Climate-induced increases in micronutrient availability for coral reef fisheries

• Published in: One earth (Cambridge, Mass.) Vol. 5; no. 1; pp. 98 - 108
• Main Authors: Robinson, James P.W., Maire, Eva, Bodin, Nathalie, Hempson, Tessa N., Graham, Nicholas A.J., Wilson, Shaun K., MacNeil, M. Aaron, Hicks, Christina C.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 21.01.2022; Cell Press Elsevier
• Subjects: aquatic foods; coral bleaching; fish biomass; food security; marine heatwave; nutrition; regime shift; small-scale fisheries; thermal stress; tropical fisheries; marine heatwave; fish biomass; nutrition; small-scale fisheries; tropical fisheries; regime shift; food security; aquatic foods; thermal stress; coral bleaching
• ISSN: 2590-3322; 2590-3330; 2590-3322
• DOI: 10.1016/j.oneear.2021.12.005

Climate change is transforming coral reefs, threatening supply of essential dietary micronutrients from small-scale fisheries to tropical coastal communities. Yet the nutritional value of reef fisheries and climate impacts on micronutrient availability remain unclear, hindering efforts to sustain food and nutrition security. Here, we measure nutrient content in coral reef fishes in Seychelles and show that reef fish are important sources of selenium and zinc and contain levels of calcium, iron, and omega-3 fatty acids comparable with other animal-source foods. Using experimental fishing, we demonstrate that iron and zinc are enriched in fishes caught on regime-shifted macroalgal habitats, whereas selenium and omega-3 varied among species. We find substantial increases in nutrients available to fisheries over two decades following coral bleaching, particularly for iron and zinc after macroalgal regime shifts. Our findings indicate that, if managed sustainably, coral reef fisheries could remain important micronutrient sources along tropical coastlines despite escalating climate impacts. •Coral reef fishes are important sources of essential dietary nutrients•Nutrients available to fisheries increased after mass coral bleaching•Iron and zinc were higher in reef fishes caught on macroalgal habitats•Coral reefs can remain key sources of nutritious food despite climate impacts Tropical small-scale fisheries supply nutritious and affordable seafood to hundreds of millions of people, including catches from coral reefs that are vulnerable to marine heatwaves. Climate changes therefore threaten seafood supply in places where food insecurity is most prevalent, but what is the nutrient value of climate-impacted coral reefs? We analyzed nutrient content of 43 tropical reef fish species in Seychelles and found that coral reef fish contain similar levels of iron, selenium, and zinc as chicken, pork, and beef and higher levels of calcium and omega-3 fatty acids. By integrating nutrient data with fish surveys collected before and after mass coral bleaching, we show that high post-bleaching fish biomass led to greater nutrient supply for fisheries, particularly for iron and zinc. Sustainable management of reef fisheries can therefore continue to support tropical food and nutrition security, despite climate impacts to reef ecosystems. Marine heatwaves are transforming coral reefs, yet the nutritional value of reef fisheries and climate impacts on micronutrient availability remain unclear. We show that reef fish contain levels of calcium, iron, selenium, zinc, and omega-3 fatty acids equivalent to or greater than other animal-source foods. Using monitoring data from Seychelles, we also find nutrient availability to fisheries increased after mass coral bleaching, due to greater herbivore productivity. Sustainably managed reef fisheries can support food and nutrition security along climate-impacted tropical coastlines.