THESIS APPROVAL

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reported that ingested sediment contributed up to 61% of the total pyrene body burden
in Lumbriculus variegatus during 8 d sediment exposure. An increased accumulation
of pyrene and benzo (a) pyrene in this worm tissue after 816 h test was caused by this
feeding behavior (Leppanen and Kukkonen, 2000a). In similar with Weinstein et al.
(2003) who observed that ingestion was an important route of uptake fluoranthene for
M. rubroniveus when exposed to sediment contamination. Based on these evidences,
it is assumed that naphthalene uptake across the body surface is the predominant route
of uptake of L. hoffmeisteri in this study.
Assessment of bioaccumulation and fate of PAHs in oligochaetes needs
information on biotransformation capability. The metabolism of PAHs composes of
two phases. The first step involves cytochrome P450-dependent MFO system which
inserts oxygen atom on PAH ring. The second, various enzymes may catalyze further
reactions and result in water-soluble products which can be excreted (Varanasi et al.,
1989). Although very little information exists on the metabolism of PAHs in
oligochaetes and the main mechanisms are also unknown (Lee, 1998), the ability to
metabolize PAHs has been reported supporting with low biotransformation of these
animals. Current information in the literature has indicated that Lumbriculus
variegatus is not able or has slow biotransformation rate to metabolize pyrene and
benzo (a) pyrene (Harkey et al., 1994a; Leppanen and Kukkonen, 2000b). Similarly,
the high BCF reported for Monopylephorus rubroniveus may be the result of the
inability to metabolize fluoranthene (Weinstein et al., 2003). However, from the
apparent result it may not be assumed that L. hoffmeisteri is probably not able to
biotransform naphthalene despite no sign of metabolites compounds present in the
HPLC trace (Appendix Figure A3). Certainly, apparently more research in the future
is need to investigate whether naphthalene are biotransformed by this oligochaete
species.
5.2 Trophic Transfer of Naphthalene in an Aquatic Food Chain
In the present study, the results showed that fish from the treatments were
naphthalene contaminated via trophic transfer. This apparent data was resembled to