Warnings for blue-green algae toxins to be at minimal ‘detectable’ level

Posted 8/9/20

TALLAHASSEE — The July 29 meeting of the Florida Blue Green Algae Task Force tackled the questions of how to educate the public about the toxins that may be present in algae blooms, and how algae …

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Warnings for blue-green algae toxins to be at minimal ‘detectable’ level


TALLAHASSEE — The July 29 meeting of the Florida Blue Green Algae Task Force tackled the questions of how to educate the public about the toxins that may be present in algae blooms, and how algae blooms in Lake Okeechobee could affect the U.S. Army Corps of Engineers’ decisions about lake releases.

The task force agreed to a conservative approach for warnings to the public — setting the threshold at any detectable toxin level. They also agreed they did not have enough data to make a recommendation in regard to lake releases. The corps will be invited to discuss this issue at the next task force meeting.

Task force members are: Dr. Evelyn Gaiser, of Florida International University; Dr. Wendy Graham, of the University of Florida; Dr. Michael Parsons, of Florida Gulf Coast University; Dr. Valerie Paul, of the Smithsonian; and, Dr. James Sullivan, of Florida Atlantic University Harbor Branch. Florida State Science Officer Dr. Thomas Frazer was the meeting moderator.

Florida Department of Environmental Protection (DEP) Secretary Noah Valenstein said the work of the task force has already resulted in the state making some changes, such as increasing penalties for sewage spills. The state is also in the process of updating stormwater rules.

“Nutrients are the primary driver of algae blooms in this state,” said Frazer. The task force identified septic tanks as one of the contributors to the nutrient overload in waterways. He said at the recommendation of the task force, the Florida Legislature passed legislation transferring the regulation of septic tanks from the Department of Health (DOH) to DEP in July 2021.

He said the state is investing in innovative technology to better forecast algae blooms and to treat algae blooms.

He said DEP and DOH are coordinating innovative solutions to disseminate health advisories on toxic algae blooms.

Frazer said the EPA has provided some recommendations in regard to human health in regard to both Microcystins and Cylindrospermopsin.

David Whiting, of DEP, said EPA criteria for determining an impaired waterway includes magnitude, duration and frequently of toxic algae blooms.

He explained the 8 micrograms per liter limit for recreational use is based on the toxin exposure to a small child, age 6-10, while recreating in water. In setting this standard, the EPA researchers assumed a child might swallow some water while swimming or playing in the water. He explained they tested the urine of children who swam in chlorinated pools for chlorine levels to estimate how much water a child ingests while swimming.

Not all cyanobacteria produce toxins, and cyanobacteria capable of producing toxins do not always do so. Laboratory tests are needed to determine if toxins are present.

“If we observe cyanobacteria dominant in a sample, that is cause for a cautionary advisory. If we detect cyanotoxin at any level, that is reason for health advisory,” he said.

“When we do detect toxins, we will retest until we no longer detect toxins,” he explained. When toxins or no longer detected, that would be the basis for removing the health advisory.

“You could take two different dips of water at the same location and get different results. You could go an hour apart and get different results,” he said.

“Because conditions change so rapidly, reliance on a bloom sample result that is already three to four days old is not adaptive enough,” he said. It might not reflect the actual conditions across the site that is experiencing a bloom.

He said there are a number of cyanotoxins in addition to the two they currently measure. EPA is working on tests for total cyanotoxins.

“We need to circle back around in terms of the patchiness of these cyanobacteria blooms,” said Parsons. The DEP, the district and local counties are not going to be able to sample every hundred yards along the lake, he added.

He said public education is important. He suggested public service announcements to the effect: “If you see a bloom, don’t go in the water.”

“When these waters are being discharged out the lake, the U.S. Army Corps of Engineers is expressing a willingness to take toxin levels into consideration, but they don’t want to be in charge of setting the criteria up. That’s up to the state,” he said.

He said they are going to have to “put a number on it.”

Cyanobacteria blooms have been known to make thick clumps that ducks can walk across, but other blooms may be in the water column and not even be visible from the surface, he said. “We can’t sample all the time. We need numerical criteria but we need something else to protect the public,” he said.

Whiting said the corps is reviewing the plans for the Lake Okeechobee System Operating Manual (LOSOM). Because there is not a long-term data set for the toxins, the corps decided to look at historic chlorophyll levels for their modeling.

Graham said she did not see a strong correlation between chlorophyll A and microcystin. “One is looking at shifts in flora and fauna and one is looking at health effects,” she said. “Chlorophyll A is not indicative of any particular blue-green algae.”

All phytoplankton have chlorophyll in them, agreed Frazer.

Sullivan said chlorophyll is one of the things they can measure with the satellite images, but there is no strong correlation between chlorophyll A and toxins. “That’s bad science,” he said.

Parsons said chlorophyll is not a good indicator of microcystis.

Frazer suggested the task force invite the corps to present their models at the next meeting.

“The root source of toxins is algae,” said Frazer. The waterways that are high in nutrient load are already designated as impaired.

“DEP is not putting signage up. We’re providing the data,” said Whiting. DOH staff look at data from DEP and decide whether a caution advisory or a health advisory should be issued.

Frazer said DEP and the South Florida Water Management District (SFWMD) now sample regular sites in Lake Okeechobee at regular intervals even when there are no blooms present.

There is a state responsibility to set the criteria for the toxin levels in its waters, said Sullivan. “If we’re going to tell the corps, you can’t dump water with toxin in it, you’ve got to set a level,” he said.

“If we were going to adopt the criteria rather than a swim advisory, there will have to be more testing,” said Whiting.

Dr. Kendra Goff of FDOH said caution signs are put in places where they know have recurring problems with blue-green algae blooms. The message is “If you see algae, stay out of the water.”

Health alert signs are placed if sampling indicates the presence of toxins. She said the “health alert” signs are placed in addition to the caution signs.

The overall goal to increase awareness of blue -green algae blooms, said Frazer. He said the educational signs will be designed to be permanent fixtures that can be installed at common public access points.

Goff said DOH now has signs in Spanish available for communities that request those.

“There is no safe level of toxin,” said Sullivan. “I like the fact that at any level of toxin, the signs go up.”

During the public comment period, Mike McGrath of the Sierra Club said many who use the waterways do not speak English, so warning signs should be printed in Spanish and Haitian Creole as well as English.

“These organisms grow everywhere. They are not just in Lake Okeechobee,” Dr. Barry Rosen of Florida Gulf Coast University. “There’s also growth in the canal systems themselves. We have to look at that. Looking at just one place like S-80 (the St. Lucie Lock) is not enough. We need a more intense network to be protected.” He said in addition to microcystins and cylindrospermopsin, they should also be thinking about anatoxins and saxitoxins.

Nyla Pipes of One Florida Foundation said she likes the idea of a text message system to alert residents of areas with toxic algae blooms. “We are treating the symptoms,” she said, adding that it is important to address the sources of the excess nutrients going into the waterways.

Kurt Spitzer with Florida Stormwater Association said city and county governments that have permits already have criteria they must abide by concerning nutrients, the root causes of blue-green algae. He said if the goal is to reduce blue-green algae, the goal should be to reduce the nutrients that cause the excess growth of blue-green algae.

Mike Elfenbein, director of the Foundation for Balanced Environment Stewardship, said there is very limited funding available for plans to reduce nutrient load in Lake Okeechobee. He said reducing the nutrient load is the key to reducing harmful algae blooms.

Another speaker asked that more public notification should be done about the levels of coliform bacteria in water.

Hailey Bush of 1000 Friends of Florida said they should consider changing demographics and Florida’s growing population in regard to water quality issues. “Smart growth and sustainable development should be part of the solution to our state’s water quality issues,” she said.

Drew Martin with the Sierra Club said more signage is needed at public access areas near lakes and waterways. “It is important to let people know, especially those who fish.

“We need to do more about protecting wetlands,” he added. He said the over-watering of landscapes is another problem. When homeowners have applied fertilizer, this fertilizer is washed into the waterways and feeds the algae.

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