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Facing a Sea of Challenges for a Better Environment

Image of the Black Sea at Sunset
Chemistry

 

Biology: Jellyfish

Almost a third of the total land area of the European continent drains into the Black Sea through major rivers such as the Danube, Dnieper, and Don. The 700-mile-long Black Sea is nearly landlocked: its only connection to the world's oceans is through the narrow Bosporus. Thus, it takes nature hundreds of years to replenish the Black Sea's bottom waters with fresh seawater.

Due in large part to natural conditions, over 90% of the Black Sea is devoid of oxygen. It has the largest "dead zone" — where no oxygen exists — in the world. Only its thin surface layer contains oxygen, and it is here where almost all of its marine life dwells.

However, the biological diversity of the Black Sea has declined dramatically in the past 40 years. Large nutrient inputs from untreated sewage and other sources have fueled blooms of algae that eventually rob the water of oxygen as the tiny plants are decomposed. Overfishing, industrial pollutants, and a recent invasion of alien jellyfish delivered via the ballast water of foreign ships are among the many other factors that also have taken their toll on this ancient sea

A recent report from the Global International Waters Assessment GIWA), an initiative led by the United Nations Environment Programme, indicates that around a third of the Black Sea's fish stocks have been lost in the past 20 years. Only six of the 26 species commercially exploited in the 1960s remain in commercial quantities, with decreases in sturgeon, salmon, gray mullet, sprats, horse mackerel, and goby. More than 60 plant and animal species deemed essential to the Black Sea ecosystem, including dolphins and seals, are now endangered or extinct.

The Black Sea Basin Strategic Partnership is among the programs now under way to help improve and restore the Black Sea. It will involve organizations such as the Global Environment Facility, the United Nations Development Programme, the World Bank, the European Union, and the United Nations Environment Programme (UNEP). A major goal of the project is to reduce the levels of phosphorus and nitrogen entering the Black Sea.

For a better understanding of the Black Sea's unusual chemistry and to meet one of its "alien invaders," please check out these Web pages: Chemistry and Biology.

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