BOTTOM INVERTEBRATES IN STREAMS OF THE TUGUR PENINSULA (KHABAROVSK TERRITORY)

Abstract

The group structure of the macrozoobenthos communities in the rivers of the Tugursky Peninsula, located in the Tugur- Chumikansky district of the Khabarovsk Territory, was described for the fi rst time. The material was collected in four rivers fl owing into the Ulban Bay of the Sea of Okhotsk and nine streams of the Tugur Bay with estuaries. Most of the surveyed rivers belong to the category of small salmon streams of the submountain type and are the environment and reproduction for anadromous and freshwater fi shes, which feed on benthic invertebrates. It has been established that the faunistic composition of benthic invertebrates in the streams of the Tugur Peninsula is relatively rich, represented by more than 155 taxa from 16 taxonomic groups. Average macrozoobenthos density varies from 2320 to 29568 ind./m2, biomass from 3,7 to 36,4 g/m2. In the benthic communities of all streams chironomids were dominant in density. In estuaries aff ected by tides, the category of dominants in terms of density and biomass is formed by oligochaetes. Mayfl ies predominate in the benthos structure in the upper and middle reaches. Stonefl ies and caddisfl ies mostly fall into the categories of subdominants and minor groups. The high coeffi cients of faunal similarity in diff erent parts of the streams suggest that the impact of tidal events on the taxonomic composition of benthos in estuaries is minimal. At the same time, signifi cant changes were revealed in the structure of estuarine communities among the dominant groups of macrozoobenthos. According to the EPT index, the ecological state of most streams is assessed as good or good-medium.