PhD: The volatile nature of tropical reef ecosystems in a changing world
Lyell Centre, Heriot-Watt University
Ocean Sciences (OS)
Supervisors: Drs Heidi Burdett (Lyell Centre), Nick Kamenos (University of Glasgow), Clayton Magill (Lyell Centre) & Dan Exton (Operation Wallacea – CASE partner)
Deadline for applications: Friday 8th January 2021 at 5pm (GMT)
Project aummary: Tropical coastal ecosystems are some of the most diverse and productive on Earth. They are also significant producers of biogenic volatile organic compounds (BVOCs), volatile chemicals with key ecophysiological functions, major roles global biogeochemical cycling of elements and a role in local-regional climate regulation. Understanding BVOC dynamics, and drivers of variability is therefore crucial for predicting how these ecosystems may respond to projected climate change (e.g. warming, acidification and changes to ecosystem structure).
Dimethylsulphide (DMS) and isoprene are two of the most abundant BVOCs, respectively responsible for the ‘smell of the sea’, ‘blue haze’, observed in forested mountains. In tropical reef systems, the land-sea ecosystem transition (i.e. mangroves to coral reefs) results in a BVOC continuum. However, our understanding of BVOC dynamics and their role in local-regional biogeochemical cycling is limited, preventing us from incorporating this crucial ecosystem feature into conservation and management plans.
The aim of this project is to quantify the natural dynamics of this BVOC continuum, using compound-specific quantification and isotopic differentiation to identify the sources and sinks of isoprene and DMS within the mangrove-seagrass-coral reef system. Field studies conducted on Caribbean reefs (including Honduras, Dominica) and lab-based aquarium experiments will enable the environmental and biological drivers of BVOC variability to be determined, allowing projections for future BVOC signatures to be estimated.
The PhD student will have the opportunity to collect samples from mangrove forests, seagrass meadows and coral reefs from multiple sites within the Caribbean (SCUBA diving is optional) for BVOC quantification. In situ experiments (e.g. herbivore exclusion and macrophyte removal plots) will enable biological and environmental BVOC drivers to be identified. BVOCs will be quantified using gas chromatography and their potential sources identified using state-of-the-art compound-specific isotope analyses, using facilities available at the Lyell Centre. This could be conducted in the laboratory and supplemented by the considerable volume of historical biodiversity data available from Operation Wallacea, should Covid-19 travel restrictions still be in place. 3D modelling of the ecosystem will enable biogeochemical results to be scaled up to the coverage of local management boundaries; comparison to historical survey records will indicate how BVOC biogeochemistry has been impacted by human disturbance. Further mechanistic insight will be gained via the opportunity to conduct multifactorial laboratory aquarium experiments under highly controlled conditions of light, temperature, nutrients and carbon chemistry, using state-of-the-art facilities available within the Lyell Centre research aquarium. Climate change experiments and modelling (based on IPCC projections) will enable the scholar to project how BVOC dynamics will likely change over the coming decades, and identify how this may impact future ecosystem function.
Eligibility & application: This project is competition-funded thorugh the NERC Iapetus2 DTP. Full details on the studetnship can be found here: https://heidiburdett.wordpress.com/2020/11/15/phd-the-volatile-nature-of-tropical-reef-ecosystems-in-a-changing-world/