THE PROBLEM OF DECREASED BIODIVERSITY IN FRESH-WATER BODIES

Individual natural and anthropogenic factors which decrease the divers ity of fish communities in freshwater bodies of the former USSR (warmi ng of climate, regulation of river flow, biogenic eutrophication, and contamination of water bodies) are analyzed. Specific causes affecting the natural reproduction of fish populations are considered: disturbe d gametogenesis, mortality of eggs and young and adult fish, genetic d efects, etc. Some approaches to preservation and restoration of the di versity of freshwater fish have been formulated.