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Blue-green Algae


Blue-green algae, or cyanobacteria, are a naturally occurring part of the food chain. Although they are most closely related to bacteria, they contain chlorophyll and depend on sunlight to grow, like plants.

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. Blue-green algae are common throughout the United States.

Some, but not all, blue-green algae can produce toxins that can contribute to environmental problems and affect public health. Scientists know little about what causes the algae to produce these toxins. Even those blue-green algae that are known to produce toxins do not always do so. You can find more information on health aspects of blue-green algae from the Florida Department of Health.

Blue-green algae bloom

The occurrence of blue-green algae is natural and has occurred throughout history. Still, to better understand the phenomenon, Florida monitors blue-green algae closely because nutrient (such as nitrogen and phosphorus) pollution appears to intensify blue-green algae outbreaks. The state is taking long-term measures that will reduce nutrient loading and improve water quality.

Algal blooms were documented in Florida’s coastal waters as early as the 19th century. In 1998, a Florida Harmful Algal Bloom Task Force was created to address potential concerns regarding microalgae, including blue-green algae, through monitoring and investigation.  DEP continues efforts to respond to and analyze all algal bloom reports. For more information on state agency partners and algal bloom response and analyses efforts, please visit the Response and Analyses Page.

To learn more, listen to the U.S. Geological Survey CoreCast with useful information about algal blooms.

Report any illness from exposure to harmful algae to the toll-free Aquatic Toxins Hotline: 1-888-232-8635

Report fish kills to the Florida Fish and Wildlife Conservation Commission: 1-800-636-0511

Blue green algae in Lake Marian
"There are no short term solutions to rectifying the situation; this is a naturally occurring phenomenon that the State monitors closely. However, the state is taking measures that in the long-term will reduce nutrient loading and improve water quality."

Last updated: April 12, 2016

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