Rising ocean temperatures could cut key omega-3 fats in seafood by half
Rising ocean temperatures could reduce the concentration of EPA and DHA omega-3 fats in marine food webs by up to 50% under high-warming scenarios, according to new research. These fats are essential for human brain, eye, and heart health, and seafood is the primary dietary source. The decline would also affect other animals that rely on these nutrients.
The research pooled data from 489 experiments covering 132 marine species, including algae, invertebrates, and fish. Marine algae are among the few organisms that naturally produce EPA and DHA, and these fats move upward through the food web as predators consume prey. The study examined both ocean warming and acidification, noting that ocean temperatures have already risen 0.6°C since 1980, with marine heat waves doubling in frequency. Under the most severe warming projections, omega-3 concentrations could fall by half.
The findings distinguish between three warming levels: low (0–6°C), medium (6–10°C), and high (over 10°C). Even the low range, which already occurs during marine heat waves, produced a 19% reduction in fish omega-3 levels in experiments lasting up to six months. This decline compounds the effect of warming on the nutritional quality of the food fish consume, meaning wild populations may face even greater losses than laboratory studies suggest.
This decline could affect billions of people who rely on seafood as their primary omega-3 source, potentially increasing risks of cardiovascular disease, cognitive decline, and inflammatory conditions. Communities dependent on fishing for nutrition and income may face compounded pressures, while marine predators like seabirds and larger fish could experience health consequences that ripple through ecosystems. Dietary supplements and plant-based alternatives may partially offset human impacts, but they remain less accessible in many regions.