Inter- and intraspecies differences in biomarker responses and contaminant levels in two mysticete species (Balaenoptera physalus and Balaenoptera edeni) of Gulf of California (Mexico) and Mediterranean Sea

Inter- and intra-species differences in biomarker responses and contaminant levels were investigated in twomysticete species, finwhale (Balaenoptera physalus) and the unexplored species Bryde whale (Balaenoptera edeni) of Gulf of California (Mexico) and fin whale of Mediterranean Sea, using skin biopsy as diagnostic tool.We developed a non lethal “multi-trial-biomarker-tool”, combining protein (western blot of CYP1A1, CYP2B) and gene expression biomarkers (qRT-PCR of CYP1A1, ER, AhR, and E2F-1) with analysis of OCs, PAHs and PBDEs. In the first phase of the project we explored the level and effects of contaminants in skin biopsies of the two species of Gulf of California in comparison to fin whale ofMediterranean Sea. In the second, in-vitro, phasewe applied this approach to fin whale biopsy slices treated with mixtures of OCs and PBDEs in order to explore the different toxicological effects of contaminants. This “multi-trial-diagnostic-tool”, applied to skin biopsies, underlined differences in contaminant levels and biomarker responses between the two species of Gulf of California and also between the two fin whale populations. Higher levels of OCs and PAHs were detected in the zooplankton-eating species (fin whale) in comparison to the fish-eating species (Bryde whale); on the opposite, higher levels of CYP1A1 and CYP2B were detected in the fish-eating species, similar to odontocete species. The interspecies investigation showed the presence of a higher “toxicological stress” in the Mediterranean fin whale population, highlighted bywarning signals such as CYP1A1 induction and up-regulation of ERα and E2F-1 genes, combined with a lack of CYP2B induction in field and in vitro experiments.