MAIN GOALS AND TASKS

• Ecology of organisms and communities
• Biodiversity

The most important achievements of the subdivision for the recent 10 years

Expedition to the Barents Sea

Biological interactions in model symbiotic associations (holothurians and madreporarian corals of the genus Galaxea) were examined. It was demonstrated that the formation of these associations was determined primarily by interspecies interactions (competition - interference), and at a lesser extent, by intraspecies ones (competition, predation). A hypothesis about redistribution was suggested which determined casual-investigatory relations between the character of spatial distribution of symbionths on their hosts, territorial behavior and the character of settling.

The study of three model species of polychaets with cosmopolitan distribution from different families revealed the existence in all cases the complexes of sibling species. These results explain the difficulties of usage of Polychaeta for biogeographic zoning of the benthic zone. The main reason is not their peculiar spatial distribution, but the common occurrence of the complexes of sibling species among polychaets.

For the first time the anatomy of the stomachs for 20 species of Buccinoidea, referring to the families of Buccinidae (6 species), Buccinulidae (4), Melongenidae (3), Fasciolariidae (5), Nassariidae (1), Columbellidae (1) was studied. Specificity of stomach morphology for the family level was shown. A new hypothesis of the stomach functioning was suggested on the basis of the stomach observations in living mollusks.

For the first time an annotated list of marine, freshwater and terrestrial mollusks of Russia and adjacent countries (within the borders of the former USSR) was compiled and published as a monograph. Each species entry included synonymy, data on type material and general distribution of the species (within the borders of Russian economic area). Fauna consists of 3674 species belonging to 6 classes. Marine mollusks are represented by 1744 species, terrestrial gastropods by 736 species, and freshwater mollusks by 1194 species. On the basis of comparison of size structure of the mollusks of Russian Far-Eastern seas with that of other regions of the Ocean in the tropic, subtropic and boreal zones, it was concluded that the structure to a great extent depended on the level of the region exploration (the better studied fauna included a higher percentage of small species). Judging from the size structure ot the fauna of Russian Far East waters, one can expect the presence of a large number (150-500 species) of micromollusks, not registered previously. As a whole, biodiversity of marine mollusks in Russia is low compared to adjacent areas (the Sea of Japan, the Mediterranean Sea etc.). An illustrated catalogue of marine and brackish water Gastropoda was published.

During recent 10 years an outburst of the number of the red king crab which was introduced into the Barents Sea at the beginning of 60s has occurred. The studies of the inshore benthic communities carried out by us, did not confirm a notion about a drastic negative influence of the crab on their structure. The crab indeed has become an important component of bottom communities, however for the past 40 years the species composition, peculiarities of distribution and quantitative characteristics of the communities on hard bottoms has not changed fundamentally. The study of the structure of the soft bottoms communities in the model defined area water showed that these communities were not disturbed. The data obtained evidence for the ability of bottom associations of the Barents Sea to endure the increased load.