Researchers have confirmed predictions based on computer modelling that oxygen-depleted areas in tropical oceans are on the rise, possibly due to climate change.
Scientists have found oxygen-depleted regions inthe world\'s tropical oceans are increasing. Image: Map of the world\'s oceans. Credit: National Oceanic and Atmospheric Administration
An international team of physical oceanographers has found that the regions marine life can live or enter in search of food is reducing due to the expansion of the regions lacking in enough oxygen.
Led by Lothar Stramma from the Leibniz Institute of Marine Sciences (IFM-GEOMAR) in Kiel, Germany,and co-authored by Janet Sprintall, a physical oceanographer at Scripps Oceanography and others, the research has found that levels of oxygen at a depth of 300 to 700 meters (985 to 2,300 feet) have declined during the past 50 years.
"We found the largest reduction in a depth of 300 to 700 meters (985 to 2,300 feet) in the tropical northeast Atlantic, whereas the changes in the eastern Indian Ocean were much less pronounced," said Stramma. "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."
The scientists say such an increase in the "underwater deserts" could have a severe biological and economic impact and say it may be possible the regions are spreading horizontally.
"We think there are areas that are extending, but we don't have the maps to show that right now," Stramma said.
The study, which appears in the journal Science, is based on a detailed database of oxygen measurements in the ocean.
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