engleski

Bioaccumulation of organochlorine pesticides and biomarker responses in Dreissena polymorphaand D. bugensis after exposure to native suspended particulate matter

The zebra mussel, Dreissena polymorpha, is widely used as sentinel organism for the assessment of environmental contamination in freshwater environments. In Germany, it is collected e.g. for regular chemical monitoring and for long-term storage of samples for retrospective research in the frame of the German environmental specimen bank (ESB). However, in the river Rhine the D. polymorpha population is declining while the closely related quagga mussel Dreissena bugensis is found in high numbers at some sampling locations. In the present laboratory study, D. polymorpha and D. bugensis were exposed to natural sediments for up to two weeks. Wet sediment (< 63 μm, 100 mg L-1 dry weight) was simulated as suspended particulate matter to mimic the mussels’ main uptake route for chemicals. The sediments were sampled in a) the river Elbe in Dessau, a site known to be highly polluted with e.g. organochlorine pesticides, and b) in Havelberg in the river Havel, one of the Elbe’s tributaries and a relatively unpolluted site. Chemical analysis of organochlorine pesticides (7 PCBs, DDT and metabolites, HCHs, HCB) in soft tissue of mussels showed significantly higher values of PCB 101, PCB 118, PCB 153, PCB 138, PCB 180, the sum of seven PCBs as well as p, p’-DDD in D. bugensis compared to D. polymorpha. 14 days of exposure increased the concentration of p, p’-DDE and p, p’-DDD in both species. Furthermore, exposure to the Dessau sediment resulted in elevated levels of p, p’-DDD in mussel tissue compared to Havelberg sediment. Interspecific differences were less pronounced when regarding chemical concentrations to lipid content instead of dry weight of tissue since D. bugensis had higher levels of total lipid than D. polymorpha. DNA damage in gills, measured with the COMET assay, was higher in D. bugensis compared to D. polymorpha. Simultaneously, the content of heat shock protein (Hsp70) in gills was higher in D. polymorpha than in D. bugensis. DNA damage and Hsp70 were not induced by neither exposure time nor sediment type. Protein carbonylation in gills and soft tissue, however, showed no difference between species and exposure time, but in soft tissue it was slightly elevated in mussels exposed to the Havelberg sediment.

bioaccumulation; Dreissena; organochlorine compounds; suspended particulate matter;

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