Coral reef ecosystems are under severe pressure from stressors ranging from global climate change to local effects of fishing and pollution. Many reefs have become severely degraded, typified by reductions in coral cover and associated diversity, and increases in organisms such as fleshy algae. Importantly, local stressors, principally fishing and water quality (nutrients and sediments), have the potential to be managed locally, on relatively short time scales, and are likely to give reefs a better chance to survive the impacts of larger scale stressors such as climate change. For example, following a major climate-driven warming event in the Seychelles where over 90% of live coral was killed, two of the factors that predicted which reefs bounced back and recovered were fishing and nutrients.
Robust proxies for fishing pressure on coral reefs have been developed, ranging from the distance to commercial markets, to the standing stock of fishable biomass. This has enabled threshold points at which ecological processes show major changes to be identified, enabling ecosystem-based management targets for fishing pressure. However, estimating nutrient loads impacting reefs has proved far more challenging because direct measures of nutrient loads in the water column are inherently variable on both short (e.g. currents, tides) and long (e.g. rainfall events flushing nutrients off land) time scales, requiring long-term, near continuous, and expensive monitoring. Proxies that integrate nutrient conditions over time offer one solution. One approach is to assess nutrient loads assimilated in macroalgal plants. It has been shown that the ratio of carbon to nitrogen or phosphorus in macroalgae is a relatively stable, longer-term indicator of ambient nutrient regimes at a given location, with nutrient inputs incorporated into algal tissue averaged over the active growing period. Further, stable isotopes of nitrogen (δ15N) may provide an even more accurate measure of assimilated nutrient loads and sources in macroalgae. Although these techniques hold great promise to more accurately assess nutrient loads on coral reefs across larger spatial scales, as well as test threshold levels at which major ecosystem change occurs, the accuracy of the measures to capture nutrient regimes remain poorly tested, particularly for Indo-Pacific coral reefs.
This PhD project will characterise and assess the accuracy of nutrient signals assimilated into macroalgae, and then assess the utility of these techniques in detecting threshold points of ecosystem change. Specifically, the project will address the following aims:
1) Experimentally determine signals in macroalgae exposed to differing nitrogen sources and concentrations during their active growing period.
2) Ground truth macroalgae nutrient content on reefs of known nutrient input.
3) Identify threshold responses in ecosystem states and processes in response to gradients in nutrient regimes.
Academic Requirements: First-class or 2.1 (Hons) degree, or Masters degree (or equivalent) in an appropriate subject.
Deadline for applications: Midnight 23 March 2016
Provisional Interview Date: To Be Confirmed
Start Date: October 2016
Further Information: http://www.lancaster.ac.uk/sci-tech/downloads/phd_281.pdf
Application process: Please upload a completed application form (download from http://www.lancaster.ac.uk/media/lancaster-university/content-assets/documents/lec/pg/LEC_Funded_PhD_Application-Form.docx) outlining your background and suitability for this project and a CV at LEC Postgraduate Research Applications, http://www.lec.lancs.ac.uk/postgraduate/pgresearch/apply-online.
You also require two references, please send the reference form (download from http://www.lancaster.ac.uk/media/lancaster-university/content-assets/documents/lec/pg/LEC_Funded_PhD_Reference_Form.docx) to your two referees and ask them to email it to Andy Harrod ([email protected]
), Postgraduate Research (PGR) Co-ordinator, Lancaster Environment Centre by the deadline.
Due to the limited time between the closing date and the interview date, it is essential that you ensure references are submitted by the closing date or as soon as possible.