The Black Sea is a deep (about 2 km) elliptic basin with zonal and meridional dimensions of approximately 1000 km and approximately 400 km, respectively, located roughly between 28° and 42°E longitudes, 41° and 46°N latitudes (Figure 1). It has only a narrow opening to the shallow (<75 m deep) Bosphorus Strait; otherwise, it is a completely enclosed marginal sea. Until the early 1970s, the Black Sea consisted of a mosaic of diverse ecosystems that provided a vital habitat for many commercial species. It supported fisheries almost five times richer than those of neighboring Mediterranean. Then, it has been gradually transformed into a severely degraded marine habitat suffering from the introduction of large volumes of nutrients and contaminants from the Danube River and others along the northwestern coast (Mee, 1992). The state of the ecosystem after the mid-1970s reflected severe environmental deterioration, intense eutrophication, dramatic decreases in biodiversity and fish stocks, especially in the northwestern shelf and the Sea of Azov (Zaitsev and Mamaev, 1997).