African Oasis Shelters Marine Life from Rising Water Temperatures
Coral in the basin remained healthy during neighboring heat waves.
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A basin formed by Mount Kilimanjaro thousands of years ago off the coast of Africa is a newly-discovered coral refuge.
Running 150 miles from Kenya to Tanzania, the region’s cool, deep water acts as a shelter for marine life against ocean heatwaves and rising seawater temperatures.
“This area off the coast of Tanzania and Kenya is a small but vibrant basin of marine biodiversity,” says Dr. Tim McClanahan, lead coral scientist for the Wildlife Conservation Society team that discovered the refuge, in a press release. “Our study shows that while warming waters may devastate surrounding reefs, this area could become an incredibly important sanctuary where marine species big and small will flock to find refuge from climate change.”
Species big and small already have. Marine life in the basin includes rare dugongs and coelacanths, a prehistoric fish species once believed to be extinct. It also has the highest density of dolphins in East Africa.
To confirm that the basin was, in fact, not impacted by the marine heatwaves becoming increasingly common in the area, McClanahan set temperature gauges along the coastline. As warming events happened, he strapped on a dive tank and made firsthand observations in the basin.
“Outside that area, the corals are bleached and dying,” McClanahan says. “But inside the area, of around 400 square kilometers [150 square miles] they retain their color and their health."
He further describes this phenomenon to InsideClimate News: "It would be like running hot water into a cold bathtub; if the bath is cold, it would take a long time to warm up. By the time these hot water events pass, they haven't really raised the temperature of the water all that much. So you maintain these coral sanctuaries where the water is cool."
Although the area is still subject to other threats, such as coastal development and unsustainable fishing practices like dynamite fishing, researchers hope the recent discovery will stress the importance of protecting this area.
“If well protected,” says McClanahan, “this key transboundary marine ecosystem will remain a jewel of biodiversity for the entire East African coast."