| Ocean acidification disrupts the behavior of fish shoals | |
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The rising concentration of carbon dioxide in the atmosphere is causing major changes in ocean surface temperatures and acidification, to the detriment of an increasing number of marine ecosystems.
A new study led by the University of Adelaide shows that the way fish interact in groups has been significantly modified by both ocean acidification and global warming. In particular, fish shoals become less cohesive and less capable of dodging predators when the water is more acidic.
“Fish show gregarious behavior and cluster in shoals, which helps them to acquire food and protect themselves against predators,” said study leader Ivan Nagelkerken, a professor at the University of Adelaide’s Environment Institute and Southern Seas Ecology Laboratories. |
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“Many gregarious tropical species are shifting poleward under current ocean warming and interacting in new ways with fish in more temperate areas.”
The scientists investigated how fish species interacted and behaved when water temperatures and acidification changed under controlled laboratory conditions. When coordinating together in a shoal after being spooked by predators, tropical and temperate fish species usually tend to move to the right. However, this bias significantly diminished in conditions when ocean acidification levels were higher.
“Mixed shoals of tropical and temperate species became less cohesive under future climate conditions and showed slower escape responses from potential threats,” explained study co-author Angus Mitchell, a doctoral student at the University of Adelaide who performed the laboratory experiments. |
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