Blue-Green Algae (Cyanobacteria) FAQ

What are blue-green algae?
Blue-green algae, also known as cyanobacteria, are simple plant-like organisms that occur naturally in both fresh and salt water. They are found worldwide and are common in Florida lakes, rivers, streams, and ponds. Blue-green algae can be found as individual cells, clumps, filaments, or large mats.

What is a blue-green algae bloom?
When environmental conditions (light, nutrients, and temperature) are favorable, algae can grow rapidly, accumulate, and become a bloom. Although blooms can occur at any time of year, they usually occur in late summer or early fall in most places and can last days or even weeks. In Florida, blue-green algae blooms are an ongoing and increasing problem.

How long have blue-green algae existed?
Blue-green algae are among the oldest organisms found on earth. Fossils date back 3.5 billion years, and blooms are noted throughout recorded history.

What is a blue-green algae mat?
A large accumulation of blue-green algae is called a mat. Algal mats can be inches thick or can look like foam, scum, or paint floating on water surfaces. They can appear blue, green, brown, orange, or red in color and can leave a strong, foul odor.

When is a bloom harmful?
A bloom is considered a harmful algal bloom (HAB or cyanoHAB) when there is a threat to human or animal health or to the environment.

Do blue-green algae produce toxins?
Most blue-green algae species don't produce toxins, but several species can under the right conditions. Some blue-green algae toxins can make humans and animals sick, causing stomach and intestinal illness, respiratory distress, allergic reactions, skin irritations, liver damage, and neurotoxic reactions.

Are the toxins visible?
You cannot see, smell, or taste blue-green algae toxins.

How do algal blooms and toxins affect the environment?
Toxic and nontoxic blooms disrupt and damage sensitive ecosystems. They alter the food web by blocking sun from submerged vegetation, reducing oxygen availability to other living species, and introducing toxicity that passes through the food chain. Toxicity and/or blooms disappear suddenly over time but can accumulate in fish and shellfish.

Does cooking remove toxins from fish and shellfish?
Cooking will not remove toxins from fish and shellfish.

How are we exposed to blue-green algae?
Exposure to blue-green algae can occur through ingestion of contaminated drinking water, food, or dietary supplements; contact with contaminated recreational waters; and inhalation of algal aerosols.

What will happen if I ingest blue-green algae toxin?
Swallowing even small amounts of blue-green algae toxin can result in flu-like symptoms including nausea, vomiting, and diarrhea. In large amounts, algae toxins can damage the liver, kidneys, or nervous system.

What will happen if I swim in a blue-green algae bloom?
Direct contact with a bloom, such as while swimming or wading, can result in skin irritation, hives, blisters, or a rash.

What will happen if I inhale blue-green algae toxins?
Inhalation through activities such as wading, swimming, boating or using a personal watercraft, water skiing, and irrigating with untreated water where a bloom is occurring can result in hay fever-like symptoms such as itchy eyes, sore throat, and congestion.

How do blue-green algae affect children and pets?
Children and pets are at greater risk for algae toxin poisoning than adults because they are relatively smaller. A number of dog deaths have been linked to algae toxin poisoning after they ingested algae mats or drank contaminated surface water.

How can I prevent exposure to blue-green algae toxins?
The best way to prevent exposure to blue-green algae toxins is to avoid water where scum, foam, or algae mats or a greenish color is present. Additional precautions include the following:

• Do not cook with, eat, or drink from these waters (boiling will not remove toxins).
• Do not swim or shower in these waters.
• Do not allow your pets to swim in, drink from, or play near these waters.
• Do not water ski or ride a personal watercraft over algae mats.
• Do not water your lawns or gardens with these waters.

What should I do if I am exposed or if my pet is exposed to blue-green algae toxins?
Rinse off immediately and thoroughly with fresh water and soap if you or your pet has had contact with contaminated water. Wash the animal's coat thoroughly before it starts to groom itself. Avoid swallowing if you have had oral contact. Contact your local health authority or veterinarian immediately if you or your pet suddenly becomes lethargic or shows signs of poisoning such as vomiting, diarrhea, convulsions, or seizures.

How does human activity affect blue-green algae blooms?
Although blue-green algae blooms are natural events, human and animal wastes and fertilizers can increase the size or frequency of blooms, worsening existing algae problems.

How can I help prevent a blue-green algae bloom?
You can help prevent a blue-green algae bloom by minimizing runoff and the use of fertilizers, which may enter nearby surface waters. Excess nutrients can encourage the growth of blue-green algae blooms.

What should I do if I see a blue-green algae bloom?
Report foul-smelling or foul-tasting water to your local water utility. Monitoring and response of blue-green algae blooms is important for good health safety, since many are treatable.

Can I treat a blue-green algae bloom myself using an algicide such as copper sulfate?
Copper sulfate or other algicides should not be used when toxic forms of blue-green algae are present because it may cause a sudden release of toxins. Contact your county environmental agency or regional Florida Department of Environmental Protection office for evaluation and assistance.

How do I get more information about the health effects of blue-green algae?
For treatment, advice, or additional information on the health effects of blue-green algae, contact the Aquatic Toxins Hotline at (888) 232-8635 (toll-free), or visit the Florida Department of Health, Division of Environmental Health Web site at www.myfloridaeh.com.

What should I do if I see a fish kill?
To report fish kills, contact the Florida Fish and Wildlife Research Institute's Fish Kill Hotline at (800) 636-0511 (toll-free) or on the Web site at Submit a Fish Kill Report.