Effects of long-term sublethal exposure to copper on subsequent uptake and distribution of metal in the shore crab Carcinus maenas

As in many aquatic organisms, the gill epithelium is the main site of the uptake of copper and toxicity in the shore crab. Long term pre-exposure to sublethal doses of water-borne copper has been shown to lead after some weeks to progressive recovery from the initial toxic effects. We report experimental results that shed light on some of the mechanisms underlying these acclimatory effects. The metal adaptation seems related to an important reduction of copper uptake from the ambient medium and to a better efficiency of metal transfer from hemolymph to the tissues. As a consequence, steady-state hemolymph levels of exogenous copper are strongly decreased during a further lethal exposure in pre-acclimated crabs compared to controls. A 17-day sublethal pre-acclimation period appears, however, to be too short to improve the resistance of the animals to a further challenge at usually lethal doses of copper.