MODERN GEOECOLOGICAL TRANSFORMATIONS IN THE KERCH STRAIT ECOSYSTEM

Resumo

The distribution, structure, and dynamics of the bottom communities of the Kerch Strait macrozoobenthos were studied based on an analysis of literary sources in 1934 and 1955, archival data of hydrobiological field studies by the Southern Research Institute of Marine Fisheries and Oceanography (YugNIRO, Kerch) in 1986 and 1989, and the results of a joint Russian–Ukrainian benthic survey of the Kerch Strait (47 stations) carried out by the Institute of Geography, Russian Academy of Sciences (RAS), and YugNIRO in summer 2010. It has been revealed that over the past 75 years, populations of bivalve filter-feeding mollusks (sestonophages) have degraded in the strait’s ecosystem, whereas populations of polychaetes (detritovorous collectors) preferring silty beds have increased. Species of benthic animals and areas of the strait in which maximum changes have occurred have been identified. After analyzing the dynamics of the structure of bottom sediments in the strait based on the archival YugNIRO data and the results of a diving survey by IG RAS in 2008 (49 dives), it was proved that one reason for the established transformations was silt deposition in a significant part of the floor of the strait as a result of previous (burial of dredged sediments, 1960–1990 ) and modern (construction of the Tuzla dam, 2003) economic activity. Since the character of the recorded transformations prevents the assumption of these reasons as unique, the authors consider various hypotheses explaining the mechanism for these changes. A conclusion is drawn about the need for further research on the geoecological dynamics of the Kerch Strait ecosystem, especially today, after construction of the Crimean Bridge.