Combined effects of natural and anthropogenic stressors in fish

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Fish are exposed to a variety of stressors in their environment. Like other ectotherms, their internal temperature reflects environmental temperature and hence fluctuates seasonally. Fish are also exposed to contaminants released by industry, cities and agriculture. Metals are a peculiar type of contaminants, because they are also naturally present in the environment and several of them, like iron or copper, are essential for life. However, other metals like cadmium are non-essential, and all metals, essential or not, become toxic at high concentrations. This research program aims at examining the combined effects of variations in temperature and metal exposure on fish condition and health. We will investigate whether the stress induced by elevated temperatures increases their sensitivity to metal contamination, and vice-versa. The program also investigates the limits of tolerance to these stressors for several species of Canadian freshwater fish.