Eutrophication |
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Two highly respected marine science collaboration papers, both published in the journal "Science" recently have highlighted the dangerous process of atrophism in coastal seas. The first of these by Robert Diaz, an oceans expert at th US Virginia Institute of Marine Science, College of William and Mary at Bloucester Point and Rutger Rosenberg of the department of Marine Ecology at the University of Gothenberg mapped the number of coastal dead zones worldwide - with more than 405 recorded.
Dead zones are large swathes of the coastal ocean where critically low levels of oxygen have in effect suffocated ocean life. The threat posed to the oceans is on a par with overfishing. The cause of these spreading dead zones are man-made fertilizers, used in excessive doses in intensive agriculture which then run off the land and find their way to the sea. On the way these nitrate rich fetilizers create massive algai blooms that them decay thanks to the bacteria that feed on them and in so doing they
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use up the oxygen in the water, starviing other organisms and sea-creatures and affecting the food chain from the bottom up. The second paper, co-authored by Lothar Stramma of the Leibniz Institute of Marine Sciences in Kiel, Germany and Janet Sprintall, a physical oceangrapher at Scripps Institution of Oceanography in California warns that organisms such as fish, crabs, lobsters and prawns will die in these zone. Already the Baltic sea, has lost about 30% of its available food energy which has led to a significant decline in its fisheries. The lack of oxygen can also force fish into warmer waters closer to the surface, perhaps making them more susceptible to disease. In this study, also published in Science, the authors collated hundreds of readings fo oxygen concentrations taken over the last 50 years in both the Atlantic and Pacific noting a dramatic decline in oxygen levels. Global warning and rising seas temperatures are also implicated in this asphyxiation of coastal waters. Coastal waters contain the vast majority of ocean life. |
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