A huge dead zone is forming in the Gulf of Mexico
An area covering half of the surface of Switzerland and where no life remains has been spotted in the Gulf of Mexico. It is due to the fertilizers of American agriculture that flow into the sea.
This is a disturbing phenomenon that is currently affecting the Gulf of Mexico. A huge dead zone, the size of half of Switzerland, is forming in the depths of this inland sea between the USA and Mexico.
It is believed to be the result of rainwater runoff and especially significant flooding this spring in the US Midwest. These would have carried into the sea very large quantities of nitrogen and phosphorus from fertilizers in the agricultural industry. These products would then have allowed giant algae to proliferate, algae that then smothered other marine organisms, reports the National Geographic website.
According to predictions from the Universities of Louisiana and Michigan, which study the phenomenon with the US National Oceanic and Atmospheric Administration, the area would have an estimated size of more than 20'000 km2. Such a phenomenon had already been observed in 2002. But it would be even more important this year.
These dead zones would be common in summer at the estuary mouth of the great American rivers, whether in the oceans or even the great lakes. But Europe is not spared, since the largest lifeless area ever recorded was spotted in 2010 in the waters of the Baltic Sea, according to National Geographic. A sea that is home to at least 7 10 largest dead zones on the planet ...
Black dots are the dead zones in this 2008 map
Heavy consequences on biodiversity
The phenomenon has serious consequences for marine ecosystems. It kills wildlife that colonizes the ocean floor, such as crustaceans, mussels or worms. However, this usually abundant food is the happiness of fish who are thus deprived of their favorite habitat.
Studies conducted in the Baltic Sea and in the United States since the end of the 1990 years show that many fish, which one could imagine that they could easily escape these areas without oxygen, lose there quickly and die asphyxiated. And lobsters or shrimps are not fast enough to move and also die ineluctably.
The phenomenon is temporary. If it occurs mostly in summer, it does not reproduce every year. And reversibility seems possible. But getting back to normal takes a lot of time. It requires, however, that the man intervene at the source of the problem, the chemicals used in agriculture. And here, the bet is far from being won ...
http://www.tdg.ch/sante/environnement/U ... y/23586750