Results of studies of bottom communities in the Amur river basin

Comprehensive studies of aquatic biota were carried out in the 30s and 40s years of the 20th century. In this regard, it was necessary to collect updated data on different groups of aquatic animals. The purpose of this work was to conduct research on the collection of zoobenthos in the area from the Amur Estuary to the city of Blagoveshchensk. The work was carried out in 2018–2020 years using a GR-91 rod grab, a Levanidov bentometer (0,4×0,4 m), and a shellfish collection frame (0,5×0,5 m). According to our observations and literature data, the distribution of benthic animals in the channel part of the Amur and floodplain lakes is greatly influenced by the level regime of the water body. The highest values of biomass in collections were given by mollusks due to their large size. Insect larvae and oligochaetes had a high abundance but low biomass due to their small size. During the work, most of the samples turned out to be empty, which is associated with periodic rises and falls in the water level. The maximum values of biomass from 0,5 to 1,0 kg/m2 were noted in areas of mollusk concentrations, mainly Nodularia douglasiae. In other places, quantitative indicators were several orders of magnitude lower, from several mg to several g/m2.