Conclusions.

This conclusion completes one more review concerning the natural condition of the Caspian Sea and the principal trends of change in the second half of the 20th century. The change in the mean sea level variations that occurred in the mid-1970s, when the long-term fall was replaced by a rapid and significant rise, represents an important indicator of the changes in the natural regime of the Caspian Sea, including thermohaline structure, and nutrients and oxygen distribution. The most important consideration is chemical pollution (oil and oil products, phenols, detergents in the North Caspian), which grows with the intensification of human activity on the sea coasts and in the sea proper and represents one of the most hazardous kinds of anthropogenic impact on the Caspian ecosystem. The biological section of the monograph discusses the main problems concerning the biological diversity, the introduced species, and the biological resources. One of the most catastrophic aftereffects of anthropogenic intervention into the Caspian ecosystem is related to the population of sturgeons. Special attention is paid to socioeconomic, legal, and political problems in the Caspian Sea region. The unsettled delineation of the Caspian Sea and the uncertainty in its legal status are the main obstacles to successfully coping with many issues, including environmental protection and preservation of the biological resources. [ABSTRACT FROM AUTHOR]