Is red tide outbreak in southwest Florida a threat to Palm Beach County?

A late-season bloom of red tide has a foothold in Southwest Florida with a toxic punch causing fish kills and triggering a beach hazard alert late last week. But experts said the chances it will reach Palm Beach County are low.

As of Friday, concentrations of the harmful Karenia brevis algae were measured at high levels in parts of Lee and Collier counties with about 40 reports of fish kills between late December and Sunday.

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Richard Stumpf, a scientist with the National Centers for Coastal Ocean Science, said the current bloom began in November, two to three months later than normal.

While the red tide has been sloshing around between Captiva and Marco Island, Stumpf said NOAA is watching its movement in case it gets closer to the Keys – and currents that could bring it to the east coast. 

“As for the east coast, I can only go with past occurrence at this point, which is that east coast ‘red tides’ are rare,” Stumpf said Monday.

In late September 2018, the bacteria – deadly to marine mammals, fish and birds – was so long-lasting and widespread it made its way into the Florida Current, which runs through the Florida Straits and into the Gulf Stream.

The Gulf Stream’s proximity to Palm Beach County meant strong easterly breezes brought the aerosolized red tide to shore, closing beaches and causing respiratory problems in humans including scratchy throats, trouble breathing and watery eyes.

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Dead fish were reported on beaches from Boca Raton to Jupiter. MacArthur Beach State Park closed after scores of dead fish were found rolling in the whitewater or trapped in the wrack line. 

Previous to 2018, Palm Beach County hadn't experienced a full-blown red tide since January 2008. Florida Fish and Wildlife records show only nine high-level east coast red tide instances since 1953. 

MORE: PHOTOS: Red tide closes Palm Beach County beaches

Gil McRae, director of the Florida Fish and Wildlife Research Institute, said last month that cloud-obscured satellite images made it difficult to detect the current red tide bloom. 

The first indication the algae had reached the west coast came when more than a dozen sick cormorants were brought into a rehabilitation facility on Sanibel Island and tested positive for red tide brevetoxins, McRae said during a December FWC commission meeting. 

“As of right now it doesn’t appear to be nearly as large scale as what we’ve seen in the recent past,” McRae said about the bloom. “Given it’s a late season red tide, we are expecting it to behave differently, so we are doing our best to stay on top of it.”

Karenia brevis grows naturally 20 to 40 miles offshore in the Gulf of Mexico. It's possible the active 2020 hurricane season, which included the Oct. 31 to Nov. 13 Hurricane Eta in the Gulf of Mexico, disrupted the currents that bring red tide to the west coast, said Kate Hubbard, FWC scientist and lead of the Research Institute's harmful algal bloom program. 

The red tide toxin is a systematic killer, working its way up the food chain from little snails on sea grasses eaten by manatees to fish eaten by turtles, birds and bigger fish.

The toxin it produces affects the nervous system. That means manatee drown when they can't get to the surface for air, turtles swim in circles, and pelicans lose their waterproofing because they can no longer preen themselves. 

Red tide usually subsides by the end of March into early April.

The 2020 rainy season — which lasted deep into November for Palm Beach, Broward and Miami-Dade counties — may have made the southeast coast more vulnerable to red tide, said Florida Atlantic University algae expert Brian LaPointe.

“This means more nutrient-rich runoff and slightly lower salinity values along the east coast, which could help support a red tide,” LaPointe said. “But this would happen only if enough seed Karenia brevis is transported from the west coast to the east coast via the Loop Current.”

Check the current status of red tide in Florida at this website:

myfwc.com/research/redtide/statewide/

Kmiller@pbpost.com

@Kmillerweather