by Hans Peterson, Saskatchewan Research Council
Drinking water quality can affect human health and livestock production in a multitude of ways. Surface water reservoirs often have high levels of nutrients resulting in intense microbial growth and the formation of "water blooms". On the Canadian prairies, these blooms are mainly composed of microscopic green and blue-green algae. The blue-green algae look like algae, but are in fact bacteria. We will refer to them as cyanobacteria. The formation of the water blooms can make the water unsuitable for consumption due to:
a great traveller and a writer of works on medicine that were chiefly compilations and commentaries, noted that water containing impurities or having a fetid smell might be made fit to drink by boiling or mixing with judiciously selected wine. (Neuberger 1930). |
Water Blooms: Dugout Culprits
1) Cyanobacteria (Blue-green algae)
Cyanobacteria occur world-wide. Cyanobacteria growth is greatest when the water is warts. They will often float close to the surface during periods of calm weather and in windy weather they will be blown to the shore where they can be present in large concentrations. Such concentrations can look like a layer of solid green paint on the dugout surface. When looking into the dugout they often form visible clumps or "grass clippings". These clumps and clippings contain hundreds of cells. They will act like slime and run through your fingers if picked up. If they remain in your hand and you can squeeze them, they are probably not cyanobacteria. In addition, toxic cyanobacteria are never attached to the bottom from where they grow up through the water, they are always just floating around.
Like many types of water microbes, they will create odours but unlike most microbes they will also produce toxins. These toxins can damage liver, nerves, lungs and heart in livestock. Cases of cattle dying from toxin ingestion have been reported from across the world including Saskatchewan, Alberta and Manitoba. Cattle that drink directly out of a dugout are at risk if toxic cyanobacteria have concentrated where they drink.
It is, however, often difficult for an untrained person to distinguish between green algal and cyanobacterial blooms. The cyanobacteria often form clumps and clippings in the water and the green algae often look like lime juice with no distinct clumps. It would be most useful if extension personnel had access to a microscope in their office to provide fast diagnosis: examination of the sample for a couple of minutes should be enough to determine what type of alga is present.
2) Green Algae
The green algae that have caused most problems are small, tolerate high copper sulphate levels and grow fast. Their small size easily makes them airborne and any water body will soon be inoculated with algae from the air. The green algae may pass through commercially available filters, resulting in tap water that looks like lime juice. These algae will most likely not cause any toxic effects in humans or livestock. Application of copper sulphate may increase, rather than decrease the intensity of some green algae blooms.