Marine Heatwaves Trigger Sudden Coral Deaths: A Rising Global Threat

Unprecedented Coral Die-Off in Florida

It was already known that marine heatwaves could cause coral bleaching, but their ability to cause sudden coral death was not well understood. However, this is exactly what happened to the coral reefs off the southwest coast of Florida following the 2023 marine heatwave, according to a study published on October 23.

In the summer of 2023, sea surface temperatures in this region soared to 31°C or higher for over 40 days, which is 2.2 to 4 times hotter than in previous years. This severe heat event led to the almost immediate death of the corals. Scientists noted that the living tissues of the corals began detaching from their calcareous skeletons just days after the temperature peak.

Typically, rising water temperatures result in coral bleaching, where corals slowly die from starvation or disease. However, this type of sudden death due to heat had seldom been observed before.

Another alarming finding from the study is the functional extinction of two coral species, Acropora palmata and Acropora cervicornis. Functional extinction occurs when species are no longer able to fulfill their role in the ecosystem. Here, these species were crucial in forming the structure of the reef and helping to dissipate wave energy. In southwest Florida, between 97.8 and 100% of the colonies of Acropora palmata and Acropora cervicornis have died, compromising the integrity of the entire coral reef system.