Temperature elevation stage-specifically increases metal toxicity through bioconcentration and impairment of antioxidant defense systems in juvenile and adult marine mysids

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Metals are of serious concern due to their toxicity, persistency, and accumulation potential in aquatic animals. However, limited information is available on the combined effects of metal with temperature elevation, which is one of the future climate changes suggested for the oceans. In this study, the effect of temperature elevation was investigated by analyzing toxicity, bioconcentration, and antioxidant response in juvenile and adult marine mysids upon exposure to 20 °C and 25 °C for 48 h and 96 h. Based on LC50 values, toxicity of metals was highly reliant on temperature, exposure period, and age. Elevation in temperature significantly increased the whole metal toxicity in juveniles. Bioconcentration was elevated by increasing exposure period and metal concentration. Significant elevation of malondialdehyde (MDA) and depletion of glutathione (GSH) was measured in juveniles, while significant elevation of both MDA and GSH was detected in adults. Subsequently, enzymatic activities of antioxidant enzymes in catalase (CAT) and superoxide dismutase (SOD) increased significantly in adults at 48 h and 96 h, whereas most activities were significantly lowered in juveniles at 96 h. These results suggest that the early life stage of marine mysids is more sensitive to the combined effect of metal and temperature than adult stage due to an impairment in the induction of the antioxidant defense system.