Restoring the Black Sea in Times of Uncertainty

Abstract

It was not until the late 1980s that the international community became aware of the magnitude of the ecological crisis underway in the Black Sea. Major components of the ecosystem had begun to collapse as early as 1973 when records show signifi cant areas of summer hypoxia (low oxygen content) on the northwestern shelf as a result of eutrophication (an increase in the water's nutrient content, which enhances plant growth, but leads to oxygen depletion). In a remarkably short space of time, perhaps as little as fi ve years, these hypoxic areas extended over most of the shelf, some 12 percent of the surface of the 420,000 km 2 Black Sea (Zaitsev, 1992). In the late 1980s, the hypoxic events had become so severe that huge quantities of benthic organisms had died and were washed up and rotting on the beaches of Romania and Ukraine. At the same time, commercial yields of the relatively abundant anchovies had plummeted throughout the Black Sea following a decade of decline of fi sheries of higher-value predatory species. Then, there was the arrival of the uninvited comb jelly Mnemiopsis leydi, transported in ballast water from the eastern seaboard of America.