by Elizabeth Cronin, North Dakota State University

Cyanobacteria, also known as blue-green algae, can produce toxins that are harmful to livestock, wildlife and people.

During one week in July, the North Dakota Department of Environmental Quality reported three cyanobacteria blooms on lakes and reservoirs in the state. For a list of reported blooms visit their website.

The growth of this bacteria is facilitated by high temperatures. The hot, dry conditions we experience in the summer months are perfect for the production of cyanobacteria.

Cyanobacteria is caused by an excess of nutrients, particularly nitrogen (N) and phosphorous (P). When manure and commercial fertilizers are misused, either by inappropriate rate or timing of application, the potential for nutrient leaching to surface water is increased. When these nutrients enter surface water, they stimulate growth of cyanobacteria and other microorganisms.

There may be an increased potential for cyanobacteria blooms in some areas of the state this year. Above average rainfall has increased runoff and may have transported nutrients to waterbodies, increasing nutrient loads and the potential for blooms.

Given the current conditions, farmers, ranchers and the public should be on the lookout for cyanobacteria blooms.

Blue-green algae often occurs in stagnant ponds or dugouts with elevated nutrient levels, forming large colonies that appear as scum on or just below the water surface. Live cyanobacterial blooms can be green, but also red or yellow, and often turn blue after the bloom dies and dries on the surface or shoreline.

Some species of cyanobacteria can be toxic when livestock and wildlife ingest them. Toxicity is dependent on the species consuming the water, the concentration of the toxin or toxins, and the amount of water ingested.

Cyanobacteria can produce neuro- and liver toxins. Signs of neurotoxin poisoning can appear within five minutes to up to several hours after ingestion. In animals, symptoms include weakness, staggering, muscle tremors, difficulty in breathing, convulsions and, ultimately, death.

Animals affected by liver toxins may exhibit weakness, pale-colored mucous membranes, mental derangement, bloody diarrhea and, ultimately, death. Typically, livestock are found dead before producers observe symptoms. If cyanobacterial poisoning is suspected as the cause of death, producers should check the edges of ponds for dead wildlife.

If a farmer or rancher suspects cyanobacteria poisoning as the cause of a livestock death, a veterinarian should conduct a necropsy. Contact your veterinarian to determine which samples would be appropriate for your situation.

When collecting a water sample, follow NDSU Extension’s Livestock Water Testing Guidelines. Contact your local Extension agent for assistance collecting samples.

Be sure to wear gloves, as cyanobacteria can be toxic to humans. Collect a sample of the suspected cyanobacterial bloom from the surface of the water and deeper in the water. Keep the sample cool but not frozen, and submit it to the NDSU Veterinary Diagnostic Laboratory or a commercial laboratory.

The sample can be evaluated microscopically for algae, or the water can be analyzed for several of the toxins at commercial labs at a higher cost.

For more information on sample collection and submission, contact your NDSU Extension agent.

Here are some ways farmers/ranchers can prevent cyanobacterial poisoning of livestock:

• Reduce nutrient levels entering the water source by implementing a nutrient management plan or establishing buffer strips with perennial plant species.
• Create a designated drinking area where the risk of cyanobacteria is minimal.
• Fence off the pond and pump water from the pond to the water tank.
• Use water from other sources following periods of hot, dry weather.
• Pump water from the center of the water body, well below the surface, where the bacteria are unlikely to concentrate, to a water tank.

Unfortunately, the risk for cyanobacterial blooms will remain unless steps are taken to reduce the nutrient load and minimize the potential for nutrients to enter the body of water. Here are some management practices to consider to reduce nutrient loads:

• Follow proper methods for the application of nitrogen and phosphorous to fields. Consider the rate, time, amount and type of nutrients applied.
• Adopt soil conservation practices that reduce erosion.
• Hay or graze buffer strips to reduce the release of phosphorous as plants decompose.

Contact your local NDSU Extension agent for more information on cyanobacteria and nutrient management. Additional information regarding water quality can be found on our website.

Editor’s note: Elizabeth Cronin is an information specialist and interim director of ag communication for NDSU.
Angus Beef Bulletin, Vol. 16, No. 7-B