WASHINGTON (Xinhua): An international team of physical oceanographers has discovered that oxygen-poor regions of tropical oceans are expanding as the oceans warm, limiting the areas in which predatory fishes and other marine organisms can live or enter in search of food.
The results of the study was released on Thursday and will appear in the May 2 issue of journal Science.
The researchers found through analysis of a database of ocean oxygen measurements that oxygen levels in tropical oceans at a depth of 300 to 700 meters have declined significantly during the past 50 years. The width of the low-oxygen zone is expanding deeper but also shoaling toward the ocean surface.
"We found the largest reduction in a depth of 300 to 700 meters in the tropical northeast Atlantic, whereas the changes in the eastern Indian Ocean were much less pronounced," said Lothar Stramma, lead research from the Leibniz Institute of Marine Sciences in Germany.
"Whether or not these observed changes in oxygen can be attributed to global warming alone is still unresolved. The reduction in oxygen may also be caused by natural processes on shorter time scales," said Stramma.
Researchers say that these low-oxygen zones are "underwater deserts," which will likely have far-reaching impacts on ecosystems because important organism can not survive in them.
Courtesy: thehindu.com
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