Seasonality of Macroinvertebrates on a Temperate, High Wave Energy Sandy Beach

Seasonal changes in macrobenthic community structure on a temperate, western Atlantic, high energy beach were examined over a 15-month period during 1976 and 1977. Twelve macroinvertebrate species were collected from the intertidal and nearshore surf zones during bimonthly day and night sampling. There were distinct patterns in species fluctuations on both a seasonal and diel scale. Decapod crustaceans and molluscs were more numerous during warmer months, while haustoriid amphipods were dominant in winter. Vertical distribution of the five top dominant species varied seasonally, tidally and with sunlight. Portunid and ocypodid crabs moved into the intertidal wash zone at night and fed on mole crabs (Emerita talpoida) and coquina clams (Donax variabilis and Donax parvula). Mole crabs and coquinas appear to be important trophic links on this beach between plankton and detrital energy sources and beach predators. Trophic relationships and migration patterns reveal that considerable overlap exists between intertidal and subtidal faunal assemblages.