Gulf of Mexico
Drone footage captured Aug. 5, 2021, by Manatee County crews shows the Gulf of Mexico's red tide conditions right across from Longboat Key's Bayfront Park. The darker areas tend to show where concentrations of the red tide algae may be present. Courtesy image

FL - Local experts search for red tide answers

Red tide blooms are like chili: Everyone’s recipe is different, said one panel member at the "Red Tide in the Gulf Coast" discussion.

Red tide.

It’s a naturally occurring phenomenon, but there are ways to mitigate the impacts.

The "Red Tide in the Gulf Coast" panel discussion on Nov. 13 allowed local officials to share experiences through multiple sectors relating to red tide. The panel was hosted by the Science and Technology Society, along with University of South Florida Sarasota-Manatee.

A show of hands around the USF Sarasota-Manatee auditorium proved everyone in attendance had lived through at least one red tide bloom.

“We still need answers, we still need solutions, we still need people who care and we still need much more information,” USF Sarasota-Manatee Chancellor Karen Holbrook said. “So I think today’s meeting is extremely important.”

The panel was moderated by Barbara Kirkpatrick, senior advisor with the Gulf of Mexico Coastal Ocean Observation System.

She began with a brief introduction to red tide, which is an algal bloom event caused by the microscopic algae Karenia brevis, or K. brevis.

The algae produces toxins that can kill fish, birds and marine mammals. Inhaled toxins by humans or pets can lead to respiratory system issues.

Fish kills are common during red tide.File photo

Red tide events have significant impacts on local health, tourism and fisheries, she said.

The mitigation for events can be costly as well, such as cleaning up dead fish from beaches and waterways.

A “perfect storm” is needed to produce bad blooms, like the one in 2017-2018, according to Kirkpatrick. Biology, chemistry and physics all come together to produce, exacerbate and move the bloom onshore.

“That’s really where it wreaks havoc in our community and our lives,” Kirkpatrick said.

She compared red tide blooms to chili. It’s a dish that everyone makes, but everyone’s recipe is different.

“It’s not the same recipe every time,” Kirkpatrick said.

Feeding cycle

Executive Director of the Sarasota Bay Estuary Program Dave Tomasko followed Kirkpatrick, emphasizing that red tide is naturally occurring, but humans can worsen it.

Nutrient runoff, mainly nitrogen, feeds the K. brevis organism, allowing it to grow. Once the bloom begins, the process of fish kill can also release nitrogen as a byproduct. That starts a cycle that allows K. brevis to be self-sustaining.

Tomasko said the threshold to consider a bloom severe, or in “high abundance,” is 100,000 cells per liter.

In the 2017-2018 bloom event, he said some readings were as high as 14 million cells per liter in Sarasota Bay — 140 times the threshold.

Longboat officials clean-up red tide from local canals in 2018.

“That was a wicked strong red tide that set us back,” Tomasko said.

Tomasko also shared findings of one of his latest research papers which is currently in review. Results should be viewed as tentative until the paper is accepted, he said

But the preliminary findings proved that the amount of nutrients running into critical waterways that feed Sarasota Bay does have an impact on the duration of red tide events.

“We’ve never not had red tide, but we seem to be making red tide last longer,” Tomasko said.

Quality outreach

Sandy Gilbert talked about his organization called Solutions to Avoid Red Tide. Gilbert is the chairman and CEO of the organization.

Gilbert said START focuses on public education, water quality outreach and nutrient control programs.

To inform the public, START has created multiple informative presentations for local groups and homeowners associations about what red tide is and what communities can do to help.

Water quality outreach for START means contacting federal and state legislators, and staying up-to-date with local ordinances. Right now, Gilbert said his organization is working with Sarasota County on an ordinance for “no-mow zones,” where mowing would be prohibited within a certain amount of feet from a pond’s edge.

START also has a focus on stormwater and stormwater pond enhancements, which are a significant source of nutrient runoff.

“About two-thirds of all these ponds flow downstream, … so we’re looking to clean these ponds up so the water in the bay has less nitrogen and doesn’t encourage as much red tide growth,” Gilbert said.

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