New Discovery: Ocean Pollution Prevention Could Be the Key to Preventing Coral Bleaching

On December 22nd, some corals managed to survive a globally unprecedented heatwave. The scientists of this study report that the coral's resilience to temperature gives hope for the long-term survival of coral reefs.

In the years 2015-2016 heat stress from the El Niño triggered a global coral bleaching event, causing coral mortality on reefs around the world. Its epicenter was Kiritimati, where the heatwave lasted an unprecedented 10 months. Corals are sensitive to the temperature of the surrounding waters. During a heatwave, corals release the microscopic algae that live in their tissues, causing the corals to turn completely white, a phenomenon known as coral bleaching. However, prolonged bleaching often causes corals to die from starvation as these released microscopic algae are the Coral's only food source.

In recent experimentation, Daniel Thornhill, a program officer in NSF’s Division of Ocean Sciences, reported that "given experimentally induced heat stress, coral can change the kind of symbiotic algae they host to a more heat-tolerant species." These tested corals only exhibited this capacity if they were not also exposed to other types of human-caused stresses (such as water pollution). The coral samples from the experiment that obtained heat tolerant algae were then returned to the ocean. It was unknown whether this algae would protect the coral reefs from more intense heat waves, however as of December 22nd we now know it can, as numerous coral reefs that were in the experiment survived. Until now, it’s been unclear if local reef management could help improve corals’ chances of surviving climate change. However, now we know that a reduction of human stressors such as water pollution and human invasion could potentially allow coral reefs to survive the coming years of climate change. This would save hundreds of species that live in these coral reefs. There is still a way for us to make a difference. It's not too late!

Citations:

Du Toit, A. Surviving the heatwave. Nat Rev Microbiol19, 74 (2021). https://doi.org/10.1038/s41579-020-00500-9