SUBLETHAL EFFECTS OF CADMIUM ON THE ENERGETICS OF A TROPICAL FRESH-WATER SNAIL, BROTIA-HAINANENSIS (BROT, 1872)

An increase in cadmium concentrations resulted in a significant reduct ion in the consumption rates, absorption rates, and scope for growth ( SfG) in Brotia hainanensis. There was, however, no significant change in the amount of energy lost in respiration. The no observed effect co ncentration and lowest observed effect concentration for cadmium were 0.4 and 0.8 mg/L, irrespective of whether consumption rates, absorptio n rates, or scope for growth were used as the end point. Results sugge sted that the SfG assay could be simplified by (1) focusing on the mea sure of consumption rates as a performance indicator, and (2) shorteni ng the exposure duration from seven to four days. This technique showe d great potential as an ecotoxicological assessment tool for tropical lotic waters. The benefits and potential problems associated with the SfG assays are discussed. (C) 1996 by John Wiley & Sons, Inc.