Already an endangered species, manatees are dying by the dozen off both coasts of Florida, Wired reports. Biologists say a red tide—an algal bloom that can be fatal to manatees, fish, and people—has killed 200 manatees in the Gulf of Mexico this year. But manatee deaths on the east coast, near Cape Canaveral, remain a mystery. "There are indications of the animals being otherwise completely healthy—but having died of shock and drowning," says a marine biologist.
Experts are combing through the stomachs of those manatees and finding a nontoxic seaweed that they don't normally eat. Perhaps an algal bloom that killed off manatees' regular diet of seagrass plays a role—if the bloom carries runoff from septic fields, storm drains, and fertilizer-laced lawns. Meanwhile, rescuers are having some success saving manatees in the Gulf and cleansing their system of toxins. "In contrast, I don’t know of any manatees that have been found alive from what’s happening on the east coast," says a biologist.