THE DANUBE ? CONTROLLING FACTOR OF THE ECOLOGY OF THE DANUBE DELTA AND THE BLACK SEA

The Danube represents the essential factor that influences the main ecological characteristics of the Danube Delta and, mostly, of the Black Sea. The hydrological, physical-chemical, and hydro-biological quantitative and qualitative variations bring to the modifications of the biotic and abiotic structures of the Danube Delta and the Black Sea in a rhythm and concordancxe with the dynamics of the physical-chemical and biological parameters specific to the Danube. Starting from this point, it can be noticed the controlling character of the ecology of the Danube Delta and the Black Sea. This fact appears more obvious in the conditions of the last 50 years, when the large pollution of the river led to radical ecological modifications within the Danube Delta and the Black Sea, during a very short historical period. The main factor, which determined fundamental modifications in the structure and functionality of the aquatic ecosystems is due the intensification of the man-induced eutrophication process. Phytoplankton increased, but submerged macrophytes disappeared at the same time with certain populations of invertebrates and species of fish that populated the associations of macrophytes.