It’s Not Just Ocean Acidification Anymore: Study

Posted on January 22, 2012

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CO² Makes Fish Drunk.  Something like 2.3 billion metric tons of human CO² emissions (approximately 2.5 billion US tons) dissolve into the world’s oceans every year.  The dissolved CO² has been demonstrated to form into carbonic acid, which is slowly tipping the ph-balance of the oceans towards the acidic.  The acidification which results has already been identified as a danger to coral reefs and shellfish.

 See      Of Pteropods & Armageddon Timepieces

A Warning on Ocean Acidification from the European Science Foundation

Ocean Acidification: NOAA State of the Science Fact Sheet 2008

However a recent paper in Nature Climate Change says that the issue might be more complex than that.  And worse.  Professor Philip Munday of the ARC Centre of Excellence for Coral Reef Studies and James Cook University along with a team of colleagues who collaborated on the paper have identified a whole new set of problems with the carbon dioxide itself.

Professor Munday says, “We’ve now established it isn’t simply the acidification of the oceans that is causing disruption — as is the case with shellfish and plankton with chalky skeletons — but the actual dissolved CO² itself is damaging the fishes’ nervous systems.”

Professor Munday and his team worked with baby coral fishes, testing their performance in waters containing elevated levels of CO², levels predicted for future oceans if fossil fuel emissions continue to remain high.

“We’ve found that elevated CO² in the oceans can directly interfere with fish neurotransmitter functions, which poses a direct and previously unknown threat to sea life,” Prof. Munday says.

The CO² interferes with the ability of fish to do the things they need to evade predators, and, at least with the fish studied, the interference targeted the prey more than the predator.  Many more baby coral fish died than was usual.  Malfunctioning neurotransmitters affected fishes’ ability to hear and smell.  They were confused by sounds, acted inappropriately, and lost their natural instinct to turn left or right—an instinct necessary for schooling behavior because it allows fish to swim in unison.

And when fish get out of step, when they lose the school, they get eaten by predators.

The fish most likely to be affected in this way by elevated CO² levels, according to Professor Munday, are those with high oxygen consumption.  But of course, effects on one part of the system will inevitably echo through the system as a whole.

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See Carbon Dioxide Is ‘Driving Fish Crazy’ – ScienceDaily

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