Heat is of little importance in blue algae development: study

A new international study involving a Laval University researcher found that water temperature plays a minor role in the development of blue-green algae, even though cyanobacterial explosions occur mainly during the hottest periods of the summer.

"It is mainly the concentration of nutrients such as phosphorus and nitrogen in the water that is to blame," write the authors in the journal Harmful Algae. "Without these nutrients, no matter how hot it gets, there will be no cyanobacteria blooms."

Conversely, blue-green algae can proliferate in very cold weather if they have the right nutrients. The researchers documented the case of a lake in Resolute, on Cornwallis Island, one of the coldest inhabited places in the world, which experienced blooms in the past because the wastewater from an airport and a military base provided nutrients.

"Cyanobacteria, especially the potentially toxic forms, are a threat to water quality and drinking water almost everywhere in the world," said professor Dermot Antoniades of the Department of Geography and the Centre d'études nordiques at Laval University, who spoke to The Canadian Press about the findings of the study. "If we want to protect sources of drinking water and lakes, this is a very important issue."

Blue-green algae can also pose a risk to human health.

Contact with these algae can cause digestive symptoms, headaches, fever and irritation of the skin and throat.

This report by The Canadian Press was first published in French on July 5, 2023.