Overview

roject Highlights:

  • Join a world-class team of scientists working to understand the links between extreme climate events and ecosystem dynamics
  • Constrain the dominant patterns, responses and driver(s) of marine ecosystem change
  • Learn a diverse range of key statistical, palaeobiological and geochemical techniques to investigate controls on past life and relevance to modern communities

The Palaeocene-Eocene Thermal Maximum (PETM) ~56 million years ago, is the largest of a series of abrupt Cenozoic global warming events. During this event, the oceans rapidly warmed by >5 °C and became more acidic, and the world became wetter and stormier with profound consequences for life on land and in the oceans. The PETM was driven by the injection of isotopically light carbon (likely from volcanism) into the atmosphere, and many of the associated environmental changes are similar to those occurring today. Therefore, the PETM is often considered the best geological analogue to understand anthropogenic environmental change and its impacts. However, whilst a large number of studies have investigated PETM biotic and environmental change, very few have investigated the response and long-term impact on marine vertebrates. This is, at least in part, because the body fossil record is patchy, because of a lack of suitable sediments and very poor age control on available sequences to assess short-term biological responses. Yet, resolving the response and resilience of top level trophic consumers to modern anthropogenic change is of vital importance because of predictions of significant reductions in tropical communities productivity, diversity and body size over the coming century with critical implications for many marine-ecosystems and human populations dependent on these resources.

Fortunately, ichthyoliths (= fish teeth and shark denticles, generally <1 mm in size) are pervasive in marine sediments and are an underutilized but powerful resource for generating relatively continuous and highly temporally and spatially resolved records of fish and shark communities through time. The student will utilise this novel archive to compile existing records and generate multiple new records of changes in the productivity and diversity of fish and shark communities across the PETM globally. These data will be integrated with extensive palaeoenvironmental datasets. Key questions that will be addressed include:

  • How did shark and fish communities change across the PETM?
  • Did high vs low latitude communities respond similarly?
  • Was temperature the dominant driver of change in fish and shark communities?
  • What role do abrupt climate events play in shaping fish and shark evolution?
(a) PETM sea surface temperature (Dunkley Jones et al., 2013), (b) examples of fish teeth and sharks dermal denticles (Sibert et al. 2017) and (c) Modern Basking Shark (https://www.pinterest.co.uk/pin/467600373788296513/?lp=true).

Methodology

The student will prioritise data collection at sites with good age models to increase the spatial and temporal coverage. This will include IODP materials, e.g., new material from IODP Expedition 369, Indian Ocean, Natural History Museum collections and fieldwork, e.g., Forada, Italy. The student will process deep-sea sediments, and then extract, image and identify ichthyoliths with a binocular light microscope (and SEM). Diversity and abundance will be considered alongside records of sedimentation rate and environmental changes (e.g., temperature, stratification, primary productivity, and oxygenation) from the same site and elsewhere to elucidate controls on the record. Where key environmental records are absent they will be generated, e.g., temperature from carbonate-bound d18O and primary production from barium abundances in bulk sediment. The student will also collate existing PETM datasets. The resulting data compilation will quantity changes in the community structure and function across the PETM utilising cutting-edge palaeobiological and –ecological tools.

Training and Skills

The student will gain experience in data synthesis, creating new and using existing databases, taxonomic identification of fossil nektonic organisms and in applying geochemical, sedimentological and palaeoecological techniques to address key questions in earth system sciences. The student will develop skills in multivariate statistical techniques, graphing and mapping in the free R environment. Opportunities for travel to visit museum collections, core repositories or fieldwork are possible, and relevant training will be provided. These skills are highly transferable within academia and industry, and will enable the student to specialise as a palaeontologist or palaeoclimatologist.

Timeline

Year 1: Complete literature review and initial data compilation of marine nekton records from body fossils and microfossil records as well as corresponding environmental records across the PETM from the same sites where available. Identify key sites to target for data collection. Presentation of initial results at Palaeontological Association annual meeting in 2021. You will have regular meetings with your co-supervisor at the NHM, London throughout the PhD and will pay an extended visit to work with Dr Elizabeth Sibert in year 1 or 2.

Year 2: Continued data collection, interpretation, and develop manuscript 1. Presentation of results at large international meeting in 2021/2022 such as the Geological Society of America (GSA) annual meeting and a UK based meeting, e.g., Palaeontological Association.

Year 3: Complete outstanding data collection, analyses, and interpretation. Prepare remaining manuscripts and thesis write-up. Presentation of final results at European Geosciences Union Meeting in Vienna or GSA, and Palaeontological Association annual meeting

 

Partners and collaboration (including CASE)

This project was developed in collaboration with Hannah Bird and the NHM. It brings together expertise from different areas to tackle pressing questions relating to the impact of abrupt environmental change on marine communities. Each supervisor has a complimentary skill set: Edgar is a Cenozoic microfossil specialist and palaeoceanographer specialising in abrupt ancient global warming events; Twitchett specialises in the early Mesozoic warming-related mass extinction events and effects on marine ecosystems; Sibert utilises ichthyoliths to reconstruct Cenozoic fish and shark communities. Sansom is a vertebrate palaeobiologist focussing on the evolution, palaeocology and biogeography of fossil fish and sharks.

Further Details

Please contact Dr Kirsty Edgar (k.m.edgar@bham.ac.uk) for more project specific details. See the CENTA2 webpage for information on how to apply and general information. Check out the Palaeobiology and Palaeoclimate group webpages for more information on the group that you would be joining: https://www.birmingham.ac.uk/research/activity/earth-sciences/index.aspx or follow us on twitter @Palaeo_bham.