Organohalogenated compounds are widespread in the marine environment and can be a serious threat to organisms in all levels of aquatic food webs, including elasmobranch species. Information about the concentrations of POPs (persistent organic pollutants) and of MeO-PBDEs (methoxylated polybrominated diphenyl ethers) in elasmobranchs is scarce and potential toxic effects are poorly understood. The aims of the present study were therefore to investigate the occurrence of multiple POP classes (PCBs, PBDEs, DDXs, HCB, CHLs) and of MeO-PBDEs in various elasmobranch species from different trophic levels in estuarine and marine waters of the southeastern United States. Overall, levels and patterns of PCBs, PBDEs, DDXs, HCB, CHLs and of MeO-PBDEs varied according to the species, maturity stage, gender and habitat type. The lowest levels of POPs were found in Atlantic stingrays and the highest levels were found in bull sharks. As both species are respectively near the bottom and at top of the trophic web, with juvenile bull sharks frequently feeding on Atlantic stingrays, these findings further suggest a bioaccumulation and biomagnification process with trophic position. MeO-PBDEs were not detected in Atlantic stingrays, but were found in all shark species. HCB was not found in Atlantic stingrays, bonnetheads or lemon sharks, but was detected in the majority of bull sharks examined. Comparison with previous studies suggests that Atlantic stingrays may be experiencing toxic effects of PCBs and DDXs on their immune system. However, the effect of these compounds on the health of shark species remains unclear. dinsdag, 31 Maart 2015
SHARKS DON'T HAVE CANCER A BOOK FROM THE NINETIES OR SOME ....THEY DO THEY DO IT TAKES TIME AND EXTRAS In 2013 the First Great White Shark ever was discovered with a Cancerous Tumor, a species which Humans have been studying for ever and ever and never just all of a sudden pops up with a Cancer tumor two years after the Nuclear disaster in Japan.
But let us not forget the list of other extreme cases of environmental shock caused by the radiation exposure.
noticed a large tumor protruding from the mouth of a great white shark, as well as another mass on the head of a bronze whaler shark. The great white's tumor measured 1 foot (30 centimeters) long and 1 foot wide, according to a study describing the tumors published online in November in the Journal of Fish Diseases.