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Frequently Asked Questions: Cyanobacteria/Blue-Green Algae

What are cyanobacteria/blue-green algae? Blue-green algae are a group of organisms that can live in freshwater, salt-water or in mixed "brackish" water. Most of us know them as "pond scum." They also have been found to share some characteristics with bacteria, which has led to them being referred to as "cyanobacteria."

What is a cyanobacterial bloom and how do they form? Cyanobacterial blooms occur when the algae that are normally present grow in numbers more than normal. Within a few days, a bloom can cause clear water to become cloudy. Winds tend to push some floating blooms to the shore where they become more noticeable. Cyanobacterial blooms can form in warm, slow moving waters that are rich in nutrients. Blooms can occur at any time, but most often occur in late summer or early fall. They can occur in marine, estuarine and fresh waters, but cyanobacteria blooms that can cause concern are those that occur in fresh water, such as drinking water reservoirs or recreational waters.

What do cyanobacterial blooms look like? Some cyanobacterial blooms can look like foam, scum, or mats on the surface of fresh water lakes and ponds. The blooms can be blue, bright green, brown, or red and may look like paint floating on the water. Some blooms may not affect the appearance of the water. As algae in a cyanobacterial bloom die, the water may smell bad.

What are some tips for avoiding cyanobacteria/blue-green algae? It is important that adults, children and pets avoid swimming in or drinking water containing blue-green algae. It is best not to come in to contact with water in areas where you see foam, scum, or mats of algae on the water.

What should I do if I come in contact with cyanobacteria/blue-green algae? In high amounts, cyanobacteria toxins can affect the liver, nervous system and skin. Abdominal cramps, nausea, diarrhea, and vomiting may occur if untreated water is swallowed. Some people who are sensitive to the algae may develop a rash or respiratory irritation. If you come into contact with an algae bloom, wash with soap and water right away. If you experience an illness, please contact your healthcare provider.

What agency should I contact to report fish kills, algal blooms or illness associated with blue-green algae?  Fish Kill Hotline (Florida Fish & Wildlife Conservation Commission) 1-800-636-0511  Bloom Reporting (Florida Department of Environmental Protection) 1-855-305-3903 Human Illness (Florida Poison Control Center) 1-800-222-1222

Can I eat fish harvested from areas near or in algae blooms? Fish tested from water with blue-green algae blooms show that the cyanotoxins from algae do not accumulate much in the edible portion of fish which is the muscle or fillet meat. Exposure to cyanotoxins from catching and eating the fish from areas with blue-green algae is minimal. Many lakes and rivers in Florida are large with blooms not covering the entire water body. Most of the fish are not in the area where blooms exist. Blooms also tend to be temporary, especially by place and time as they move around due to wind, waves and currents. We suggest that people do not harvest fish near or in the blooms.

Is it OK to use algae water for showering or irrigation? Untreated water from the bloom area should not be used for irrigation when people could come into contact with the spray. Do not use untreated water from an area with a bloom for showering or bathing.

Where is there more information on algal blooms and health? Additional information on health issues related to algal blooms is available on the DOH website http://www.floridahealth.gov/healthy-environments/aquatic-toxins/index.html, and the US Centers for Disease Control and Prevention webpage: https://www.cdc.gov/habs/index.html.