A sudden marine heat wave off the coast of Florida has sent water temperatures soaring to unprecedented highs, threatening one of the most severe coral bleaching events the US state has ever seen.
The bleaching is already happening in the Florida Keys, which is home to 6,000 individual reefs. Eleven observations of partial bleaching were confirmed by the Mote Marine Laboratory in June. Experts said they expected that number to grow exponentially in the weeks to come.
Sea surface temperatures have reached the highest levels on record since satellites began collecting ocean data, alarming scientists. The warming has occurred much earlier than normal. The exceptional temperatures are close to 97 degrees Fahrenheit in some areas, disturbing the coral reefs.
Extreme ocean heat and its duration are critical in deciding the survival of coral reefs. Temperatures that are too hot for too long cause coral to bleach, making these turn white as they eject their algal food source and gradually starve to death. Not all coral that bleachdie, but the more intense the heat and the longer it lasts, the more certain death becomes, say coral experts.
Sea surface warming of 1 degree Celsius, or 2 to 3 degrees Fahrenheit, beyond the reef’s normal highest temperature triggers the heat stress that leads to bleaching. The sea surface temperatures around Florida are more than 2 degrees Celsius above that normal range and have been for one to two weeks, alarming scientists.