Composition and Seasonality of Sand-Beach Amphipod Assemblages of the East Coast of Florida

Abstract

Sand-beach amphipods were sampled across an intertidal-subtidal gradient at several locations on the east central coast of Florida in 1982-1983 and 1985-1986. The amphipods collected represented 16 families and 40 species, although the Haustoriidae dominated (83%) total abundance. Five species, in order of abundance, Bathyporeia parkeri, Parahaustorius longimerus, Eudevenopus honduranus, Rhepoxynius epistomus, and Parahaustorius holmesi, made up 90% of total amphipod abundance. Only 1.5% of total amphipod abundance was found in the intertidal zone in this study, in marked contrast to other studies of sand-beach amphipods on the east coast of the United States. Abundance and species richness of amphipods increased sharply just below the swash zone. This spatial pattern is consistent with the hypothesis of Dahl (1953) that intertidal amphipods should become a less abundant component of the fauna on tropical beaches as compared to temperate ones. Strong seasonal patters of abundance and species richness are present, with lowest values in the winter months. This temporal pattern does not appear to correlate with predator activity.