Long-range transport of POPs to the central Atlantic Ocean: using a resident population of bottlenose dolphins (Tursiops truncatus) as sentinel species

The Saint Peter Saint Paul archipelago (SPSPA) is situated in the central Equatorial Atlantic, approximately 1000 km from the northeastern coast of Brazil. A small population of common bottlenose dolphins (Tursiops truncatus) exhibits strong site fidelity to the remote archipelago. As apex predators, these dolphins can act as sentinels for the transport and bioaccumulation of organohalogen compounds in isolated marine environments. Remote biopsies were collected from nine individuals (n = 9) to investigate pollutant exposure. Blubber samples were analyzed for polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs), brominated flame retardants (BFRs), and naturally produced methoxylated organobromines (MeO-BDEs), using gas chromatography coupled with electron capture detection or mass spectrometry. Skin samples were analyzed in an isotopic ratio mass spectrometer. The profile of the chemical markers observed in these bottlenose dolphins was dominated by high molecular weight PCBs and high δ¹³C, similar to coastal dolphin species. Atmospheric transport, adsorption to benthic substrates, and species-specific metabolic capacity possibly shape contaminant accumulation in this population. Naturally produced MeO-BDEs and carbon ratios suggest low oceanic-coastal dispersal of dolphins. These findings suggest the efficient transport of man-made pollutants to isolated locations and the key role of apex predators, such as bottlenose dolphins, as POPs reservoirs in oceanic zones.