Climate change could soon strip fish of their healthy image

Fish have long symbolized a healthy diet because they provide EPA and DHA, two omega-3 fatty acids associated with lower risks of atherosclerosis, diabetes, some cancers and premature birth, as well as benefits for brain, cardiovascular and eye development.

That nutritional advantage may weaken as the oceans change. Researchers from the University of Adelaide wrote that warming and acidification pose a critical threat to marine biodiversity and human diets by fundamentally altering the biochemical composition of marine organisms. They expressed particular concern about a possible decline in omega-3 fats, which people obtain mainly by eating seafood.

The nutrients originate largely in algae, phytoplankton and seagrass at the base of the marine food chain. Fish consume these organisms and accumulate the unsaturated fats in their bodies. Larger fish then acquire them by eating smaller species, allowing the nutrients to move through the food web.

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The rise in temperature and ocean acidification pose a critical threat to marine biodiversity and human diets, fundamentally changing the biochemical composition of marine organisms.

The researchers analyzed data from 489 separate experiments involving 132 marine organisms, including algae, invertebrates and fish. The experiments lasted from 24 hours to six months. They noted that global ocean temperatures have risen by 0.6 degrees Celsius since 1980 and that the number of marine heatwave days has doubled.

The researchers examined warming scenarios of 0 to 6 degrees, 6 to 10 degrees and more than 10 degrees Celsius. Even the lowest range, which can occur during current marine heatwaves, produced a striking response: omega-3 levels in fish fell by as much as 19%. The source also reports larger reductions under more severe warming scenarios, including a potential decline of up to 50%.

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The greatest concern is the potential decline in omega-3 fats, which play an essential role in human health and are obtained mainly through seafood consumption.