Assessing overall lake health across Canada to identify sites for restoration and conservation

Photo credit to the blue, red, green and purple sampling team of the NSERC Canadian Lake Pulse Network, as well as to Andréanne Dupont. From top to bottom rows, left to right: blue team, red team, green team; purple team, green team, purple team; Andréanne Dupont, red team, green team.

Canadians love to swim, fish, and navigate in and on the countless lakes across the country. But Canadian lakes are under a considerable amount of pressure from human activities in their watersheds.

The expansion of cities, intensive farming, wetland loss, and industrial development all result in the transfer of pollutants to aquatic habitats, threatening lake health and the ecosystem services they provide.

Read this open access paper on the FACETS website.

Where are lakes being used across Canada? What conditions are lakes in and is their use under threat from different pressures? To answer these questions, we combined information from many different sources, including a national scale lake assessment, through the NSERC Strategic Network Cluster Lake Pulse to create the first social-ecological geography of southern Canadian lakes.

Regionally specific reference conditions were established from lakes considered healthy due to limited human activities in their watersheds.

When lakes with impacted watersheds were compared to healthy ones within their specific region, two early warning signals of human pressure emerged across the country: nitrogen pollution found in agricultural fertilizers and sewage, and chloride found in road salt.

We combined these two health indicators as the potential altered state of lakes together with information on their future threats, and recreational use by the population. By using a colour-coded mapping technique, we were able to identify regions where lakes were altered, threatened, and used.

These regions occurred primarily around dense urban areas of southern Ontario and Quebec, and major cities on the east and west coasts. Lakes in the Prairie Provinces were altered and threatened, but seemingly less used.

This novel approach is very adaptable, easy to understand, and could be used by stakeholders at more local scales to determine priority sites for conservation and restoration, and effectively communicate the state of overall lake health.

Read the paper — A social–ecological geography of southern Canadian lakes by Andréanne Dupont, Morgan Botrel, Nicolas Fortin St-Gelais, Timothée Poisot, & Roxane Maranger.