Ecology Seashores The of © 2001 by CRC Press LLC Marine Science Series The CRC Marine Science Series is dedicated to providing state-of-the- art coverage of important topics in marine biology, marine chemistry, marine geology, and physical oceanography. The series includes volumes that focus on the synthesis of recent advances in marine science. CRC MARINE SCIENCE SERIES S ERIES EDITOR Michael J. Kennish, Ph.D. P UBLISHED TITLES Artificial Reef Evaluation with Application to Natural Marine Habitats, William Seaman, Jr. Chemical Oceanography, Second Edition, Frank J. Millero Coastal Ecosystem Processes, Daniel M. Alongi Ecology of Estuaries: Anthropogenic Effects, Michael J. Kennish Ecology of Marine Bivalves: An Ecosystem Approach, Richard F. Dame Ecology of Marine Invertebrate Larvae, Larry McEdward Environmental Oceanography, Second Edition, Tom Beer Estuary Restoration and Maintenance: The National Estuary Program, Michael J. Kennish Eutrophication Processes in Coastal Systems: Origin and Succession of Plankton Blooms and Effects on Secondary Production in Gulf Coast Estuaries, Robert J. Livingston Handbook of Marine Mineral Deposits, David S. Cronan Handbook for Restoring Tidal Wetlands, Joy B. Zedler Intertidal Deposits: River Mouths, Tidal Flats, and Coastal Lagoons, Doeke Eisma Morphodynamics of Inner Continental Shelves, L. Donelson Wright Ocean Pollution: Effects on Living Resources and Humans, Carl J. Sindermann Physical Oceanographic Processes of the Great Barrier Reef, Eric Wolanski The Physiology of Fishes, Second Edition, David H. Evans Pollution Impacts on Marine Biotic Communities, Michael J. Kennish Practical Handbook of Estuarine and Marine Pollution, Michael J. Kennish Seagrasses: Monitoring, Ecology, Physiology, and Management, Stephen A. Bortone © 2001 by CRC Press LLC Ecology Seashores The of George A. Knox, M.B.E., F.R.S.N.Z. Boca Raton London New York Washington, D.C. 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Corporate Blvd., Boca Raton, Florida 33431. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation, without intent to infringe. © 2001 by CRC Press LLC No claim to original U.S. Government works International Standard Book Number 0-8493-0008-8 Library of Congress Card Number 00-058573 Printed in the United States of America 1 2 3 4 5 6 7 8 9 0 Printed on acid-free paper Library of Congress Cataloging-in-Publication Data Knox, G. A. The ecology of seashores / by George A. Knox. p. cm. — (Marine science series) Includes bibliographical references (p. ). ISBN 0-8493-0008-8 1. Seashore ecology. I. Title. II. Series. QH541.5.S35 K66 2000 577.69 ′ 9—dc21 00-058573 CIP 0008_frame_FM Page 4 Monday, November 13, 2000 9:30 AM © 2001 by CRC Press LLC Preface Because of its accessibility, the intertidal zone has offered excellent opportunities to study the adaptations of indi- vidual organisms and populations to their environment, and the factors controlling community composition. Early work on seashores concentrated on the problems of life in an environment characterized by steep gradients in physical conditions, but in more recent years, the focus of research on the fascinating shore ecosystems has been on understanding the processes controlling their produc- tivity and dynamic functioning. The emphasis has been on processes such as primary production, grazing, preda- tion, competition, impact of disturbance, secondary pro- duction, detritus formation, decomposition, and the role of microorganisms. My own involvement in seashore research began when I embarked on a M.Sc. thesis in zoology on the ecology of the rocky shores at Taylors Mistake, Banks Peninsula, with special reference to the serpulid polychaete Pomato- ceros cariniferus (Knox, 1948; 1953). In the late 1950s, I became involved in research on a local estuary, the Avon- Heathcote Estuary. This research evolved into a compre- hensive interdisciplinary research program that has con- tinued until the present time. It has involved a large num- ber of research associates, research assistants, and research students and culminated in two major reports (Knox and Kilner, 1973; Knox, 1992). A multiauthor book bringing together the results of 50 years of research on this estuarine ecosystem is in an advanced stage (Knox and Robb, in preparation). Over the period of 1959 to 1983, I directed the activities of the Estuarine Research Unit, Zoology Department, University of Canterbury, Christchurch. This unit carried out research on estuarine and coastal ecosystems throughout New Zealand and com- piled some 28 major reports. The research aimed at under- standing the interaction of estuarine plants, microorgan- isms, animals, and man with each other and their environment. Such research, while contributing to basic ecological principles, also provided information necessary for the management of New Zealand coastal ecosystems (Knox, 1983c). I was scientific coordinator of a multidis- ciplinary study of the Ahuriri Estuary, Hawke Bay (Knox and Fenwick, 1978; Knox, 1979b), and coordinator of the biological aspects of the Upper Waitemata Harbour Catch- ment Study, a comprehensive five-year interdisciplinary study of the land and water resources of the mangrove- fringed Upper Waitemata Harbour, Auckland (Knox, 1983a; 1983b). A fellowship at the East-West Center, Honolulu, enabled me to undertake a study of coastal zone resource development and conservation in Southeast Asia with special reference to Indonesia (Knox and Miyabara, 1983). This estuarine research culminated in 1983 with the publication of a two-volume work on estuarine eco- systems (Knox, 1983a,b). Over the years I have also been involved in research on the intertidal ecology of rocky shores (Knox, 1963a; 1968; 1969b; 1988; in preparation; Knox and Duncan, in preparation) and sand beaches (Knox, 1969a). Field work has been carried out on rocky shores throughout New Zealand, the Subantarctic Islands (Snares, Auck- land, Campbell, and Chatham Islands), Antarctica, the west coast of Chile, and the southern coasts of Australia. Shores in Peru, Argentina, the eastern and western coasts of Canada and the United States, England and Scotland, and tropical shores in Guam, the Palau Islands, Fiji, and Hawaii have been briefly examined. A book on New Zealand seashore ecology will be published shortly (Knox, in preparation). This work has also involved an examination of the evolution and biogeography of the Southern Hemisphere, especially the Pacific Ocean, intertidal and shallow water biotas (Knox, 1960; 1963a; 1975; 1988). The approach used in this book is somewhat different from that used in many texts in marine ecology in that the emphasis is on ecological processes and the use of systems analysis in understanding such processes. This book is an attempt to bring some order to some of the most complex of ecosystem types, those of the seashores of the world. Wherever possible the energy circuit language of symbols and diagrams developed by H. T. Odum has been used as a basis of understanding (Odum, 1983). The book is divided into seven chapters. The first provides an introduction and sets the scene for the suc- ceeding chapters. The second deals with zonation patterns on hard shores, the basic causes of zonation, the biology of the major divisions of the biota, the biology of some key faunal components (mussels, limpets, and barnacles), and the flora and fauna of special habitats. The third chapter covers the physicochemical environment of soft shores, and the general ecology of the biota from produc- ers through microbes to macrofauna. Two large sections deal with microbial ecology and detritus and nutrient cycles in representative ecosystems. The fourth chapter gives an account of ecological niches on the shore and the establishment and maintenance of zonation patterns. Chapter 5 attempts to synthesize the various factors such as grazing, competition, predation, disturbance, and 0008_frame_FM Page 7 Monday, November 13, 2000 9:30 AM © 2001 by CRC Press LLC succession that determine the distribution, diversity, bio- mass, and production of the various categories of con- sumers. Energy budgets, patterns of energy flow, trophic structure, and food webs are discussed in Chapter 6, while in Chapter 7, examples of ecosystem models for the var- ious ecosystem types on both hard and soft shores are detailed. Finally, the application of the relatively new technique of network analysis to gain greater insight into ecosystem processes and enable the comparison of differ- ent ecosystems is outlined. As will be seen by the reference list at the end of this book, there is a considerable volume of recent literature on seashore ecosystems, although the list contains only a frac- tion of the published work. Extensive literature citations have been included so that the book might serve as a resource for those engaged in research on and management of the coastal zone. Because of this growing volume of literature, I have had to be selective in the material included. Thus, of necessity, I have concentrated on work published since 1970, and in particular in the last decade. Regretfully, except in a few instances, it has not been possible to develop the history of the concepts considered. Examples have been carefully chosen from the pool of published research to illustrate these concepts. There are doubtless other exam- ples that could have been equally used, and I apologize to authors whose work has not been included. I have attempted to include as wide a geographic range of examples as pos- sible, and in particular have included Southern Hemisphere examples that often do not appear in texts originating in the Northern Hemisphere. The book has been designed for use by upper level undergraduate and graduate students and professionals engaged in coastal zone research and management. I hope that they find it useful. 0008_frame_FM Page 8 Monday, November 13, 2000 9:30 AM © 2001 by CRC Press LLC Author George A. Knox, M.B.E., F.R.S.N.Z., was head of the Department of Zoology, University of Canterbury, Christchurch, New Zealand, from 1959 to 1976. He is now professor-emeritus in zoology. Professor Knox was born in New Zealand and received his education at the University of Canterbury where he was appointed a staff member in 1948. He has been a visiting fellow at the East-West Center, Honolulu, and a visiting professor at the Department of Oceanogra- phy, Texas A&M University and the Department of Envi- ronmental Engineering, University of Florida, Gainesville. He has visited and worked in laboratories in the U.S., Canada, Chile, Japan, Australia, Western Europe, the USSR, and China. Professor Knox’s research has been wide ranging and includes: (1) the systematics and distribution of polycha- eta with special reference to New Zealand and Antarctica; (2) rocky shore intertidal ecology and biogeography; (3) the ecology and conservation of islands; (4) studies on the pelagic and benthic ecosystems beneath the sea ice in McMurdo Sound, Antarctica; and (5) estuarine and coastal ecology and management. He established and directed the Estuarine Research Unit in the Department of Zoology and the University of Canterbury Antarctic Research Unit. He has participated in many field expeditions, including the Chatham Islands 1954 Expedition (leader); the Royal Society of London Darwin Centennial Expedition to southern Chile (marine biologist and deputy leader); thir- teen summer expeditions to McMurdo Sound, Antarctica; the establishment of the Snares Islands Research Pro- gramme (participated in three field expeditions); and par- ticipation in field expeditions to Campbell and Auckland Islands. He has published over 100 scientific papers and 28 environmental reports, written five books, and edited and co-authored three other volumes. Professor Knox has received a number of awards and fellowships for his contributions to science, including Fel- low of the Royal Society of New Zealand (FRSNZ), 1963; Hutton Medal, Royal Society of New Zealand, 1978; Con- servation Trophy, New Zealand Antarctic Society; Mem- ber of the Most Excellent Order of the British Empire (MBE), 1985; New Zealand Marine Sciences Society Award for Outstanding Contribution to Marine Science in New Zealand, 1985; and the New Zealand Association of Scientists’ Sir Ernest Marsden Medal for Service to Sci- ence, 1985. Throughout his career, professor Knox has been active in international scientific organizations. He has been a member of the Scientific Committee for Oceanic Research (SCOR) and the Special Committee for the International Biological Programme (SCIBP). He has been a delegate to the Scientific Committee for Antarctic Research (SCAR) since 1969, serving 4-year terms as secretary and president, and a member of the governing board of the International Association for Ecology from 1965 to 1990, also serving 4-year terms as secretary-general and president. 0008_frame_FM Page 9 Monday, November 13, 2000 9:30 AM © 2001 by CRC Press LLC 0008_frame_FM Page 11 Monday, November 13, 2000 9:30 AM © 2001 by CRC Press LLC Acknowledgments I would like to express my indebtedness to the late Professor Edward Percival, who by his enthusiasm and teaching skills started me on my career as a marine biologist, to Professor Howard Odum who inspired by interest in the energy anal- ysis approach to ecosystem modeling, and to my colleagues in New Zealand and various parts of the world with whom I have discussed many of the ideas in this book. My thanks are also due to all those who gave me permission to reproduce original figures and tables. Finally, I am indebted to John Sulzycki and the staff of CRC Press, in particular Amy Rodriguez and Pat Roberson, for their patience and support during the preparation of this volume and for seeing the project through to the completion of such a high quality product. George A. Knox November, 2000 Christchurch, New Zealand Contents Chapter 1 The Environment 1.1 Introduction 1 1.2 Environmental Gradients and Stresses on the Shore 2 1.3 Salient Features of the Shore Environment 2 1.4 Patterns of Zonation on the Shore 16 Chapter 2 Hard Shores 2.1 Zonation Patterns on Hard Shores 20 2.2 Zonation Patterns on Representative Shores 24 2.3 The Causes of Zonation 36 2.4 Hard Shore Microalgae 51 2.5 Hard Shore Micro- and Meiofauna 53 2.6 Rocky Shore Lichens 54 2.7 Hard Shore Macroalgae 56 2.8 Key Faunal Components 58 2.9 Special Habitats 70 Chapter 3 Soft Shores 3.1 Soft Shores as a Habitat 87 3.2 The Physicochemical Environment 92 3.3 Soft Shore Types 96 3.4 Estuaries 98 3.5 Soft Shore Primary Producers 107 3.6 Soft Shore Fauna 153 3.7 Biological Modification of the Sediment 181 3.8 Microbial Ecology and Organic Detritus 188 3.9 Nutrient Cycling 209 3.10 Estuarine Shelf Interactions 228 Chapter 4 Adaptations to Shore Life 4.1 Introduction 238 4.2 Ecological Niches on the Shore 238 4.3 The Establishment of Zonation Patterns 251 4.4 The Maintenance of Zonation Patterns 263 Chapter 5 Control of Community Structure 5.1 Introduction 277 5.2 Hard Shores 277 5.3 Soft Shores 317 5.4 Synthesis of Factors Involved in Controlling Community Structure 344 Chapter 6 Energy Flow, Food Webs, and Material Cycling 6.1 Introduction 356 6.2 Food Sources 356 6.3 Energy Budgets for Individual Species 360 6.4 Optimal Foraging 374 6.5 Secondary Production 377 0008_frame_FM Page 13 Monday, November 13, 2000 9:30 AM © 2001 by CRC Press LLC 6.6 P:B Ratios and Production Efficiency 380 6.7 Relative Contribution of Soft Shore Benthic Infauna to Secondary Production 381 6.8 Community Metabolism 385 6.9 Trophic Structure and Food Webs 389 6.10 Carbon Flow Models 406 6.11 Stable Isotopes and Food Web Analysis 412 6.12 Top-down and Bottom-up Control of Trophic Structure 421 Chapter 7 Ecosystem Models 7.1 Introduction 426 7.2 Hard Shores 427 7.3 Sand Beaches 428 7.4 Intertidal Mudflat in the Lynher Estuary, Cornwall, U.K 433 7.5 Salt Marshes 433 7.6 Sea Grass Ecosystems 440 7.7 Mangrove Ecosystems 442 7.8 Estuaries 443 7.9 Network Analysis 456 7.10 Potential Applications of the Ascendency Concept 469 7.11 Emergy Analysis 471 Appendix 473 References 477 0008_frame_FM Page 14 Monday, November 13, 2000 9:30 AM © 2001 by CRC Press LLC [...]... spring tides The average of the lowest high waters reached by the sea on the fortnightly neap tides The lowest of the high waters reached by the neap tides during the year The average of the high and low waters throughout the year The highest of the low waters reached by the neap tides during the year The average of highest low waters reached by the sea on the fortnightly neap tides The average of lowest... with the state of the tide but with the contours of the surface Such variations will impact on the processes discussed above 1. 3.5.2 Topography and Aspect The effects of topography on the distribution of intertidal organisms is very complicated due to the enormous variety of shores ranging from mudflats through sand-mud 0008_frame_C 01 Page 14 Monday, November 13 , 2000 9: 31 AM 14 The Ecology of Seashores. .. while the northern side consists of steep shaded cliffs, the southern side slopes gently and is exposed to the sun (Figure 1. 13) The zonation patterns on each of the two coasts are markedly different, despite the similarity of the tidal range and wave action on each side of the island Figure 1. 14 illustrates the relation of the zone boundaries to some eight tidal levels Line A marks the lower limit of. .. of inequalities in the magnitude of the two tides each day at certain latitudes and at different times of the year 1. 3.3 1. 3.2 TIDES Tides are caused by the gravitational pull of the Sun and Moon on the Earth, and their regular variations in height and time result from the regular differences in the positions of the Sun and Moon to each other (Figure 1. 1) The Earth and the Moon together rotate around... its axis The period of rotation of the Earth-Moon couple, however, is 29.53 D; thus there is an average retardation of the time of each tide by 24.5 min The same process applies to the couple formed by the Earth and the Sun However, the center of rotation is closer to the Sun because of the latter’s greater mass, although the tide-generating forces are approximately 46% of those produced by the Moon,... factors determine the type of community on the seashore: (1) the amount and intensity of wave action; (2) the type of substrate (whether rock, sand, mud, or some combination of these); and (3) the amplitude of the tides To consider each of these in turn: 1 Waves are caused by wind, and their size is primarily determined by the uninterrupted distance or “fetch” over which the wind can blow, the velocity... in the depth distribution of the plants and animals found there Furthermore, some sublittoral species extend up into the intertidal zone proper In this book, both of the transitional zones between the intertidal zone and the land above and the sublittoral below will be considered The extent of the intertidal zone depends on a variety of factors, the most important of which are the angle of slope of the. .. of the distribution of the component species Such patterns are one response to the impact of tidal rise and fall Generally, where the range of the tides is small or the slope of the beach is © 20 01 by CRC Press LLC steep, the bands are narrow; where the range of the tides is great, or where the slope of the beach is gentle, the zones are wide Heavy wave action widens the zones and the upper and lower... Africa, showing the number of species of macrofauna per 2 × 0.5 m2 samples (above) and the distribution of the macrophytes and principal components of the macrofauna Note that (a) the number of species decreases toward the unpredictable conditions of the upper shore; (b) the standing stock of algae is reduced on the lower shore by the effects of grazing by herbivores (principally Patella); (c) the filter... direction of the wind, and to a lesser extent the depth of the water Thus, the severity of wave action in any given locality is 1 © 20 01 by CRC Press LLC 0008_frame_C 01 Page 2 Monday, November 13 , 2000 9: 31 AM 2 The Ecology of Seashores determined by its geographical position in relation to the factors listed above As a consequence, there is every gradation in wave shock, from the pounding surf of exposed . Chapter 1 The Environment 1. 1 Introduction 1 1.2 Environmental Gradients and Stresses on the Shore 2 1. 3 Salient Features of the Shore Environment 2 1. 4 Patterns of Zonation on the Shore 16 . Emersion 7 1. 3.5 Modifying Factors 9 1. 3.5 .1 Wave Action 10 1. 3.5.2 Topography and Aspect 13 1. 3.5.3 Climatic Factors 16 1. 4 Patterns of Zonation on the Shore 16 1. 1 INTRODUCTION The relatively. 23.5° off the vertical (relative to the plane of the Earth’s orbit about the Sun), and the 5° inclination of the Moon’s orbital plane to the orbital plane of the Earth are the causes of inequal- ities