Scientists with tiger sharks to discover the largest area of seagrasses on Earth.
A massive survey of the Bahamian Reefs — a cluster of underwater plateaus surrounding the Bahamas archipelago — reveals 92,000 square kilometers of ocean, marine biologist Oliver Shipley and colleagues report in November. The Nature of Communication. That area is about half the size of Florida.
The discovery expands the estimated global area covered by seagrasses by 41 percent — a potential role for Earth’s climate, says Shipley, the Herndon, Va.-based ocean conservation nonprofit Beneath the Waves.
Seagrasses can sequester carbon for millennia at rates 35 times faster than tropical rain. The newly deformed seagrass can store 630 million metric tons of carbon, or about a quarter of the carbon captured by seagrasses worldwide, the team estimates.
Mapping that many seagrass beds would be needed, says Shipley. Guided by previous satellite observations, he and a collegiate pigeon surveyed the meadows 2,542 times in the sparkling blue waters. The team also recruited eight tigers to support their efforts. Like lions that stalk wildly through the tall grasses of the African savannah, they roam the undulating plains of seagrass to graze the animals to eat (SN: 1/29/18; SN: 5/21/19; SN: 2/16/17).
“We wouldn’t be anywhere close to describing how far we’ve come without the help of tiger sharks,” says Shipley.
A team caught the sharks with drums and pulled each one into a boat, mounting a camera and tracking device on the animal’s back before releasing it. The sharks were typically in the water in under 10 minutes. The team operated like a “NASCAR cage crew,” says Shipley.
Researchers have previously suggested that sea turtles feed on tracks and manatees to locate pastures. But tiger sharks were a tough choice because they roam farther and deeper, says Marjolijn Christiansen, a marine ecologist at Wageningen University & Research in the Netherlands, who was not involved in the new work. “This is an advantage.”
Shipley and colleagues plan to collaborate with other animals — including ocean sunfish — to discover more underwater meadows (SN: 5/1/15). “With this [approach]’ the oysters of the world,’ he said.
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