Keeping an eye on red tide in Southwest Florida
On Oct. 25, the Florida Fish and Wildlife Conservation Commission (FWC) reported that the red tide organism (Karenia brevis) was found in background to high concentrations in 49 samples offshore of Southwest Florida, according to the Sanibel-Captiva Conservation Foundation.
The SCCF reported that red tide — a harmful algal bloom caused by K. brevis — can develop or intensify due to multiple factors: wind, ocean currents, or upwellings of nutrient-rich water from storms. Once a red tide bloom is present, polluted watershed runoff or Lake Okeechobee releases can lead to intensification. It can have massive impacts on ecosystems, communities and economies.
In Lee County, data from the NOAA National Center for Coastal Ocean Science (NCCOS) and the FWC indicate multiple offshore samples with very low to medium red tide concentrations. The SCCF Marine Laboratory’s samples from the beach on Sanibel on Oct. 29-30 did not detect K. brevis.
“The dynamics of this event are hard to predict,” Marine Lab Director Dr. Eric Milbrandt said on Oct. 30. “Over the last week the bloom seems to have gone from larger and higher counts around Tampa and where Hurricane Milton made landfall in the Sarasota area, to being transported south, and now it seems to be moderating and getting smaller.”
Fish kills have been reported along Boca Grande and on Manasota Key, but they could be concentrated cases.
“We don’t know if it’s going to get worse or going to get better. The possibility of fish kills and wildlife in distress, that’s certainly something we’re watching out for,” he said. “Otherwise we are in wait-and-see mode.”
K. brevis cells release a toxin that attacks the nervous system of animals. The neurotoxins, called brevetoxins, are often fatal to fish, birds, sea turtles and marine mammals and can have adverse impacts in humans. Report wildlife behaving erratically — unable to stand or fly, displaying tremors, or apparent weakness or confusion — to the Clinic for the Rehabilitation of Wildlife (CROW), where treatment can be administered. Contact CROW’s Wildlife Hospital at 239-472-3644, ext. 222.
The SCCF reported that although Lake Okeechobee releases to the west coast of Florida began on Oct. 26, average flows to the Caloosahatchee remain in the optimum range for estuarine health. If the red tide bloom does intensify, it will advocate for no stressful or damaging flows (greater than 2,100 cubic feet per second at the W.P. Franklin Lock and Dam) from Lake Okeechobee.