Supplementary material from "The geological imprint of neodymium isotopes in marine gastropods"

Due to their precision and predictability, radiogenic isotopes are prized for tracking the movement of terrestrial and freshwater species, as well as the origins of natural products. Yet, their use in marine systems is rare. Here we investigate neodymium isotope ratios, a radiogenic isotope system that is rarely used in biology but has characteristics that makes it useful for marine biological applications. Neodymium isotopes ratios are influenced by continental geology, as such, we analysed 143Nd/144Nd or ƐNd in 112 gastropod shells (abalone) collected from 11 geologically diverse sites in southern Australia. We found strong spatial differences in isotope ratios, which ranged from -18 ƐNd in the west of Australia to -4 ƐNd in the east. Such differences can be broadly linked to exposed continental rock age – a trend that was also apparent when comparing our data to published ƐNd data from northeast Asia. This study represents the largest analysis of ƐNd in modern biological material and provides insight into spatial trends and its usefulness as a radiogenic marker. Our findings highlight the exciting potential of ƐNd as a tool for biologists to understand marine animal movement, and the origins of marine products.