SEAWEED IS HAVING a moment. Once relegated to sushi rolls, kelp and other “sea greens” are now appearing in an array of American foods and beverages, including pasta, chips, burgers, butter, bread, beer, salsa, tea, muffins, and even ice cream. Enthusiasts love seaweed for its subtle umami taste, plentiful vitamin and mineral content, and environmental benefits: As they grow underwater, kelp forests can suck up nitrogen and phosphorus pollution in the ocean and absorb carbon dioxide; by doing so, they raise the pH of coastal waters and help reduce ocean acidification. When introduced in small amounts as a feed additive for cattle, some seaweed may even dramatically cut down on the methane—a potent greenhouse gas—emitted by cattle through their burps and farts.
As demand has grown, seaweed farming has flourished.…