Biology subjects

Hanninger, E.-M. F.

Publications and source records attributed to Hanninger, E.-M. F..

3 recordsLinked to original sources

bioRxiv2026

Epigenetic age acceleration is associated with contaminant exposure in common dolphins (Delphinus delphis)

Metals and per- and polyfluoroalkyl substances (PFAS) represent a significant environmental concern, yet their association with epigenetic age acceleration (EAA) remain largely understudied in marine mammals. Here, associations between EAA in common dolphins (Delphinus delphis) and life history (sex and sexual maturity), trace metals, and PFAS were investigated. EAA was calculated as the residual in the regression of epigenetic age vs chronological age, hence providing a direct measure of the deviation of the epigenetic age of an organism (positive or negative) by comparison with expectation, given their actual chronological age. Sixteen trace elements were quantified in hepatic and renal tissues (n = 53). In addition, 28 PFAS were quantified in hepatic tissue (n = 58). Associations between EAA and explanatory variables were assessed using regression-based and multivariate modelling approaches (linear models and canonical analysis of principal coordinates). No effect of sex was observed, although sexual maturity did significantly increase EAA. Exposure to metals was significantly associated with EAA, explaining 55.4% of the variation, with hepatic metals (Se, Zn, Cu, Al, Mn) driving this relationship. Although EAA was not significantly related to the total PFAS exposure overall, a subset of PFAS variables (PFBA, PFDA, PFHxS-B, PFNA) showed significant association with EAA after adjusting for sex and sexual maturity. Together, these subsets of metal and PFAS variables, in addition to the selenium-to-mercury (Se:Hg) molar ratio, explained 66.7% of the variation in EAA. Our results identify sexual maturity and specific contaminant mixtures as key potential drivers of EAA in common dolphins, highlighting the possible use of EAA as a biomarker of environmental and physiological stress in marine mammals.

zoology↗

bioRxiv2026

PFAS exposure is associated with accelerated epigenetic ageing in a wild marine mammal

Chronic contaminant exposure may impose hidden physiological costs long before obvious demographic or health effects become detectable in wildlife populations. Epigenetic clocks quantify biological ageing and may provide sensitive biomarkers of cumulative toxicological stress. Per-and polyfluoroalkyl substances (PFAS) are persistent contaminants that bioaccumulate in marine food webs, yet their long-term physiological consequences for wildlife remain poorly understood. Here, we tested whether PFAS exposure is associated with accelerated biological ageing in common dolphins (Delphinus delphis). We analysed liver PFAS concentrations and skin DNA methylation profiles from 30 stranded or bycaught dolphins from New Zealand waters. Epigenetic age was estimated using a recently developed species-specific epigenetic clock, and age acceleration was calculated as the residual deviation between epigenetic and chronological age. Using an information-theoretic modelling framework, we assessed the effects of total PFAS burden, sex, and their interactions on epigenetic age acceleration. Total PFAS concentrations were positively associated with epigenetic age acceleration, indicating that dolphins with higher PFAS burdens were biologically older than expected for their chronological age. Each 1 ng g{square}{superscript 1} increase in total PFAS was associated with an average increase of 0.031 years in biological age. Sex did not significantly influence age acceleration, suggesting that PFAS-associated ageing effects occur across both sexes. Although modest, this effect is consistent with PFAS acting as a chronic physiological stressor influencing molecular ageing processes. Our findings provide the first evidence linking PFAS exposure to accelerated biological ageing in a wild mammal, highlighting epigenetic ageing as an integrative biomarker of long-term contaminant effects in wildlife.

ecology↗

bioRxiv2025

Dental aging offers new insights to the first epigenetic clock for common dolphins (Delphinus delphis)

Determining exact age in wild odontocetes is essential for understanding population dynamics, survival, and reproduction, yet remains logistically challenging. While epigenetic aging is emerging as a valuable approach, only nine species-specific clocks currently exist. Most have been calibrated using captive known-age animals or well-studied wild populations. Only two previous studies have used dental ages from stranded or bycaught individuals. This is due to concerns that dental age inaccuracies, especially in older animals, may affect epigenetic clock performance. To explore this, we developed the first species-specific epigenetic clock for common dolphins (Delphinus delphis), analysing DNA methylation at 37,492 cytosine-phosphate-guanine sites in skin samples from stranded and bycaught dolphins with estimated dental ages. Elastic net models with Leave-One-Out Cross-Validation were applied to three subsets: the relaxed subset (all individuals; n = 75, median absolute error (MAE) = 2.02, r = 0.81, R2 = 0.66), the strict subset (excluding individuals with minimum dental age estimates only; n = 73, MAE = 2.29, r = 0.81, R2 = 0.66), and the restricted subset (excluding outliers with prediction errors > 6 years; n = 63, MAE = 1.80, r = 0.91, R2 = 0.82) to compare performance. Our models consistently underestimated the age of dolphins >16 years, even when minimum dental ages were applied, suggesting absolute errors between dental and epigenetic estimates unlikely reflect dental aging error. Additionally, post-mortem decomposition condition code (DCC 1 to 3) did not affect age prediction, signalling promise for future epigenetic clocks calibrated with strandings and bycaught individuals.

genetics↗