Rocky intertidal zonation of gammaridean amphipods in Long Island Sound, Connecticut

Rocky intertidal organisms are distributed in zones characterized by a Pew dominant species. In this study, the zonation patterns and the seasonal cha nges of the gammaridean amphipods were investigated in the rocky intertidal in Long Island Sound, U.S.A. A total of 9,773 amphipods of eight species w as collected from the two study sites. The results showed that rocky intert idal amphipods occur in zones, associated with species of algae. The differ ences in total abundance, the number of species, and the abundance of each of these species of amphipod were shown. The upper zone (Fucus vesiculosus) had fewer species and lower total amphipod abundance than the lower zone ( Chondrus crispus) and the two zones did not share all species. In addition, there were differences in the amphipod species composition between the two study sites. Several physical and biological factors may regulate such a p attern of abundance.