Ocean warming will massively reduce omega-3 fatty acids

Climate change has already caused significant damage, including longer and more intense heatwaves, accelerated sea level rise, and the loss of polar sea ice. Now, by performing the first-ever survey of planktonic lipids in the world’s oceans, a research team led by the Woods Hole Oceanographic Institution (WHOI) has found that, as global warming advances, there may be fewer and fewer omega-3 fatty acids produced by plankton at the base of the food web, which will mean less of these lipids available for fish and human beings.

Omega-3 fatty acids are essential fats that the human body cannot produce on its own. They are regarded by scientists as highly beneficial, increasing cardiovascular health and promoting healthy aging. 

“The lipids in the ocean affect your life,” said study co-author Benjamin Van Mooj, an expert in Marine Chemistry at WHOI. “We found that the composition of lipids in the ocean is going to change as the ocean warms. That is a cause for concern. We need those lipids that are in the ocean because they influence the quality of the food that the ocean produces for humanity.” 

The researchers collected 930 lipid samples from 146 locations across the world’s oceans during seven oceanographic research expeditions from 2013 to 2018. 

“Focusing on ten molecularly diverse glycerolipid classes we identified 1,151 distinct lipid species, finding that fatty acid unsaturation (i.e., number of carbon to carbon double bonds) is fundamentally constrained by temperature. We predict significant declines in the essential fatty acid eicosapentaenoic acid [EPA] over the next century, which are likely to have serious deleterious effects on economically critical fisheries,” the study authors reported.

Although planktonic community lipidomes are affected by a variety of environmental factors, such as nutrient availability, the most fundamental control of their composition appeared to be temperature. “Indeed, it is striking that the relationship between temperature and unsaturation emerges from our dataset despite spanning such diverse and disparate planktonic communities, from the nutrient-depleted subtropical gyres to the highly-productive Antarctic coastal shelf,” the authors wrote.  

To determine how the upper and lower limits for the composition of omega-3 fatty acids may shift under future warming conditions, the scientists generated maps using end-of-century sea surface temperature conditions for various climate change scenarios. Under a worst-case scenario with unmitigated greenhouse gas emissions, some ocean regions may witness a drastic decrease of up to 25 percent of these beneficial lipids.

These findings provide examples “of how human activities are perturbing the oceans in ways that we never expected, and of the uncertainty of how the ocean is going to respond to warming,” concluded Dr. Van Mooj. 

The study is published in the journal Science. 

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By Andrei Ionescu, Earth.com Staff Writer