Untargeted Blubber Metabolomics Reveals Biochemical Signatures Associated with Physiological Status in Live, Free-Ranging Bottlenose Dolphins

Background/Objectives: Dolphins inhabiting coastlines can be influenced by anthropogenic factors. As biochemical changes accumulate in blubber over weeks to months, blubber metabolites may be informative biomarkers of molecular adaptations to environmental changes. Methods: We investigated the blubber metabolomic signatures of live free-ranging bottlenose dolphins for the first time. This exploratory study analyzed blubber samples from 35 common bottlenose dolphins (Tursiops truncatus) in South Texas waters using untargeted ultra-high-performance liquid chromatography-Orbitrap metabolomics. Results: Blubber samples exhibited distinct temporal and spatial metabolic patterns. Pathway enrichment analyses comparing detected metabolites (n = 2777) revealed that dolphins sampled in the spring had enhanced lipid quality and immune regulation, while dolphins sampled in the summer showed stress-associated metabolic responses. Dolphins inhabiting areas previously reported to experience heavy vessel traffic and contaminant burdens exhibited enriched immune- and inflammation-associated pathways. Dolphins that visually appeared to have poorer body condition exhibited metabolite profiles suggestive of increased protein catabolism. Dolphins in extreme salinity conditions had more abundant membrane maintenance and endocrine pathways. Conclusions: Dolphins from each system exhibited distinct metabolic signatures that may be associated with differing physiological responses, highlighting the potential utility of blubber biomarkers for assessing physiological adaptations in free-ranging marine mammals. Improved understanding of habitat-specific physiological responses offers critical insights into how cumulative impacts may affect the health and adaptive capacity of vulnerable species in dynamic coastal ecosystems.