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Harmful Algae Blooms: Blue-Green Algae


Blue-green algae, or cyanobacteria, is a type of algae found naturally in freshwater environments. This algae is a microorganism that functions like 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.

What causes an algal bloom? 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 state’s bloom response team encourages everyone to be on the lookout for blooms and report them. Residents statewide can easily report algal blooms to the department 24 hours a day, 7 days a week. Information can be reported online through at, as well as through a statewide toll-free number at 1-855-305-3903.

To report fish that are either dead or in poor physical condition, residents should contact the Fish Kill Hotline 1-800-636-0511.

Centers for Disease Control and Prevention (CDC) Assessing Health Effects


WHAT ARE WE STUDYING? You may have heard about cyanobacteria, also called blue-green algae. These microorganisms grow in water. Some types of cyanobacteria make toxins that can make people sick. We are researching whether these toxins can get into our bodies through the air we breathe.

WHO CAN PARTICIPATE? If you are interested in participating in the study, please email or call 561-297-4631. Some of the eligibility criteria include: • Adults aged 18 or older • Live or work on Lake Okeechobee, St. Lucie River, Caloosahatchee River, Cape Coral Canals, or other nearby waters in Florida • Spend at least two hours outside on most days

WHAT CAN PARTICIPANTS EXPECT? Participants will meet with study staff members 5 times during a bloom season, which is about March through October. We will ask you to complete surveys about your symptoms, provide urine specimens and nasal swabs, perform a simple lung function test on your own in your home (also called remote spirometry), and provide some blood specimens. We will test the urine specimens and nasal swabs for cyanobacterial toxins in this study. We will test the blood samples for changes in liver and kidney function. We will ask you to allow us to save your de-identified survey questions and specimens so we can test them for other important environmental toxins in the future. Your specimens will not be tested for anything else. Staff members will also work with you to record air quality measurements and time spent outdoors.
There is no cost to be in this study. For volunteering your time, we will give you gift cards as you complete study activities. We will also give you the results from the blood specimen tests. We will not be able to tell you if any of the symptoms you report on the survey your symptoms are specifically from exposure to these toxins. By looking at the results from all study participants, we may be able to tell which symptoms are likely to be a result of exposure to cyanotoxins.

Please be assured that CDC will take all necessary steps to protect members of your community from COVID-19. The exposure assessment will be conducted following all state, local, and CDC guidelines in place at the time the exposure assessment is conducted. CDC team members will be monitored twice daily for fever and any COVID-19-related symptoms and will wear surgical masks and gloves to ensure the protection of participants. Participants will be asked to always wear a face covering or mask when interacting with exposure assessment personnel. If you do not have a mask, one will be provided to you before you enter the facility. If you are unable to wear a mask for medical reasons, please let us know. Part of our COVID-19-related precautions include doing the simple lung function test on your own in your home (also called remote spirometry).
To participate or learn more: call: 561-297-4631 | visit: | email:


  1. View/Subscribe to Weekly Updates from the Florida Department of Environmental Protection on harmful algae bloom monitoring and response
  2. Algal Bloom Dashboard (map and sampling results)
  3. Health Questions and Concerns 
  4. Frequently Asked Questions