Grant: Discovery Grants Program - Individual

Freshwater environments, and the biota therein, are under increasing pressure from processes such as global climate change, which can introduce a variety of stressors (e.g. elevated temperature, increased salinity, reduced dissolved oxygen, altered calcium availability) capable of affecting organism and ecosystem health. To assess the impacts of environmental change on freshwater animals a novel paradigm is proposed. First, tolerance to stressors is assessed in the laboratory and expanded to include studies determining the molecular, biochemical and physiological mechanisms underpinning tolerance. These studies are then coupled with field investigations using environmental DNA (eDNA) and environmental RNA (eRNA) techniques. Environmental DNA/RNA is genetic material shed by the animal into the water, which can be non-invasively sampled to provide data regarding the presence and health of the biota therein. Measurements of eDNA will be used to characterise animal distribution and will be correlated to habitat metrics including the levels of stressors found at the point of sampling. This will enable characterisation of freshwater niches that are habitable by a given species. The specific profile of eRNA in the water is likely to reflect the organismal response to the stressors present and thus offers a non-invasive insight into animal health. The target eRNAs will be those that reflect tolerance as discerned from the laboratory exposures to the stressors of interest. Characterisation of eRNA profiles provides information as to whether biota are subjected to sublethal stress in their current habitats, data that may act as an early warning of future population change. This paradigm will be validated using three scenarios. Arctic grayling health will be related to elevated temperature and dissolved oxygen concentrations to determine if these stressors are responsible for the diminishing habitat range of this iconic fish species. The current distribution, and future invasive potential, of the northern crayfish will be assessed to establish whether their tolerance of stressors known to shape freshwater crayfish distributions (temperature, water calcium concentration) will limit their westward and northward spread. Finally, the capacity of the circumpolar crustacean species Daphnia middendorffiana to adapt to elevated temperature and water calcium will be investigated using multigenerational laboratory exposures, and validated against field distribution and health. Ultimately, this paradigm will facilitate identification of populations at their physiological limits, an outcome that can be applied to conservation management strategies for species at-risk and for invasive species.