Climate change is favorable for red tides

In addition to unusual blooms such as those that occurred in 2008, toxic algae Alexandrium catinella, Known as the red seaweed, it blooms regularly here and there in the bay.

Researchers have been monitoring it for 24 years using stations scattered all over the bay.

It is one of the most toxic algae in the world.

Under unfavorable conditions, the algae form a kind of sac in which it traps itself during the latency period. Wake up when environmental conditions allow.

Already, associations between toxic algal blooms as well as higher water temperature and precipitation suggest to researchers increased flowering in the bay and estuary.

Modeling three climate change scenarios combined with historical observations of red algal blooms confirm this.

The seasons of flowering

In the three scenarios studied, the model indicates a gradual increase in the number of days/risks up to the year 2100.

The average number of hazard days for the St. Lawrence Estuary ranges from 50 hazard days per year for the current period to more than 75 days per year by the end of the century, an increase of up to 50% , points to Michelle Starr, oceanographer and phytoplankton ecologist at Fisheries and Oceans Canada.

The specialist adds that the extension of the favorable period for flowering can be felt already within ten years.

endangered species

The extent of outbreaks in the Gulf and estuary will also increase, particularly due to the reduced salinity of surface waters resulting from heavy rainfall.

The model shows that days/risks will increase in sectors such as the Lower North Shore or the Magdalen Islands, currently very little affected by flowering.Alexandrium.

Scientists believe this increased range of blooms in the bay and on the Scottish shelf could threaten the survival of already endangered species such as the beluga and North Atlantic right whales.

Bigger outbreak

In addition, the data shows significant variation between years. For example, flowering will be more significant during one year, but it will be almost absent the next. This increase in year-to-year differences leads to increasingly extreme events.

Unusual blooms, such as the one in 2008, which stretched from the mouth of the Saguenay River to Sainte-Anne-de-Monts, in Gaspey, could be more frequent.

All of these expected changes in the timing and distribution of blooms, as well as in their intensity and diversity, could become major problems for fisheries and aquaculture in Quebec and the Maritimes.

new tool

Already, two years ago, Michel Starr wanted to create a system for predicting outbreaks of toxic algae. He intended to combine Environment Canada’s weather forecasts with more than 20 years of accumulated data on toxic algal bloom conditions.

It is now over. The tool is there and will be implemented in March for the next season on the Observatoire Global du Saint-Laurent (OGSL) website.

disease outbreak prediction map

Maps like these will be posted on the St. Lawrence Global Observatory website and will allow aquarists to learn about the risks of an outbreak.

Photo: Radio Canada

These forecasts, in the form of maps, published four times a day for the next 24 to 48 hours, will be used, among other things, by aquarists, who will thus be able to protect their crop from the crippling and dangerous poison for humans. consumption.

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Canada’s Food Inspection Agency will also be able to use the tool to improve its detection of contaminated sites and close them for collection, if necessary.

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