French River Watch
Blue green algae and phosphorus
Blue-green algae, also known as cyanobacteria, are photosynthetic bacteria which are a natural part of aquatic ecosystems and an important part of the food chain. However, when colonies become overgrown (bloom) they can disrupt a balanced ecosystem and adversely affect human and animal health.
The dynamics of algae colonies is complex but research shows that phosphate availability can be limiting for algae growth and that increased levels of phosphates and other nutrients due to human activities can directly contribute to algae blooms. It is likely that problems at the Noelville sewage treatment lagoons have contributed to recent blooms in the French River. The blooms can appear as green clumps floating in the water or later in its development a bloom can look like a green paint spill. In addition to making the water unpleasant for recreational use, some algae types produce toxins that pose a danger to human and animal health.
An additional problem arises when the algae die and are decomposed by various bacteria. This can lead to the depletion of oxygen levels in the water, which stresses fish populations. Furthermore, oxygen depletion causes the release of phosphorus from sediments, thereby creating a positive feedback loop that can amplify the problem.
Phosphate levels, blue-green algae and oxygen depletion
Tests done by the Ontario Ministry of the Environment (MOE) in October 2007 and November of 2009 confirmed the presence of blue-green algae in the French River. Samples taken by the MOE contained Anabaena, a species of blue-green algae capable of producing toxins. Toxins can irritate the skin and, if ingested, cause diarrhea and vomiting. At high enough levels, toxins can cause liver and nervous system damage.
While algae blooms are visible, the Sudbury & District Health Unit recommends that residents on the French River:
-DO NOT use water from the French River to drink, bathe, or shower. Do not allow children, pets and livestock to drink or swim in the water.
-DO NOT use herbicides, copper sulphate or other algaecides that may break open the algae cells and release toxins into the water.
-DO NOT boil the water. Boiling the water may release more toxins into the water.
-DO NOT cook with the water. Your food may absorb toxins from the water.
-DO NOT eat the liver, kidneys and other organs of fish caught in the water. Be cautious about eating fish caught in water where blue-green algae blooms occur.
-DO NOT treat the water with a disinfectant like bleach. This may break open algae cells and release toxins into the water.
-DO NOT rely on water jug filtration systems because they do not fully protect against toxin poisoning.
More information on cyanobacteria can be found on the web sites of many government and scientific organizations.
The Sudbury & District Health Unit has an excellent page with advise and some usefull links that can be viewed here. The
World Health Organization has put together a report on blue-green algae that can be found here.
© 2009-2010, French River Watch