Bottom Communities of Nyivo Lagoon (Northeastern Sakhalin)

Clasterization of benthic stations by biomass of common species using an index of coenotic similarities allowed us to distinguish three communities of macrophytobenthos (Zostera marina + Z. japonica, Zostera japonica, and Potamogeton pectinatus) and eight macrozoobenthos communities (Macoma balthica, Limnodrilus hoffmeisteri + Anisogammarus tiuschovi, Spio filicornis + Archaeomysis grebnitzkii, Kamaka kuthae, Glyptotendipes paripes, Neomysis awatschensis + Dolielinotus moskvitini, Neomysis mirabilis, and Anisogammarus tiuschovi + Littorina sitkana + Crangon septemspinosa). The bulk of the bottom surface is occupied by a community of Zostera marina + Macoma balthica with the mean biomass of the dominating species reaching 0.3–1386.6 and 573.9 g/m², respectively. Specific geomorphologic and hydrologic features, as well as the presence of many estuarine areas in Nyivo Lagoon, provide conditions for numerous different fresh-and brackish water communities and variations of them. However, bottom communities cannot be clearly separated into mostly freshwater and mostly brackish communities, which is the case for Pil'tun Lagoon, a well studied lagoon in eastern Sakhalin. Several decades of timber rafting in the Tym' River has had a significant effect on bottom biota and the communities of Nyivo Lagoon. Considering the well-known negative effects of phenol and its derivatives on benthic biota and communities derived during timber decomposition, the sources of pollution of the natural environment in the lagoons of eastern Sakhalin must be evaluated and differentiated.