TOXICITY OF SEDIMENT-ASSOCIATED PYRENE AND PHENANTHRENE TO L1MN0DR1LUS HOFFMEISTERI (OLIGOCHAETA: TUBIFICIDAE)

摘要

Acute and sublethal toxicities of sediment-spiked pyrene and phenanthrene to Limnodrilus hoffmeisteri Cleparede were investigated. Phenanthrene was acutely toxic at high sediment concentrations (10-d median lethal concentration of 297.5 μg g~(-1); 252.2-348.3, 95% confidence interval [CI]). Pyrene was not acutely toxic, even at concentrations as high as 841 μg g~(-1). A significant impact of pyrene and phenanthrene on the feeding activity of L. hoffmeisteri was demonstrated through daily collection of egested fecal material during 5- and 10-d experiments. A short (5-d) exposure detected toxic effects more efficiently than a 10-d exposure, yielding IC25 values (estimated concentration causing a 25% reduction of measured endpoint in relation to the control[s]) of 58.9 μg g~(-1) (32.1-89.4, 95% CI) for pyrene and 28.4 μg g~(-1) (10.0-41.3, 95% CI) for phenanthrene. Effects on burrowing behavior and reproduction were assessed in a 28-d sediment exposure. Low burrowing avoidance ( < 25%) was detected in high phenanthrene concentrations (143-612 μg g~(-1)) but was not detected with pyrene. Offspring production was significantly reduced in dosed sediments yielding IC25 values of 59.1 μg g~(-1) (38.3-112.5, 95% CI) for pyrene and 40.5 μg g~(-1) (12.1-165.5, 95% CI) for phenanthrene. Decreases in egestion rates in the presence of nonpolar contaminants should be quantified when investigating the effects of bioturbation by deposit feeders on the flux of contaminants from sediment into the water column.