Algae blooms normal for the lake in summer

OKEECHOBEE — How do you know there’s an algae bloom on Lake Okeechobee?

Look at the calendar. Those familiar with the area will tell you that if it’s summer, there’s a good chance there’s an algae bloom somewhere on the Big O. You might not see it — at 40 miles across, it’s a big lake — but algae is part of the lake’s natural ecosystem, and hot weather causes it to bloom.

The lake’s native algae is only a threat to fish if a large bloom sucks the oxygen out of the water as it dies, and the fish cannot get out of the way in time.

However, some blue-green algae produce microsystins which are toxins; when an algae bloom is reported, the Florida Department of Environmental Regulation tests the algae to determine the type of algae and whether any microsystins or other toxins are present. Just because a type of algae can release toxins under certain conditions does not mean it will release toxins — there are other factors in play, such as water temperature. The only way to know if toxins are present is to run the tests, which are conducted by FDEP.

According to the Florida Department of Environmental Regulation, 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.

“Although blue-green algae are found naturally, increases in nutrients can exacerbate the extent, duration and intensity of blooms. Other factors that contribute to blooms include warm temperatures, reduced water flow and lack of animals that eat algae. Although they can occur at any time, blue-green algae are most common in Florida during the summer and early fall, with high temperatures and abundant sunlight. The summer also brings storms that have the potential to deliver nutrients into waterways through stormwater runoff,” the FDEP website states.

Brandon Tucker, who was appointed to the South Florida Water Management District Governing Board in June, said SFWMD uses satellite imagery to track algae blooms on Lake Okeechobee. In early July they tracked a bloom off the northwest shore of the lake.

Although this was the same time frame during which water as being backpumped into the lake from the south to relieve flooding in the Everglades that endangered wildlife, no algae blooms were documented on the south area of the lake, he said.

The water from the Everglades was clean water, and water managers did what they could to avoid mixing the Everglades rainfall with runoff from farms in the EAA as they pumped it north.

No water from Lake Okeechobee has been released to the east coast this year; in fact, billions of gallons of untreated drainage have been flowing into Lake Okeechobee at Port Mayaca from Martin County. The water from the C-44 basin is higher in phosphorus than the water in the lake, SFWMD tests show.

FDEP has responded to several algae bloom reports this summer.

• On June 28, an algae bloom was reported in Lake Okeechobee, Latitude 27.0840, Longitude -80.8561 (several miles offshore, south of Buckhead Ridge.) FDEP took water samples. The dominant algae was Dolichospermum circinale; while this species of algae is capable of creating a toxin, no toxins were detected in the water. Dolichospermum circinale does not form mats; it may form small clusters or filaments.

• On July 18, the Florida Department of Environmental Regulation responded to a surface algae bloom reported in Lake Okeechobee in Glades County (several miles offshore, south of Brighton Seminole Reservation). The dominant algae was Dolichospermum circinale. No toxins were detected.

• On July 24, an algae bloom was reported on Lake Okeechobee, Latitude 26.9072, Longitude -80.6596 (south of Port Mayacca). FDEP found the dominant taxon is Microcystis aeruginosa. No toxins were detected in the water.

According to “Physiological and biochemical responses of Microcystis aeruginosa to glyphosate and its Roundup formulation” published in the Journal of Hazardous Materials,  Microcystis is characterized by small cells. These cells  are organized into colonies that begin in a spherical shape, but lose their coherence over time. While this type of algae can release toxins, warmer temperatures cause it to be less likely to release toxins. The risk of toxins is greatest below 68 degrees; while warm temperatures cause the algae to grow, the toxin risk decreases as the water temperature rises.

DEP reviews citizen reports of algal blooms received via the online reporting form or hotline and coordinates with other agencies who are also sampling to determine the sampling team to respond based on the location of the bloom relative to the sampling schedule for that day.

On May 31, an algae bloom was reported near Jensen Beach. The FEDP sampling found the dominant taxon was Gymnodinium sp. No toxins were found.

No water from the lake has been released to the Caloosahatchee since the rainy season started. During the drought, lake water was released into the Caloosahatchee River to prevent salt water intrusion; Lee County officials actually complained because they did not think the river was getting enough freshwater from the lake during that period.

Since the rainy season started, several algae blooms were reported on the Caloosahatchee River at the Alva boat ramp. The most recent report was on June 13; FDEP found no algae there to test.

To report an algae bloom, call 855-305-3903 or go online to

Data on algae bloom and maps showing locations in which blooms were reported are available at

No fish kills have been reported on Lake Okeechobee this year; fish kills reported in the Kissimmee River were related to low dissolved oxygen levels related to heavy rainfall.

Last summer when a large algae bloom stretched for miles in the lake, no fish kills were reported in the areas of that bloom.

To report a fish kill, call 1-800-636-0511.

Algae bloom, July 18, 2017, on Lake Okeechobee. Greenish tinge on the lower right of the photo is the bloom.

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