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Tiger Sharks Find World's Biggest Blue Carbon Sink

Seagrass ecosystems form lush, underwater meadows and play host to an incredibly diverse range of sea animals like fish, turtles, crabs, and other marine mammals. They are also one of the most efficient global sinks of carbon dioxide on Earth - roughly 35 times more efficient than rainforests.

Tiger shark swimming over seagrass meadow in the Bahamas
Credit: Cristina Mittermeier | SeaLegacy

It was always known that there were vast seagrass meadows in the Bahamas but the true extent of the meadows was discovered thanks to tiger sharks. How so?

Researchers attached bio-logging cameras on the dorsal fins of the sharks, and then used satellite tags to track the individual tiger sharks as they swam in the Bahamas. Though cameras have been used on animals before, this study showed the first-ever use of 360-degree cameras on a marine animal, to map seafloors, the authors told Popular Science.

Whilst helping map the seafloor, "we found that tiger sharks spent around 70 percent of their time swimming over seagrass meadows," Wells Howe, a program manager on Beneath the Waves‘ Blue Carbon project, said in an interview with PopSci.

The sharks proved to be of immense help; they allowed researchers to peer into areas inaccessible by humans. They swam more than 2,465 miles in both regions of the Bahamas banks. Thanks to the cameras, the researchers were also able to map - albeit unexpectedly - the extent of the seagrass meadows.

Scientists now believe that there up to 92,000 km2 (35,521 square miles) of seagrass habitat across The Bahamas Banks. That's very good news as coastal seagrass beds store up to 83,000 metric tons of carbon per square km, according to the US National Science Foundation.

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