Interactive Effects of Acidity and Aluminum Exposure on the Life Cycle of the Midge Chironomus riparius (Diptera)

ABSTRACT

The chronic toxicity of acidic pH and the toxicity of aluminum at pH 5.6 and pH 5.0 to the midge Chironomus riparius were determined in 30–day flow–-through exposures. The survival of midges was only ll% at pH 4.5 and 52.3% at pH 5 .8. In soft water (12 mg/l as CaCO³) at pH 5.6, survival declined significantly at aluminum concentrations of 61 to 259 μg/1, but significantly increased at 14.6μg/1. In soft water at pH 5.0, survival increased at concentrations of 14.6 to 111.4 μg/1, but toxicological response of midges to aluminum was thus biomodal, in that acid stress was slightly ameliorated by relatively low aluminum concentrations, but exacerbated by higher concentrations.