Blooming algae: a Canadian perspective on the rise of toxic cyanobacteria

• Published in: Canadian journal of fisheries and aquatic sciences Vol. 73; no. 7; pp. 1149 - 1158
• Main Author: Pick, Frances R
• Format: Journal Article
• Language: English
• Published: Ottawa NRC Research Press 01.07.2016; Canadian Science Publishing NRC Research Press
• Subjects: Algae; Algal blooms; Aquatic ecosystems; Bioaccumulation; Biomass; Canada; Causes of; Climate change; Contaminants; Cyanobacteria; drinking water; Ecosystem protection; Environmental aspects; Eutrophication; fish; food webs; guidelines; human health; Invasive species; issues and policy; Lakes; microcystin-LR; Microcystins; nitrogen; nutrients; Overfishing; phosphorus; poisonous algae; pollution; Recreational waters; toxicity; Canada; ANW, Canada
• ISSN: 0706-652X; 1205-7533; 1205-7533
• DOI: 10.1139/cjfas-2015-0470

Algal bloom reports are on the rise across Canada. While eutrophication is the main driver, other stressors of aquatic ecosystems, specifically climate change and food web alterations from the spread of invasive species and overfishing, are compounding factors acting in concert or independently. Current models can predict the average algal and cyanobacterial biomass concentrations across temperate lakes as a function of nutrients, but models to specifically predict harmful algal composition and toxicity are lacking. At the within-lake scale, where management occurs, strong year to year variations in cyanobacterial blooms remain challenging to explain, let alone predict. The most common cyanotoxins, the hepatotoxic microcystins, are chemically diverse with some variants more toxic than others and with greater propensity for persistence and bioaccumulation. These differences have been largely overlooked, as current guidelines have been based on microcystin-LR, considered the most common variant. Microcystin-LA is also encountered in Canadian waters and appears to exhibit greater persistence and bioaccumulation. With cyanobacterial blooms most likely to increase across the country, including the north, guidelines and policies for cyanotoxins in drinking and recreational waters as well as fish will need to be developed for the protection of ecosystem and human health. Ultimately, control of eutrophication is the most important option for managing toxic cyanobacterial blooms; nitrogen and phosphorus need to be considered as environmental contaminants, as both play a role in controlling the dominance of toxigenic cyanobacteria.