Deer Antler δ 18 O Records Desalination in Israel's Water Supply

ABSTRACT Rationale Stable oxygen isotope ratios ( δ ¹⁸O) in mammalian tissues are widely used to reconstruct past climates, seasonal patterns, and animal origins. These analyses assume that animals drink local rainwater—an assumption now challenged by large‐scale anthropogenic water management. Here we present a δ ¹⁸O time series from Mesopotamian fallow deer ( Dama mesopotamica ) antler carbonate spanning 2006–2021, a period coinciding with the major expansion of desalinated water in Israel's national grid. Methods Antler samples were collected across 2006–2021, and carbonate δ ¹⁸O values were measured using an automated carbonate preparation device (KIEL‐III) coupled to a gas ratio mass spectrometer (Finnigan MAT 252) at the University of Arizona's Environmental Isotope Laboratory. Measurements were calibrated against repeated analyses of NBS‐19 and NBS‐18 standards; analytical precision was ±0.1‰ for δ ¹⁸O (1σ). Results Antler δ ¹⁸O values show a systematic shift toward isotopically elevated compositions through time. This temporal trajectory closely tracks the sequential commissioning of five major reverse osmosis facilities between 2005 and 2015. One‐way ANOVA confirmed significant differences in δ ¹⁸O across pre‐desalination, transitional, and post‐expansion sample groups ((2,33) = 11.21,   Conclusions These findings demonstrate that anthropogenic water management can induce isotopic shifts in mammalian tissues that rival natural climatic variability, introducing systematic errors into provenance reconstructions. Researchers working with modern or recent historical faunal assemblages in water‐managed landscapes should incorporate documented water supply histories into their interpretive frameworks alongside climatological isoscapes.