Bottlenose dolphins (Tursiops truncatus) are prone to accumulating complex mixtures of persistent organic pollutants (POPs). While variations in POP patterns have been previously observed for populations separated across regional and fine-scale geographic ranges, less is known regarding the factors influencing contaminant patterns within localized populations. To assess the variation of POP mixtures amongst individuals of a population, polychlorinated biphenyls (PCB), organochlorine pesticides (OCP) and polybrominated diphenyl ethers (PBDE) were measured in blubber and milk of bottlenose dolphins resident to Sarasota Bay, FL. Principal components analysis (PCA) was used to explain mixture variations in relation to age, sex and reproductive maturity and demonstrated significant variation among the resident dolphin community. Patterns in young dolphins resembled milk, and were dominated by lower-halogenated PCB and PBDE congeners. In contrast, adult females patterns were dominated by the higher halogenated POPs, and highly persistent PCB congeners and the pesticides 4,4 -DDE and trans-nonachlor predominated in adult male blubber. A significant correlation between PC2 and age in male dolphins indicated that over time, juvenile contaminant patterns gradually shift away from the milk-like contaminant pattern; a likely result of the selective accumulation of persistent POPs over time. Changes to POP patterns were gradual for juvenile females, but dramatic at the age of sexual maturity. Thereafter, patterns gradually shifted back towards pre-parturient profiles. Congener-specific blubber/milk partition coefficients suggest changes in female profiles result from the selective offloading of compounds during the first reproductive event and the gradual re-accumulation of these compounds thereafter. Overall, these results indicate that variations in contaminant mixtures can exist amongst localized populations, with life history factors driving individual differences.
Citation: Science of the Total Environment
Pub Type: Journals
persistent organic pollutants, POPs, contaminant mixtures, life history, bottlenose dolphin, Tursiops truncatus