Dioxins, furans and co-planar PCBs in juvenile harbour porpoises (Phocoena phocoena) from the Belgian coasts

Dioxins, furans and PCBs are lipophilic anthropogenic contaminants that have found their way into marine food webs and accumulate in top predators such as marine mammals, adding a stress factor to an already vulnerable population. In this study 7 congeners of dioxins (PCDDs), 10 congeners of furans (PCDFs) and 4 congeners of coplanar PCBs (cPCBs) were determined using high resolution gas chromatography and mass spectrometry in the blubber of 19 juvenile harbour porpoises (Phocoena phocoena) stranded along the Belgian North Sea coastline between 1995 and 2001. These results were contrasted with nutritional status (emaciated or not), sex and trophic
level (through stable carbon and nitrogen isotope analysis). Mean blubber concentrations of SPCDD/Fs were 12.8 pg/g lw (lipid weight) and mean related toxicity 1.84 pg TEQs/g lw (TEQs = TCDD toxic equivalents). Mean cPCB concentrations were 223,5 pg/g lw and mean related toxicity 4,47 pg TEQs/g lw. The levels detected in these individuals were of the same order as those found in a previous study in the Wadden Sea (Bruhn, 1999). Both sexes show rather similar levels. No significant relationship was observed between stable carbon or nitrogen isotope values and pollutant levels. Concentrations and toxicity show a tendency to be higher in emaciated ndividuals than in nonemaciated ones. This could indicate a possible relationship between the nutritional status of the animals and dioxinlike pollutants (which could participate in weakening the animal). This situation should be further studied on adult individuals in order to obtain a more global view of the possible effects on the population.