Effects of Polinices duplicatus (Gastropoda: Naticidae) on infaunal community structure at Barnstable Harbor, Massachusetts, USA

摘要: Effects of the predatory naticid snail Polinices duplicatus (Say) on species composition, diversity and density, infauna intertidal sand-flats at Barnstable Harbor, Massachusetts, USA, were studied using field experiments. Responses molluscs (prey P. duplicatus) nonmolluscs (nonprey) considered separately to distinguish between effects feeding sediment disturbance during foraging. The fauna 0.25 m2 predator-exclusion cages, coarse-mesh sieved areas, controls was followed for 1 yr. Species associations within cages from which predators excluded denser, more diverse, richer in than those other treatments. Larger areas (3×3 m) natural bottom fenced maintained as exclosures enclosures two seasons. For both nonmolluscs, (H'), number species, evenness (SD), density all decreased with increasing density. Intense predation pressure selective thin-shelled bivalves, rare, removed individuals community. Comparison samples taken inside outside trails made by snails showed that surface layers abundance spionid polychaetes total nonmolluscs. sipunculan Phascolopsis gouldi bivalve Gemma gemma dominated community experimental treatments little affected activity duplicatus. Predation lowered removing less abundant generally population densities below level where strong competition would occur.