Ocean acidification, global warming affecting supply of seafoods

A school of Japanese amberjack at the north-east coast of Taiwan. A new report warns that ocean warming and acidification are affecting the behaviour of fish. Copyright: Vincent C. Chen(CC BY SA 4.0). This image has been cropped.

Seafood supplies risk been affected if ocean acidification and global warming continue to interfere with the group interaction of fishes. This is according to a study.

Ocean acidification and global warming are interfering with the way fish interact in groups, posing a threat to their survival which could affect seafood supplies, researchers say.

Marine ecosystems worldwide have shown an increased dominance of warm water species following seawater temperature rise, with parallel changes in the species composition of fish catches since the 1970s, according to a report by the Intergovernmental Panel on Climate Change (IPCC).

Global fish catches

Fisheries from marine ecosystems provide foodnutrition, income and livelihoods for many millions of people around the world, the IPCC, said. Globally, total fish catches amount to 80—105 million tonnes annually, generating over US$80 billion in revenue, the report said.

“Fish show gregarious behaviour and cluster in shoals which helps them to acquire food and protects them against predators,” says Ivan Nagelkerken, professor at the University of Adelaide’s Environment Institute and Southern Seas Ecology Laboratories and author of a study on the effect, published in Global Change Biology.

Warming, acidification, marine ecosystems

Under controlled laboratory conditions, the researchers observed how species interacted and behaved in new ways with changing temperature and acidification. While warming and acidification are different phenomena, they interact to the detriment of marine ecosystems.

According to Nagelkerken, mixed shoals of tropical and temperate species became less cohesive under future climate conditions and showed slower escape responses from potential threats. Strong shoal cohesion and coordinated movement, whether to acquire food or evade predators, are important for fish survival.

IYBSSD2022, 7 February 2022. Press release.

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