Faculty research reveals a negative affect of ocean acidification on fish

December 11, 2013

In collaboration with the Scripps Institution of Oceanography at the University of California – San Diego, a MacEwan University faculty member made a unique discovery: ocean acidification is affecting anxiety levels in fish.

“Ocean acidification is a basic process that is occurring in our environment,” says Trevor Hamilton, psychology. “Through the increase of carbon dioxide levels in our air, some CO2 gets absorbed into water, including lakes, rivers, and oceans. When CO2 is absorbed, it causes a lowering of pH” – a lower pH level indicates greater acidity.

Working with honours student Adam Holcombe and Scripps marine biologist Martin Tresguerres, Trevor administered the same CO2 concentration that is projected 100 years from now. The question they sought to answer was what will this do to fish if projected CO2 levels actually occur? Trevor adds that the projected concentration levels are based on purely scientific estimates.
To explore this question, Trevor and Adam went to San Diego in 2012 to study a species known as rockfish, important to California’s commercial fisheries.

“It’s a very relevant species for people in the fishing industry,” explains Trevor.

The research included—after administering CO2 into the fish’s environment—a light/dark test (in which fish that are more anxious go to the darker side of the arena) and a shelter test (in which the anxious fish are more likely to seek out the available shelter in the arena). Researchers also used drugs to determine that this change in anxiety was due to an alteration in the way neuronal GABAA¬ receptors function. The ocean acidification causes them to work in an opposite way to normal, which is consistent with other research.

While the results were recently published in the journal Proceedings of the Royal Society B, Trevor says there is more to discover.

“The next thing we’re going to study is their adaption over long, slow increases in CO2,” he says.

Trevor is careful to state that the research was conducted under experimental conditions, but that the results could be an indication of what’s to come if carbon dioxide levels continue on this trajectory.

“It means that there’s the potential for a profound effect of elevated carbon dioxide levels on basic behaviour of fish.” That could have implications for how a fish interacts with a predator or with another member of its own species. It could also have implications for the fishing industry.

The project has caused quite a stir in the media, with coverage in the Los Angeles Times, the Montreal Gazette, the Edmonton Journal and on several online journals, evidence of the potential importance of the research.

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