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(38-16) Feeding behaviour of earthworms and its consequences for bioaccumulation of organic chemicals. Jager, Tjalling*,1, Fleuren, Roel2, Roelofs, Willem2, Van der Wal, Leon3, 1 Department of Theoretical Biology, Amsterdam2 Laboratory for Ecotoxicology, Bilthoven3 IRAS, Utrecht ABSTRACT- Earthworms are able to take up organic chemicals through their external skin as well as through feeding. The quantitative contribution of these two routes however remains a matter of debate. A model has been developed that incorporates the gut contents as a separate compartment, but the physiological parameters required for this model are not routinely measured. In this study, the feeding behaviour of the earthworm Eisenia andrei is studied in OECD artificial soil, with and without a preferred food source (ground cow manure) and at two temperatures (10 and 20 C). Several experimental and statistical techniques were developed to determine gut volume, degree of selection for organic particles, digestion efficiency, gut retention time, and fraction of manure in the total diet. It was observed that Eisenia is able to selectively feed on OECD soil (ingesta have two times more organic matter than bulk soil). In case manure is present at the soil surface, the diet still contains an appreciable fraction of soil. Furthermore, retention times appear to be temperature dependent. Subsequently, an accumulation experiment was performed using three model compounds (two chlorobenzenes and a PCB), spiked in soil and in manure. It is attempted to use the parameterised mechanistic model to describe the accumulation curves and draw conclusions on the contribution of both exposure routes. Key words: bioavailability, bioaccumulation, earthworms, feeding |
