Red tide, a naturally occurring toxic algae bloom that can be harmful to people with respiratory problems has spread throughout the Gulf of Mexico, drifting in the water since it began in October. Red tide happens due to the presence of nutrients in the water and an organism called a dinoflagellate.
A detail photo taken through a microscope of Karenia brevis (red tide) cells during water sampling processing.
Stretching about 240 kilometers, it’s affecting communities from Naples in the south to Anna Maria Island in the north and appears to be moving northward. The algae turns the water toxic for marine life, and in recent weeks beachgoers have been horrified to find turtles, large fish like goliath grouper and even manatees wash up dead.
In late July, a 26-foot long whale shark washed ashore on Sanibel Island, which is known for its pristine beaches. In places like Longboat Key, more than 5 tons of dead fish have been removed from beaches. This week, nine dead dolphins were found in Sarasota County, and marine biologists are investigating whether the deaths are related to red tide.
The Florida Wildlife Research Institute says the number of dead and stranded sea turtles is nearly three times higher than average. More than 450 stranded and dead sea turtles have been recovered in four affected counties this year, and the institute estimates that 250 to 300 died from red tide poisoning. In Bradenton Beach, the stench was impossible to ignore.
Work crew clean up dead fish on Coquina Beach in Bradenton Beach, Florida.
“I can’t describe the smell. It’s like unbelievable. It makes you throw up,” said Holmes Beach resident Alex Kuizon, who has lived in the area for decades. “Off the west coast of Florida, we have persistent red tide events that occur with some frequency,” said Steve Murawski, a marine science professor at the University of South Florida.
Blue-green algae
Another algae problem plagues Florida’s waterways, Murawski said. Blue-green algae affect freshwater, and Murawski said it has a direct correlation to agricultural and urban runoff. “If you’ve got large nitrogen discharges, you could actually be fueling both the harmful algal bloom and the discharge of the blue-green algae. It’s an area of very active concern,”Murawski said.
Why this year’s red tide is so intense is up for debate. Some researchers have noticed aggressive blooms after hurricanes; Irma swept past Florida’s Gulf Coast in the summer of 2017 and a period of red tide affected Florida after the powerful 2004-2005 hurricanes.
