Macrozoobenthos of the estuary of Susuya river (Sakhalin Island): II. bottom communities and distribution of key species
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Abstract
Communities of macrozoobenthos and their characteristics in the river estuaries of Sakhalin Island have not been sufficiently studied. The composition of bottom communities in most estuaries of short rivers on Sakhalin Island is very limited, compared to estuaries of other rivers in the Russian Far East. The estuary of the Susuya River, full-sized compared to the estuaries of the small rivers of the island, was surveyed in September 2022. The aim of the work is to describe the main patterns of distribution of bottom communities, their structure, key species and trophic characteristics of macrozoobenthos along the salinity gradient in the full-size estuary of the Susuya River on Sakhalin Island. The bottom communities of the estuary were identified using cluster and ordination analysis methods. The main communities and trophic characteristics, distribution features of the key macrozoobenthos species along the estuary of the Susuya River (Sakhalin Island) are described. The main patterns of distribution of macrozoobenthos communities, key species and trophic groupings in the estuary of the Susuya River are given. 11 communities of macrozoobenthos were identified, united into five types: the community of the rift bounding the estuary from above, the communities of the δ-chorogaline zone, the communities of the middle estuary oligogaline zone, the communities of the lower estuary poly-mesogaline zone and the community of the mouth of the river. The community of the water's edge is confined to the mouth of the river and to the poly-mesohaline zone. Communities "Corbicula japonica", "Macoma balthica" and "Fluviocingula nipponica + Macoma balthica" are the main communities of the estuary. The main environmental factors affecting the distribution of key macrozoobenthos species are the water salinity and, to a lesser extent, the depth. The type of sediment is not a determining factor.