Reliability of shell carbon isotope composition of different land snail species as a climate proxy: A case study in the monsoon region of China

Carbon isotope compositions of land snail shells (delta C-13(shell)) are shown to be indicative of local climate conditions. However, it is largely unknown how the responses of delta C-13(shell) to climatic factors changes amongst different species. In this study, we collected 3 species of land snail shells across the East Asian monsoon region of China to explore the overall relationship between delta C-13(shell) as well as the response of individual species to the regional climate. Results show that, whereas all species collectively can provide a consensus relation between delta C-13(shell) and local climatic factors such as temperature and precipitation; the response of individual species to the fluctuations of these factors is not uniform. Specifically, while the southerly species Bradybaena similaris exhibits robust delta C-13(shell)-mean precipitation correlation in both linearity and sensitivity, a common northerly species, Cathaica fasciola, only finds limited utility as a climate indicator, particularly for precipitation. Meanwhile, the south-central species Acusta ravida appears to be able to faithfully record past climate conditions despite showing a wider distribution and a broader habitat. Such species-dependent nature in the relations between delta C-13(shell) and local climatic factors can be attributed to the effect of ingested carbonate and variations in eco-physiological factors of different species, and is expected to be widespread, suggesting the need to be taken into consideration for future studies. (C) 2018 Elsevier Ltd. All rights reserved.