Effect of Cu and Ni on cellular energy allocation in Enchytraeus albidus

Effects of nickel and copper on Enchytraeus albidus (Oligochaeta) were investigated using the cellular energy allocation approach. This methodology is used to evaluate the energetic status of an organism and is indicative of its overall condition. Enchytraeids were exposed to the reproduction Effect Concentrations (EC 50 and EC 90 ), and the parameters measured were the total energy reserves available (protein, carbohydrate and lipid budgets) and the energy consumption [based on electron transport system activity] which were further integrated to obtain the cellular energy allocation over different periods of exposure (0–2, 2–4 and 4–8 days). Carbohydrates (in comparison to lipids and proteins) were the only energy source mobilized in the case of nickel within 8 days of exposure. For copper exposure, protein budgets were also strongly reduced. Energy consumption increased in a time and dose-dependent way for copper and in the longer exposure period (4–8 days) at the EC 90 for Ni exposure, indicating that this is a good biomarker for effects of short-time metal exposure, while cellular energy allocation was only significantly reduced for the EC 90 of copper (4–8 days) and EC 50 of nickel (2–4 days). The effects of nickel at concentrations causing 50 and 90 % decrease in reproduction were likely not due to the changes in cellular energy allocation within 8 days of exposure.