Moss stable isotopes (carbon‑13, oxygen‑18) and testate amoebae reflect environmental inputs and microclimate along a latitudinal gradient on the Antarctic Peninsula

• Main Authors: Evans, Jessica, Amesbury, Matthew J, Roland, Thomas P, Jones, Glyn D, Convey, Peter, Griffiths, Howard, Hodgson, Dominic A, Charman, Dan J
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer 2016
• Subjects: climate change; 13C; 18O; precipitation; water line; assemblage; Antarctic; The Antarctic; Antarctic Peninsula; Protector; Kendrick; Antarc*
• Online Access: https://www.repository.cam.ac.uk/handle/1810/254572

The stable isotope compositions of moss tissue water (δ$^{2}$H and δ$^{18}$O) and cellulose (δ$^{13}$C and δ$^{18}$O), and testate amoebae populations were sampled from 61 contemporary surface samples along a 600-km latitudinal gradient of the Antarctic Peninsula (AP) to provide a spatial record of environmental change. The isotopic composition of moss tissue water represented an annually integrated precipitation signal with the expected isotopic depletion with increasing latitude. There was a weak, but significant, relationship between cellulose δ$^{18}$O and latitude, with predicted source water inputs isotopically enriched compared to measured precipitation. Cellulose δ$^{13}$C values were dependent on moss species and water content, and may reflect site exposure to strong winds. Testate amoebae assemblages were characterised by low concentrations and taxonomic diversity, with $\textit{Corythion dubium}$ and $\textit{Microcorycia radiata}$ types the most cosmopolitan taxa. The similarity between the intra- and inter-site ranges measured in all proxies suggests that microclimate and micro-topographical conditions around the moss surface were important determinants of proxy values. Isotope and testate amoebae analyses have proven value as palaeoclimatic, temporal proxies of climate change, whereas this study demonstrates that variations in isotopic and amoeboid proxies between microsites can be beyond the bounds of the current spatial variability in AP climate. The research was funded by the Natural Environment Research Council Antarctic Funding Initiative grant NE/H014896/ to DJC, PC, DAH and HG. PC, DAH and JR contribute to the BAS ‘Polar Science for Planet Earth’ research programme. Carbon isotope analyses were undertaken by Chris Kendrick at the NERC Isotope Geosciences Laboratory. Sample collection was supported by HMS Protector and HMS Endurance. Thanks to Iain Rudkin and Ashly Fusiarski for fieldwork support, to Adrian Dahood for water sample collection and to Sue Rouillard in the University of Exeter ...