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(38-15) Sublethal effects of phenanthrene on the life history of a parthenogenetic earthworm Dendrobaena octaedra after repeated exposures. Widarto, T.*,1, Forbes, V.1, Holmstrup, M.2, 1 Roskilde University, Denmark2 National Environmental Research Institute, Denmark ABSTRACT- The life history of a parthenogenetic earthworm, Dendrobaena octaedra, in response to phenanthrene exposure was followed for 6.5 months in the laboratory. We assessed its life-history traits, such as growth, time to first reproduction, cocoon production and viability in response to five different sublethal concentrations of the chemical during repeated exposures. For this study we used juveniles that were 7-14 days old. During the exposure, phenanthrene showed no effect on individual worm growth. Reproduction also was not noticeably influenced by phenanthrene. The treated worms reproduced for the first time at the same age as those in the control. They started to produce cocoons after they reached 120 ± 17 days of age. The number of cocoons produced, however, showed a decreasing tendency from 0.25 ± 0.03 cocoons/worm/day in the control to 0.20 ± 0.05 cocoons/worm/day in the highest concentration (75 mg/kg). The viability of cocoons produced by the worms, either in terms of hatching success or of hatching time was not affected. In the control, the hatching success was 76.7 ± 9.7 % and the hatching time was 90 ± 7.3 days. Key words: Dendrobaena octaedra, phenanthrene, growth, reproduction |
