How does habitat influence metabolism? Clues from biomarker response and contaminant profile in Tursiops truncatus (Montagu, 1821) subspecies living in parapatry

In western South America (WSA) two subspecies of bottlenose dolphin are recognized: Tursiops truncatus gephyreus, predominantly found in estuaries and river mouths, and Tursiops truncatus truncatus, occurring along the continental shelf. Despite a partial spatial overlap, both subspecies are considered to occupy different habitats and ecological niches. In the present study, chemical analyzes as well as biochemical and molecular biomarkers were used to inves-tigate the influence of niche partitioning over metabolic pathways associated with the detoxification of persistent or-ganic pollutants (POPs), antioxidant metabolism, immune activity and lipid metabolism in Tursiops truncatus subspecies living in parapatry. Overall, the profile and levels of bioaccumulated PCBs, pesticides and PBDEs were sim-ilar between groups, with a greater variety of pesticides, such as gamma-HCHs, heptachlor, oxychlordane and o,p'DDT, de-tected in T. truncatus gephyreus. Multivariate analysis of variance (MANOVA) and non-metric multidimensional scaling (NMDS) results indicated that glutathione reductase (GR) and superoxide dismutase (SOD) enzymatic ac-tivities were higher in coastal dolphins, as were the mRNA levels of metallothionein 2A (MT2A), interleukin-1 alpha (IL-1 alpha), ceramide synthase 3 (CERS3) and fatty acid elongase (ELOVL4). In parallel, mRNA levels of fatty acid synthase complex 1 (FASN 1) were higher in oceanic dolphins. These findings suggest that, due to their occur-rence in coastal habitats, T. truncatus gephyreus is more exposed to environmental pollutants and pathogenic mi-croorganisms. Likewise, niche partitioning may influence lipid biosynthesis, possibly due to differences on

Automated summary

The study examined the influence of niche partitioning on metabolic pathways in two subspecies of bottlenose dolphins. It found differences in the detoxification of pollutants, antioxidant metabolism, immune activity, and lipid metabolism. Coastal dolphins were more exposed to environmental pollutants and showed higher enzyme activity and mRNA levels related to detoxification and immune response, while oceanic dolphins showed higher mRNA levels related to lipid biosynthesis.