Long-Term Variations in Zoobenthos Characteristics in Watercourses on the the Khektsir Ridge

The results of long-term studies are used to present, for the first time, the structural organization of zoobenthos communities and the dynamics of their density and biomass in rivers and brooks of the the Khektsir Ridge, including the boundaries of the Bol’shekhekhtsirskii Reserve, Khektsirskii Wildlife Reserve (the southern part of the Russian Far East). The benthic organisms were found to contain 23 groups (22 groups in the spring and summer, 19 groups in the autumn, and 8 groups in the winter). Leading in the occurrence frequency (>90%) were chironomids, mayflies, and oligochaetes. The chironomids and amphipods accounted for 37.0 and 19.1% of the total benthos density, and mollusks and amphipods, for 32.1 and 29.7% of the total biomass, respectively. Dominants in terms of density and biomass were amphipods; chironomids dominated in terms of density, and mollusks, in terms of biomass. The mean density of benthic organisms was 637 ± 21 spec./m2, and the mean biomass was 1.8 ± 0.2 g/m2. The benthic communities of rift segments in the rithral zone were found to be most productive. It is shown that the seasonal and long-term dynamics of zoobenthos communities is pronounced and can be traced in the group composition, structure, and quantitative characteristics.