July is not too early for toxic blue-green algae (cyanobacteria) to appear on your pond or lake, says Roxanne Johnson, North Dakota State University Extens ion Ser vice water quality associate.
A rural Devils Lake family lost a dog and two horses recently following possible ingestion of water from a nearby pond. The dog was the first to become ill with symptoms typical of cyanobacteria ingestion: an inability to stand, frothing at the mouth and vomiting large amounts of fluids. The dog succumbed in a short period of time. The next morning, the first horse appeared with symptoms, including staggering and fluttering of eyes, followed by convulsions and death. The animals’ feet were green with algae scum.
Charlotte Klose, a veterinarian at Golden Valley Veterinary Services in Park River, performed an autopsy on one of the horses and Neil Dyer, a veterinarian and director of NDSU’s Veterinary Diagnostic Laboratory, confirmed the animal died as a result of microcystis.
Microcystis is a unicellular cyanobacteria that is microscopic. It forms colonies that can turn the water bluish green and may form surface scums. Some microcystis species may produce a family of toxins called microcystins, which primarily affect the liver in animals and are known as hepatotoxins.
Symptoms may take 30 minutes to 24 hours to appear, depending upon the size of the animal affected and the amount of toxic bloom consumed. Microcystin toxicosis may include jaundice, shock, abdominal pain/distention, weakness, nausea/vomiting, severe thirst, rapid-weak pulse and death.
Johnson warns anyone with livestock or pets or people who may be recreating in water that has an algae growth on it to be cautious. Restrict livestock access to stagnant water, especially when a substantial amount of algae scum is visible.
Algae blooms can be controlled in ponds through the use of copper sulphate (blue stone), but the rapid die-off of algae may result in a fish kill. If copper sulphate is used, the recommended application rate to water depends on the alkalinity of the water.
Livestock (especially sheep) should not be watered at ponds with blue-green algae for at least five days after the last visible evidence of the algae bloom.
The best method to control algae is to eliminate the source of nutrients entering