Coral reefs are affected by extreme heat waves – albeit to different degrees: corals with heavy coral colonization are especially good at tolerating high temperatures. Researchers led by Gregory Asner of Arizona State University published this in the specialized journal “Proceedings of the National Academy of Sciences”.
Scientists studied which reefs around the six major Hawaiian islands were resistant to marine heat waves. To do this, they evaluated satellite and infrared images of coral reefs before and after a hot period that lasted from July to October 2019. At the beginning of 2019, nearly 23 percent of 21,000 hectares were still covered with live corals, but one year later It has shrunk by 26 percent. However, individual reefs have been affected to varying degrees: Up to 30 percent of corals died in the reefs of Hawaii’s smallest island, Lana’i. In contrast, the researchers identified seven coral reefs of which survived up to 40 percent more than neighboring areas. They all had in common that a greater part of their area was colonized by coral reefs.
Also, the number of corals that died within the reef depends in part on the extent to which the shoreline extension has been developed and polluted by humans. And even within the reef, some areas withstood the heat better than others. The researchers explained that this is probably due to the different genetic makeup of the local corals.