Macrobenthos of Accumulative Plains and Slopes of Ekspeditsii Bay (Pos'eta Bay,Sea of Japan)

The submarine accumulative plain of Ekspeditsii Bay is heterogeneous in terms of ground pattern and the composition and biomass of macrobenthos. The smallest values of the total biomass are characteristic of soft pelites (58.9 g/m²), siltstone pelites (55.9 g/m²), and pelites with an insignificant admixture of broken mollusk shells (108 g/m²). The greatest total biomass (649.2 g/m²) is registered around biogerms, in bottom areas composed of pelites with large fragments and entire valves of mollusk shells. On accumulative slopes of the bay, in the community of seagrasses, Zostera marina constitutes 90% of the biomass and macrofauna provides the remaining 10%. The values of the total biomass of macrobenthos of the accumulative plain and macroflora of the accumulative slopes of the bay are close to each other (about 12000 tons); however, both values are only 0.4 times as great as the biomass of macrobenthos on biogerms that occupy only 6.2% of the total bottom area in the bay.