Toxic algae.

Adapted from the MPCA Web site

Lake lovers, especially those with pets or livestock, should be aware of a potential hazard stemming from algae growth in lakes during summer. Under certain conditions some algae species, called blue-green algae, can become toxic. Pets and livestock drinking lake water containing the toxic form of these algae may become sick and even die.

Special characteristics of blue-green algae allow them to become more abundant than other types of algae. Some bluegreen algae are able to use nitrogen from the air as well as nitrogen dissolved in the water, which gives them an advantage over algae that depend only on nitrogen in the water.

Blue-green algae can use sunlight more efficiently than most algae. Some contain pockets of gas allowing them to float on the water surface and out-compete other algae for sunlight. In nutrient-rich lakes, blue-green algae can become so abundant that they completely dominate other free-floating algae. The whole appearance of the lake water can be changed by these large concentrations of algae. This condition is called an algae bloom.

The lake water will become cloudy, with a green or bluegreen cast, and is often described as looking like pea soup. It often develops a strong musty or earthy odor as the algae accumulate in large floating mats and begin to decompose. In extreme cases, surface scums of dead and decomposing algae may occur.

These algae blooms can occasionally become toxic. Most problems occur when the algae are concentrated by wind along a shoreline and livestock, pets, wild animals, and birds drink the water or otherwise ingest the algae. Toxic effects in animals can occur only when they ingest the contaminated water or algae.

The degree to which an animal is affected depends on several factors: the amount of water or algal cells ingested, the animal’s body size, amount of food in the animal’s stomach, the sensitivity of the species and individual animal, and the type and amount of toxin present in the bloom. An animal that has ingested toxins from an algae bloom can show symptoms ranging from nausea and skin irritation to severe disorders involving the circulatory, nervous and digestive systems, and severe skin lesions. In the worst case, the animal may suffer convulsions and die.

Humans are seldom seriously affected by toxic algae because the unpleasant odor and taste of water associated with a blue-green algae bloom tends to make them avoid it. However, humans and animals may experience illness or other health effects if their skin is in contact with algal toxins or they ingest large amounts of algae while toxins are being produced.

The Minnesota Department of Health recommends that you not ingest the water, or let children or pets enter the water. Avoid contact with the algae whenever possible. If contact does occur wash off the material thoroughly, paying special attention to the swimsuit area. If your pet comes in contact with a bloom, wash off your pet’s coat to prevent it from ingesting the algae while licking.

If you suspect an animal has been affected by an algae bloom, contact your veterinarian as quickly as possible. Some of the toxins that can form in a bloom have the ability to kill in an hour or less, while some may take up to 24 hours to take effect. For more information on toxic algae or to report a possible toxic bloom, please contact: Matt Lindon, MPCA, at 651-297-8218, or toll-free from Greater Minnesota at 1-800-657-3864. You can download a PDF of a new poster about toxic blue-green algae at the MPCA web site.

Posted in Lakes |