PhD: When was the South Pacific colonised?

Title: When was the South Pacific colonised? A lake sediment approach to understanding climate:human drivers of ecosystem change on remote Pacific Islands

Location: University of Soithampton (Geography & Environment)

Supervsiory team: Dr. Sandra Nogué, Prof Mary Edwards, Prof. David Sear, Dr. William Gosling (University of Amsterdam), Prof. Inger (Tromso University), Prof. Janet Wilmshurst (Landcare research and University of Auckland)

Rationale: The Pacific islands of Polynesia were among the last places on earth to be colonised by humans. The precise dates of colonisation are debated – a situation which arises from the different sources of evidence (1, 2). New lake sediment records from the Cook Islands (Atiu, Mangaia) and Samoa (Upolu) and Tonga show very clear evidence of disturbance, but what is unclear is to what extent the signal represents the arrival of humans or a change in climate (2). A key question for the analysis of sedimentary records is the ability to distinguish natural variability in the environment of Pacific Islands from that arising from the arrival of humans in a temporal and spatial context. We aim to use a multi-proxy approach based on SedDNA, lipid biomarkers, fossil charcoal, and pollen preserved in lake sediments to identify: a) the presence of humans and/or livestock that were brought with them, and b) the related environmental change. Multiproxy approaches supported by statistical analysis, will be deployed to four sites where we already have good chronological controls and high resolution records of palaeoclimate. We are well placed to apply new methods and higher resolution analyses to address fundamental questions about the response of remote pacific islands to climate and human forcings.

Methodology: The student will be able to focus on reconstructing detailed palaeoecological proxy records from each lake (Tonga, Cook Islands, Samoa), and undertake comparison between these records and those from other proxies in the wider tropical Pacific (e.g. Polynesia, New Caledonia and New Zealand).

The student will work on existing lake sediment cores collected from the study lakes in 2014/2015/2016/2017. Further fieldwork may be required to collect additional material, including modern pollen/biotic samples. Biotic analyses will initially focus on developing a pollen training set for the Islands, and the reconstruction of environmental change over the period of possible human colonization (last 0.8-3ka). This will include the application of  sedimentary aDNA (3) lipid biomarkers (i.e. human settlement, Chicken and Pigs), pollen (i.e. vegetation change) and charcoal methods (i.e. burning activities) in association with stable isotopes (lake ecosystem productivity, precipitation), and high-resolution geochemical proxy data (ITRAX) for detecting the earliest presence of people (and/or their animals). Thereafter, the emphasis will focus on understanding the response of Island ecosystems to human and climate driven forcings (using available datasets e.g. ITRAX leaf wax), drawing on complex systems modelling approaches to identify different forms of ecosystem response (critical transitions, tipping points, and slow/fast processes).

Training: The SPITFIRE DTP programme provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial/policy partners. The student will be registered at the University of Southampton and hosted at the Palaeoenvironmental Laboratory at the University of Southampton (PLUS) at the Department of Geography and Environment.

Specific training will include: 1) Training in palaeoecological methods such as aDNA, palynology (fossil pollen), biomarkers (e.g. Lipid biomarkers), fossil charcoal, C/N ratios, Stable isotopes, and ITRAX; 2) Statistical analysis and mathematical modelling using R, and 3) the student will be trained in developing, understanding and integrating datasets within a complex systems science framework.

We anticipate the student travelling to the laboratories of Prof. William Gosling (University of Amsterdam) and Prof. Janet Wilmshurst (Landcare research and University of Auckland) to obtain additional training and support.

Eligibility & Funding Details: The SPITFIRE project is open to applicants who meet the SPITFIRE eligibility, alongside other exceptional applicants and will come with a fully funded studentship for UK students and EU students who meet the RCUK eligibility criteria.  To check your eligibility and find information on how to apply click here.

UK applicants and EU students who meet the RCUK eligibility criteria please contact spitfire@southampton.ac.uk

This project is also open to applicants who DO NOT meet the SPITFIRE funding eligibility criteria via applying to PGRapply.FSHMS@southampton.ac.uk

Please make sure you apply to the correct programme any applications from non SPITFIRE eligible applicants will be rejected automatically.

Background Reading:

1, Wilmshurst JM, Hunt TL, Lipo CP, Anderson AJ (2011) High-precision radiocarbon dating shows recent and rapid initial human colonization of East Polynesia. Proc. Natl. Acad. Sci. USA 108:1815–1820.

  1. Prebble, M. and J.M. Wilmshurst (2008). Detecting the initial impact of humans and introduced species on island environments in Remote Oceania using palaeoecology.Biological Invasions 11:1529-1556.
  2. Bremond, L., et al., (2017). Five thousand years of tropical lake sediment DNA records from Benin, Quaternary Science Reviews, Volume 170: 203-211, ISSN 0277-3791.

Contact Email: S.Nogue-Bosch@soton.ac.uk; D.Sear@soton.ac.uk

 

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