Effects of the polycyclic aromatic hydrocarbon fluoranthene on growth rate and nucleic acid composition of Capitella sp. I |
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Authors: | H E Foss V E Forbes |
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Institution: | (1) Department of Life Sciences and Chemistry, Roskilde University, P.O. Box 260, DK-4000 Roskilde, Denmark, DK |
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Abstract: | Body volume growth rate, dry tissue weight, organic carbon content, and nucleic acid content (RNA and DNA) of individual
Capitella sp. I were measured after 14 d of exposure to natural sediment, sediment contaminated with fluoranthene (in acetone) and sediment
treated with acetone only. Exposure to 101 μg fluoranthene g−1 sediment dry wt during 2 weeks reduced body volume specific growth rate by 50%. Dry tissue weight and carbon content were
also lower in fluoranthene-exposed worms. However, when corrected for differences in body volume, worms from fluoranthene-contaminated
sediment had a higher dry weight and carbon content per unit body volume than worms from the control and acetone treatments.
Part, but not all, of the reduction in body volume growth rate in response to fluoranthene may have been due to a reduction
in tissue water content. The correlation between RNA:DNA ratio (which has previously been used as a predictor of recent growth
rate) and worm growth rate was weak in the control group and was significantly influenced by sediment treatment. Not only
did the fluoranthene-exposed worms have a lower growth rate than expected based on their RNA:DNA ratio, but analysis of this
group separately indicated that measured growth rate was independent of the RNA:DNA ratio. Our results not only confirm previous
indications of a weak relationship between nucleic acid content and actual growth, but indicate that empirical, predictive
relationships between these variables measured under favorable growth conditions should not be extrapolated to predict growth
under toxicant-stressed conditions.
Received: 6 April 1997 / Accepted: 7 May 1997 |
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