CLIMATIC OPTIMUM DURING THE HOLOCENE AND THE DISTRIBUTION OF WARM-WATER MOLLUSKS IN THE SEA OF JAPAN

The geographical distribution of warm-water mollusks has been analyzed and the paleobiogeographical significance of the climatic optimum during the Holocene in the formation of the shallow-water malacofauna in the Sea of Japan has been assessed. The shift of the southern boundary of the Pacific boreal region was 700-800 km to the north compared to its present-day position (based on bivalve mollusks). On the continental coast of the Sea of Japan this boundary is observed in Peter the Great Bay (approximately 43-degrees-N) and on the Japanese side it seems to be at the central part of Hokkaido. It can be concluded that a temperature increase of the surface water mass of 0.1-0.2-degrees-C can cause a shift of about 100 km of the northern boundary of the area of warm-water mollusks.