As the days get longer and the weather gets warmer, reports are already coming in about algae bloom sightings. With those sightings come concerns about toxins.
The bad news: Algae blooms have already been seen this year in Florida lakes, canals and rivers.
The good news: So far, most of the algae tested in Lake Okeechobee have been mixed algae with no dominant species and no toxins. A single sample at the Pahokee marina was Microcystis aeruginosa and had microcystis toxins levels 2.31 micrograms per liter. Algae sightings have been common at the Pahokee marina in the past, although it is unknown if this is due to wind action pushing the algae into that area or if there is some additional nutrient load there.
The World Health Organization (WHO) considers levels under 10 micrograms per liter safe for recreational contact.
Cyanobacteria (commonly called blue green algae) and other types of algae are commonly found in Lake Okeechobee as part of the natural ecosystem. More than a dozen species of cyanobacteria have been documented in the lake, including some that are capable of producing toxins. Cyanobacteria capable of producing toxins do not always do so.
At the South Florida Ecosystem Task Force meeting on April 26 in West Palm Beach, Keith Loftin of the United States Geological Survey (USGS) said scientists are still not certain what causes cyanobacteria to sometimes produce toxins.
At that same meeting, Barry Rosen, also of USGS, explained that almost all algae can “bloom.” He said those that do not produce toxins can still be harmful. For example, a thick bloom can cause fish kills at night when the oxygen in the water is depleted if the fish cannot escape. Fish kills related to such algae blooms usually occur in canals.
According to the Environmental Protection Agency (EPA), toxins can be produced by a wide variety of cyanobacteria. Microcystins are the most widespread toxins spread by cyanobacteria.
Microcystins are produced by Anabaena, Fischerella, Gloeotrichia, Nodularia, Nostoc, Oscillatoria, members of Microcystis, and Planktothrix. Each genus of cyanobacteria capable of producing toxins may also contain multiple species, per the EPA website. Laboratory tests are conducted on water samples to determine the dominant species (if there is one) and the toxins (if present).
Florida Department of Environmental Regulation reports samples taken in the past 30 days have shown some low levels of toxins from cyanobacteria.
All of the samples tested so far this year were below 10 micrograms per liter. The highest concentration of the microcystin toxin was 9.36 micrograms per liter at the Alva boat ramp. The dominant species present was Microcystis sp.
• April 16, Microcystis sp. found in sample taken upstream of the Franklin Lock in Lee County. No microcystin detected.
Samplings in the past 30 days include:
• March 26 mixed algae found at Alva boat ramp in Lee County. No dominant species in sample.
• March 26, Microcystis aeruginosa identified as the dominant taxon in an algae bloom sample taken at Davis boat ramp in Lee County. Microcystin level was barely detectable at 0.52 micrograms per liter.
• April 2, Microcystis sp. found in sample from Alva boat ramp in Lee County. Microcystin level barely detectable at 0.77 micrograms per liter.
• April 2, mixed algae found at the Franklin Locks, Lee County. No dominant species detected. No microcystin detected.
• April 3, Microcystis aeruginosa and Dolichospermum circinale detected in a water sample from the Clewiston boat ramp in Hendry County. No microcystin was detected.
• April 3, Microcystis aeruginosa detected in water sample from the Pahokee dock in Palm Beach County. Microcystin level was 2.31 micrograms per liter.
• Apri1 7, mixed algae observed at Indian River Veterans Memorial Park Boat Ramp in St. Lucie County.
• April 7, mixed algae found at Indian River Riverside Park Pier in Martin County. No dominant species detected in water sample.
• April 7, mixed algae found at Sanspirit Park Boat Ramp in Martin County. No dominant species detected in water sample.
• April 8, specks of green algae seen in the Caloosahatchee River in Hendry County. Water sample had mixed algae with no dominant species. No microcystin was detected.
• April 8, Planktolyngbya limnetica and Cylindrospermopsis raciborskii found in the center of Lake Pierce in Polk County. No microcystin detected.
• April 8, Coelosphaerium dubium and Anabaena sp.found in Lake Pot in Seminole County. No microcystin detected.
• April 9, mixed algae found at the Alva boat ramp in Lee County. No dominant species detected. No microcystin detected.
• April 9, Oedogonium sp found in Lake Estelle in Orange County. No microcystin detected.
• April 10, Aphanizomenon flos-aquae found in water sample form St. Johns River Channel Marker 13. No microcystin detected.
• April 11, Aphanizomenon flos-aquae found in sample from St. Johns River at Brown’s Landing. No microcystin detected.
• April 11, mixed algae found in Parkshore Marina Moorings Bay in Collier County. No microcystin detected.
• April 16, Microcystis aeruginosa found in sample from Alva boat ramp in Lee County. No microcystin detected.
To report an algal bloom, call the FDEP toll free hotline at 855-305-3903.
Algal bloom sampling results are online at floridadep.gov/dear/algal-bloom/content/algal-bloom-sampling-results.