Evaluating the Biggenden Banded Snail (Figuladra bayensis) as a climate archive for SE Queensland, Australia, using stable isotopes and 14 C dating

Land snails can be utilized to infer paleoclimate variability due to the preservation and incorporation of stable isotopes in their aragonite shells (δ 18 O shell and δ 13 C shell ). A Figuladra bayensis (Biggenden Banded Snail) shell was collected shortly after death from Coalstoun Lakes National Park (CLNP), Queensland, Australia to investigate if this species is suitable for paleoclimate investigations. A total of 200 samples were collected for δ 18 O shell and δ 13 C shell analyses and additional eight radiocarbon ( 14 C) dating samples were collected along the shell’s growth axis from the apex to the aperture (234 mm) from one typical modern (recently dead) specimen. Results indicate that the Biggenden Banded Snail lived approximately 4.5 years with “step-like” shell growth rates between 23.7 and 144.3 mm yr −1 . Our 14 C ages permit the record to be tied to observed extreme rain events (i.e. ex-tropical cyclones) without inferring time-based growth intervals or isotopic fluctuations alone. The δ 18 O shell values depict seasonal variability with a rapid decrease immediately after large precipitation events, followed by more gradual increases in δ 18 O shell as conditions dry. In contrast, the δ 13 C shell record reflects variability in the snail’s C 3 diet with the seasons and as the specimen matures. The one exception to this pattern is the one large decrease during a phase of higher moisture and warmer temperature that may be related to snail reproduction. The development of an event-informed interpretive age-growth model constrained using multiple 14 C measurements along the growth axis represents an important innovation in snail isotope studies. This work establishes the first Biggenden Banded Snail isotope time-series while improving our understanding of the general relationships between land snail shell stable isotope records and climate.