Resumen del producto

The presence of Organochlorine Contaminants (OCs) such as Organochlorinated Pesticides (OCPs) and Polychlorinated biphenyls (PCBs) in animal tissues can affect their reproduction and development. Top predators are particularly susceptible to accumulate high levels of OCs due to their high trophic position, longevity and inability to process and excrete certain components. Understanding the degree of exposure to contaminants is a critical first step for the management and conservation of the species. The present study determines the exposure level of white sharks (WS) and Northern elephant seals (NES) to OCs in Guadalupe Island, one of the most important aggregation sites for both species, and compares the bioaccumulation patterns among different age classes and sexes. Biopsy samples were taken from 32 freeranging WS and 35 NES and its lipid was extracted via Soxhlet to be analyzed for DDT and its metabolites (n = 6), Chlordanes and 54 congeners of PCBs, using GCMS (Gas Chromatography–Mass Spectrometry). The chromatograms indicated the presence of 5 different compounds OCPs and 10 PCB congeners in WS, and 7 OCPs and 22 PCB congener in NES. The average concentrations and ranges for WS expressed in ng/g d.w. basis were 97.7(13.4-291) of tDDTs, 3.09 (0-16.5) of tCHLs and 31.1 (0-219) of tPCBs, and the average concentrations for NES were 3827 (429-28744) of tDDTs, 184 (0-703) of tCHLs, and 587 (0-4487) of tPCBs. The levels of tDDTs were significantly higher in adults than in juveniles of both target species, suggesting an age class-based bioaccumulation, and confirming the differences described in literature between the feeding behavior of adults and juveniles of both species. Although no significant differences in tDDT, tCHL and tPCB concentrations were found, a higher variability was observed in females NES, which could be explained by the diet variation between adult males and females described in literature using stable isotope analysis. WS and NES showed a similar OC average abundance pattern, suggesting the NES as a potential source of contamination for the WS, its main predator in Guadalupe Island.

Palabras clave: organochlorine contaminants; Carcharodon carcharias; Mirounga angustirostris

Para obtener una copia del documento contacta la personal de la biblioteca a través del correo bibliocicimar{a}ipn.mx