Acclimation effect and fitness cost of copper resistance in the marine copepod Tigriopus japonicus.

Copper (Cu) contamination is common and widespread in coastal marine environments. This study used the marine copepod Tigriopus japonicus to test whether Cu resistance can be developed through multigeneration acclimation to elevated Cu levels and whether the resistance has a fitness cost. T. japonicus (F0) were acclimated to three Cu concentrations (0, 10, and 100 microg l(-1)) and offspring (F1 and F2) of each treatment were subsequently acclimated at these three concentrations, respectively. Our results evidently indicated that Cu resistance of the copepod was increased even after one generation of acclimation to 100 microg Cu l(-1). The acquired Cu resistance had a fitness cost, as the intrinsic population growth rate of this Cu resistant lineage was significantly lower than the control. The Cu resistance of the offspring from Cu resistant copepods, when raised under control conditions, returned to a level comparable to the control implying a plastic physiological adaptation.