Seagrasses:^^T"* • "I T-1Biology, Ecology

and Conservation

edited by

Anthony W.D. Larkum,

Robert J. Orth

and Carlos M. Duarte

A \J Springer

Contents

Foreword xiii

1 Taxonomy and Biogeography of Seagrasses 1-23C. den Hartog and John Kuo

I. Introduction 1II. Key to the Angiosperm Families Containing True Marine Species 2III. Seagrasses: General Taxonomy 3IV. Biogeography 16V. Conclusión and Outlook 18References 19Appendix: A List of the Seagrass Species of the World 22

2 Seagrass Evolution, Ecology and Conservation:A Genetic Perspectiva 25-50

Michelle Waycott, Gabriela Procaccini, Dónalo H. Lesand Thorsten B. H. Reusch

\ Introduction 25II. The Evoíution of Seagrass Diversity 26III. Ecological and Reproductivo Processes 35IV. Concluding Remarks 44Acknowledgments 45References 45

3 Seagrass Morphology, Anatomy, and Ultrastructure 51-87J. Kuo and C. den Hartog

I. Introduction 51II. General Morphology of Seagrasses—Size and Shape 52III. Vegetative Morphology and Anatomy 52IV. Reproductive Morphology and Anaíomy 69V. Water Movement in Seagrass Leaves and Roots 81VI. Morphological, Anatomical and Ultrastructural Modifications

in Relation to Environmental Conditions 82Vil. Discussion and Concluding Remarks 83Acknowledgments 83References 83

vi Contents

4 Sexual Reproduction of Seagrasses: Pollination¡n the Marine Context 89-109

Josef Daniel Ackerman

\ Introduction 89II. Defining Seagrasses 90III. Evolutionary Ecology 90IV. Morphologicai Patterns: Reproductiva Organs 94V. Rollen " 96VI. Reproductive Patterns 96Vil. Pollination 98VIH. Post-Pollination: Pollen Tubes, Embryonic and Seedling Development 102IX. Evidence for Pollination Success 104X. Conclusions 105Acknowledgments 106References 106

5 Ecology of Seagrass Seeds and Dispersal Strategies 111-133Robert J. Orth, Matthew C. Harwell and Graeme J. Inglis

Introduction 111Seeds and Seed Production 112

III. Seed Banks, Dormancy, and Seed Germination 113IV. Seed Dispersal 114V. Seed Recruitment and Seedling Establishment 122VI. Seagrass Conservation and Restoration: Utility of Seeds 123Vil. Conclusions and Emerging Paradigms 126Acknowledgments 128References 128

6 Seagrass Beds and Coastal Biogeochemistry 135-157Nuria Marbá, Marianne Hoimer, Esperanga Gacia and Cristina Barrorí

I. Introduction 135II. Role of Particuiates and Dissolved Material 136III. Mineraüzation of Organic Matter and Nutrient Cycling

in Seagrass Sediments 145IV. Summary and Future Work/Outlook 151Acknowledgments 153References 153

7 Carbón Flux in Seagrass Ecosystems 159-192Miguel A. Mateo, Just Cebrián, Kenneth Dunton, and Troy Mutchler

I. Introduction 159II. Seagrass Production 160III. The Fate of Seagrass Production 164IV. Ecosystem Carbón Budgets and Carbón Sinks 179V. Summary and Future Work 185Acknowledgments 186References 186

Contenís vii

8 Fluid Dynamics in Seagrass Ecology—from Moléculasto Ecosystems 193-225

Evamaría W. Koch, Josef D. Ackerman, Jennifer Verduinand Michael van Keuten

\ Introduction 193II. Fluid Dynamics: Fundamentáis 194III. Micro-Scale Processes at the Molecular Level (/¿m) 198IV. Processes at the Shoot Level fmm-cm) 200V. Processes at the Canopy Level (m) 205VI. Hydrodynamically-Mediaíed Processes at the Landscape Level

(100-1000 m) 212Vil. Hydrodynamic Processes atthe Meso-Scale Level (>1,000 m) 216VIII. Summary and Outlook 218Acknowledgments 219References 219

Nutríents Dynamics in Seagrass Ecosystems 227-254Javier Romero, Kun-Seop Lee, Marta Pérez, Miguel A. Mateo,and Teresa Alcoverro

\ Introduction 227II. Nutrient Economy: Acquisition, Transport, and Storage 228III. Nutrient Fluxes in Seagrass Ecosystems 235IV. Nutrient Limitation and Nutrient Imbalances 243V. Conclusión and Future Goals 247Acknowledgments 248References 248

10 Oxygen Movement ¡n Seagrasses 255-270Jens Borum, Kaj Sand-Jensen, Thomas Binzer, Ole Pedersen,and Tina María Greve

I. General Introduction 255II. Measuring Oxygen Dynamics and Transport 256III. Oxygen Sources 257IV. Oxygen Sinks 260V. Internal Movement of Oxygen 263VI. in Situ Oxygen Variability in Seagrass 265Vil. Anoxia and Seagrass Die-off 267VIII. Summary 267Acknowledgmenís 268References 268

viii Contents

11 Dynamics of Seagrass Stability and Change 271-294Carlos M. Duarte, James W. Fourqurean, Dorte Krause-Jensen,and Birgit Olesen

I. Introduction 271II. Components of Seagrass Meadows: from Apical

Meristems to Meadows 272III. Shoof Dynamics 275IV. Clones and Patch Dynamics 281V. Gap Dynamics 283VI. Dynamics of Seagrass Meadows at Different Time Scales 284Vil. Prospect: Forecasting Seagrass Dynamics 290Acknowledgement 290References 290

12 Aquatic Optics: Basic Concepts for Understanding How LightAffects Seagrasses and Makes them Measurable from Space 295-301

Richard C. Zimmerman and Amoló G. Dekker

\ Introduction 295II. A Primer on Hydrologic Optics 295III. Radiative Transfer in Natural Waters 300References 301

13 Light and Photosynthesis in Seagrass Meadows 303-321Richard C. Zimmerman

I. Introduction 303II. Radiation Transfer and Light Interception 304III. Canopy Architecture and Leaf Orientation 304IV. Leaf Optical Properties 307V. Radiative Transfer and Submerged Plant Canopies 309VI. Irradiance Distributions Within the Seagrass Canopy 311Vil. Productivity and Carbón Balance in Submerged Plant Canopies 312VIH. Leaf Orientation, Canopy Density, and Self-Shading 313IX. Effects of Water Quality on Seagrass Productivity and Distribution 315X. Potential Impacts of Climate Change on Seagrass Productivity 316XI. Effects of Epiphytes on Leaf Photosynthesis 316Acknowledgment 319References 319

14 Photosynthesis and Metabolism in Seagrassesat the Cellular Level 323-345

Anthony W. D. Larkum, Edward A. Drew, and PeterJ. Ralph

\ Introduction 323II. Photosynthetic Adaptations to Marine Submergence 324III. The Diffusive Boundary Layer (DBL) * 324

Contents ix

IV. Inorganic Carbón Uptake Mechan i sms 325V. Rates of Q Uptake 326VI. Photosynthetic Efficiency, Light-Harvesting and the Package Effect 328Vil. Mechanisms of C02 Fixation, CAM, Photorespiration and Oxygen Cycles 329VIII. Fluorescence Studies 330IX. Leaf Anatomy, Oxygen Effects and Depth Limitations in Seagrasses 337X. Initial Photosynthetic Products in Seagrass Leaves 338XI. Translocation and Exudation 338XII. Storage and Utilisation 339XIII. Secondary Metabolites and Chemotaxonomy 340XIV. Summary 341Acknowledgements 342References 342

15 Remote Sensing of Seagrass Ecosystems: Use of Spaceborneand Airborne Sensors 347-359

Arnold Dekker, Vittorio Brando, Janet Anstee, Suzanne Fyfe,Timothy Maithus and Evanthia Karpouzli

\ Introduction 347II. Principies of Remote Sensing of Seagrass Ecosystems 350III. Optical Properties of the Overlying Water Coíumn 351IV. Optically Deep and Shallow Waters: Physical Definitions 353V. Methodological Approaches to Assessing Seagrass Ecosystem

Characteristics from Remote Sensing 355VI. Conclusions, Recommendations, and Outlook 357References 358

16 Zostera: Biology, Ecology, and Management 361-386Kenneth A. Moore and Frederick T. Short

\ Iníroduction 361II. Comparative Biology 361III. Ecology 370IV. Management and Restoration 372V. Future Research Needs 378References 378

17 Biology of Posidonia 387-408Sylvie Gobert, Marión L Cambridge, Branco Velimirov,Gérard Pergent, Gules Lepoint, Jean-Marie Bouquegneau,Patrick Dauby, Christine Pergent-Martini, and Diana I. Walker

I. Introduction 378II. Systematics 388III. Distribution oftheGenus 388IV. Development of Meadows and Patches 391V. Biomass Dynamics and Production of the Plañí 391

x Contents

VI. Reproduction 393Vil. Dynamics of Carbón and Nitrogen 395VIII. Food Webs 397IX. Species Status and Anthropogenic Impact 400X. Summary 401References 401

18 The Biology of Thalassia: Paradigms and Recent Advancesin Research 409-439

Brigitta I. van Tussenbroek, Jan A. Vonk, Johan Stapel,Paul L. A. Erftemeijer, JackJ. Mt'ddelburg, andJayC. Zieman

I. Introduction 409II. Basic Environmental Requirements 410III. Hístorical Development in Research 411IV. 7fta/ass/a-Sediment Interactions 412V. Nutrient Dynamics 412VI. Plant Development 416Vil. Population Dynamics 422VIH. Community Ecology 423IX. Conclusions 430Acknowledgments 431References 431

19 Epiphytes of Seagrasses 441-461Michael A. Borowitzka, Paul S. Lavery, and Michaei van Keulen

\ Introduction 441II. The Role of the Epiphytic Organisms 441III. Distributíon and Abundance of Epiphytic Organisms 443IV. Factors Affecting Distribution and Abundance 450V. Conclusions 456References 456

20 The Central Role of Grazing in Seagrass Ecology 463-501John F. Valentina and J. Emmett Dufíy

\ Introduction 463II. Philosophy of the Review 465III. An Evolutionary Perspective on Seagrasses and their Grazers 466IV. The Modern Seagrass Community Interaction Web 467V. Direct Grazing on Seagrasses 468VI. Indirect Effects of Grazing on Seagrass Communities: A Delicate Balance 481Vil. Botíom-Up and Top-Down Control in Seagrass Communities 485VIII. Altérnate Stable States in Seagrass Ecosystems? 488IX. Questions and Recommendations for Future Research 489X. Summary 491Acknowledgments 492References 492

Contents X1

21 Seagrasses, Fish, and Fisheries 503-536Bronwyn M. Gillanders

I. Introduction 503II. Use of Seagrass Beds by Fish Species 503III. Comparison of Abundance, Diversity, Growth, and Survival of Fish

in Seagrass Habitáis, with Other Nearshore Habitáis 505IV. Spatial Scales—Factors Influencing Abundance of Fish

in Seagrass Beds 509V. Temporal Scales— Factors Influencing Abundance of Fish

in Seagrass Beds 516VI. Links Between Seagrass and Fisheries 517Vil. Conservation and Management Issues 524VIII. Future Research Directions 527Acknowledgments 530References 530

22 Predation in Seagrass Beds 537-550Kenneth L Heck and Robert J. Orth

\ Introduction 537II. Effects of Seagrasses on Predator-Prey Interactions ¡n Ecological Time 537III. Effects of Seagrass on Predator-Prey Interactions in Evolutionary Time 545IV. Summary 546References 547

23 Decline and Recovery of Seagrass Ecosystems—TheDynamics of Change 551-565

Diana I. Walker, Gary A. Kendrick, and Arthur J. McComb

I. Introduction 551II. Changes in Seagrass Distributions 551III. Loss of Seagrass Beds 552IV. Case Study 1: Why did We Lose Seagrasses ¡n Cockburn Sound

Whereas Seagrass Área has Expanded on Neighbouring Parmeliaand Success Banks? 556

V. Case Study 2: Florida Bay 560VI. Species-Specific Recruitment and Growth Characteristics 560Vil. Can Seagrass Management be Proactive? 562References 562

24 Human Impacts on Seagrasses: Eutrophication, Sedimentationand Contamination 567-593

Peter J. Ralph, David Tomasko, Kenneth Moore, Stephanie Seddon,and Catrioná M. O. Macinnis-Ng

I. Introduction 567II. Anthropogenic Stressors 568III. Management of Anthropogenic Pollutants 584IV. Recommended Research Directions 586V. Summary 587References 587

xü Contents

25 Seagrass Conservation Biology: An Interdisciplinary Sciencefor Protection of the Seagrass Biome 595-623

W. Judson Kenworthy, Sandy Wyllie-Echeverria,Robert G. Coles, Gérard Pergent and Christine Pergent-Martini

\ Introduction 595II. The State of Seagrass Science Relativa

to Conservation Biology 604III. Seagrasses Conservation Biology: An Approach

for the Future 605IV. Sclence-Based Proíection Approaches 610V. Implementing Conservation Tools: Two Examples 612VI. Summary and Outlook 617Acknowledgments 617References 617

26 Seagrass Ecology: New Contributionsfrom a Landscape Perspective 625-645

Susan S. Bell, Mark S. Fonseca, and Nathaniel B. Stafford

I. Introduction 625II. The Landscape Approach 626III. Historical Overview 629IV. Terrestrial vs. Marine Landscapes 635V. Landscape Dynamics 636VI. Boundaries and Seagrass Landscapes 638Vil. Conceptual and Methodological Improvements 639VIII. Future Directions 640IX. Summary 641Acknowledgments 641References 641

Epilogue 647

Index 649