Tlic maciotaiina oi inlcrtidal Hats contributes 

 a much higher profiortion to total commtinity 

 biomass than the meiofauna at any given time. 

 Since macrofauna are also much larger and easier 

 to study, a great deal more is known about their 

 ecological function in soft-sediment systems. For 

 North Carolina, several fairly complete studies of 

 the macro-intauna of intertidal flats are available 

 for the following groups: haustoriid amphipods 

 (Dexter 1967), polychaetes (Gardner 1975), 

 and the total invertebrate infauna (Lee 1974, 

 Committ) 1976, Wilson 1978). Although prepared 

 to cover the South Carolina coastline, Zingmark's 

 (1978) checklists are excellent for the southern 

 half of North Carolina's coastline. Taxonomically, 

 the macrofauna of an intertidal flat is usually 

 dominated by polychaete worms, bivalve mol- 

 luscs, amphipods, other crustaceans, cnterop- 

 ncusts, sipunculid (peanut) worms, nemertean 

 worms, gastropod molluscs, and echinoderms. 

 Trophically, the macrofauna is ordinarily sub- 

 divided into four categories: suspension feeders, 

 deposit feeders, predators, and scavengers (San- 

 ders et al. 1962, Levinton 1972). Distinctions 

 among these trophic categories are often compli- 

 cated by the great diversity of ways of making a 

 living in soft-sediment communities. Nevertheless, 

 differences among benthic species in modes of 

 feeding and in diet justify an attempt to produce 

 such a trophic classification. 



Suspension feeders take their food by cap- 

 turing particles suspended in the water column. 

 This typically requires the use of some sort of fil- 

 ter. Bivahe molluscs (clams) are probably the 

 most common suspension feeders on most inter- 

 tidal flats. Suspension-feeding clams pump a 

 water current through the body cavity and past 

 the gills, which serve as a food-collecting filter. 

 Most suspension feeders are usually considered to 

 be herbivores which consume phytoplankton. 

 While it is surely true that phytoplankton contri- 

 bute greatly to a suspension feeder's diet on an 

 intertidal flat, many suspension feeders in this 

 environment probably also capture and assimilate 

 both resuspended benthic algae and to some ex- 

 tent detritus and its surface microbiota. The de- 

 gree to which these possible additional sources of 

 food contribute to the diet of intertidal suspen- 

 sion feeders is not known. 



Deposit feeders are so named because of their 

 general feeding mode. A deposit feeder ingests 



sedimentary deposits and presiunably assimilates 

 the bacteria and fungi on detrital particles as well 

 as the li\ing microalgae. Many different types of 

 benthic deposit feeders ha\e been distinguished 

 by researchers who study soft-sediment systems. 

 Most deposit feeders harvest siu-face dept)sits, but 

 some feed upon food soiuces at depth. Some are 

 more selective of individual particle size and type, 

 while others are apparently nonselective in their 

 feeding (Sanders et al. 1962). One type of deposit 

 feeder is termed a fimncl feeder because it c(jn- 

 structs feeding fiuinels in the surface sediments 

 which it ingests. These fimnel feeders and other 

 deposit feeders can process and "turn over" large 

 volumes of surface sediments on both sand and 

 mud flats (Myers 1977a, b, Powell 1977, Reise 

 1978). 



Because most deposit feeders ingest living 

 cjrganisms along with detritus, it is often difficult 

 to distinguish between a predator and a deposit 

 feeder in soft sediments. .\ ptuc predator is a 

 species which selectively ingests individual living 

 animals. Fauchald and Jumars (1979) have sug- 

 gested that it might be better to distinguish be- 

 tween benthic feeding modes on the basis of 

 relative prey size. One feeding type (which in- 

 cludes most pure predators) consumes prey which 

 are large relative to the body size of the consumer. 

 These can be called macrophages. Microphages, in 

 contrast, take prey items which are small relative 

 to their own body size. Microphages tend to be 

 nonselective in their feeding because of the per- 

 ceptive difficulties and excessive energetic costs 

 of distinguishing among very small potential food 

 particles. The true microphage is thus a deposit 

 feeder in the classic sense. Infaunal species illus- 

 trate not only these extremes in food preferences, 

 but also all the intermediate strategies as well. 

 The macrophage-microphage distinction is, never- 

 theless, one that can often be drawn and that 

 helps to explain differences in foraging strategies 

 among the infauna. Common predators, or macro- 

 phages, on intertidal flats include polychaetes in 

 the genus Glycera (bloodworms) and nemertean 

 worms (ribbon worms). 



Scavengers are relatively mobile species which 

 can move to any source of dying or dead animal 

 matter. Mc:)st infaunal scavengers in shallow marine 

 substrates are gastropod molluscs, usually domi- 

 nated by various species in the Nassariidae family. 

 The common mud snail, Ilycniassa ubsoleta , often 



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