The Influence of Thermal Stress on Cadmium Uptake in Arctic Charr (Salvelinus alpinus) and Its Effects on Indicators of Fish Health and Condition, with Implications for Climate Change

Given the implications of heat stress on contaminant uptake and the importance of salmonid fish to Northern Indigenous peoples, investigating temperature-driven patterns in trace metal bioavailability is essential for assessing climate change risks. Here, juvenile Arctic charr were exposed for 8 weeks to cadmium (Cd) at a nominal concentration of 3 µg·L−1 (measured Cd: 1.81 ± 0.47 µg·L−1) or controls (measured Cd: 0.03 ± 0.03 µg·L−1) at a low (6 °C) or high (16 °C) temperature. Cd concentrations were measured in dorsal muscle, liver, and kidney tissues, and antioxidant (superoxide dismutase (SOD), catalase (CAT)) and anaerobic (lactate dehydrogenase (LDH)) capacities were assessed in liver tissue. Elevated temperatures significantly increased Cd uptake in analyzed tissues. Log10SOD activity decreased in the 6 °C-Cd treatment, while log10CAT activity declined in high-temperature treatments and log10LDH activity was reduced in Cd-exposed groups. The results highlight the influence of temperature, but also of combined thermal and trace metal stressors on Arctic charr’s antioxidant and anaerobic capacities. Biometric data indicate that temperature exerted a stronger negative influence on growth than Cd, with synergistic effects of temperature and Cd on the hepatosomatic index. Overall, this research highlights the thermal stress impacts on Cd uptake and Arctic charr physiology.