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Aquatic Biodiversity: Multiple Stressor Effects

Measuring stream algal productivity | Photo: Environment CanadaMultiple stressor effects on aquatic biodiversity are difficult to quantify and predict because of interactions in an additive or multiplicative manner (e.g., nutrients, sediments and flow in agricultural watersheds). Aquatic ecosystems may change abruptly and unexpectedly in response to the accumulation and interaction of multiple environmental stressors.

These ecological effects include the degradation of water quality and biodiversity in Canada’s rivers and lakes as a result of nutrient and contaminant stressors related to point and non-point sources, as well as climate change.

Environmental scientists believe that declining biodiversity and ecosystem health are the result of long-term and multiple environmental stresses.

Water S&T Research

Environment Canada scientists are developing diagnostic bioassessment approaches that incorporate state-of-the-art technologies to identify the effects of complex stress regimes on aquatic ecosystems (e.g., interactive effects of nutrient-pesticide inputs on biodiversity). Advances include the application of biological, trait-based, methodologies to identify the sources of human-induced changes to aquatic ecosystem quality.

Researchers are applying stable isotope techniques in environmental assessments to evaluate exposure of aquatic organisms to municipal and industrial effluents, to measure the effects of pollutants on aquatic ecosystem metabolism, and to generate novel methods to trace sources and fate of chemicals in rivers and lakes.

Scientists are using advanced mesocosm technologies to understand and predict the ecological effects of non-point stressors linked to land usage, including the effects of pesticide, and nutrient and sediment stressors that can degrade agricultural watersheds.

Environment Canada scientists are leading the development of approaches and techniques to support a national strategy for monitoring and reporting on the biodiversity of Canada's inland waters (Canadian Aquatic Biomonitoring Network; CABIN). Key developments include the application of genetic barcoding techniques to facilitate biological identification and improvement in sharing/linking distributed biological data sources.

Scientists are contributing to major ecosystem initiatives including the Lake Winnipeg Basin Initiative, and have developed environmental standards for key water quality variables for the National Agri-Environmental Standards Initiative.

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