Red tide, fish kill reported in Tampa Bay waters near Piney Point

MANATEE COUNTY — Red tide levels are rising in areas of Tampa Bay near Port Manatee, where 215 million gallons of nutrient-rich wastewater was released in April from the former Piney Point fertilizer plant.

The wastewater has high levels of nitrogen and phosphorus, leaving stakeholders waiting for answers to one looming question — whether Karenia Brevis, the organism that causes red tide, would find and thrive in those areas.

The Florida Fish and Wildlife Conservation Commission's daily sample reports on Thursday confirmed that K. Brevis has grown more abundant in the region. 

“We are seeing a cascade of different algae species that are able to capitalize on those nutrients,” said Maya Burke, assistant director of the Tampa Bay Estuary Program. “They are basically cycling through the system.”

Did you know?:Environmental groups prepare lawsuit against DEP, Port Manatee and owners of Piney Point

More:As toxic algae looms, Sarasota County calls to reduce use of fertilizer

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The red tide is impacting the southeastern shore of Tampa Bay, an ecosystem that boasts a significant amount of seagrass flats, hard-bottom habitats that support soft corals and sponges, and fishery resources.

“These are really shallow areas with very extensive seagrass flats,” Burke said. “Those seagrass habitats have been some of our most robust and healthiest within all of Tampa Bay and really this region of Florida.”

Areas near Port Manatee now show medium levels of K. Brevis in the area, which is enough to cause respiratory irritation and has the potential for fish kills.

Staff from Tampa Bay Estuary Program visited sites near Port Manatee on Friday and reported a fish kill associated with the bloom to the FWCC hotline, Burke said. No further details were available on the preliminary sighting.

The organization has regularly sampled waters near the Piney Point wastewater release and has documented various algae blooms in the area since the incident began.

“We really worry about the fishery resources that hadn't seemed like they had taken a hit yet,” Burke said. “This is also where we have commercial harvest of shellfish, clams and oysters, and it has the potential to impact their livelihoods and their business.” 

Signs of red tide on Thursday led the Florida Department of Health in Hillsborough County to issue a red tide bloom advisory for lower and middle Tampa Bay near Moody Point, Manbirtee Key, Camp Key, and Little Cockroach Island — all areas most impacted by Piney Point wastewater releases.

The DOH in Manatee County has not issued an advisory now that levels have increased, but in late May, the agency issued an advisory for areas near Longboat Key and Anna Maria island based on lower levels of K. Brevis in those waters at that time.

Experts said it is too soon to understand the link between Piney Point and the current red tide bloom, as many factors can contribute.

University of South Florida scientists released their first research in May related to the Piney Point wastewater release, finding that the initial “pulse” of nutrients had largely diluted. 

During that press conference, Bob Weisberg, a physical oceanography professor at USF, said it is too soon to attribute the presence of red tide to Piney Point. He added that the red tide bloom did not occur in a silo, and sample data shows that K. Brevis slowly crept north from an outbreak earlier this year. 

“Red tide that had been down by Charlotte Harbor actually systematically made its way up here,” Weisberg said in May. “So what we saw at the mouth of the bay, and we are still seeing now, are organisms that came from the south, and they are living here now. It is not really due to anything that came out of Piney Point.”