Contamination levels in part of Tampa Bay near a massive discharge of polluted water from the old Piney Point fertilizer plant site have declined, researchers said Monday.
Initial results show the effects of the release in early April were relatively contained in an area of lower Tampa Bay, according to professors at the University of South Florida College of Marine Science. But many questions remain about the consequences of the spill for fish, seagrasses and what — if any — harm might emerge over time.
“We’re fairly fortunate that we didn’t see a long-lived, widespread effect on that ecosystem,” said Thomas Frazer, dean of the college.
Researchers from the university began taking samples from Tampa Bay while the release was ongoing. Early on, they reported a bloom of a form of algae thought to be non-toxic, immediately around Port Manatee. It encompassed about 10 square miles. The bloom has since dissipated, they said Monday, along with concentrations of nutrients such as nitrogen and phosphorus. Over time, the wastewater was flushed and mixed into the greater bay, reducing concentrations. Today, the scientists believe levels are more in line with historic averages.
Researchers are still awaiting some lab results for metals such as cadmium, nickel and cobalt that could have been added to the bay off Piney Point, said Kristen Buck, a chemical oceanography professor. One outstanding question is whether nutrients from the spill are being held within sediment at the bottom of the bay, and therefore whether storms might one day stir them up, encouraging future algal blooms.
Technicians are also working with fish samples to understand how contamination might have affected marine life. Steve Murawski, a marine ecosystems professor, said he did not see fish from the area with lesions or obvious signs of damage.
“Fish were relatively abundant off Port Manatee,” he said.
The owner of Piney Point, HRK Holdings, pumped about 215 million gallons of polluted water to Tampa Bay last month. Florida Department of Environmental Protection regulators allowed the discharge in an attempt to reduce pressure on the site, fearing that a leak in a plastic-lined reservoir would burst open, causing the collapse of a wall and catastrophic flood.
Crews released the water through Port Manatee. It held high levels of nutrients that clean water advocates warned could — much like fertilizer on land — spur growth in algae, some of which are harmful.
The discharge was similar in nitrogen to dumping approximately 100,000 bags of hardware-store fertilizer into the bay over several days, according to one estimate from the Tampa Bay Estuary Program’s director.
Port Manatee sits between a couple of aquatic preserves, Cockroach Bay in Hillsborough County and Terra Ceia to the south.
Sampling over recent weeks has detected very low to low levels of the organism found in Red Tide around lower Tampa Bay, according to the Florida Fish and Wildlife Conservation Commission. Those results do not indicate a full-on bloom. Sustained Red Tide is a major concern, because it can cause fish kills, breathing trouble for people along the shore and shellfish harvesting closures.
The Piney Point discharge alone would not cause the Red Tide to show up in Tampa Bay, researchers have said, but extra nutrients could help fuel a bloom.
University of South Florida scientists said they will keep taking samples and analyzing results over the next month.
“We should not be walking away from this,” Murawski said.
Frazer, the dean, said the Piney Point crisis has shown the need for consistent environmental monitoring in Tampa Bay, so scientists have a solid baseline by which to measure the effects of pollution. He recently wrote in a letter to the Tampa Bay Times that “we have not invested adequately in a robust and consistent monitoring of Tampa Bay despite its role in providing a backbone to the region’s economy,” and researchers wished they had of a greater record of data to inform studies of Piney Point.
On Monday, he said, “We need to better understand how the ecosystem in the bay responds to a pulse event like this.”