Acute effects of copper exposure and predation risk in five coastal copepods

Natural stressors, including predation risk, can affect the response of organisms to anthropogenic contamination. Copper, used as an antifouling agent, can affect non-target organisms. We tested for effects of excess copper on survival with and without predator cues in five species of coastal copepods. We exposed adult copepods to four copper concentrations (0-1350 μg L-1, 48h) on an automated imaging platform and analysed the data using the reduced General Unified Threshold model for Survival (GUTS) to detect potential species differences in underlying toxico-kinetics and -dynamics. Calanoid copepods had elevated mortality during early copper exposure compared to a harpacticoid and a cyclopoid species. Species-specific dominant rate constants, which represents the time it takes for damage to reach a steady state, best explained the time-dependent toxicity. Over time, most predicted mortalities converged to a similar level regardless of species. Predation risk reduced mortality at the intermediate copper concentration, potentially explained by reduced copper bioavailability by binding of copper to kairomone molecules, or other intrinsic and extrinsic factors. Models like GUTS can reveal the underlying toxicity mechanisms and improve toxicity predictions in a multi-stressor world.