Creating tools to predict the ecological mechanisms of stressor effect and recovery in freshwater systems.

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Freshwater resources in Canada can be impaired by any number of contaminants (chemical and biological) as a result of human activities on the landscape. These include pesticides, human and veterinary-use pharmaceuticals, nutrients, and as we are recently learning, organisms bearing antibiotic-resistant genes (ARGs). These stressors can pose significant risks to both human health and ecological structure and function. The two most common sources of these contaminants to surface waters are release of municipal wastewater effluent and agriculture in general; two activities that will not cease in the foreseeable future. Therefore, we need to understand and predict how these contaminants can impact water quality, and explore solutions to mitigate their release and effects. My laboratory’s long-term research objective is to understand the ecological mechanisms by which chemical and non-chemical stressors can induce change(s) in aquatic ecosystems. With this Discovery, we will investigate the role of zooplankton and benthic invertebrates in removing undesirable antibiotic resistance-bearing organisms, especially those from wastewater and agricultural inputs, from the environment via grazing pressure, and the influence of primary producers, nutrients, and pesticides on this relationship. A new tool (the molting enzyme, chitobiase) will be used in attempts to predict invertebrate structure (abundance and biomass) and function (i.e., ARG grazing), as a means by which to assess the status of systems around this ecological service and secondary production in general. By defining and understanding ecological mechanisms of toxicity and potential for recovery (and creating tools to measure and predict these changes, i.e., biomarkers of effect), we can weigh the evidence to determine whether a stressor is having a significant biological effect. The work has implications for the use of treatment wetlands for polishing wastewater treated in lagoons, particularly those under a local, ecologically appropriate context, i.e., the Canadian Prairies, where passive treatment of rural sewage is the norm, as it is in many regions globally. Specifically, it will directly inform design features and management approaches in constructed wetlands as related to attenuation of ARGs. Thus, this work will contribute to improving surface water quality, reducing human and ecological risks, and a better understanding of the ecology and services of these systems.