LAKE OKEECHOBEE – Two algal blooms were reported on the edges of Lake Okeechobee last week, in areas where blooms have commonly be found in previous years.
On April 12, an algal bloom was reported inside the Port Mayaca Lock. FDEP tests found the dominant taxon was Microcystis aeruginosa. Microcystin toxin levels were 22 micrograms per liter. Levels above 8 micrograms per liter are considered unsafe for human recreational contact by the World Health Organization.
Also on April 12, an algal bloom was reported at the Pahokee Marina. FDEP samples found mixed algae with no dominant taxon. No toxins were detected.
Hot weather, stagnant water and plenty of available nitrogen and phosphorus are all factors that contribute to algal blooms. The U.S. Army Corps of Engineers stopped releases from the lake at Port Mayaca on April 10. The only water movement in the lock occurs when boats lock through.
You can’t tell what kind of algae or cyanobacteria is present just by looking at it. You cannot tell if toxins are present. Florida Department of Health advises residents and visitors to stay out of the water and keep pets out of the water if algae is visible.
Algae and cyanobacteria are part of the natural ecosystem of all freshwater systems – the base of the food chain. Most of the time, these microscopic organisms are not visible to the human eye. Algal blooms are common on Lake Okeechobee in the Spring and Summer when the weather is warm. On the big lake, most blooms are thin, wispy and ephemeral; they come and go, blown about by the wind. Cyanobacteria may move up and down in the water column with the use of gas vesicles.
Of the 28 species of cyanobacteria that have been documented by the U.S. Geological Survey in the Lake Okeechobee Waterway, about 25% are capable of producing toxins. Cyanobacteria capable of producing toxins do not always do so. The Lake Okeechobee Waterway includes the St. Lucie River, the St. Lucie Canal (C-440), Lake Okeechobee and the Caloosahatchee River.