Red tide, a recurring puzzle for Florida

(Sarasota) Sun, white sand, and turquoise water. Lido Key Beach in Sarasota would be a postcard-perfect Florida beach if it weren’t for the dozens of dead fish lying on the ground as a result of the red tide affecting this US state’s west coast.

Gerard Martinez

Agence France-Media

This recurring natural phenomenon, caused by the proliferation of microalgae “Karenia brevis”, occurred this year during spring breaka spring break during which thousands of young Americans meet on the Florida coast.

“We had a lot of cancellations,” said Jeff Napier, 62, an employee at the Lido Beach Resort. “People are getting sick. Why would anyone want to spend so much money and stay here” under the circumstances?

When the concentration of these harmful algae is very high, such as in recent weeks, they release a potent neurotoxin that can kill marine life and cause respiratory problems in humans.

Try Dick Bowser. “It smelled so bad,” recalls the 80-year-old tourist as he walked by the sea, stick in each hand, happy that the sea currents had temporarily kept the red tide away, giving him a short respite.

“I couldn’t get close to the beach,” he adds. “The constant cough bothered me. I had a sore throat every day, and eye or sinus problems.”

Jeff Napier, suffered five days of migraines and didn’t want to live with that. “We must treat this red tide,” he says, even if he doesn’t know how.

cutting edge research

50 km from Sarasota, scientists at the Mote Marine Laboratory have been working since 2020 to mitigate the impact of this phenomenon already known to Spanish explorers in the XV^H xvi^H After centuries of exchange with the indigenous people.

Their goal is to “destroy the algae, alter their toxins and have no appreciable effect on non-target species,” explains Dr. Michael Crosby, head and director of the lab.

The researchers’ center is 2600 m² They grow specimens of Karenia brevis and can test the substances for neutralization in huge saltwater tanks that mimic the Gulf of Mexico ecosystem.

Crosby said they have so far identified dozens of successful approaches and will spend the next two years finding the best way to use these solutions in the ocean.

The white-bearded scientist, with a smirk, walks proudly through the research center’s six laboratories, convinced that his team will succeed in reducing the environmental impact of the red tide and its consequences for the quality of life and economy in the region. .

“But we will not completely get rid of the red tide,” he exasperated.

Mainly because unlike other phenomena of harmful algal blooms, as a result of human activities such as agriculture, this phenomenon is natural.

Florida’s red tide begins 40 miles (64 km) off the state’s west coast, and moves inland or offshore depending on ocean currents.

This year’s seaweed eruption is largely due to the hurricane Ian that hit Florida in late September, according to Dr^s Crosby.

Once on the coast, they breed on contact with nutrient-rich waters, natural or agricultural.

“We are studying the extent to which human activity, particularly terrestrial nutrient inputs, can accentuate red tides in terms of intensity and duration,” explains Michael Crosby.

“But even if we wiped out all the humans in Florida, there would still be a red tide,” he says.

“It’s been like this for hundreds of years,” Jeff Napier, quitter frontman of the Lido Beach Resort, murmurs.