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Abstract
Mercury (Hg) is a ubiquitous ecological contaminant, with elevated exposure risk stemming from anthropogenic activity. Due to the propensity of certain metals to bioaccumulate over time and biomagnify across trophic levels, long-lived apex predators can carry significant body burdens in affected ecosystems. Yet, how interactions between organismal ontogeny and habitat contribute to variation in exposure is not well resolved. Total Hg, carbon (δ13C), and nitrogen (δ15N) isotopic ratios were assessed in blood samples (n=133) across three distinct habitats in the southeastern US to investigate how size and dietary shifts in the American alligator (Alligator mississippiensis) influence Hg accumulation. Collectively, findings demonstrate that whereas Hg concentrations in A. mississippiensis are primarily driven by site-level dynamics, diet and size are linked to individual variation within populations, suggesting that organismal ontogeny interacts with site-specific contamination and ecological factors to affect Hg body burdens. Further exploration of patterns associated with individual variation is recommended.