Due to their role as top predators and their long life span, elasmobranchs (e.g., sharks) are prone to accumulate high concentrations of persistent organic pollutants (POPs) in their tissues. In addition, many elasmobranch species live in coastal areas and estuaries to reproduce and nurse their young. These areas in particular are very susceptible to pollution because of industrial and agricultural run-off, untreated waste water etc. that enters these areas through run-off from the rivers. In this thesis, trophic and reproductive transfer of organic compounds (POPs such as PCBs, DDXs, CHLs and PBDEs and naturally-occurring MeO-PBDEs) was investigated in bonnethead sharks (Sphyrna tiburo), lemon sharks (Negaprion brevirostris), bull sharks (Carcharhinus leucas), blacktip sharks (Carcharhinus limbatus) and Atlantic stingrays (Dasyatis sabina) from coastal Florida. Bull sharks were found to accumulate the highest concentrations for all POPs, due to their high trophic position. Atlantic stingrays had the lowest concentrations of all pollutants. PCBs were higher in bonnethead sharks than in lemon sharks, most likely due to their presence near an Aroclor 1268-contaminated site, but all other POPs were lower in bonnethead sharks. In addition to this trophic transfer, POPs are also transferred through the mother’s reproductive system. PCB concentrations (ng/g lw) were even higher in embryo livers than in the liver of their mothers. For the other pollutants, there was no clear preference of accumulation in certain tissues, although ova and ovaria also accumulated a considerable amount of POPs. Human consumption of shark fin soup is a related exposure pathway to organic pollutants. During the preparation, fins are cooked several times and cooking water is drained. However, the most POPs are still found to be present in the final soup, although not in harmful concentrations. |
