Crumbling reefs: quantifying risk of cold-water coral habitat loss in a changing ocean

This PhD will quantify the risk of cold-water coral habitat loss in present day and future conditions, using experimental and theoretical approaches

Supervisors:
Dr. Sebastian Hennige (Main supervisor), School of Geosciences, University of Edinburgh.
Prof. Murray Roberts, (Co-Supervisor) School of Geosciences, University of Edinburgh.
Dr. Uwe Wolfram (External supervisor), Heriot-Watt University
Dr. Nick Kamenos (External Supervisor), University of Glasgow

Background: Cold-water corals (CWC) are key habitat-forming organisms found throughout the world’s oceans from 30 to 3000 m deep. The complex three-dimensional frameworks made by these vulnerable marine ecosystems support high biodiversity and commercially important species. Given the importance of cold-water habitats, the Convention on Biological Diversity (1) recently stated that there is “a need to develop predictive model research to determine how projected climate change will impact cold-water biodiversity over different timescales”. We currently have no way to monitor and assess the structural integrity of CWC reefs in situ, or to determine how this may change under projected future ocean acidification scenarios. The PhD scholar would seek to create such a model.

The structural integrity of CWC reefs, which is a function of the growth rate of live coral, the dissolution rate of dead coral, and the load bearing capacity of both live and dead fractions, is at risk from ocean acidification (2). Cold-water corals are at particular risk from ocean acidification due to their depth range and their proximity to the aragonite (calcium carbonate) saturation horizon (ASH). At depths below the saturation horizon, where aragonite in the water is undersaturated, exposed skeleton will dissolve. Considering that 95% of reefs are currently above the ASH, we need to develop the means and data to assess whether reefs and the associated ecosystems will persist in their present forms under projected environmental changes, as the reefs themselves may become structurally weaker, leading to smaller reefs and less supported biodiversity. Currently these impacts are not understood to an extent that allows integration into computer simulation environments which would allow analysing risk of habitat degradation of CWC habitats in a changing ocean. A major outcome for this project will be to quantify how projected changes in ocean acidification will affect the structure-mechanical integrity and stability of CWC reefs. These data would lead to a greater understanding of the future potential of CWC reefs for biodiversity support and ecosystem services, for policy makers and environmental managers.

Methodology: To determine the range of aragonite saturation levels that CWC reefs may be subjected to by the year 2100, the scholar will perform a meta-analysis of published data and integrate distribution information of CWC reefs and ocean acidification scenarios into GIS. Existing biogeochemical and nanoindentation data from previously collected coral samples will be complemented by (µCT) imaging and micropillar compression testing, to determine how different environmental conditions interact with sample porosity and density, and structural integrity. This data will then be used to construct finite element models, so that coral strength and degradation can be related to projected future ocean acidification conditions. There may be the opportunity to collect further samples through fieldwork.

Scholar support and training: The School of Geosciences at the University of Edinburgh has a large research student cohort that will provide peer-support throughout the research program. The scholar will participate in post-graduate research conference events, providing an opportunity to present their research to postgraduates and staff within the university, and to also learn about the research conducted by their fellow postgraduate peers. A comprehensive training programme will be provided comprising both specialist scientific training and generic transferable and professional skills, and the scholar will be encouraged to attend specialist courses that will directly contribute to the proposed project. Analytical training will be provided by the supervisors and / or specialist technicians for all instrumentation required for analyses.

Requirements – The scholar sought for this project must have interests in coral ecology and structural mechanics, and may have a background in biology, (computational) material or engineering mechanics, or biophysics. Good data analysis/programing skills are essential, as is the willingness to work at multiple campuses in Edinburgh.

Full details: https://www.geos.ed.ac.uk/postgraduate/PhD/getDocument?SerialNo=1285

How to apply: http://e3dtp.geos.ed.ac.uk/apply.html