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Environment

Reef fish lose brain power as oceans acidify

Tuesday, May 20, 2014 - 02:11

May 20 - Researchers at the Georgia Institute of Technology say reef fish are likely to suffer from cognitive decline as they adapt to higher levels of CO2 in the water over the next century. The scientists say they are already seeing the decline in species inhabiting waters off the New Guinea coast, where a carbon dioxide seep is providing a view of future conditions. Ben Gruber has more.

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Off the coast of Papua New Guinea, there's a carbon dioxide seep that's giving marine biologists a view into the future. The water around the seep, while abundant with life, is highly acidic, with CO2 levels much like those predicted for surface ocean water 100 years from now. Georgia Institute of Technology biologist, Danielle Dixson, says the seep is a time machine of sorts, offering a glimpse into how fish will be affected if climate models of the future are correct. She says the evidence so far does not favor the fish. Acidification has impaired their sense of smell and their ability to avoid predators. (SOUNDBITE) (English) DANIELLE DIXSON, ASSISTANT PROFESOR OF BIOLOGY, GEORGIA INSTITUTE OF TECHNOLOGY, SAYING: "Fish that have been treated to ocean acidification levels that are expected to occur in the next 100 years actually prefer the smell of a predator." In other words, she says, the fish get stupid. In order to adjust to increasing acidification, fish will boost their bicarbonate levels. And while the change allows them to cope with lower PH levels, Dixson says it also leads to cognitive decline, affecting their ability to smell and learn from peers. (SOUNDBITE) (English) DANIELLE DIXSON, ASSISTANT PROFESOR OF BIOLOGY, GEORGIA INSTITUTE OF TECHNOLOGY, SAYING: "It's funny that their ability to cope with ocean acidification is actually the thing that is causing the problem because it is almost self-afflicted because they are fixing one problem and causing another." And according to Dixson, the rapid rate at which the oceans are acidifying and the vast amount of carbon in the atmosphere that still hasn't been absorbed by ocean waters, means there is very little that can be done to help the fish. (SOUNDBITE) (English) DANIELLE DIXSON, ASSISTANT PROFESOR OF BIOLOGY, GEORGIA INSTITUTE OF TECHNOLOGY, SAYING: "All of the different anthropogenic things that we are doing that are putting all of this gas into the atmosphere and it then going into the water from there. We have already acquired so much in the atmosphere that it actually hasn't all equilibrated yet. So even if we stopped driving and flying airplanes and all of that stuff, the oceans will still continue to get acidic because of how much CO2 is in the air now." And based on the evidence around the seep, as CO2 levels rice, predatory fish numbers will decline. And all the while, the reef fish will continue to lose their ability to distinguish between friend and foe.

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Reef fish lose brain power as oceans acidify

Tuesday, May 20, 2014 - 02:11