Seaweed is burying the beaches of the Caribbean and the Gulf of Mexico, choking the shoreline, killing what lives along it and emptying towns that live on visitors. The University of South Florida's Optical Oceanography Lab counted some 27 million metric tons of sargassum across the Atlantic, the Caribbean and the Gulf in July, in a report released Friday.
What has changed is where the weed grows. Until this year the belt fed itself on the crossing from West Africa and arrived on the current; now scientists are recording it reproducing in quantity inside the Caribbean and the Gulf. Brian Barnes, a marine scientist at the university, said none of this is normal. Last year's record of 40 million metric tons, he said, was large enough that it never really left, and it seeded a bloom of its own. The belt has grown since 2011; researchers point to farm runoff, warmer water and shifting winds.
Mexico said Thursday it would put $115 million against the problem. On its worst days it reckons 9,000 tons come ashore on its Caribbean coast and that it can lift 1,200. In Playa del Carmen a waiter, Alan Vázquez, shut his restaurant one evening for want of customers; the decomposing weed has turned the turquoise water black. Four of his colleagues were laid off two months ago, and businesses in Quintana Roo put the first half of the year down 30 percent.
Out at sea the floating mats are habitat: turtles, fish and seabirds breed in them. The same weed near the coast strips oxygen from the water, smothers mangrove roots and shades out coral and sea grass, and on the sand it can stop newly hatched turtles reaching the sea, while the machines that clear it wreck their nests. Puerto Rico's natural resources secretary said he could not recall this much of it in so many places at once.
The level is SARGASSUM SHIFT, built for the original Nintendo Entertainment System. That distinction is the game: a skiff works a current seam, nursery on one side, beach on the other, netting what has come inshore, dropping booms against the rest, and clearing a path for four hatchlings before the window shuts. Net the offshore mats instead and the habitat score falls. Play it here in the browser, or download the ROM and run it on real hardware.