CS13 Environmental Ecotoxicology
Date: Friday, June 14, 2002
Time: 11:00:00 AM
Location: Esquimalt
GranbergME, Gothenburg University/Kristineberg Marine Research Station, Fiskebaeckskil, Sweden, m.granberg@kmf.gu.se
Hansen, R, , Roskilde University, Roskilde, Denmark, 
Selck, H, , Roskilde University, Roskilde, Denmark, selck@ruc.dk
Importance of macrofaunal sediment burrows for the microbial degradation of the organic contaminant pyrene: impact of macrofaunal functional group and sediment
Aquatic sediments harbour complex systems of macrofaunal burrows differing greatly in biogeochemistry compared to the surrounding sediment. The significance of these biogenic structures for microbial mineralization of organic matter has long been recognised, whereas knowledge is sparse on their importance for the degradation of organic pollutants. We investigated the importance of biogenic structures for microbial degradation of pyrene as a function of macrofaunal species and organic matter quality. The experiment consisted of two phases; pre-exposure and incubation. During pre-exposure, brittle stars (Amphiura filiformis) and polychaetes (Nereis diversicolor) where added to aquaria containing organically enriched (labile microalgae or refractory lignin) pyrene contaminated sediment. After 35d, samples were taken from surface, burrow-walls and bulk sediment, and transferred to CO2-incubation-traps spiked with 14C-pyrene, where microbial 14CO2 production was monitored over five months. Microbial pyrene-degradation-potential (MPDP) was one order of magnitude higher in pyrene-preexposed sediments. Surface-MPDP was higher with microalgae and burrow-MPDP was higher with lignin. A.filiformis facilitated microbial pyrene-degradation in burrows more than N.diversicolor. Results stress the importance macrofaunal-microbial interactions, biogenic structures and trophic status for degradation of organic contaminants in aquatic sediments