Dr Erin Reardon - Fishes in extreme environments: life under

Although hypoxia (low dissolved oxygen) occurs naturally in many tropical aquatic systems, this environmental stressor is becoming increasingly widespread as increased municipal wastes and fertilizers accelerate eutrophication and pollution globally. Thus, it has become extremely important to understand the ecological and evolutionary consequences of hypoxia for fishes. First, we explored a suite of life-history, behavioural and energetic consequences of hypoxia across populations in the African mouth-brooding cichlid, Pseudocrenilabrus multicolor, using field surveys and lab experiments. This fish is found across a range of oxygen concentrations, including extreme hypoxia, and we found that it exhibits flexibility in many traits in response to divergent oxygen environments. Second, using hypoxia as an environmental stressor, we investigated the energetic cost of communication in two species of South American weakly electric fish, Apternotus leptorhynchus and Eigenmannia viscerens.  For these species, we quantified respiratory metabolism in association with the frequency and amplitude of the electric organ discharge (EOD) across a range of oxygen concentrations. Combined, this work illustrates how the integration of physiology ecology, behavioural ecology and evolutionary ecology can be important in understanding the role of hypoxia as a divergent selective agent.