Algal bloom toxin levels investigated

An unusually high level of microcystin toxin from a sample taken at an algal bloom on Lake Okeechobee near Canal Point on Aug. 1 could be related to wind action.

“The majority of the samples collected this year continue to be non-detect,” said Dee Ann Miller of the Florida Department of Environmental Regulation.

The Canal Point sample, which showed toxins at 815 micrograms/liter was the highest toxin result last year or this year to date, she explained. That sample was collected from a concentrated algal area from shoreline. “Based on the photographs taken at the time the elevated sample was collected at Canal Point, we do know that the cyanobacteria was concentrated and pushed to the shoreline in a wind row. When the cyanobacteria is clumped together or concentrated in one area, the toxin levels themselves may be higher because of that fact,” she explained. These readings would not be an indicator of overall water quality conditions outside of this narrow band of algae along the shoreline, she added.

According to the World Health Organization, a level below 10 micrograms/liter is considered safe for short term recreational contact. Some – not all – blue-green algae can produce toxins, and even those that are capable of producing toxins are not necessarily always producing toxins, explained Ms. Miller. “You also can’t tell whether algae is producing toxins or not just by looking at it. That is why toxin analysis is performed to see if the algae is producing toxins and if so, at what levels – and why persistent blooms are routinely monitored and retested.”

During 2016, the highest level of toxins reported in the state was at Bathtub Reef Beach, Ms. Miller said. “The sampling results, from the week of June 27, 2016, indicated elevated toxin levels of 414.3 micrograms per liter at the Atlantic Ocean Bathtub Reef Beach, 5 meters from shore. Another sample taken at Bathtub Reef Beach closer to the shore was non-detect for toxins,” she stated. “The Florida Department of Health at Martin County issued an advisory encouraging Floridians and visitors to exercise caution to minimize their risk and encouraging them to stay out of the water when a bloom is present.” FDEP will continue to monitor reports of algae blooms, and test water samples from areas where blooms are found.

A bloom reported Aug. 14 on Lake Okeechobee in Glades County noted water green in color with algae suspended in the water column. No toxins were detected.

A bloom reported Aug. 14 offshore from Port Mayaca had a microcystin toxin level of 3.7 micrograms per liter. A bloom reported Aug. 16 at Port Mayaca had blue green algae dispersed through the water column within the lock and structure, according to the FDEP report. Test results were not available at press time.

FDEP and Florida’s water management districts frequently monitor Florida’s water quality and routinely collect algal bloom samples as soon as they are observed to identify algal type and test toxin levels. In addition, staff are deployed to take additional samples in response to reported blooms – whether from a citizen, other response team agencies or other sources. To keep residents and visitors informed of the latest algal bloom monitoring results and activities, FDEP has a website where it posts the dates and locations of samples collected. Test results are added as they become available. Persistent blooms are routinely monitored and retested.

Individuals should avoid contact with algae and can report algal blooms using DEP’s toll-free hotline at 855-305-3903 and online at

According to the FDEP, blue-green algae, or cyanobacteria, is a type of bacteria found naturally in freshwater environments. This bacteria is a microorganism that functions like algae or a plant in that it feeds through photosynthesis and derives its energy from the sun. Blue-green algae can be found all over the world, and occur in Florida’s freshwater and brackish habitats, such as lakes, rivers and estuaries.

Publisher Katrina Elsken can be reached at

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