Red tide levels are low, but growing season is just beginning
The good news is that a particularly strong red tide that's ravaged the area for about a year is retreating.
The bad news is that red tide season is just starting, and some speculate that the outbreak may be with us until early next year.
Tuesday marks one year since the National Oceanic and Atmospheric Administration first documented red tide conditions along Southwest Florida's coast.
It's the longest outbreak since a bloom formed in late summer 2004 and lasted until spring 2006.
And while red tide counts have been low in recent weeks, the growing season is upon us.
In case you missed it: Lee, Collier waters clear of red tide after Hurricane Michael
"Normally you'd expected a red tide to pick up a little later in the autumn if we've had a lot of watershed discharges from things like hurricanes, or heavy rain events, or if they're releasing a lot of water out of Lake Okeechobee," said Jim Beever with the Southwest Florida Regional Planning Council.
Hurricanes and tropical storms haven't impacted the area this year, and the rainy season has been average.
But there have been Lake O releases, and many think Hurricane Irma in 2017 was a culprit that stirred up nutrients that have fed the bloom this year.
Late summer into early fall is a time when rain water generally washes nutrients off the landscape and into local bays and the Gulf of Mexico and Atlantic Ocean.
Warm water temperatures combined with nutrient runoff fuel blooms.
Counts this summer in Southwest Florida have been as high as 200 million cells per liter but have been at natural, background concentrations in recent weeks.
Breathing irritation and fish kills can start once levels reach 10,000 cells per liter, according to the Florida Fish and Wildlife Conservation Commission.
Red tide has also popped up in other areas of the state.
"The latest reports show that we're below 1,000 cells per liter for Lee and Collier but it's still active (to the north) and there are spots active in the east coast and even north of Key West," Beever said. "So it's not completely gone from the state."
Water samples may be cleaner for Lee County waters but sick and injured animals continue to show up at the Center for the Rehabilitation of Wildlife, or CROW, on Sanibel.
"Even if the water is legitimately clear of Karenia brevis (the organism that causes red tide), once it gets into the food chain it can linger in there for quite some time," said CROW animals hospital director Heather Barron. "For us things really haven't changed in terms of our case load."
Barron said case loads tend to go up in October, and that they're at their highest in November and December.
Between January and April is typically when the red tides go away.
"This year has been an unusual year but I don't have any reason to think that things won't continue on as in years past," Barron said. "I don't expect this year to be substantially different in terms of the number of cases in terms of what we're getting from now until spring. I think it will be steady."
Beever said cooler water temperatures will eventually kill off the bloom, although conditions in the Gulf of Mexico off Fort Myers Beach are a balmy 84 degrees, according to the Sanibel-Captiva Conservation Foundation.
"But we're staying pretty warm right now," Beever said.
The National Oceanic and Atmospheric Administration says there is an above-average chance for above-average temperatures over the next three months.
Beever said Hurricane Michael could have helped break up the bloom but that it will take cooler conditions to make it fully go away.
"Normally you get this combination of cooler temperature and there is a lot less discharge in the dry season from the watersheds so there are less nutrients getting into the Gulf along with cooler water," Beever said.
The University of South Florida College of Marine Science predicts that currents should blow what red tide is still out there in a southwesterly direction over the next three days.
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