Biological Responses of Lumbriculus variegatus Exposed to Fluoranthene-Spiked Sediment

Abstract

Abstract. Lumbriculus variegatus was used as a bioassay organism to examine the impact of the sediment-associated polycyclic aromatic hydrocarbon (PAH) fluoranthene on behavior, reproduction, and toxicokinetics. The number of worms increased between the beginning and end of the experiment at 59 g g Ϫ1 fluoranthene, but at the next higher treatment (108 g g Ϫ1 ) the number of worms found was lower and not different from the control. Worms exposed to 95 g g Ϫ1 also exhibited increased reproduction when fed a yeast-cerophyltrout chow mixture. On a total biomass basis, only the 95 g g Ϫ1 exposure with food exhibited a statistically significant increase over the nonfed control. Evaluation of reproduction at the two highest treatments was compromised by a brief aeration failure 2 days before the end of the experiment. The behavioral responses were followed as changes in biological burial rate (sediment reworking rate) of a 137 Cs-labeled marker layer. The biological burial rate increased toward a plateau as the concentration increased from the control (3.9 g g Ϫ1 dry weight total PAH) to 355 g g Ϫ1 dry weight fluoranthene in sediment. The aeration failure had minimal impact on the determination of reworking rate because all the data for the rate determination were collected prior to the aeration failure. Uptake and elimination rates declined with increasing treatment concentration across the range of fluoranthene concentrations, 59 -355 g g Ϫ1 dry weight sediment. The disconnect between the increasing biological burial rates and the decreasing toxicokinetics rates with increasing exposure concentration demonstrates that the toxicokinetic processes are dominated by uptake and elimination to interstitial water. The bioaccumulation factor (concentration in the organisms on a wet weight basis divided by the concentration in sediment on a dry weight basis) ranged from 0.92 to 1.88 on day 10 and declined to a range of 0.52 to 0.99 on day 28 with the lowest value at the highest dose.

An Integrated Experimental and Modeling Approach to Predict Sediment Mixing from Benthic Burrowing Behavior

“…L. variegatus motion was highly heterogeneous. Although this organism is commonly described as an upward conveyor, , we observed several distinct behaviors, including sediment excavation, particle ingestion/egestion, rapid reworking of interfacial sediments, and deep burrowing. Burrows were biased to the upper 10 mm of the bed (99.6% of events), which left extensive areas of the subsurface unaltered (Figure a).…”

“…We added 0.250 g of L. variegatus (Aquatic Research Organisms, Hampton, NH, United States) evenly over the SWI immediately following sediment stabilization. This corresponds to an organism density of 6300/m 2 , 37 which falls within the typical range of oligochaete densities in freshwater sediments (1000−40000/m 2 ). 38−40 L. variegatus egested and excreted the organic-rich test sediments, and no exogenous food was added during the experiment.…”

Comparison of three microquantity techniques for measuring total lipids in fish

“…However, we found no evidence to this effect in our study for these two microquantity approaches; we also did not find that the ability to estimate lipids between methods differed among species of varying lipid content or between tissue types (somatic vs. gonadal). Landrum et al (2002) also demonstrated that the microcolorimetric SPV and microgravimetric methods produce comparable results for aquatic algae. Additionally, measurement precision did not differ between microquantity methods in this study, regardless of species or tissue type analyzed.…”

“…Because microgravimetric analysis is more time-and labor-intensive than microcolorimetric SPV analysis (Landrum et al 2002(Landrum et al , 2004Inouye and Lotufo 2006), it was conducted only on samples collected during 2005. These samples included yellow perch, walleye, and walleye gonads (Table 1).…”

“…Gardner et al (1985), however, did find that their microgravimetric assay correlated strongly with Iatroscan TLC-FID measurements for individual amphipods and oligochaetes. Further, although Van Handel's (1985) microcolorimetric SPV approach has been preferred over Gardner et al's (1985) microgravimetric method for measuring total lipids of benthic macroinvertebrates, because it is more time-and labor-efficient (Landrum et al 2002(Landrum et al , 2004Inouye and Lotufo 2006), a true comparison of the relative performance of these two microquantity methods has not yet been conducted for any organism.…”