Tuesday, June 5, 2012

 Dead lakes, too?

Dead zones are also found in the Great Lakes. A dead zone in Lake Erie now happens every year in the lake’s shallow central area off Cleveland. Factors contributing to Lake Erie’s hypoxic zone are low water levels and fertilizer runoff from large farms. The lake’s dead zone has expanded for the past seven years and now consumes the oxygen in the deepest waters of the lake, the lowest 7.6 meters of the 23-meter-deep lake. Scientists fear that it is affecting the dynamics of the lake’s food web, including fish stock abundance and production. Increased nutrient input to the lake, perhaps from forest disturbance to clear fields for corn and other crops, caused bottom-water anoxia and altered the lake’s diatom community structure. According to a study done by Lisa Osterman in 2005, seasonal dead zones in the northern Gulf of Mexico are not rare. These existed since the 1800's, but have developed to an astounding rate in modern days. This not only surprised Osterman, but also lead to a launching of a large study in order to compare previous and recent dead zones. The astonishing rate at which dead zones are being created has become a problem for countless underwater creatures, who have been displaced by the problems. The low-oxygen levels in the deep has killed numerous life forms, such as catfish, skate, and flounder. Iroquois settlement in the region died out in the 15th century. But the ghostly remains of a dead zone still lurk in Crawford Lake, waiting to surface should excess nutrients again be added to its waters. States Ekdahl, “The eutrophic diatom assemblage from the time of the Iroquois occupation remains in place, primed for further nutrient input despite the hundreds of years that have passed.” Will that be the fate of the Great Lakes, the Gulf of Mexico, the Baltic Sea, and the Black Sea, hundreds of years after we’re gone? Or will we use the insights we’ve gained to change the future? Through the combustion of contemporary scientific information, and willingness to accommodate life forms, individuals may be able to adapt to a new life that will in turn save the lakes from damage by dead zones.   

By: Shaza Karam

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