The effect of naphthalene on oxygen consumption and hemoglobin concentration in <i>Chironomus attenuatus</i> and on oxygen consumption and life cycle of <i>Tanytarsus dissimilis</i>

Abstract

Abstract The effects of naphthalene on the physiology and life cycle of two species of benthic macroinvertebrates, Chironomus attenuatus and Tanytarsus dissimilis (Diptera: Chironomidae), were determined. The acute effects measured were survival, oxygen consumption, hemoglobin concentration and total body glycogen content. A flow-through system was used to determine chronic effects on life cycle and reproduction parameters. Both species had LC50 values of approximately 13 mg/L. After exposure to naphthalene for 1 h, the oxygen consumption of both species decreased. Tanytarsus was more sensitive than Chironomus, which is consistent with the life histories of the two species. The decrease in oxygen uptake was due to inhibition of the electron transport chain or interference with functioning of the nervous system. Hemoglobin concentrations in Chironomus were not good indicators of naphthalene stress. Although hemoglobin in Chironomus decreased after 4 h of exposure, the decrease was not significant. The decrease could not be accounted for by alteration of hemoglobin structure or by inhibition of synthesis. Life cycle exposures at naphthalene concentrations of less than 0.5 mg/L resulted in minimal effects. Egg hatching and adult emergence were the best indicators of chronic exposure. Pupation times and numbers of eggs were not significantly changed.