Establishing environmental DNA (eDNA) monitoring for causal analysis of amphibian occupancy and aquatic ecosystem risk assessment

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Across Canada, freshwater wetlands are rapidly declining in number and quality, and there is an urgent need to understand the causes of their decline and develop protocols for their effective monitoring and assessment. Amphibians are important components of aquatic ecosystems but worldwide their populations are declining, and in Canada several species are listed at-risk or are absent from apparently suitable habitat. Amphibian declines and local extinctions likely are related to deterioration of their aquatic habitat, including mortality associated with water-borne pathogens (chytrid fungus, ranavirus) acting either directly or interactively with other environmental stressors (e.g., climate, contaminants, habitat loss). However, the precise cause of most amphibian declines is poorly known due to inadequate population monitoring combined with weak causal relationships between numerical trends and environmental stressors; such trends may portend changes in freshwater quality and aquatic system services. Capitalizing on new animal survey methods using environmental DNA (eDNA), and improved landscape mapping and modeling techniques, this work will provide a rigorous assessment of the causes of observed amphibian occurrence patterns. Specifically, we will: 1) Establish water-based sampling protocols for detecting and quantifying amphibians and their primary pathogens (chytrid fungus, ranavirus) in a Canadian context; 2) Use land cover and environmental variables (moisture regimes, contaminants) associated with field-collected data to develop models for amphibian and pathogen occupancy, and assess their utility as bioindicators of wetland quality; and 3) Develop models