DISTRIBUTION OF BENTHOS (CNIDARIA AND ECHINODERMATA) IN ROCKY SHORES OF ILHA GRANDE BAY, RIO DE JANEIRO, BRAZIL

Abstract

Rio de Janeiro Stare lies in a transition zone between tropical and temperate faunas, presenting a coastline with large bays. Analyses of anthozoans (Cnidaria) and echinoderms present in eight stations (27 line transects, at depths from 1 to 7m) in rocky shores of Ilha Grande Bay were made. The presence of each species within each transects' meter was recorded. The sum of a species presences/meter along the transects related to its total length was defined as the relative frequency. Cluster analysis of the line, indicated six groups, the first with dominance of Echinometra lucunter and further divided in four subgroups, according to their associate fauna: the second with a dominance of cnidarians and divided in two subgroups, one with dominance of Palythoa caribaeorun and other of Mussismilia hispida; the third group was characterized by zoanthids and Echinaster brasiliensis; the fourth was composed by one station with large numbers of P. caribaeorum and E. lucunter; the fifth presented many cnidarians, showing characteristics of subgroups of the second group; the sixth was also formed by a single line characterized by Astrangia rathbuni and Carijoa riisei. The distribution of lines in groups suggests that depth is the most important factor in the communities' distribution and that distance from the entrance to the bay plays a minor role.