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| Wednesday, January 03, 2007 |
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Frequently Asked Questions – What is Blue-Green Algae? What is blue-green
algae? Blue-green algae is not an algae, but a bacteria called "cyanobacteria." This bacteria produces a toxin that can cause skin and eye infections, liver damage, gastroenteritis, sickness and, at times, death. How can I identify blue-green bacteria?
Blue-green algae will have a shimmering, blue-green colour. It may also have a foamy sheen-like appearance, that looks like spilled paint floating on top of the water. Heavy blooms appear like a solid shimmering blue-green sheen across the water’s surface, or have an appearance and consistency similar to pea soup. Where does blue-green bacteria from? Weather conditions this spring have been conducive to the formation of blue-green bacteria blooms on dugouts and ponds. Warm daytime conditions in the summer months of June and July, combined with a nutrient rich body of fresh water, accelerate algal growth, including that of blue-green bacteria. What time of year does blue-green bacteria form? Blooms of bacteria begin to appear during the month of June, and persist throughout the warm summer months. How can I treat for blue-green bacteria? The most common treatment of blue-green algae in an open dugout or pond is with a registered product containing copper sulphate. A list of registered, commercially available products is contained in the Prairie Farm Rehabilitation Administration (PFRA) Fact Sheet “Copper Treatments for Dugouts” - (http://www.agr.gc.ca/pfra/water/copper_e.htm). A treatment rate of one pound (0.45 kilogram) of copper sulphate (by weight) will treat 250,000 gallons (947,000 litres). There are two common application methods: the copper sulphate can be dissolved in warm water, which is then sprayed over the water’s surface; or, the copper sulphate can be weighted into a cloth bag with a rope spread from side to side, and with the assistance of another individual, the bag can then be dragged back and forth across the water’s surface. The copper sulphate kills the blue-green algae, releasing toxins into the water. Therefore, it is recommended that 12 to 14 days should pass prior to any livestock, pet and/or human contact with the contaminated water. If treating a dugout containing fish, it is recommended that only one-third of the dugout should be treated, using one-third of the recommended copper sulphate weight applied in treatments over a three day period. Table 1. Approximate Dugout Capacities (Water depth 14 ft., 1.5:1 side slope, 4:1 end slope)
Do not use more than the recommended amount of copper sulphate. Higher levels will destroy some of the beneficial organisms such as zooplankton, that actively feed on bacteria and algae. The treatment process described above applies to non-draining waterbodies, such as dugouts, which are wholly contained on private land. In the case of waterbodies that drain to adjacent properties or waterways, a permit for the chemical control of aquatic nuisances is required from Saskatchewan Environment. When
should I apply copper sulphate to control blue-green bacteria? If blue-green bacteria is being controlled, prevent livestock, human and pet consumption of the water for 12 to 14 days post-treatment to allow the blue-green bacteria toxins to dissipate. The rate of copper sulphate listed above will provide good control of the blue-green bacteria, but exercise caution when treating heavy blooms. A treatment of copper sulphate in these situations rapidly kills the bacteria. High concentrations of toxins may be released into the dugout water following treatment. The toxins can be lethal. For control of regular bacteria, copper sulphate should be applied later in the evening after the cattle have had their afternoon drink. This method should prevent accidental ingestion of copper sulphate by the cattle. By morning, the copper sulphate will have mixed with the water and is safe for livestock to drink (wait 24 hours before using treated dugout water for human consumption). If treating a dugout containing fish, it is recommended that only one-third of the dugout should be treated, using one-third of the recommended copper sulphate weight applied in treatments over a three day period. Is copper sulphate a registered product? Granular copper sulphate is used as an ingredient for feed and fertilizer. It also functions as an algaecide and fungicide, and as such is registered under the federal Pest Control Products Act. What other products are available to treat blue-green bacteria? A list of registered, commercially available products is contained in the Prairie Farm Rehabilitation Administration (PFRA) Fact Sheet “Copper Treatments for Dugouts” (http://www.agr.gc.ca/pfra/water/copper_e.htm). Lime, alum and ferric chloride are coagulation products that bind to all bacteria. Once bound, the bacteria clumps together and sinks to the bottom of the dugout. While these products work to remove blue-green bacteria from the water surface, the dead blue-green bacteria cells can rupture, releasing toxins into the water.
How can I prevent blue-green bacteria? Blue-green bacteria prefers freshwater dugout and pond environments that are high in nutrients such as nitrogen and phosphorus, and where there is little to no water movement. Moving water by means of natural flow or aeration disrupts water temperature gradients, and maintains a more even water temperature at all depths of the body of water. Aeration also ensures a healthy aerobic environment which will promote the constant cycling of nutrients, and prevent a build-up of nutrients from occurring. For more information, contact: Saskatchewan Agriculture
and Food Agriculture Knowledge Centre
at 1-866-457-2377 | ||||||
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