Red tide: When will it go away? Patchy blooms along Southwest Florida coastline persist
Rick Bartleson gets asked every year: Will red tide ruin my Southwest Florida stay?
Would-be vacationers from up north on the verge of a week on the Gulf Coast start seeing headlines about red tide and panic – understandably. So they call the Sanibel-Captiva Conservation Foundation research scientist for the inside scoop. Few are as close to the daily details as Bartleson, who regularly samples the region's saltwater for harmful algal blooms like Karenia brevis and other water-fouling microorganisms.
Bartleson can't offer any guarantees, especially lately.
For more than a month, red tide has been lingering in patches along the Southwest Florida coastline from Marco Island to Captiva and beyond. In high enough concentrations, it can make a day – or a week – at the beach miserable. In some places, it's killing fish.
Short-term, red tide toxins can produce effects ranging from back-of-the-throat tickling to coughs to blinding headaches. In the animal world, it can sicken or wipe out fish, birds and mammals like manatees and dolphins. Scientists are studying what it might do to humans over time.
Although other life forms can produces what's commonly known as red tide, in Southwest Florida, Karenia brevis is the usual suspect. It's a dinoflagellate, a single-celled organism that moves with a pair of thread-like whips called flagella and can make food from the sun by photosynthesizing as plants do. Yet it's not a plant. Karenia belong to the Protista kingdom, which includes amoebas and slime molds – and for that reason, some say it shouldn't be lumped with algae either. But for those potential visitors, such technicalities may be less important than whether or not the stuff is going to wreck their trip to the beach.
“Somebody from New Jersey called me yesterday,” Bartleson said. “Every year, when the red tide starts making the news, they start calling from wherever they are, because they want to know if they can come for vacation.”
He had to tell her it was “pretty bad down here (and) that there’s no sign of (red tide) disappearing.”
That’s not to say it won’t. Sometimes, Bartleson says, the red tide organisms themselves get a virus or bacteria – “some kind of infection that seems to take care of all of them all of a sudden and no matter how large the bloom is, it just all goes away at once.” But so far this year, “we’re not seeing any sign of it going away,” he said, and he can’t predict when it will. “I wouldn’t be able to say,” Bartleson said. “I don’t have that crystal ball.”
In Collier County, the most recent red tide samplings Jan. 7 show four of five county-maintained beaches with high counts of Karenia brevis. Barefoot Beach, at the county’s northern boundary had medium levels.
“Respiratory irritation is being reported at all Collier County beaches whenever winds are blowing onshore,” the county’s website says. “Numbers of dead fish being reported have diminished on Naples beaches, but have increased on Marco Island and in back bays of Moorings Bay, Naples Bay and Marco Island.”
In Lee County, levels have been highest near the Sanibel lighthouse, the causeway and the north side of the island.
Concentrations are measured by using a microscope to count how many cells are visible in a liter of water. Fewer than 1,000 are considered “background” levels and probably won’t trouble beachgoers or wildlife. Above 100,000 is “medium,” and will likely cause respiratory irritation and fish kills and other wildlife impacts, according to the Florida Fish and Wildlife Conservation Commission, which issues regular updates on conditions.
As of Wednesday, the bloom “persists in Southwest Florida," the report said. "Background to high concentrations of K. brevis were detected in 42 samples over the past week.” Thirty-two samples collected from Lee and Collier counties had concentrations above the 100,000 cell per liter threshold.
As Bartleson puts it, “We’re colonized with it and it’s sticking around, so far.”
Red tide symptoms, visible signs
Marco Island City Manager Mike McNees spent Wednesday traveling around to see how things look.
“From what I saw today and speaking to homeowners along the way where we have the worst accumulations, it’s been moving around and migrating,” McNees said. “A couple people told me it was bad here yesterday but fine today.”
Overall, he said it doesn’t seem to be a huge issue on the island, but there are isolated places where dead fish accumulate in canals, making things unpleasant.
“(Collier) County is very responsive on the beach front and dealing with kills there,” he said. “They clean the beaches because they have the access and equipment.” But it can be tricky for the city to get inland where fish kills build up in canals and back bays.
“We don’t have the equipment or capacity with city crews to send someone out there to clean up dead fish,” he said. The city does have a contract it can “piggyback” on, he said, but just “turning the meter on” costs the city $20,000.
McNees said his Wednesday tour of the island didn’t detect any irritation from the red tide. “Certainly, a number of calls have come in, but my observation today, up close, is it’s certain Mother Nature is doing her job,” he said. “By and large it looks like we're in good shape.”
In case you missed it:Red tide patches move along Southwest Florida coast
In Naples, Katie Laakkonen, an environmental specialist, said the city plans to release a public service announcement on red tide. Laakkonen said there are 16 beach ends with signs up to educate beachgoers on red tide, and the city’s community services staff rakes the beaches daily. A contractor to clean up dead fish in tidal waters and others can be mobilized to scoop dead fish from Naples Bay.
“The City coordinates closely with the County during these bloom events as the County is the repository for red ride data, dead fish and respiratory irritation reports from the public and staff,” she wrote in an email. “The County samples the beaches twice a week and distributes the data results to City staff and any public that wishes to receive it.”
Beyond dead fish, Calusa Waterkeeper John Cassani points out that the recent red tide is killing other sea creatures like crabs and shellfish. “I’m concerned about the animals that aren’t vey mobile trying to escape the toxicity,” he said. And, he notes, little is known about red tide’s long-term effects on wildlife. Chronic exposure might reduce reproductive success, re-route migrations or re-draw territorial boundaries.
Blooms can make trouble after they're gone, Cassani said. “There could be what they call a dead zone effect, when the bloom crashes and we see oxygen depletion, which may have as much effect on mortality as the direct toxicity.
“I just don’t think there’s a lot of good monitoring of birds and other animals higher in the food chain.”
Multiple suspects when blooms occur
So the next question, Cassani says, is: "What do we do about it?" The Gulf of Mexico is essentially an inland sea, he says. Researchers have long sought to understand how the surrounding landscape interacts with its warm, shallow waters and how runoff from the land might spark or feed blooms.
"If you look at where the chlorophyll concentrations are the highest – and chlorophyll is a proxy for algae – it seems to be around the very near-shore areas," Cassani said. "Maybe that’s because Karenia is relatively closer to the surface in-shore, but (maybe) it’s responding to higher nutrient concentrations."
He cites a University of Florida study from last August that “created a splash” by saying “anthropogenic nitrogen runoff facilitated the growth of K. brevis blooms near Charlotte Harbor and suggest that bloom events would be mitigated by nitrogen source and transport controls within the Caloosahatchee and/or Kissimmee River basins.”
That’s science-speak for “human runoff-fertilized blooms,” and goes against years of official statements exonerating humans of responsibility for the blooms.
This peer-reviewed paper “created an alternate narrative from some of these large interest groups that say the inland contributions are not a factor,” Cassani said, and bolsters the growing dissent from the oft-heard position that human activity doesn't affect red tide – a position mining and agricultural interests have used to absolve themselves of responsibility from blooms in the past, he said.
"This study tended to counter that narrative," he said.
As our understanding of red tide’s causes and consequences increases, so does citizen interest in avoiding and preventing it. Danette Kinaszczuk, manager with Collier County’s pollution control division, said whenever red tide shows up on county-maintained beaches, it posts signs notifying the public. This week, the county also is running an awareness campaign on its social media on dealing with red tide.
One tool, a website still in early stages, is the respiratory irritation forecast by the Gulf of Mexico Coastal Ocean Observing System (GCOOS).
The site uses data from HABScope and the National Weather Service to weigh the respiratory risk to people headed to the beach. It highlights risks using color coding and a “very low” to “high” scale, showing where the greatest potential for respiratory irritation can happen.
The county also put together a detailed Frequently Asked Questions page on its website. There, users can learn about the county’s red tide sampling, how to plan beach days during red tide events, and what they can do to help. Later this week, the county will post to its social media accounts a call to action about how individuals can help efforts against red tide, Kinaszczuk said.
“There are things people can do if they are upset and feel helpless,” she said. “It’s the little things like don’t overfertilize, clean up pet waste and don’t over-water. Every single thing we do on land can affect the water.”