The Commerson's dolphin as Subantarctic sentinel of POPs: Insights into the pollutant status in one of the southernmost coastal areas of the globe.

Persistent organic pollutants (POPs) are halogenated contaminants found globally. Cetaceans are impacted by these pollutants, and nowadays, it is essential to understand their presence to mitigate their impacts. This study aimed to establish baseline levels of POPs in the blubber of Commerson's dolphins (Cephalorhynchus commersonii) within the Subantarctic ecosystem. A wide range of POPs concentrations were measured among individuals: ΣPCBs from 289.5 to 15264 ng g lw and ΣDDTs from 540.4 to 17657 ng g lw. Levels of HCB and mirex ranged from 48 to 1703.7 ng g lw and 5.1-1917.4 ng g lw, respectively. The predominant POPs were mid-to high molecular weight PCBs (hexa-PCBs), consistent with other findings in cetaceans of the southern hemisphere. The mean ratio of ΣDDT/ΣPCB was 0.44, with p,p'-DDE/ΣDDT at 0.56, indicating p,p'-DDE as the dominant DDT isomer. Furthermore, differences in POP concentrations were observed based on sexual maturity, with mature males exhibiting higher levels of ƩPCBs, HCB, ƩDDT, and mirex. Age and total body length of animals were strongly correlated with POP concentrations. Our study provides valuable insights into the pollutant status of POPs in the Subantarctic population of Commerson's dolphins inhabiting the southernmost coastal regions of South America.