Coral bleaching refers to the process by which coral lose their bright, vibrant colors and turn white. This happens when coral get stressed and “expel” the microscopic bacteria that live on them and give them their bright colors. Stressors include changes in ocean temperature and lack of sufficient nutrients. Between 2014 and 2017, it’s estimated that almost three quarters of the world's coral reefs experienced ocean temperatures warm enough to trigger some kind of bleaching event.
Because coral reefs are diverse and crucial ecosystems, bleaching can have destabilizing effects on local ecosystems. As climate change worsens, researchers have long held that the frequency of coral bleaching could have serious effects on fishing industries, which help feed millions who live on coastlines.
New research, however, suggests that some fish populations living in ecosystems changed by coral bleaching may still be thriving and full of nutrients–perhaps even more so than before.
Published in One Earth, researchers report on findings from a surveying effort of a reef ecosystem in the Seychelles that underwent a bleaching event 20 years ago. While over half of the reef recovered, about 40% did not. Seaweed, instead, took over in the portions that did not recover. Long-term monitoring of the reef by the research team, including a variety of fishing, nutrient analysis, and survey techniques of the fish communities, revealed interesting and unexpected results about the fish living in the reef.
Specifically, researchers found that fish in the region were high in various nutrients in minerals (such as calcium and omega-1 fatty acids). Interestingly, fish living in these reefs where seaweed had taken over had higher concentrations of iron and zinc. Researchers attributed this to the presence of the seaweed, which is naturally high in minerals.
Researchers concluded that reef ecosystems may be a bit more resilient to climate change than previously thought. However, they caution that more research is needed on the long-term effects of climate change on reefs. Nonetheless, these findings suggest that through sustainable fishing practices, fish caught in these regions can continue to provide crucial, nutritious foods for people living in coastal regions.