Blue-green algae

With continued drought conditions in the region and rising temperatures, we would like to share a reminder to monitor water sources for the presence of blue-green algae. Drinking water from stagnant ponds and dugouts during hot dry weather can cause sudden death in animals. This water can contain certain species of cyanobacteria, commonly known as blue-green algae. Blue-green algae often occurs in stagnant ponds or dugouts with with elevated nutrient levels, forming large colonies that appear as scum on or just below the water surface. The formation of toxic blooms is unpredictable.

When placing livestock onto pastures with water sources, check lakes, ponds, sloughs, and slow streams with stagnant water for areas of cyanobacterial – algal blooms. Monitor the water source and cattle frequently (daily if possible) for algal blooms (typically a bluish-green color). Remove livestock from pastures with water sources containing an algal bloom or fence off the water with an algal bloom and provide alternative potable water. Livestock, horses, dogs, cats, fish, some birds, and humans are at risk and carcasses might be observed around the water source.  It is critical that water samples be submitted since in many cases tissues from affected animals lack lesions or have no diagnostic changes. Note that the NDSU-VDL can examine livestock water microscopically for toxigenic cyanobacteria but does not analyze for cyanotoxins. Cyanotoxin analysis can be referred to outside laboratories if required.

Learn more about the blue-green algae (cyanobacteria) identification offered at the NDSU-VDL here. Review the Cyanobacteria Poisoning Bulletin issued by the NDSU Extension Service for more information about blue-green algae.