METABOLIC RESPONSES TO ACUTE TOXICITY OF ALKYLPHENOLS AND ALKYLPHENOL POLYETHOXYLATES IN ELLIPTIO COMPLANATA MEASURED BY CALORESPIROMETRY

摘要

Alkylphenol ethoxylates (APEs) are important contaminants of world water systems with effects on aquatic life. Metabolic responses to short-term acute toxicities of alkylphenol and alkylphenolethoxylates were investigated in the freshwater bivalve mollusk Elliptio complanata using isothermal batch microcalorimetry and respirometry. Metabolic heat rates were altered following short-time exposure of the gill tissue to these compounds over the concentration range of 10~-6 to 10~-3 M. There was a time and concentration dependence of the effects of alkylphenol and alkylphenolethoxylates on metabolic heat rates. In general, treatment with alkylphenols and alkylphenolethoxylates at concentrations ranging from 10~-6 to 10~-4 M caused stimulation of metabolic heat rates, possibly due to uncoupling of oxidative metabolism. Higher concentrations subsequently caused inhibition of metabolic activity and thus decreased heat rates. Rates of oxygen consumption by the gill tissue exposed to the surfactants, as a measure of effects on electron flux through mitochondria, showed a similar pattern of respiratory rate stimulation at low concentration and inhibition at higher concentration. Therefore, the batch calorespirometric method proved to be a useful technique to assess the toxicity of a group of surfactants on the control of energy flux in gills of a freshwater bivalve mollusk.