Spatial variation of biologically available strontium isotopes (87Sr/86Sr) in an archipelagic setting: a case study from the Caribbean

► We report strontium (Sr) isotope results of plants and animals from the Caribbean. ► We evaluate these Sr isotope data relative to underlying geology. ► Large differences found between geological and biological Sr isotope ranges. ► Clear spatial patterning of bioavailable Sr isotopes relative to geology. ► Spatial variation of bioavailable Sr is promising for studies of ancient mobility.