Brachiopod shell samples from the Kapp Starostin Formation, West Spitsbergen, provide evidence for a large and rapid drop in seawater strontium isotopic ratios close to the Permian-Triassic boundary. The strontium isotopic shift is associated with similarly dramatic declines in carbon and oxygen isotope curves recorded in the same samples. This pattern can be explained by a paleoceanographic model that we have proposed previously, a model in which there is replacement of a largely stagnant, stratified ocean by a vigorously mixed one at the Permian-Triassic boundary.