Red tide crisis: The science behind the toxic algal bloom on Florida’s Gulf Coast



Florida’s purple tide, which was declared an emergency by Gov. Rick Scott on Monday, has been devastating marine life on Florida’s Gulf Coast this summer time. Seashores have been plagued by lifeless sea life on account of the naturally occurring poisonous algae.

“A purple tide, or dangerous algal bloom, is a higher-than-normal focus of a microscopic alga (plantlike organism),” explains the Florida Fish and Wildlife Conservation Fee, in an announcement. “In Florida and the Gulf of Mexico, the species that causes most purple tides is Karenia brevis, typically abbreviated as Okay. brevis. To differentiate Okay. brevis blooms from purple tides brought on by different species of algae, researchers in Florida name the previous the ‘Florida purple tide’.”

The realm isn’t any stranger to purple tide occasions. “Purple tides have been documented within the southern Gulf of Mexico way back to the 1700s and alongside Florida’s Gulf coast within the 1840s,” explains the Florida Fish and Wildlife Conservation Fee. “Fish kills close to Tampa Bay have been even talked about within the data of Spanish explorers.”


This summer time’s purple tide has already brought about the deaths of lots of of sea turtles, in addition to giant fish like goliath grouper and even manatees. In locations like Longboat Key, greater than 5 tons of lifeless fish have been faraway from seashores.

This week, 9 lifeless dolphins have been present in Sarasota County. Marine biologists are investigating whether or not the deaths are associated to purple tide.

Purple tides may also trigger respiratory irritation for people. “For folks with extreme or power respiratory circumstances, reminiscent of emphysema or bronchial asthma, purple tide could cause critical sickness,” officers clarify.


The poisonous algal bloom can final as little as just a few weeks or longer than a yr, in response to the Florida Fish and Wildlife Conservation Fee, which notes that purple tides may even subside after which reoccur. “The length of a bloom in nearshore Florida waters is determined by bodily and organic circumstances that affect its development and persistence, together with daylight, vitamins and salinity, in addition to the velocity and path of wind and water currents,” it says.

The most recent purple tide has unfold all through the Gulf of Mexico, drifting within the water because it started in October. Stretching about 150 miles, it is affecting communities from Naples within the south to Anna Maria Island within the north; the most recent bloom seems to be shifting northward.

On Monday, Florida Gov. Scott declared a state of emergency as a consequence of impacts of purple tide in Collier, Lee, Charlotte, Sarasota, Manatee, Hillsborough and Pinellas counties. “As Southwest Florida and the Tampa Bay space continues to really feel the devastating impacts of purple tide, we are going to proceed taking an aggressive method by utilizing all out there assets to assist our native communities,” he stated, in an announcement. 

The Florida Fish and Wildlife Conservation Fee explains that the purple tide will be present in bays and estuaries however not in freshwater techniques reminiscent of lakes and rivers. “As a result of Okay. brevis can’t tolerate low-salinity waters for very lengthy, blooms normally stay in salty coastal waters and don’t penetrate higher reaches of estuaries,” it says. “Nevertheless, different dangerous algae, together with cyanobacteria (blue-green algae), usually bloom in freshwater lakes and rivers.”

Final month, Gov. Scott declared a separate emergency to fight algal blooms brought on by Lake Okeechobee water discharges from the Military Corps of Engineers.

The Related Press contributed to this text.

Observe James Rogers on Twitter @jamesjrogers


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