Elevated levels of Red Tide were detected in water samples taken from parts of Tampa Bay. Now Hillsborough County health officials are advising people against swimming in certain areas.
Medium concentrations of Red Tide were detected in four samples from June 1 and June 2 pulled around Port Manatee in lower Tampa Bay, according to a map from the Florida Fish and Wildlife Conservation Commission. That area, near the Hillsborough-Manatee border, is where more than 200 million gallons of wastewater were discharged in early April from the old Piney Point fertilizer plant property.
“It’s sort of a worst-case scenario for us right now going into the rainy season,” said Ed Sherwood, executive director of the Tampa Bay Estuary Program.
Runoff from storms typically washes pollution into the water. But the Piney Point release makes this season different.
“It’s basically been seeded or fertilized already,” Sherwood said.
He said the worst outcome for Tampa Bay would be if the Red Tide lingers and grows more intense, killing fish, which would hurt both the ecosystem and the local economy. The state’s lower Gulf Coast experienced a devastating Red Tide event from 2017 to 2019.
The Florida Department of Health in Hillsborough County sent a bulletin to warn that blooms in lower and middle Tampa Bay could cause respiratory irritation and fish kills. The highest levels were detected near Moody Point and Manbirtee Key, according to the agency, with lower but still problematic levels near Camp Key and Little Cockroach Island.
“Some people may have mild and short-lived respiratory symptoms such as eye, nose and throat irritation similar to cold symptoms,” health officials wrote. “Some individuals with breathing problems such as asthma might experience more severe symptoms. Usually symptoms go away when a person leaves the area or goes indoors.”
Officials urge people not to swim close to dead fish, to be careful or stay away from the water if they suffer from chronic respiratory problems and — if they catch healthy fish in the area — to rinse fillets with clean water and throw out the guts. They suggested that residents should keep pets away from the water in places where the samples were drawn.
Clean water advocates have worried ever since the Piney Point release that high levels of nitrogen in the polluted water could fuel toxic algal blooms in Tampa Bay.
Last week, University of South Florida researchers said contamination from the discharge had diluted in the bay without major initial problems, but they still had questions about the long-term consequences.
Scientists have said pollution from Piney Point would not on its own cause Red Tide to show up here, but the added nutrients could help a bloom grow.
Very low to low concentrations of the organism in Red Tide have been found around the region for weeks, but the latest monitoring shows an intensification.
“Once they start approaching medium in more than one site, that’s what gives us cause for concern,” Sherwood said.
The Conservation Commission, in a Red Tide update issued Wednesday, did not report any fish kills in Tampa Bay. If the Red Tide here reaches high concentrations, Sherwood said, dead fish will probably follow.
Capt. Scott Moore, who fishes out of Holmes Beach, said medium levels of Red Tide can kill baitfish in a boat’s live well when a captain goes through a bloom. He also questions the impact of the Piney Point discharge.
“I just think that’s very strange that Red Tide went straight up to the port,” Moore said.
Soon after the release, which the state allowed amid fears that a leaking reservoir on the former plant site could collapse, scientists found a non-toxic algae bloom near Port Manatee.
In the weeks since, Sherwood said, another type of algae called Lyngbya has persisted from Anna Maria Sound to the south. Test results to determine whether that bloom is connected to Piney Point have not yet come back, he said.
Nutrients from the contaminated water may have been used up by other marine organisms at first, according to Sherwood. But as those die off, the nitrogen can be released back to the bay, serving as a potential fuel source for Red Tide.
Sherwood said scientists will be watching to see where the Red Tide might drift and whether it will worsen in the coming days. The Conservation Commission is expected to provide another status update on Friday.