Stable isotopes and mercury in a model estuarine fish: Multibasin comparisons with water quality, community structure, and available prey base

► We use δ13C, δ15N and Hg to infer trophic positioning in divergent estuarine basins. ► δ13C, δ15N and Hg directly link with key biotic and abiotic factors. ► Natural and anthropogenic influences affect prey base populations and resultant tracers. ► Estuarine heterogeneity is reflected in isotope-Hg variation over small spatial scales.