Age-related PCB dynamics in immature bull sharks
Accepted manuscript online on 01. October 2013
Age-related PCB dynamics in immature bull sharks Carcharhinus leucas
Jill A. Olin, Marina Beaudry, Aaron T. Fisk, Gordon Paterson
ABSTRACT:
Polychlorinated biphenyls (PCBs) were quantified in liver tissues of bull sharks (Carcharhinus leucas) ranging in age from <4 weeks to >3 years old. Summed values of PCBs (ΣPCB) ranged from 310–22070 ng/g (lipid wt.) across age classes with ΣPCB concentrations for the youngest sharks in the study (<4 weeks; 5230 ± 2170 ng/g lipid wt.) determined to not significantly differ from those quantified in >3 year old sharks, highlighting the extent of exposure of this young life stage to this class of persistent organic pollutants (POPs). Age-normalization of PCB congener concentrations to those measured for the youngest sharks demonstrated a significant hydrophobicity (log Kow) effect that was indicative of maternal offloading of highly hydrophobic (log Kow ≥ 6.5) congeners to the youngest individuals. A distinct shift in the PCB congener profiles was also observed as these young sharks grew in size. This shift was consistent with a transition from the maternally offloaded signal to the initiation of exogenous feeding and the contributions of mechanisms including growth dilution and whole body elimination. These results add to the growing pool of literature documenting substantially high concentrations of POPs in juvenile sharks that are most likely attributed to maternal offloading. Collectively, such results underscore the potential vulnerability of young sharks to POP exposure and pose additional concerns for shark conservation efforts.
Environmental Toxicology and Chemistry, Accepted Articles, DOI: 10.1002/etc.2402