DENSITY, BIOMASS AND COMMUNITY STRUCTURE OF MEGABENTHOS IN ISE BAY, CENTRAL JAPAN

In order to know the general features of megabenthos in Ise Bay in rel ation to the development and prevalence of oxygen-poor water in summer , an investigation was undertaken throughout the year from April 1993 to April 1994. Crustaceans and fishes were absolutely dominant from Ap ril to September 1993, while echinoderms being dominant since November . Five species of megabenthos were absolutely dominant: Oratosquilla o ratoria (Stomatopoda), Carcinoplax vestita, Charybdis bimaculata (Brac hyura), Luidia quinaria (Asteroidea), and Repomucenus valenciennei (Pi sces). Community structure (e.g. species diversity, ABC-comparison, ra nk-abundance relationships and community type) of megabenthos in Ise B ay drastically changed with season, intimately related with developmen t and perishment of oxygen-poor water at the bottom of the bay.