Researchers warn red tide is back in Southwest Florida

It may not be killing fish or burning human throats yet, but red tide is lurking along Southwest Florida’s shoreline.

Scientists sampling water for Karenia brevis, the microscopic toxic algae that produces red tide, find concentrations are declining along many Sanibel beaches, though at Lighthouse Beach, researchers from the Sanibel Sea School found concentrations of 300,000 cells per liter of water, which is considered to be a “medium” measurement.

At that level, which can cause respiratory irritation, shellfish harvesting is stopped, according to the Florida Fish and Wildlife Conservation Commission. However, as of Wednesday’s update, there’d been no reports of respiratory irritation suspected to be related to red tide.

"(It) was observed over the past week in Southwest Florida at background to low concentrations in 26 samples and at bloom concentrations," the FWC said in a release. "These observations suggest that a small, patchy bloom of  K. brevis is present along and just offshore of Lee and Collier counties."

A map of the coastline also showed a spot with a "medium" concentration near Vanderbilt Beach in Collier County.

FWC's Friday report was not available at press time.

“I haven’t been smelling anything or feeling any effects of it,” said Rick Bartleson, a research scientist with the Sanibel-Captiva Conservation Foundation who regularly samples the region’s water. “The counts have been coming down this week.”

Last week, the Department of Health in Lee County warned that Captiva beachgoers might have "mild and short-lived respiratory symptoms, such as eye, nose and throat irritation similar to cold symptoms."

Health officials recommend that people experiencing these symptoms stay away from beach areas or go into an air-conditioned space. 

"The last few days, especially since Sunday, it was pretty dense, but I went out this morning and the counts were down," Bartleson said Friday afternoon.

That’s not to say a bigger bloom won’t develop, especially after the sustained blasts of nutrient-laden water traveling down the Caloosahatchee to the estuary, said Calusa Waterkeeper John Cassani.

The U.S. Army Corps of Engineers has been releasing water from Lake Okeechobee since October to lower levels in the lake and ease pressure on its aged earthen dike. The good news, water managers say, is that the Corps has been able to steadily reduce the flows to the river.

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Environmental advocates want the freshwater releases stopped entirely.  The tidal estuary needs some freshwater to stay balanced and keep living things like oysters healthy.

“I’d hesitate to say ‘Stop the discharges,’" said Cassani, “Because as soon as it stops raining for two weeks, we’re going to need a little water.”

More:Red tide spreads out, lingers along coast

At high concentrations, red tide can be devastating to sea life and make humans sick.

The Clinic for the Rehabilitation of Wildlife has received a number of double crested cormorants and a handful of other fish-eating birds, about 60 in total since the beginning of November, with symptoms of red tide. Most of these birds have been admitted from the Fort Myers Beach area. Samples showed they had red tide toxins in their blood.

Fish kills and breathing irritation can start once levels reach 10,000 cells per liter, according to the Florida Fish and Wildlife Conservation Commission, the state agency that monitors red tide.

Red tide on satellite

The bloom is strong enough to show up on satellite imagery from the National Oceanic and Atmospheric Administration, which has shown some patches in water along the Southwest Florida coast, with one area off Collier’s coast reading "high."

Red tide is caused by the organism Karenia brevis and is naturally occurring in the Gulf of Mexico, although many water quality scientists say it can be fed by human-sourced nutrients when the blooms get close to shore.

In 2017 and 18, the region suffered through a lingering red tide bloom that killed millions of pounds of sea creatures and clobbered the local tourism, real estate and recreational fishing industries.

Water quality scientists at the University of Miami say red tide blooms are more frequent, stronger and longer in duration than they were before modern development, farming and urbanization of coastal areas.

Red tide tips

Here are recommendations from the Florida Department of Health:

If you have chronic respiratory problems, be careful and consider staying away from the location as red tide can affect your breathing.

Do not harvest or eat shellfish and distressed or dead fish from areas with red tide. If fish are healthy, rinse fillets with tap or bottled water and throw out the guts.

Keep pets and livestock away from water, sea foam and dead sea life.

Residents living in beach areas with red tide are advised to close windows and run the air conditioner (making sure that the A/C filter is maintained according to manufacturer’s specifications).

If outdoors around red tide, residents may choose to wear paper filter masks, especially if onshore winds are blowing.

Florida Poison Control Centers have a toll-free 24/7 hotline for reporting of illnesses, including health effects from exposure to red tide at 1-888-232-8635.