temporal Scales 126

3.3 Summary 127

4. Stream Ecology and Limnology as Related to Fish Assemblages 4.1 Introduction 4.2 Physical and Chemical Limnology and its Effect on Fish and

Fish Assemblages Physical Properties of Water Light in the Aquatic Environment Heat Budgets and Temperature in the Aquatic Environment Effects of Light and Heat on Fish Assemblages in Lakes Thermal Effects on Fish Distribution in Lakes Water Chemistry: Oxygen Effects of Oxygen on Fish in Lakes Water Chemistry: Alkalinity and pH, Carbonate Systems

130 130

131 133 135 136 136 137 138 138 140

Contents / ix

Effects of Environmental pH on Fish 141 Physical and Chemical Factors in Streams and Effects on Fish 142 General Physicochemical Effects on Habitat Selection by Fish 146

4.3 Lentic Versus Lotic Environments as Fish Habitats 149 Characteristics of Lentic Versus Lotic Environments 149

4.4 Characteristics of Lakes that Influence Fish Assemblages 151 Lakes 151 Lake Formation, Life Span, and Demise 152 Lake Formation and Sources of Fishes 155 Eutrophication: Trophic Status of Lakes 157 Stratification Patterns and Effects on Fishes 159 Wind and Water Movements in Lakes 163 Morphometry of Lakes 166 Summary: Limnology of Lakes 171

4.5 Characteristics of Streams that Iofluence Fish Assemblages 171 Watersheds and Ecosystem Concepts in Streams 171 Formation of River Basins and Drainage Patterns 172 Terminology for Streams of Various Sizes 174 Drainage Patterns 175 Headward Cutting of Channels-New Habitat for Fishes? 180 Sources of Water for Streams 181 Location of Flow Within Stream Channels and Configuration of

Channels 182 Stage rises, Floods, and the Hydrograph 185 Woody Debris in Streams 187 Channel Formation and Maintenance 188 Anthropogenic Effects on Hydrographs and Flood Frequency 188

4.6 Summary 189

5. Iofluence of Global to Regional Zoogeography on Local Fish Assemblages 191 5.1 Iotroduction 191 5.2 Global Zoogeography of Freshwater Fishes 192

Zoogeographic Realms 192 Testing Patterns of Fish Families on a Worldwide Zoogeographic

Template: Was Wallace Right? 194 Family Richness Among Basins, and "Basin Richness" Within

Families 196 Primary, Secondary, and Tertiary Freshwater Fishes (Myers) 197 Continental Movements and Freshwater Connections 202

Northern Landmass 205 Southern Landmass 206 Attaining Modem Configuration 207

Occurrence of Freshwater Fish Families Relative to Continental Movements 207

Zoogeography of Ostariophysians-Alternative Hypotheses 213 Application of Global Biogeography to Local Fish Assemblages?

North America as an Example 219

x / Patterns in Freshwater Fish Ecology

5.3 Subcontinental Zoogeography of Freshwater Fishes Glacial Periods of the Pleistocene-Effects Worldwide, "Land

Bridges," and Beringia North American Fish Regions as an Example of Subcontinental

Zoogeographic Effects Eurasia Southeast Asia Africa South America Australasia and New Zealand

5.4 Regional Biogeography of Fishes Importance of River Basins in Fish Biogeography Local Endemics Vicariance Biogeography and "Historical Ecology" Directional Affinities of Species in a Fauna

227

227

235 238 239 240 240 240 241 241 243 245 249

"Ecoregions" 254 Regional Versus Local Species Richness 255 Zoogeography in Individual Species: Range Sizes and Body Sizes 260

5.5 Merging Concepts of Geological, Zoogeographic, and Basin-Level Effects in Ecological Time 261

Interactive Ecology 262

6. Physical Factors Within Drainages as Related to Fish Assemblages 6.1 Introduction 6.2 Area Effects at "Drainage" Level

Drainage Area and "Insular" Effects 6.3 Local Habitat Size

Stream Width Stream Depth and "Pool Development" Depth of Lakes Volume Discharge

6.4 Habitat Structure, Cover, Complexity, and Productivity Structure or Cover Woody Debris Rock Structure in Streams "Soft" Structure: Macrophytes, Algae, Leaf Packs Cover Habitat "Heterogeneity" Heterogeneity at Increasing Scales: Connectivity of Habitat Units Primary Productivity in Local Habitats

6.5 Zonation of Fishes in Lakes and Streams Habitat Zonation in Lakes Coves as Special Habitats? Longitudinal "Zonation" or "Continuum" of Stream Fishes? A Test of the "Continuum" Versus "Zonation" Hypothesis for

Stream Fishes Stream Order and Longitudinal Distribution of Fishes

264 264 264 264 268 268 271 273 274 276 279 279 279 282 282 283 283 287 289 290 290 293 296

305 307

Contents / xi

Potential Problems with the Horton-Strahler System of Stream Order for Fish Ecologists 310

Alternatives to Stream Order? 312 6.6 Landscape Ecology: Looking Laterally, Instead of Just Up and Down

the Stream? 312 6.7 Multivariate AJ;lalyses of Fish Distributions, and Influence of

Environmental Variables 315

7. Disturbance, Harsh Environments, and Physicochemical Tolerance 318 7.1 Introduction 318

Abiotic Versus Biotic Regulation of Fish Assemblages 319 7.2 Definition and Time Scales of Disturbance 320

What Is "Disturbance"? 320 Theoretical Implications of Disturbance 322 Time Scales of Disturbance 323

7.3 Floods 326 Effects of Floods on Streams 326 Potential Long-Term Effects of Floods on Stream Ecosystems and

Fish Assemblages 331 Field Studies of Flood Effects on Fishes 333 Habitat Use by Stream Fish During and After Floods 334 A Major Flood Event in a Typically "Benign" Warm-Water Stream:

Effects on the Fish Fauna 336 7.4 Drought 341

Known Changes in Fish Assemblages During and After Drought 344 Phases of Effects of a Drought 349

7.5 Physicochemical Stress 353 Tolerance of Individual Species for Physicochemical Stress in the

Environment 353 Effects of High Temperature 354 Effects of Cold Temperature 357 Oxygen 357 pH and Acidification, Natural "Stained" Water 360 Intraspecific Variation 361 Sublethal or Indirect Effects of Stressors 363 "Harsh" Conditions-Detriment or Benefit to Individual Species? 365 An Example of Salinity Structuring a "Freshwater" River

Assemblage 365 Physicochemical Tolerances and Selectivity of Stream Fishes as

Related to Ranges and Local Distributions 366 Hypothetical Tolerance and Selectivity Strategies 368 Influence of Phylogeny on Physicochemical Tolerance? 370 Fish in Microrefugia from Physicochemical Stress: When to Stay and

When to Go? 374 7.6 Disturbance and Physicochemical Effects: Combined 377

Integrating Disturbance and Physicochemical Stress into Distribution of Fishes in a RiverlLake System 377

xii / Patterns in Freshwater Fish Ecology

8. Morphology, Habitat Use, and Life History 380 8.1 Introduction 380 8.2 Water as a Medium: Fluid Drag 381 8.3 Morphology 384

Body Regions and Relation of Their Morphology to Ecology 384 Approaches to Morphological Studies of Fish Ecology 385 Generalizations from Descriptive Morphology 386 Swimming or Holding Position Against Fluid Drag 388 Function Morphology in Swimming 389 Body and Caudal Fin Shape Relative to Hydrodynamics 390 Axial Fins: Role in Propulsion or Controlling Movements 391 Paired Fins: Control of Motion in Swimming or Their Use to Hold

Position in Flowing Water 393 Additional Morphological Features of Benthic Fishes 394 Shapes of Fishes in Nontlowing Habitats 395 Trophic Morphology of Fishes 396 Descriptive Studies of Morphology Relative to Food Use 399 Functional Analyses 400 "Other" Morphological Features Relative to Ecology 403 Ecomorphology 403

Overview 410 Intraspecific Variation in Morphology 410 Summary: Morphological Approaches and Fish Ecology 411

8.4 Hydraulics, Morphology, Microhabitat, and Food Use 412 Larval Fish Success Relative to Hydraulics of Habitat 416 Habitat Selection, Patch Choice, Effect on Feeding or Reproduction 417

8.5 Reproduction and Life History 419 Life History of Fishes 420 Overview of Life-History Patterns 421 Age at First Reproduction and Reproductive Life Span 425 Factors Regulating Length or Timing of the Reproductive Season 426 Single or Repeated Spawning? 427 Prespawning Phase of Reproduction 429 Mating Systems or Mate Selection 429

Mating patterns 429 Sexual selection 429 Alternative life histories 431

Spawning and Clutch Parameters 432 Egg Size Versus Egg Number 433 Intraspecific Variation in Clutch Parameters 434 Individual Variation 435 Effect of Reproductive Status on Morphology and Hydrodynamics

of Individuals 435 Parental Care and Guarding 435 Early Life History: Survival of Eggs and Growth of Larvae 437

Finding Food as Free-Living Larvae 438 Growth, Recruitment, and Mortality 439

Contents / xiii

Evolutionary and Environmental Constraints in Reproductive Traits 440 Intraspecific Differences in Reproductive Traits 441 Interspecific Differences in Life-History Traits 442 Life History Versus Habitat Features 442 Effects of Predators on Life History 443 Genetics or Heritability of Life-History Traits 444 Different Life-History Strategies May Work Within a Single Place 445

8.6 Movement and Migration 448 Home Pools or Limited Home Ranges 448 Short-Term Movements 450 Rheotaxis 451 Spawning Movements 451 Nonspawning Seasonal Movements and Migrations 452 Diadromy 453

9. Interactive Factors: Competition, Mixed Species Benefits, and Coevolution 455

9.1 Interspecific Competition and Resource Partitioning 455 Background 455 Niche Segregation or "Resource Partitioning" 458 Competition Among Fishes: Historical Perspective 460 Is Competition Important in Fish Communities? 464 Empirical Evidence for Competition in Fish Assemblages 466 Experimental Evidence of Competition Between Fish Species 467 Resource Partitioning in Fish Assemblages: Throug 1970 470 Empirical Evidence of Resource Partitioning: Early 1970s 474 Experimental Work-Werner, Hall, and Colleagues 476 Other Studies of Resource Partitioning: Late 1970s 478 Resource Partitioning: 1980 to the Present 480 Conclusions: Competition and Resource Partitioning in Fish

Assemblages 491 Remaining Questions About Competition and Resource Partitioning in

Fish Assemblages 496 9.2 Intraspecific Competition, Density Effects, and Resource Partitioning 497

Density-Dependent Effects 499 Competition Between Size Classes of a Species 502 Intraspecific Competition: Cold-Water Fishes 503 Intraspecific Competition in Warm-Water Stream Fishes 506 Intraspecific Resource Partitioning? 507 Summary: Intraspecific Competition or Resource Partitioning 512

9.3 Mixed-Species Effects in Assemblages 512 Background 512 Potential Benefits 513 Evidence of Mixed-Species Phenomena 515 Case Histories: Mixed Species Groups 515 Examples from Streams and Reservoirs 521 More Complex Mutualisms 522

xiv / Patterns in Freshwater Fish Ecology

Conclusions: Mixed-Species Groups in Assemblages 523 Optimal Numbers of Species in Mixed Groups? 524

9.4 Coevolution in Fish Assemblages? 525

10. Interactive Factors: Predation Effects in Fish Assemblages 532 10.1 Predation and a Hypothetical Model 532

Hypothetical Model of Interactions of Numbers of Prey and Piscivore Species 533

10.2 Empirical Studies of Piscivory 536 Background on Piscivory in Fish Communities 536 Case Histories: Introduced Piscivores in Streams 538 Case Histories: Piscivory in Lakes 539 Localized Effects of Piscivores in Streams 542 Piscivore Effects Throughout Longer Stream Reaches 544 Piscivore Influence on Distribution, Habitat, or Behavior of Prey

Species 546 10.3 Experiments with Piscivore-Prey Systems 547

Experimental Evidence: Effects of Predators in Streams and Lakes 547 Effects of the Environment on Outcome of Predator-Prey Contests 549 Effects of Other Animals on Piscivory 550

10.4 Theoretical Aspects of Predation 552 Balancing the Risk: Eat Well and Die Young(er)? 552 Theoretical Prey Behavior Under Predator Threat 554 Nonlethal Effects of Predators on Growth, Reproduction, or

Interactions of Prey Species 557 Fragmentation of Populations by Predators? 559 Quantifying Effects of Piscivory in Streams? 560 Growth as a Survival Strategy? 563

10.5 Conclusions: Effects of Piscivory in Fish Assemblages 563

11. Effects of Fish in Ecosystems 565 11.1 Introduction 565 11.2 Direct Effects of Fish in Ecosystems 567

Effects of Fish on Abundance of Macroinvertebrates 567 Effects of Fish on Life History or Behavior of Macroinvertebrates 573 Effects of Fish on Large Macroinvertebrates: Crayfish 574 Effects of Fish on Vertebrates: Frogs and Salamanders 574

11.3 Planktivory 575 Effects of Fish on Zooplankton 575 Effects of Fish on Phytoplankton 581

11.4 Herbivory 583 Algivory 583 Effects of Fish on Vascular Plants 589

11.5 Nutrient Effects and Ecosystem Engineering 590 Nutrient Changes by Fish in Ecosystems 590 Ecosystem "Engineering" 593

11.6 Indirect Effects of Fish in Ecosystems Second-Order Effects Trophic-Level Cascade Effects Fish Effects in Food Webs Biomanipulation

11.7 Keystone Species and Strong Interactors Strong Interactors An Example of a Strongly Interacting Fish Species

Literature Cited

Subject Index Taxonomic Index Locality Index

Contents / xv

594 595 597 601 604 610 611 611

617

733 744 752

Introduction

Nearly a decade ago I began planning this book with the goal of summarizing the existing body of knowledge on ecology of freshwater fishes in a way similar to that of H. B. N. Hynes' comprehensive treatise Ecology of Running Waters for streams. The time seemed appropriate, as there had been several recent volumes that synthesized much information on a range of topics important in fish ecology, from biogeographic to local scales. For example, the "Fish Atlas" (Lee et aI., 1980) had provided range maps and basic entry to the original literature for all freshwater fishes in North America, and in 1986 Hocutt and Wiley's Zoogeography of North American Fishes provided a detailed synthesis of virtually everything known about distributional ecology of fishes on that continent. Tim Berra (1981) had summarized in convenient map form the worldwide distribution of all freshwater fish families, and Joe Nelson's 1976 and 1984 editions of Fishes of the World had appeared. To complement these "big picture" views of fish distributions, the volume on Community and Evolutionary Ecology of North American Freshwater Fishes, edited by David Heins and myself (Matthews and Heins, 1987), had provided an opportunity for more than 30 individuals or groups to summarize their work on stream fishes (albeit mostly for warmwater systems).

For tropical waters, The Fishes and the Forest (Goulding, 1980) had intrigued ecologists with the intricate ecological relationships of South American freshwater fishes to seasonally flooded forests, and Lowe-McConnell's (1987) Ecological Studies in Tropical Fish Communities expanded an earlier volume (Lowe-McCon­nell, 1975) to provided a valuable synthesis both of her own work and a diverse, multilingual primary literature on the ecology of fishes in the Neotropics and Africa. Many other books or works in the primary literature set the stage for an attempt to write a comprehensive book on freshwater fish ecology, but those volumes were particularly influential for me.

IIi addition to the recent availability of these syntheses, there was also a maturing of fish ecology into a discipline linked to aquatic ecology and to ecology

xvii

xviii / Patterns in Freshwater Fish Ecology

in general, as reviewed in Heins and Matthews (1987). Much of the history of "fish ecology" is found in the all-important works on exploration and discovery of species, alpha-level taxonomy and subsequent revisions of groups, distributional museum catalogs, and "state" or regional fish books produced by many ichthyolo­gists from the 1800s to mid 1900s. By late in this century, fish distributions, evolution, and zoogeography worldwide seemed sufficiently well-known to sup­port a synthesis at that leveL The other extreme in work fundamental to present­day fish ecology is the voluminous primary literature on biology, natural history, autecology or management of individual species, dating to the late 1800s when individuals like Stephen Forbes began basic and management-oriented studies of fishes. By the 1970s there was a huge amount of information on individual species, summarized in Kenneth Carlander's two-volume Handbook of Freshwa­ter Fishery Biology.

Against this huge background of information on freshwater fish distribution, taxonomy, and biology, modem "fish ecology" began to emerge in the 1960s and 1970s. During this era two very important changes in studies of freshwater fishes began. First, there was a renewed interest in testing general ecological theory with freshwater fishes. For example, individuals like Alan Keast, Earl Werner, Thomas Zaret and others began quantitatively testing general precepts of population ecology or MacArthurian community ecology with freshwater fishes. Secondly, there was a renewal of interest (which had largely lapsed in the mid-1900s) in the effects of fish on the ecosystems in which they occurred. With the 1965 paper by J. L. Brooks and S. I. Dodson many limnologists became interested for the first time in the potential effects of fish on lake plankton and productivity, and by the early 1980s several groups began to show that fish also affected structure or function of stream ecosystems. Finally, by late in the 1980s it was apparent that biodiversity issues were not limited to tropics or rain forests, and that a "biodiversity crisis" included freshwater aquatic systems in much of the world. As a result, there was a great sharpening of interest in freshwater fish during the 1980s as barometers of the condition of ecosystems.

Thus, when I began outlining this book about 1988, there was not only a very substantial background against which to cast such a volume, but a sharp interest in ecology of fishes by individuals who would not typically consider themselves "ichthyologists". Ichthyology, natural history, general ecological thought, and management all melded during the 1970s and 1980s into something that can properly now be called freshwater "fish ecology", and many extant scientists now label themselves as fish ecologists.

Soon after undertaking the writing of a book on "freshwater fish ecology", it became apparent that a single book summarizing everything known in the disci­pline was impossible, but, thankfully, not needed. Since I began writing this book, several others have fortuitously appeared that summarize large blocks of information on freshwater fishes. Wootton's (1990) Ecology of Teleost Fishes summarized fish ecology in general, but with emphasis on ecology of individual

Introduction / xix

fishes, their energetics, and their reproduction. Gerking's (1994 ) Feeding Ecology of Fish and the volume on fish feeding ecology edited by Stouder et al. (1994) have thoroughly summarized that topic, also freeing the present book from a need to repeat much of the known details on trophic ecology of fishes. Finally, the 1992 volume Systematics, Historical Ecology and North American Freshwater Fishes edited by R. L. Mayden, has, in concert with many other publications in the primary literature, begun to make it possible for ecologists interested in freshwater fishes to place their work in an evolutionary, phylogenetic perspective, so that a mature view of "adaptation" as a paradigm can be tested. Finally, Nelson's (1994) third edition of Fishes of the World appeared, summarizing latest thinking on fish systematic relationships.

Freed from the requirement to summarize "everything" in freshwater fish ecology, I have chosen to address "patterns in freshwater fish ecology", with focus on (1) the structure of local fish assemblages, i.e., those seen in a single location in freshwater lakes or streams, and (2) on the effects of those fish in the systems where they live. This book is an attempt to assess, for graduate students, upper-division undergraduates, or professionals wanting a review, the major patterns in ecology of freshwater fishes, from the perspective of factors ranging from "deep-evolutionary/global" to "recentllocal" that influence the com­position of local fish assemblages in lakes and streams. In this, I borrow freely from the paradigm of Smith and Powell (1971) of a series of "screens" from very large to very small scale that influence composition of local assemblages.

This book has three parts. Chapters 1-4 assess general patterns in diversity of fishes worldwide; diversity, structure and stability of local fish assemblages; and the limnological and physical features that influence local fish assemblages. Chapters 5-10 focus at increasingly small spatial scales on factors that influence the structure of local fish assemblages. These range from a review of global and regional zoogeography and distributional history of freshwater fishes through evolutionary time (Chapter 5), to local physical structure or environmental stress factors (Chapters 6 and 7), to morphology and life history (Chapter 8), to interact­ive factors like competition (Chapter 9) and predation (Chapter 10). The third part of the book is a single chapter (Chapter 11) that summarizes known influences of fish species or local fish assemblages on ecosystem structure or processes where they do occur.

Numerous caveats about this book are in order. First, I have not attempted the primary literature in languages other than English, which is particularly important to some areas of Africa or the Neotropics. Similarly, most of this book draws on reprints and journals most available to me, or systems with which I am most familiar, thus North American streams are most used as examples (although I incorporate work from all areas of the world, when possible). Additionally, there will be no "great synthesis" at the end of the book proclaiming primacy of one scale of effects over another (e.g., zoogeographic vs. local interactions) in determining structure of local fish assemblages. Instead, I hope that this book

xx / Patterns in Freshwater Fish Ecology

may help a fish ecologist standing in any lake or stream to contemplate the range of factors, from those in the deep evolutionary past to those that happened only moments ago, that influence the fishes they see or collect on a given day. Parts of this book should be used with caution, because I have in places indulged in speculation or potential explanations that exceed the limits of the peer-reviewed literature, or I have included syntheses that have not been previously published in any peer-reviewed journal. Such new materials, whether presented as specific examples or as proposed syntheses (e.g., fish functional groups, Chapter 2), have not had anonymous peer-review, although they have been scrutinized by volunteer reviews of chapters that I thank below. The reader should simply be aware that in many sections I present opinions or ideas supported by some field data or observations, but that may be rejected if they are subjected to more detailed testing in the future.

Finally, some readers will be disappointed that I have not devoted more of this book to anthropogenic damage to fish assemblages or aquatic ecosystems. There is indeed great need for a synthesis of the history of the terrible effects of thoughtless actions of humankind on freshwater fishes and on aquatic systems, and for recommendations for saving these systems for the future. However, this aspect of fish ecology has such a voluminous literature that to give it adequate treatment would have swamped other aspects of this volume. Suffice to say that probably none of the aquatic systems described in this book really contain assemblages identical to those that existed before encroachment of "civilization" into a region. In most cases the pre-settlement fish assemblages were not docu­mented or were poorly studied at best, so that few living fish ecologists have ever seen a completely pristine fish assemblage with all its original components. All we can do at present is hope to retain, through careful basic study and understanding, fish assemblages and aquatic systems in as nearly intact a form as possible. A great service of and challenge to fish ecology has been and will be to identify, within the framework of the last two centuries, the degree to which variation in assemblages is natural, and thus identify magnitudes of change that signal or reflect an exceeding of natural change (typically as a result of acts of humankind).

lowe a huge measure of thanks to many individuals who have discussed ideas, helped with field work that has influenced my thinking, shared unpublished data, or served as reviewers of chapters or sections of chapters. Many of the ideas presented in this book relate to my studies in the central United States in Piney Creek, Izard County, Arkansas; Brier Creek, Marshall County, Oklahoma; Lake Texoma, Oklahoma-Texas; or at long-term sampling sites throughout the Midwest and Southwest. My brother Bob, who was instrumental in starting the Piney Creek project, urged completion of this book for years. Bob Cashner, Fran Gelwick, and Henry Robison also have been long-term collaborators and support­ers of this writing. Others who have helped in the field, many of whom are co­authors or co-holders of the data on those systems, include: Ken Asbury, Irene

Introduction / xxi

Camargo, Betty Cochran, Tony Echelle, David Edds, George Harp, Bret Harvey, Thomas Heger, Loren Hill, Jan Hoover, Steve Kashuba, Mike Lodes, Susan Matthews Jones, Andrew Marsh, Rebecca Marsh, Edie Marsh-Matthews, Doug Martin, Amy Matthews, Scott Matthews, Roland McDaniel, Mary Power, Steve Ross, Scott Schellhaass, Bill Shepard, Art Stewart, Jeff Stewart, Barbara Taylor, Chris Taylor, Bruce Wagner, and many students or technicians at the University of Oklahoma Biological Station. For help in sampling the Roanoke River during flood conditions, I thank Eric Surat, Jeff Bek, Bridgett Lambert, Jill Stockett, John Styron, Don Cherry, Tim Jesse, David High and Jody Hershey.

It is difficult to know where many of the thoughts presented in this book originated, but I suspect that I have either stolen or sharpened many ideas as a result of discussions with the persons named above, or with Ned Andrews, Cynthia Annett, Art Brown, Ken Beadles, Alan Covich, Frank Cross, Mike Douglas, Ray Drenner, Alex Flecker, Carter Gilbert, Jim Gilliam, Moshe Gophen, Owen Gorman, Nick Gottelli, Nancy Grimm, Gary Grossman, David Heins, Clark Hubbs, Vic Hutchison, Robert E. Jenkins, Mike Kaspari, Hiram Li, Mark Lomolino, Mike Meador, W. L. Minckley, Gary Meffe, Peter Moyle, Jimmie Pigg, Mark Pyron, Gary Schnell, Bill Shelton, Steve Threlkeld, Caryn Vaughn, Matt Winston, Kirsten Work, Earl Zimmerman, present or past members of the graduate student fish ecology group at the University of Oklahoma, and many visitors to the OU Biological Station or Department of Zoology.

I cannot thank enough the colleagues who reviewed entire chapters or sections of chapters. Individuals who critically reviewed one or more whole chapters were: Bob Cashner, Ray Drenner, Fran Gelwick, Moshe Gophen, Bret Harvey, Roger Lemmons, Edie Marsh-Matthews, Mary Power, Chris Taylor and several anonymous reviewers engaged by Chapman & Hall. Others who critically re­viewed, offered technical comments or shared additional information on particular sections of chapters included Bill Dietrich, John Lundberg, Richard Mayden, Peter Moyle, Steve Ross, Royal Suttkus, and Gary Wellborn. C. R. Scotese provided technical interpretation of maps of continental movements. Numerous graduate students in my fish ecology classes have provided excellent input on various chapters, particularly Keith Gido, Jacob Shaefer, Karl Polivka, Bruce Stewart, Phil Gaines, and Roger Lemmons. I particularly thank Edie Marsh­Matthews for detailed involvement in all aspects of the completion of this book. Edie suggested rearrangements of several chapters, read the final draft of every chapter for editorial detail, checked all literature cited, did much of the indexing, criticized all syntheses and ideas, suggested several new analyses, pointed out references, provided expert input on life-history concepts, and in some cases "saved me from myself" by convincing me to delete speculations that exceeded the bounds of credibility. I thank all of the reviewers above, and note to the reader that any remaining errors of logic are my own.

Numerous individuals shared unpublished data, collecting records, and similar information. Chapter 2 draws heavily on collection records and/or personal com-

xxii / Patterns in Freshwater Fish Ecology

munications provided by Bob Cashner, Alex Flecker, Rosemary Lowe-McCon­nell, Chris Peterson, Don Stewart, Donald Taphom, Kirk Winemiller, and Robin Welcomme for tropical or Australian systems. Others sharing important collection records, unpublished data, or impressions from their field work were Janalee Caldwell, Keith Gido, Mark Lomolino, Peter Moyle, Darrell Pogue, Henry Robi­son, Steve Ross, and Laurie Vitt. Finally, I thank the many individuals whose published data I have drawn on, reanalyzed, or used in some similar way in compiling this book. Without the field sampling and/or experimental work of literally hundreds of ichthyologists and fish ecologists during the last century there would be no book to write in "fish ecology".

The University of Oklahoma Biological Station (Loren Hill, Director) and Department of Zoology (James Thompson, Chair) provided intellectual and logis­tical support during writing of this book. lowe special thanks to Von Pevehouse and Donna Cobb of the Biological Station for typing some tables, and for a huge effort at compiling the literature cited from my piles of reprints and scratch notes. Coral McCallister, Illustrator in the Department of Zoology, made heroic efforts to convert my hand-drawn figures to ones suitable for publication, produced original art for the book cover, and gave permission to reprint two of her original drawings, and Caroline Tawes, Gloria Stephens, and Shalia Newby were helpful in many ways. Dan Hough, Oklahoma Biological Survey, helped in many ways with computer work during the last 15 years. Phil Lienesch helped check literature, Kirsten Work helped index and proof pages, and Becky Ziebro drew one of the original graphs.

Many individuals at Chapman & Hall were important in production of this book. Greg Payne was instrumental in initiation of the project. Henry Flesh, Lisa LaMagna, and Kendall Harris played important editorial roles.

Finally, I thank my entire extended family for their patience while this book or the field work underlying it was in progress, and for forgiving many missed holidays, family gatherings, trips and similar activities. Without their tolerance and encouragement this book would not have been possible. The book is thus dedicated "to my family", particularly to Edie, Andy and Becky, to Scott and Amy, to Bob, and to Louise P. Matthews on the occasion of her 90th birthday.