Red tide blamed for 64 sea turtle deaths on southwest coast; will the toxic tide reach us?

A red tide stalks Florida's gentle southwest coast with dozens of sea turtles felled by its paralyzing toxin found at high levels since last month.

A spread to the Atlantic Ocean is not expected, but aspects of the recent outbreak are puzzling a lead researcher who said steering currents and bloom breadth can be unpredictable.

Robert Weisberg, who leads the University of South Florida's Ocean Circulation group, said conditions so far this fall are different than during the red tide assault of 2018 when a potent and persistent bout of Karenia brevis algae landed on Palm Beach County's shores.

Most Palm Beach County beaches were closed the first week in October 2018 after waters tested positive for the saltwater infection -- a rare plague on the east coast that had officials scrambling to clean up dead fish and warn beachgoers of potential breathing problems.

Red Tide Levels Jump in Southwest Floridahttps://t.co/n74m3qmcnspic.twitter.com/RWbO6F75lg

-- Sean Breslin (@Sean_Breslin) November 22, 2019The red tide is currently traveling on the vagaries of the wind between Venice and Marco Island with high concentrations reported Wednesday in Sarasota, Charlotte, Lee and Collier counties.

Last year, a wiggle in the Gulf of Mexico's warm loop current contributed to the more severe outbreak and spread to the Atlantic.

"We tend to get red tide every year and it lasts for a few months, but the really bad years, when we get really horrendous ones like last year, it can get carried to the east coast and up to the Panhandle," Weisberg said. "We really had it everywhere."

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The loop current comes up from the Caribbean between the Yucatan Peninsula and Cuba into the Gulf of Mexico. It then hooks around and moves through the Florida Straits becoming the Gulf Stream, or Florida current, along the east coast.

Last year, the loop current sidled east toward the West Florida Shelf near the Dry Tortugas where it triggered an upwelling that forced nutrient-laden waters from the bottom of the ocean to the surface.

New red tide cells bubbled up also, and were carried more directly by the loop current through the Florida Straits to the east coast -- an intravenous feed of poison.

"We don't have that upwelling circulation going on right now so whatever is near the shore is staying near the shore," Weisberg said.

But he said the loop current's movements are capricious and once it cozies up to the Dry Tortugas, it tends to stay there a while.

Richard Stumpf, a scientist with the National Centers for Coastal Ocean Science, said 2018's red tide reached the loop current near the Dry Tortugas in late August through September. This year, it hasn't been seen farther south than Cape Romano, south of Marco Island.

"Combined with it being late in the season, I'd say there is a low risk of Karenia brevis making it to the east coast of Florida," he said.

Red tide, a naturally occurring phenomenon, grows far offshore in the Gulf of Mexico and can pile up near the coast in the fall as winter wind patterns blow cold fronts into Florida. It prefers ocean water, unlike freshwater blue-green algae, and is usually gone by the end of March.

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Red tide produces a toxin that affects the nervous system. It can work its way up the food chain from tiny snails on sea grasses eaten by manatees, or in fish eaten by turtles, birds or bigger fish.

The carnage on the west coast last year included tons of dead fish, manatees, dolphins, turtles and birds.

#ICYMI Our #RedTide Respiratory Forecast, developed in partnership with @GCOOS1 and initially implemented in Pinellas County in 2018, has been expanded to 3 beaches on Sanibel Island. Learn more: https://t.co/6mlb2eBqNLpic.twitter.com/JUfoFtunDW

-- NOAA Coastal Oceans (@noaacoastalsci) November 22, 2019By the end of 2018, 824 manatees were dead, done in either by boats, cold stress, natural causes or red tide. About 289 deaths (35 percent) were directly attributed to red tide.

This year, manatee deaths attributed to red tide stand at just 10, according to the Florida Fish and Wildlife Conservation Commission.

Sixty-four sea turtle deaths have been linked to the current bloom, but that number is likely to grow.

The Naples Daily News reported this week that Collier County sea turtle expert Maura Kraus reported 60 sea turtle strandings in October.

"Last year, the highest (stranding count) was 27 during the month of July," Kraus said. "I don't think we've ever had 60 in a month before."

Weisberg said this year's bloom started near the shoreline, instead of the more typical scenario of an offshore growth that is blown toward the shore.

"There are some years where it has a mind of its own," he said. "This year is kind of a mystery."

Kmiller@pbpost.com

@Kmillerweather

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