mercredi 15 août 2012

Toxin Microcystin in Canadian Lakes

"The truth is incontrovertible, malice may attack it, ignorance may deride it, but in the end; there it is."
~ Winston Churchill

Algues rouge dans Baie Groulx August 2008

Algues rouge dans Baie Groulx August 2008

Algues dans Baie Groulx et Baie Yelle en 2008!

(et Algues Bleu dans Baie Ours en 2005)

Video: Study raises worries over toxin in Canadian lakes
CTV Winnipeg

Liver toxins prevalent in western cottage country’s lakes, cross-Canada study finds
Globe & Mail

Manitoba, Alberta lakes surveyed have high levels of toxin

A survey of more than 250 lakes across Canada has found a potent liver toxin in every province, with the highest concentrations in central Alberta and southern Manitoba.

The survey published in a scientific journal has found the toxin in certain types of blue-green algae.

The toxin, called microcystin, is found in lakes heavily loaded with nutrients from agricultural runoff and development.

The survey found nearly 10 per cent of the 256 lakes surveyed had microcystin levels that exceeded Canadian guidelines even for recreational use. MORE >>>

Potent human toxins prevalent in Canada's freshwaters Canadian Journal of Fisheries and Aquatic Sciences

Ottawa, Ontario (August 14, 2012) – Nutrient pollution, one of the greatest threats to our freshwater resources, is responsible for the algal blooms that blanket our lakes and waterways in summer months. Large blooms of cyanobacteria (‘blue green algae’) can cause fish kills, increase the cost of drinking water treatment, devalue shoreline properties, and pose health risks to people, pets, and wildlife. A new paper just published in the Canadian Journal of Fisheries and Aquatic Sciences shows that microcystin, a toxin produced by cyanobacteria, is present in Canadian lakes in every province.

“Canadians enjoying their summer at the cottage need to know that those green scums of algae washing up on their beach are not only unsightly, but can also be a threat to their health and their children’s health,” says lead author, Diane Orihel, a researcher with the Department of Biological Sciences at the University of Alberta. “It’s time to get serious about cleaning up the nutrients polluting our lakes.”

Microcystins are well-established as potent liver toxins to humans and other mammals, and are classified as possible human carcinogens. "Blue-green algae present a growing health concern for domestic, agricultural and recreational water use in Canada and world-wide”, warns Dr. David Kinniburgh, the Director of the Alberta Centre for Toxicology at the University of Calgary. “The microcystin toxins they produce can cause acute liver failure in humans and may even cause cancer with long-term exposure."

This study is the first to report on microcystin prevalence at a national scale–data from 246 bodies of water across Canada were collected. The authors determined that water quality was most at risk in lakes with the highest concentrations of nutrients. Nutrient-rich lakes and reservoirs, particularly in central Alberta and southwestern Manitoba, proved to have highest toxin concentrations, though all regions in Canada contained lakes that reached microcystin levels of concern.

A very important finding–that calls for further research–was the strong association between low nitrogen-to-phosphorus ratios and high microcystin concentrations. The authors recommend whole-ecosystem experiments be performed to understand how changing nutrient inputs to lakes affects microcystins and other cyanobacterial toxins. This information is essential for governments to develop effective management strategies for improving water quality in nutrient-polluted lakes.

"Harmful algae blooms are a growing problem worldwide. The more we look, the more we find,” remarked international water expert Dr. Stephen Carpenter, Director of the Center for Limnology at the University of Wisconsin-Madison, “Orihel and colleagues help define the conditions when we would expect highly toxic freshwater. These insights make it possible to focus management and research on the highest-risk situations."

“This study addresses an issue that has important health consequences, but also highlights the importance of both the underlying basic science and monitoring programs essential to determine environmental changes,” says Don Jackson, Co-Editor of the Canadian Journal of Fisheries and Aquatic Sciences.

The paper “High microcystin concentrations occur only at low nitrogen-to-phosphorus ratios in nutrient-rich Canadian lakes”, published in the Canadian Journal of Fisheries and Aquatic Sciences, is available Open Access at

4 commentaires:

Anonyme a dit...

Ouf, c'est inquiétant tout cela!!! J'aime bien l'analogie du 'FAT LAKE' qui fait référence au trop plein d'abus! C'est le temps de faire 'DIÈTE' sur nos lacs!!!

Chantal (baie Groulx, lac Simon

Anonyme a dit...

Chantal une diete de quoi au juste ?La diete tu veux la faire depuis un bon bout de temp dans la baie Groulx!

Chantal Crête a dit...

Faire diète, ça implique généralement que la personne va porter PLUS ATTENTION, qu'elle va mieux DOSER et mieux SURVEILLER. Quand la liberté de l'un brîme la liberté de l'autre, c'est qu'il y a un déséquilibre important et je suis d'avis, qu'il faille l'étudier pour rétablir l'harmonie. QUand les propriétaires de la baie Groulx sont rendus qu'ils doivent silloner entre les bateaux pour entrer et sortir de chez eux, je pense que c'est un problème et qu'il faut chercher des solutions.

C'est facile de nous mettre tous les torts. C'est facile de nous accuser d'être des riches qui voulons nous approprier le lac!!! C'est loin d'être le cas! Nous cherchons, comme tous, à profiter de l'été et du lac.

Imaginez vous pour un instant si j'allais garer ma voiture, celle de mon mari et de mes enfants devant votre entrée à la maison. Si à chaque fois que vous voudriez sortir de chez vous, vous auriez à silloner entre les voitures garées dans votre rue ou pire encore, avoir l'obligation de nous demander de déplacer nos voitures. Que feriez-vous??? Qui appeleriez-vous??? Bien, c'est exactement le même contexte ici dans la Baie Groulx. Les proprios du fond doivent AFFRONTER une horde de bateaux ancrés à chaque fois qu'ils souhaitent aller faire une promenade sur le lac.

Anonyme a dit...

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