The thick, slimy brown ribbons are notorious for tangling the ankles of beachgoers and rotting in pungent piles. But kelp, according to its growing fan base, could also prove potent in protecting the health of oceans -- and us.

"We've got some bad water heading our way," said Betsy Peabody, founder and executive director of the Puget Sound Restoration Fund. In April, Peabody's small organization in Bainbridge Island, Washington, won a $1.5 million grant from the Paul Allen Family Foundation to investigate how cultivating the seaweed might help lessen the impacts of ocean acidification.

Other research has hinted at the sea plant's potential to prevent toxic algal blooms and provide habitat for marine life, as well as even generate sustainable energy and food while preserving scarce fresh water for humans.

"Kelp is a game-changer," said Bren Smith, owner of the Thimble Island Oyster Co., which grows a vertical farm of oysters, scallops, clams, mussels and kelp in Long Island Sound. "It is so resilient, fast-growing and does all of these powerful things."

Smith, too, referenced kelp's capacity to sweeten souring seas.

Rising levels of carbon dioxide are not only altering the global climate, but also changing ocean chemistry. A quarter of the greenhouse gas belched by coal and other fossil fuels is soaked up by seas. The result is increasingly acidic water that carries fewer carbonate ions, critical building blocks for the skeletons and shells of many valuable and vulnerable sea animals such as clams, crabs, lobsters, shrimp and sea butterflies.

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