Fit to be ‘tide’: County gives presentation on understanding, living with red tide
The signs on the beach are often obvious. Dead fish washed up on the shore. A stinging sensation in the eyes and noses of sun worshipers.
But that doesn't mean everyone understands what creates the problem of red tide.
To help people learn about the reality of this naturally occurring but unpleasant phenomenon, and debunk some of the myths surrounding it, the Collier County Pollution Control Division has held a series of public talks. On Tuesday, March 28, the county’s principal environmental specialist Rhonda Watkins visited the South Regional Library to share her expertise.
The organism that causes red tide, a microscopic dinoflagellate, is always present, Watkins told the audience gathered in the library’s meeting room, but only when conditions are right do the two-tailed creatures reproduce in massive numbers and produce a bloom or outbreak. There are various types of red tide throughout the world, and in the Gulf of Mexico, our particular strain is called Karenia brevis, which produces a neurotoxin called brevetoxin. Wave action or turbulence releases the toxin into the water, and then inhaling seaspray transmits it to humans.
The toxin has been measured as far as one mile inland, which is why people with respiratory issues are cautioned to stay away from the water during severe blooms. It can trigger asthma attacks or immune responses, and blooms have been correlated with increased emergency room visits for asthma, pneumonia and bronchitis. Most symptoms are relieved when you leave the beach.
Fish kills occur when red tide levels are medium or higher, said Watkins, with bottom fish such as mullet, catfish and batfish typically the first to be affected. Technically, they are not poisoned; “the toxin paralyzes the fish and they suffocate because they can’t swim.”
Shellfish, including oysters, clams, mussels and whelks, concentrate the toxin but are themselves immune. They can cause neurotoxic shellfish poisoning (NSP) in humans, and the toxin cannot be detected by taste. There are no documented cases of human deaths from NSP, but commercially harvested shellfish are tested for brevetoxin.
“Do not harvest shellfish on your own,” urged Watkins. Crustaceans, including crabs and shrimp, and the fillets of finfish, are typically safe to eat during red tide events, she said. Birds, sea turtles, dolphins and manatees can be affected by red tide, with the highest manatee red tide mortality – 277 – occurring in 2013. Dogs should also be kept away from the water during blooms.
Red tide was reported in Florida in the 1500s by the early Spanish settlers, scientifically documented in 1844, and the specific organism responsible identified in 1947. Blooms start 40 to 50 miles offshore, where the Loop Current moves warm, nutrient-rich water through the Gulf of Mexico. In general, communities further north in Florida have more problems with red tide than Collier County does. In response to a question, Watkins said red tide was not related to water released from Lake Okeechobee, and does not seem to be driven by fertilizer runoff, although those remain as serious problems for our waters.
Of the approximately 40 in the audience, well over half were boaters, and 10 were members of Team Ocean, a citizens group dedicated to helping out with marine stewardship and related efforts such as bird counts. Also in the audience was Collier County Commissioner Donna Fiala, hearing the presentation for the third time, she said.
“I learn something new every time,” said Fiala. “I learned it has always been present, and affects different people in different ways. I thought there were ways you could stop it.”
Actually, said Watkins, not only can we not eliminate red tide, we have only limited capability to predict it, or even track it successfully. Scientists are using satellite imagery, direct water samples and even aerial drones to monitor the water.
Red tide information, broken down beach by beach, is available on Collier County’s Red Tide Hotline, at 239-252-2591, and you can be notified via email by signing up at www.colliergov.net. Signs are posted on public beaches when red tide blooms occur.
Or you can sniff, and see if your eyes and nose sting.