Tiger sharks helped uncover the world’s largest seagrass prairie

Scientists have teamed up with tiger sharks to uncover the biggest expanse of seagrasses on Earth.  

An enormous survey of the Bahamas Banks — a cluster of underwater plateaus surrounding the Bahama archipelago — reveals 92,000 sq. kilometers of seagrasses, marine biologist Oliver Shipley and colleagues report November 1 in Nature Communications. That space is roughly equal to half the dimensions of Florida.

The discovering expands the estimated world space coated by seagrasses by 41 p.c — a possible boon for Earth’s local weather, says Shipley, of the Herndon, Va.–primarily based ocean conservation nonprofit Beneath The Waves.

Austin Gallagher, a marine biologist from ocean conservation nonprofit Beneath The Waves, surveys a seagrass area within the Bahamas Banks.Cristina Mittermeier and SeaLegacy

Seagrasses can sequester carbon for millennia at charges 35 occasions quicker than tropical rainforests. The newly mapped sea prairie might retailer 630 million metric tons of carbon, or a couple of quarter of the carbon trapped by seagrasses worldwide, the staff estimates.

Mapping that a lot seagrass was a colossal job, Shipley says. Guided by earlier satellite tv for pc observations, he and colleagues dove into the glowing blue waters 2,542 occasions to survey the meadows up shut. The staff additionally recruited eight tiger sharks to assist their efforts. Much like lions that stalk zebra by way of tall grasses on the African savanna, the sharks patrol fields of wavy seagrasses for grazing animals to eat (SN: 1/29/18; SN: 5/21/19, SN: 2/16/17).

“We wouldn’t have been capable of map anyplace close to the extent that we mapped with out the assistance of tiger sharks,” Shipley says.

The staff captured the sharks with drumlines and hauled each onto a ship, mounting a digital camera and monitoring gadget onto the animal’s again earlier than releasing it. The sharks had been usually again within the water in beneath 10 minutes. The staff operated like “a NASCAR pit crew,” Shipley says.

Researchers had beforehand steered monitoring seagrass-grazing sea turtles and manatees to find pastures. However tiger sharks had been a wise selection as a result of they roam farther and deeper, says Marjolijn Christianen, a marine ecologist at Wageningen College & Analysis within the Netherlands who was not concerned within the new work. “That’s a bonus.”

Digital camera-equipped tiger sharks like this one helped uncover the world’s largest seagrass mattress, penetrating areas too deep or distant for divers.

Shipley and colleagues plan to collaborate with different animals — together with ocean sunfish — to uncover extra submarine meadows (SN: 5/1/15). “With this [approach], the world’s our oyster,” he says.

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