Toxic Algae Alexandrium catenella Monitoring Application

Presentation of the application for the forecasting of Alexandrium catenella algal blooms for the estuary and gulf of St. Lawrence, eastern Canada 

The application shows the first output of the prediction model of the risk of bloom of the toxic alga Alexandrium catenella. The forecasts are updated every six hours and allow to visualize the bloom risk for the next 48 hours.

A closely monitored alga

The presence of Alexandrium catenella on the eastern Canadian coast has been monitored for more than 20 years. Its ability to produce neurotoxins (saxitoxins) makes it a potentially harmful alga. During A. catenella blooms (an algal bloom corresponds to a rapid increase of microalgae in a particular area), filter-feeding mollusks (e.g. mussels and scallops) consume the algae and concentrate the neurotoxins in their flesh. Consumers of the contaminated shellfish are then at risk of paralytic shellfish poisoning (PSP), which can cause neurological symptoms in many species, including humans. Symptoms may include headaches, nausea and dizziness. In severe cases, intoxication can lead to debilitating neuromuscular disorders (ataxia, paralysis).

Increasing bloom occurrences

Toxic algal blooms can result in significant socioeconomic consequences for affected regions. Indeed, the increased risk of marine predator mortality (Starr et al., 2017) as well as preventative closures of shellfish farming sites can severely affect human populations in these regions. Yet, the frequency and geographic extent of toxic algae appear to be changing in several regions of the world (Gobler, 2020). Climate change is thought to be one cause of the perceived increase, and several studies show that toxic algae are sensitive to precipitation and runoff, as well as oceanographic conditions such as salinity and water temperature (Weise et al., 2002; Fauchot et al., 2005; Starr et al., 2017).

An innovative project

In this context, a research program aimed at developing empirical models to predict toxic algal blooms was initiated at the Maurice Lamontagne Institute (Fisheries and Oceans Canada), under the supervision of Michel Starr (PhD), Joël Chassé (PhD), Aude Boivin-Rioux (MSc) and Denis Lefaivre (PhD). The first output of the program is the prediction model of the risk of bloom of the toxic alga Alexandrium catenella. The predictions are updated every six hours and allow to visualize the bloom risk for the next 48 hours. The results of the model can be visualized using the tools developed by the St. Lawrence Global Observatory (SLGO). Thus, forecasts from this first Canadian operational Alexandrium model are made available to federal and provincial government regulatory agencies (e.g. Fisheries and Oceans Canada, Canadian Food Inspection Agency, Ministry of Agriculture, Fisheries and Food), as well as to the aquaculture industry, municipalities, and local populations that depend primarily on marine resources for their livelihood. These organizations directly benefit from the results of this project by obtaining comprehensive information and short-term predictions needed to develop adaptation strategies that minimize the socio-economic impacts of A. catenella. This approach could eventually be extended to other harmful algae species (e.g. Dinophysis) and to other Canadian coastal areas severely impacted (e.g. Strait of Georgia) or potentially impacted (Hudson Bay, Canadian Arctic) by toxic algae.

To cite the application

St. Lawrence Global Observatory, Boivin-Rioux, A., Starr, M., Chassé, J., & Lefaivre, D. (2022). Toxic Algae Alexandrium catenella Monitoring in Estuary and Gulf of Saint-Lawrence Web Application. Observatoire Global du Saint-Laurent.

For more details, you can consult the method section of the article by Boivin-Rioux et al. (2021):