Fish Lose Fear of Predators with Elevated CO2

by | Apr 15, 2014

coralHigher carbon dioxide emissions that eventually find their way into ocean waters could cause fish to lose their fear of predators, potentially damaging the entire marine food chain.

A study by the Australian Institute of Marine Science (Aims), James Cook University and the Georgia Institute of Technology found the behavior of fish would be “seriously affected” by greater exposure to CO 2.

Researchers studied the behavior of coral-reef fish at naturally occurring CO 2 vents in Milne Bay, in eastern Papua New Guinea. Fish found living near the vents, where bubbles of CO 2 seeped into the water, were attracted to predator odor and exhibited bolder behavior than fish from control reefs, the study said.

More than 90 per cent of the excess CO 2 in the atmosphere is soaked up by the oceans. When CO is dissolved in water, it causes ocean acidification, which changes its chemistry. The Aims study found the diversity of fish at the CO 2 vents was not influenced, but that fish nerve-stimulation mechanisms were altered.

While fish at the vents faced fewer predators than usual, the consequences for fish in the wider ocean could be significant as more CO 2 was dissolved in the water, the study said.

Photo: Gareth Williams Flickr photostream


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