Evaluation of the freshwater copepod Acanthocyclops americanus (Marsh, 1983) (Cyclopidae) response to Cd, Cr, Cu, Hg, Mn, Ni and Pb

The toxic effect of cadmium, chromium, copper, mercury, manganese, nickel and lead on adult Acanthocyclops americanuscopepods was evaluated to determine the sensitivity of this species to these metals. Toxicity tests were carried out to determine the LC50, after which bioassays were carried out with environmentally relevant sublethal concentrations in order to measure oxidative damage to cell membranes as well as neurotoxic effects. Cadmium was the most toxic metal and manganese was the least harmful. Copper had the greatest oxidative effect (lipid peroxidation) and nickel had the least effect. A 3% to 79% drop was observed in acetylcholinesterase (AchE) activity, with copper causing the greatest inhibitory effect. A. americanus sensitivity to cadmium, manganese and lead was similar to that recorded for Daphnia magna neonates, but the copepods were less sensitive to chromium, copper, mercury and nickel. The response of A. americanus to exposure to metals makes it possible to propose it as a test organism to evaluate the presence and effect of these elements, particularly cadmium, manganese and lead, in toxicity studies, and possibly for monitoring purposes.