January 7th 2022
Bleached coral reefs can still support nutritious seafood, study finds
Bleached coral reefs can continue to support nutritious seafood, according to a new study conducted by the University of Lancaster.
The leading cause of coral bleaching is climate change. A warming planet means a warming ocean, and a change in water temperature can cause coral to drive out algae.
Coral bleaching matters because once these corals die, reefs rarely come back.
However, the new findings, published in the journal One Earth, show that after a mass-bleaching event, the reef fisheries can still remain a rich resource of micronutrients.
The researchers found that following a mass-bleaching event around 60% of the coral reefs recovered to a coral-dominated system and around 40% were transformed to reefs dominated by seaweeds.
These differences provided a natural experiment for the scientists to compare the micronutrients available from fisheries on reefs with different climate-driven ecosystem compositions.
The scientists, who used a combination of experimental fishing, nutrient analysis, and visual surveys of fish communities in the Seychelles, calculated that reef fish are important sources of selenium and zinc, and contain levels of calcium, iron, and omega-3 fatty acids comparable to other animal-based foods, such as chicken and pork.
They also found that iron and zinc are more concentrated in fish caught on reefs that have been transformed after coral bleaching and are now dominated by macroalgae such as Sargassum seaweeds. These seaweeds have high levels of minerals, which, researchers believe, is a key reason why the algal-feeding herbivorous fishes found in greater numbers on transformed reefs contain higher levels of iron and zinc.
Dr. James Robinson, who led the study, said: ‘Our findings underline the continuing importance of these fisheries for vulnerable coastal communities, and the need to protect against over-fishing to ensure the long-term sustainability of reef fisheries.’
The researchers also caution that while these fisheries have proved more resilient to climate change disturbance than expected, continued understanding of the long-term impacts of climate change to coral reef fisheries, and more data from other regions, are urgent priorities.
Dr Robinson added: ‘Coral reef fish contain high levels of essential dietary nutrients such as iron and zinc, so contribute to healthy diets in places with high fish consumption.
‘We found that some micronutrient-rich reef species become more abundant after coral bleaching, enabling fisheries to supply nutritious food despite climate change impacts. Protecting catches from these local food systems should be a food security priority.’