Macrozoobenthos of the Sakhalin bay of the Sea of Okhotsk in the zone of influence of Amur river waters

Abstract

Structure, quantitative indicators, distribution features and main communities of macrozoobenthos of Sakhalin Bay (the Sea of Okhotsk) are described. Mollusks (mainly bivalves), crustaceans and sea urchins determined the total macrozoobenthos biomass. The main regularities of the macrozoobenthos distribution in the bay are given. Two zones are distinguished by hydrological characteristics, distribution of the composition and quantitative characteristics of macrozoobenthos, benthic communities, and according to the data of ordination analysis: the zone of localization of the runoff lens of the Amur River with a water salinity of less than 26 psu and the zone of distribution of typical marine waters. 9 benthic communities are described: the »estuarine-lagoonal» communities of Archaeomysis grebnitzkii + Haustorioides magnus + Potamocorbula amurensis, Potamocorbula amurensis, Macoma balthica + Cyrtodaria kurriana, Siliqua alta, the typically »marine» communities of Nephtys caeca, Serripes groenlandicus, Balanus crenatus and the communities of transitional type Saduria entomon and Echinarachnius parma, which are found in both hydrological zones. Predominantly filter feeders, with a significant role of detritus feeders and detritus feeders – filter feeders, form the trophic structure of macrozoobenthos. Trophic communities dominated by filter feeders - detritus feeders and detritus feeders are represented in the coastal area of the western part of the water area, the group of filter-feeders is localized seaward. Trophic communities with a predominance of filter feeders - detritus feeders and detritus feeders are represented in the entire depth range of the eastern part of the water area. Water salinity, soil type and depth are the main factors affecting the distribution and abundance of macrozoobenthos.