PREFACE 



We have developed this community profile to 

 serve as an introduction to the ecology of inter- 

 tidal sand and mud flats. Our main goal is to des- 

 cribe the ecological processes that characterize a 

 habitat which, at first glance, appears barren and 

 almost devoid of life. We emphasize and draw all 

 our examples from tiie intertidal flats of coastal 

 North Carolina with wliich we are most familiar. 

 To the degree that we are successful in describing 

 general processes of ecosystem functicjn on an 

 intertidal flat, what we have to say can be widely 

 applied to the intertidal shorelines of sounds, 

 lagoons, estuaries, and river mouths in temperate 

 zones throughout the world. We trust that our 

 descriptions of the ecology of intertidal mud and 

 sand flats will be useful to scientists and informed 

 laymen alike. We especially hope that our text 

 will provide much of the background needed by 

 coastal planners and environmental scientists 

 whose decisions will influence the future of many 

 of our coastal systems. Intertidal mud and sand 

 flats are classified as habitat types by the National 

 Wetlands Inventory of the U.S. Fish and Wildlife 

 Service and designated as E2FL3 and E2FL2, 

 respectively. 



Our text is organized on a taxonomic and a 

 functional basis. After an introductory descrip- 

 tion of the physical environment of the intertidal 

 soft-sediment habitat (Chapter 1), we describe the 

 plants, the primary producers of most marine sys- 

 tems (Chapter 2). In succeeding chapters we 

 discuss the benthic infauna and the mobile epi- 

 benthic invertebrates (Chapter 3), the fishes 

 (Chapter 4), and the birds (Chapter 5). This pro- 

 gression is clearly taxonomic, but to a great 

 extent it is also functional, reflecting the major 

 pathways of energy flow through the intertidal 

 flat system. The benthic infauna are largely herbi- 

 vorous or detritivorous and form the prey of the 

 mobile epibenthic invertebrates. Bottom-feeding 

 fishes and shorebirds feed extensively on these 

 mobile invertebrates, as well as on the benthic 

 infauna. Some of the fishes fall victim to wading 

 or diving birds. Consequently, our progression of 

 chapters roughly corresponds to the flow of 

 energy up the food chain of a coastal flat. In our 

 final chapter (6), we address some specific applied 

 problems that emerge in managing man's activities 

 in the vicinity of intertidal flats. 



Although this publication is explicitly con- 



cerned with what occurs on an intertidal mud or 

 sand flat, we are also compelled to describe im- 

 portant processes which happen elsewhere within 

 the estuarine ecosystem. Breadth is forced upon 

 us by the open nature of the intertidal flat 

 environment: this is by no means a closed system 

 ecologically. Inputs of organic matter, various 

 inorganic particles, and even mobile animals are 

 basic to the functioning of an intertidal flat. Only 

 the benthic infauna are relatively fixed in position 

 and restricted to completing their lives in a single 

 habitat. The infauna of an intertidal flat are sus- 

 tained by primary production which occurs in 

 large measure outside this habitat and which is 

 imported by water currents. The highest trophic 

 levels, the birds and fishes, are extremely mobile. 

 Most birds and fishes are merely seasonal visitors 

 to the intertidal flat, later moving to other habi- 

 tats within the estuarine system and then on to 

 other entirely different systems. Consequently, it 

 is not surprising that when one speaks of an inter- 

 tidal mud flat community, one tends to think 

 solely of the clams, worms, crustaceans, and other 

 benthic invertebrates which can always be found 

 there. Yet our goal is to unfold the complexity, 

 both taxonomic and fimctional, that characterizes 

 the entire ecosystem of a coastal mud or sand 

 flat. 



C. H. Peterson 

 N. M. Peterson 



19 September 1979 



Any questions or comments about, or 

 recjuests ftjr this publication should be directed 

 to: 



Information Transfer Specialist 

 National Coastal Ecosystems Team 

 U.S. Fish and Wildlife Service 

 NASA-Slidell Computer Complex 

 1010 Cause Blvd. 

 Slidell,LA 70458 



This report should be cited: 

 Peterson, C. H., and N. M. Peterson. 1979. The 

 ecology of intertidal flats of North Carolina: 

 a community profile. U.S. Fish and Wildlife 

 Service, Office of Biological Services. 

 FWS/OBS-79/39. 73 pp. 



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