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

Jessica Royles,Dominic A Hodgson,Peter Convey,Howard Griffiths,Thomas P Roland,Glyn D Jones,Matthew J Amesbury,Dan J Charman

doi:10.1007/s00442-016-3608-3

Jessica Royles, Dominic A Hodgson + Show 6 more

Open Access

https://doi.org/10.1007/s00442-016-3608-3

Copy DOI

Abstract

The stable isotope compositions of moss tissue water (δ2H and δ18O) and cellulose (δ13C and δ18O), 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 δ18O and latitude, with predicted source water inputs isotopically enriched compared to measured precipitation. Cellulose δ13C 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 Corythion dubium and 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.Electronic supplementary materialThe online version of this article (doi:10.1007/s00442-016-3608-3) contains supplementary material, which is available to authorized users.

Highlights

The Antarctic Peninsula (AP) has experienced significant climate change over the past 50 years, with increasing temperatures and changing precipitation patterns (Turner et al 2005, 2009, 2014)
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
Mean monthly air temperatures recorded at Bellingshausen (62°12′S 58°58′W, near Ardley Island (ARD)) and Vernadsky stations (64°14′S 64°15′W, near Green Island (GRE)) between 2000 and 2012 fall in the range of −9 °C to +2 °C, whilst annual temperatures remain below 0 °C, but show warming trends (Figs. 1, 2; Scientific Committee on Antarctic Research 2014)

Summary

Introduction

The Antarctic Peninsula (AP) has experienced significant climate change over the past 50 years, with increasing temperatures and changing precipitation patterns (Turner et al 2005, 2009, 2014). The Oecologia (2016) 181:931–945 stable carbon (C) isotope composition (δ13C) of cellulose has been used as a proxy for the carbon dioxide (CO2) assimilation rate (Royles et al 2012), whilst testate amoebae provide an indication of microbial activity (Royles et al 2013a). Our primary aim is to test these against measurements of precipitation stable isotope composition, tissue water content and (micro-)climate in order to investigate the response of moss and amoebae to environmental and climate gradients, to test their applicability in palaeoclimate studies. This provides vital context to understand the contemporary processes driving the proxy signals, which are preserved over thousands of years in the moss bank core samples. Testate amoeba community composition diversifies, and concentration and biomass increase, as a result of higher temperatures and/or increases in water availability

Materials and methods

Results

Discussion