PhD: Drivers of marine ecosystem change during an ancient abrupt global warming event

Project 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

Description: The Palaeocene-Eocene Thermal Maximum (PETM) ~56 million years ago, is the largest of a series of abrupt global warming events known from the Cenozoic. 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 (e.g., from volcanoes or methane hydrates) 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 help us understand anthropogenic environmental change and its impacts. However, whilst a large number of studies have investigated biotic and environmental change at the PETM, these have primarily focussed on individual sites or single organismal groups, preventing an understanding of both the spatial patterns of change (e.g., development of tropical exclusion zones) and ecosystem functioning before, during and after abrupt environmental change, and the relative role of abiotic drivers on these changes.
The student will address this deficit by generating/compiling datasets to quantify marine ecosystem change globally. These data will be integrated with extensive palaeoenvironmental datasets, in many cases from the same sites. Key questions that will be addressed include:
- was there a change in ecosystem function during the PETM?
- was temperature the dominant driver of marine ecosystem change?
- how do organisms with different ecologies and habitat preferences respond to the same environmental drivers?

Methodology: The student will collate existing species abundance and diversity datasets alongside co-occurring environmental datasets spanning the PETM. In the first instance, marine benthos and nekton will be targeted and supplemented by new data collection where significant gaps are identified (e.g., ichnofossils, fish, sharks, corals). This new data collection will utilise NHM and IODP materials, including new material recovered by Edgar during IODP Expedition 369 in the SW Indian Ocean and may involve fieldwork. These data will be supplemented by morphological data as appropriate (e.g., body size). The resulting data compilation will be used to quantity changes in the ecological structure and function of marine communities across the PETM.

Data will be compared with multiple geochemical and sedimentological proxies detailing marine environmental change, including bottom water temperature, water column stratification, carbon and nutrient cycling, and oxygenation. These will be used to assess the relative influence of abiotic factors on biotic change.