Last year, a severe outbreak killed 149 manatees and helped make 1996 a record year for manatee deaths overall. This year's fatalities were discovered Nov. 6 through 26, mostly in Lee and Collier counties. One animal was found in Charlotte County on Nov. 14 in a canal off Ainger Creek. Tissue samples taken from the manatees were tested at the University of Miami. There, scientists detected toxins associated with red tide.
Red tide generates a neurotoxin that affects the nervous systems of fish and other creatures.
Scientists still aren't sure how the manatees absorb enough to kill them, or exactly what it does to them, Quigley said. Red tide is a natural phenomenon that occurs when Gymnodinium breve, a one-celled dinoflagellate, blooms in large numbers. The blooms usually begin several miles offshore in the Gulf of Mexico, and cause obvious problems only when they drift ashore. That's when dead fish turn up on the beach and beachgoers report irritation to their noses and throats - a symptom caused when toxins are released into the air by crashing waves. Before last year, scientists suspected that red tide might kill manatees.