Mechanism of acute copper toxicity in euryhaline crustaceans: implications for the Biotic Ligand Model

The Biotic Ligand Model (BLM) for copper is largely based on data obtained from freshwater fish and is currently calibrated to protect freshwater invertebrates. The extrapolation from fish to invertebrates must rely on the general assumption that the mechanisms of toxicity induced by copper in the sensitive invertebrates are the same as those observed in the less sensitive teleost fish. Therefore, the need for more invertebrate data is a critical area for the improvement of the BLM for freshwater and for its extension to brackish and marine waters. Results from our recent studies have shown that in low salinities the mechanism of acute toxicity in euryhaline crustaceans sensitive to copper is similar to that observed in freshwater fish and crustaceans, i.e., iono- and osmoregulatory imbalance induced by Na+,K+-ATPase inhibition. However, other results clearly indicate that the same mechanism of toxicity is not evident in euryhaline crustaceans more tolerant to copper. They also indicate that in sea water the mechanism of acute copper toxicity either in sensitive or more tolerant species is definitely not associated with an iono- and osmoregulatory imbalance, as opposed to marine teleost fish.