Pharmaceuticals and trace metals are increasingly prevalent in the aquatic environment, due to anthropogenic pressures. The essential trace metal zinc (Zn) and the non-essential trace metal cadmium (Cd) are particularly enriched in New Zealand settings owing to factors such as galvanised roof runoff, and superphosphate fertiliser application, respectively. The emerging pharmaceutical contaminant diclofenac is increasing in waters worldwide due to heavy usage and lack of breakdown in waste water

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... treatment. Although present at low concentrations, environmental persistence and high bioactivity of these contaminants results in toxicological impacts on aquatic biota. However, most toxicity studies in fish are conducted on model Northern Hemisphere species, and almost nothing is known regarding the sensitivity of widespread Southern Hemisphere fish such as the inanga (Galaxias maculatus). This species exhibits a number of unusual physiological traits that may alter their responses to environmental contamination. Furthermore, as one of the few amphidromous fish species they move freely through estuaries and near-coastal streams that are compromised by the presence of agricultural, urban and industrial effluents containing key contaminants such as pharmaceuticals and trace metals. In order to adopt regulations that adequately protect New Zealand's freshwater fish fauna, it is important to determine that mechanisms of toxicity and the biological foundations of regulatory modelling tools established in model species, still apply to fish such as inanga. To investigate mechanisms of trace metal toxicity, inanga were exposed to graded concentrations of Zn or Cd for 96 h. Whole body metal accumulation, ionoregulation (calcium and sodium influx) oxidative stress (catalase and lipid peroxidation), and metabolism (respirometry) endpoints were examined. Zn exposure caused increases in catalase activity and lipid peroxidation, but only at 1000 μg L-1, a concentration at which Zn also significantly inhibited calcium influx, and stim [...]