Seventy-five researchers from Florida and around the country met in St. Petersburg in August to build a consensus document regarding harmful algal blooms.

SARASOTA — A symposium of the nation’s top experts in harmful algal blooms has created a playbook for addressing deadly algae in Florida.

The consensus findings of 75 researchers, titled "State of the Science for Harmful Algal Blooms in Florida," notes that there is a dire need for better public communication and data gaps in research with the two most common harmful algal blooms, or "HABs" — the red-tide organism, Karenia brevis, and blue-green algae also called cyanobacteria.

Researchers met Aug. 20-21 at the United States Geological Survey in St. Petersburg.

Among the topics is confusion in the use of bloom terms, such as "red tide," "blue-green algae" and "cyanobacteria," which the public does not readily understand, the report states. It also said there are mixed messages regarding human health concerns, aerosol exposure and seafood safety, the causes of blooms, bloom interrelatedness, as well as bloom response and control measures.

"The goal was to make sure we are all on the same page," said Betty Staugler, a Florida Sea Grant agent for UF/IFAS Extension-Charlotte County. "Consistency is super important. There’s enough misinformation out there, and we really wanted to come to have a more unified voice."

The consensus document focuses on five primary topics: how blooms begin, develop and end; bloom prediction and modeling; how blooms are detected and monitored; how blooms might be controlled or reduced; and how blooms affect public health.

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For each of these topics, researchers determined what scientists know, what they think they know, and what they need to know. They ranked research priorities for HABs in Florida and, among their top concerns, were developing models that can separate nonpoint sources of pollution, consistent monitoring of data and improved knowledge of public health effects.

Southwest Florida has experienced Karenia brevis blooms 57 of the past 66 years with widespread impacts to fish, wildlife and humans.

"Avoidance is a key factor in reducing the impact of respiratory irritation and associated health risks," the report states. "Currently, avoidance is a crude solution."

The existing National Oceanic and Atmospheric Association HAB Bulletin that provides a county-wide assessment of day-by-day red tide effects at individual beaches is correct only 20% of the time, the report states. It called for a newer method that uses detailed daily cell counts at individual beaches to give hourly forecasts at those beaches.

Staugler said the symposium offered researchers from around the nation a chance to network and share information about HABs and provide a better understanding of their work. They discussed a better centralized database for data that could be made available to the public, including local government and state health agencies whose messages are often muddied.

"Part of the reason we were able to attract people is because we had this greater mission," Staugler said. "There is so much concern about red tide and blue-green algae that the scientific community was behind it."

The HAB document noted that the 2017-2019 red tide episode was not a singular event in Florida, which experiences outbreaks of harmful algae frequently in its marine and fresh waters. However, it said instances of HABs are increasing globally because of shifts in demographics and land use, which are confounded by direct and indirect impacts of climate change.

Florida has experienced increased temperatures, decreased water acidity, changes in water circulation and increased rainfall that can accelerate nutrient delivery. Periods of drought may lead to conditions that favor bloom formation, the report states.

Researchers cited the need to address the effects of nutrients along the entire fresh-to-saltwater continuum, and for a better grasp of mixotrophy, the mix of different sources of energy and carbon. Karenia brevis can utilize at least 13 different sources of nutrients, including multiple forms of nitrogen and phosphorus.

Researchers also discussed a need for determining what qualifies as a bloom. Currently, medium amounts of Karenia brevis over 100,000 cells per liter signals bloom conditions.

Background concentrations — trace amounts — of red tide are found in Florida waters year-round. They can cause respiratory irritation and cause fish kills but are considered typical levels.

The report noted that there are 12-13 species of Karenia algae globally, and more than one exists in the Gulf of Mexico at background concentrations.

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Researchers detailed promising mitigation techniques for Karenia brevis near shore but cautioned that many methods have not been tested because there is not a firm understanding of what role red tide plays in the ecosystem. There are concerns that mitigation, such as attempts made in 1957, could create undesirable negative results.

The first and last large-scale chemical control treatment of Karenia brevis in the U.S. dispersed about 25 square miles of copper sulfate that succeeded in temporarily decreasing red tide. However, there was broad collateral damage.

"The 1957 treatment pretty much killed everything," said Staugler, noting the death of marine life. "It was very good at killing the red tide, but it killed everything else as well. Those things came back, but so did K. brevis. It wasn’t viable, especially on a large scale. You can’t go out in the Gulf with helicopters or big vessels and spray sulfate."

Another concern is the effects of bursting algae cells, which could release a massive influx of brevetoxins into the ecosystem.

The report notes that optimal mitigation strategies should kill red tide cells, reoxygenate the water and restore water to nontoxic conditions within 24 to 48 hours. No single method will work for all regions, and multiple approaches need to be explored.

Environmental compliance currently limits what can be done.

Research priorities under public health focused on the importance of identifying all toxins, risk and level of toxicity, including microcystins related to cyanobacteria, BMAA, and stress. The report states that mental and social health problems must also be understood.

Cyanobacteria, unlike other phytoplankton, can regulate buoyancy to survive in water columns. It needs nitrogen and phosphorus, or atmospheric nitrogen to survive.

According to the report, cyanobacteria monitoring will be increased in 2020 as a result of funding from the state Legislature.

One of the goals of the report is to breach the lack of knowledge and general misconceptions about HABs — magnified by the transient people in and out of Florida — by creating broad access to information.

The UF/IFAS Extension has created a website with "Questions and Answers about Harmful Algal Blooms" online at: https://water.ifas.ufl.edu/harmful-algal-blooms/faq/questions-and-answers/.

"There is a lot we do know about these bloom species, but we have to recognize there is a lot of work to be done," Staugler said. "The report shows that there is a lot we can agree on, but it also shows we have a lot more work to do."