Overview
My research links protistology and palaeoclimatology, and primarily centers on terrestrial peat-forming ecosystems in the region surrounding Antarctica.
Impacts of changes in the ocean on coastal freshwater peatlands, and the unique biological records produced by such interactions, are the central theme of my research. More specifically, my overarching aim is to better understand how the microbial communities inhabiting coastal peatlands respond to the addition of oceanic salt, which can occur via atmospheric-spray deposition, inundation during storms, and as a result of sea-level change.
As a protistologist my principle focus is on testate amoebae, a group of microbial eukaryotes that produce decay resistant shells and can be found in almost every freshwater ecosystem on Earth. The intricate beauty, ruggedness, and ability of these protists to perform complex functions fascinates me. In addition to developing their use as salinity bioindicators, I aim to improve understanding of the other global environmental and biogeographical controls responsible for their distributional trends around Antarctica.
Previously, I studied the diversity and ecology of testate amoebae communities on sub-Antarctic Marion Island for my MSc by Research in Physical Geography. Prior to this I worked on a project assessing the global impact of sea-level change on the carbon sink of coastal peatlands, which was published in Scientific Reports in 2016. I received a first class BSc degree with Honours in Physical Geography from the University of Exeter in 2015, where I was the recipient of the Lewis memorial prize for academic achievement.
I am now based at the British Antarctic Survey, Cambridge.
I look forward to meeting and collaborating with people who share similar research interests. Please contact me at: aw424@exeter.ac.uk, or via researchgate and twitter (@alexewhittle).
Research
Research interests
My current research follows three key themes:
1) Response of testate amoebae to salinity: Using naturally occurring salinity gradients, I am working to establish the ecological importance of micro-habitat ionic concentration in governing the biomass of testate amoebae communities and in defining the distribution of individual taxa. My research aims to develop and improve the ecological basis for the use of testate amoebae as palaeoenvironmental indicators in salt-influenced ecosystems.
2) Sub-Antarctic palaeoclimate: As part of my research into the salinity response of testate amoebae I developed a novel palaeoenvironmental proxy that allows these micro-organisms to be used to reconstruct wind conditions from peatland archives. The methodology uses testate amoebae preserved in coastal peatlands to reconstruct past variation in the deposition of wind-blown oceanic salt spray, which in turn indicates former wind conditions.
3) Biodiversity and biogeography of testate amoebae: Through exploration of previously un-sampled locations, combined with a synthesis of existing records, I work toward assessing evidence for bioregionalisation and endemism in the testate amoebae communities of peatlands and lakes within the sub-, maritime- and continental Antarctic. I have a particular interest in the relationship between present day testate amoebae community composition and the glacial history and climate of the sub-Antarctic islands.
Publications
Key publications | Publications by category | Publications by year
Publications by category
Journal articles
Whittle A, Barnett RL, Charman DJ, Gallego‐Sala AV (2021). Low‐salinity transitions drive abrupt microbial response to sea‐level change. Ecology Letters, 25(1), 17-25.
Whittle A, Amesbury MJ, Charman DJ, Hodgson DA, Perren BB, Roberts SJ, Gallego-Sala AV (2018). Salt-Enrichment Impact on Biomass Production in a Natural Population of Peatland Dwelling Arcellinida and Euglyphida (Testate Amoebae).
Microbial EcologyAbstract:
Salt-Enrichment Impact on Biomass Production in a Natural Population of Peatland Dwelling Arcellinida and Euglyphida (Testate Amoebae)
© 2018, the Author(s). Unicellular free-living microbial eukaryotes of the order Arcellinida (Tubulinea; Amoebozoa) and Euglyphida (Cercozoa; SAR), commonly termed testate amoebae, colonise almost every freshwater ecosystem on Earth. Patterns in the distribution and productivity of these organisms are strongly linked to abiotic conditions—particularly moisture availability and temperature—however, the ecological impacts of changes in salinity remain poorly documented. Here, we examine how variable salt concentrations affect a natural community of Arcellinida and Euglyphida on a freshwater sub-Antarctic peatland. We principally report that deposition of wind-blown oceanic salt-spray aerosols onto the peatland surface corresponds to a strong reduction in biomass and to an alteration in the taxonomic composition of communities in favour of generalist taxa. Our results suggest novel applications of this response as a sensitive tool to monitor salinisation of coastal soils and to detect salinity changes within peatland palaeoclimate archives. Specifically, we suggest that these relationships could be used to reconstruct millennial scale variability in salt-spray deposition—a proxy for changes in wind-conditions—from sub-fossil communities of Arcellinida and Euglyphida preserved in exposed coastal peatlands.
Abstract.
Whittle A, Gallego-Sala AV (2016). Vulnerability of the peatland carbon sink to sea-level rise. Scientific Reports, 6(1).
Publications by year
2021
Whittle A (2021). Late Quaternary changes in the Westerly Winds over the Southern Ocean.
Abstract:
Late Quaternary changes in the Westerly Winds over the Southern Ocean
The latitudinal position and intensity of the Southern Hemisphere westerly winds (SHW) has important and far-reaching implications for global climate and the physical environment in the southern high latitudes. Despite this, our ability to project how they will change in the future is reduced by limited understanding of their behaviour over centennial to millennial timescales. Peatland archives on the sub-Antarctic Islands are uniquely located inside the core wind-belt (50-55˚S), and hence ideally situated to reconstruct changes in westerly wind behaviour. However, suitable proxies to develop reconstructions of wind-strength throughout the region are lacking. Westerly winds are shown to enrich the sub-Antarctic Islands with salt-spray in concentrations that are proportional to wind-strength. This research has tested the potential for peat-dwelling testate amoebae to act as a bioindicator for variations in salt-spray deposition through time. Measurements of communities in variably salt-enriched environments - spanning a gradient from predominantly freshwater to salt-marsh - revealed a strong relationship between the productivity of testate amoeba communities and salinity, which allows past salt-concentrations to be inferred from sub-fossil assemblages. Presented here are two reconstructions of SHW intensity over the South Atlantic, based primarily on changes in the productivity of testate amoeba communities. The first provides a high-resolution record of the changes in wind-intensity over recent decades, extending beyond the observational record to 1920 CE, and demonstrating that present-day wind conditions are unprecedented over the last century. The second record, collected from the same site, provides a c. 8000-year reconstruction of wind-intensity over the South Atlantic, based on changes in testate amoeba productivity as part of a multi-proxy analysis that includes three independent proxies to track the deposition of salt-spray aerosols and minerogenic particles into the peat record on Bird Island (sub-Antarctica). Three significant phases of intensified winds during this period (0.45-1.15, 2.8-3.65 and 4.45-8 k yr BP) indicate long-term correspondence between temperature and wind-strength at 54˚S. These observations suggest that with climatic warming in the 21st Century, the westerly wind belt will continue to intensify and displace southwards, leading to increased wind-stress over the Southern Ocean. Implications of this shift are expected to include; reduced precipitation supply to the Southern Hemisphere continents, reduced Antarctic ice-sheet stability and increased contributions to global sea-level, and weakening of the Southern Ocean carbon sink, allowing accumulation of more CO₂ in the atmosphere.
Abstract.
Whittle A, Barnett RL, Charman DJ, Gallego‐Sala AV (2021). Low‐salinity transitions drive abrupt microbial response to sea‐level change. Ecology Letters, 25(1), 17-25.
2018
Whittle A, Amesbury MJ, Charman DJ, Hodgson DA, Perren BB, Roberts SJ, Gallego-Sala AV (2018). Salt-Enrichment Impact on Biomass Production in a Natural Population of Peatland Dwelling Arcellinida and Euglyphida (Testate Amoebae).
Microbial EcologyAbstract:
Salt-Enrichment Impact on Biomass Production in a Natural Population of Peatland Dwelling Arcellinida and Euglyphida (Testate Amoebae)
© 2018, the Author(s). Unicellular free-living microbial eukaryotes of the order Arcellinida (Tubulinea; Amoebozoa) and Euglyphida (Cercozoa; SAR), commonly termed testate amoebae, colonise almost every freshwater ecosystem on Earth. Patterns in the distribution and productivity of these organisms are strongly linked to abiotic conditions—particularly moisture availability and temperature—however, the ecological impacts of changes in salinity remain poorly documented. Here, we examine how variable salt concentrations affect a natural community of Arcellinida and Euglyphida on a freshwater sub-Antarctic peatland. We principally report that deposition of wind-blown oceanic salt-spray aerosols onto the peatland surface corresponds to a strong reduction in biomass and to an alteration in the taxonomic composition of communities in favour of generalist taxa. Our results suggest novel applications of this response as a sensitive tool to monitor salinisation of coastal soils and to detect salinity changes within peatland palaeoclimate archives. Specifically, we suggest that these relationships could be used to reconstruct millennial scale variability in salt-spray deposition—a proxy for changes in wind-conditions—from sub-fossil communities of Arcellinida and Euglyphida preserved in exposed coastal peatlands.
Abstract.
2016
Whittle A, Gallego-Sala AV (2016). Vulnerability of the peatland carbon sink to sea-level rise. Scientific Reports, 6(1).
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