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Nutrient impacts on coral reefs captured through macroalgal isotopes

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  • Full or part time
    Prof Graham
    Prof Barker
  • Application Deadline
    No more applications being accepted
  • Funded PhD Project (European/UK Students Only)
    Funded PhD Project (European/UK Students Only)

Project Description

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.

Funding Notes

Full studentship (UK/EU tuition fees and stipend (£14,057 [tax free]) for UK/EU students for 4 years. Unfortunately studentship is not available to non-UK/EU applicants due to funding restrictions.

References

Hughes TP, et al. (2010) Rising to the challenge of sustaining coral reef resilience. Trends in Ecology and Evolution 25:633–642
Graham NAJ, et al. (2015) Predicting climate-driven regime shifts versus rebound potential in coral reefs. Nature 518:94-97
McClanahan TR, et al. (2011) Critical thresholds and tangible targets for ecosystem-based management of coral reef fisheries. Proceedings of the National Academy of Sciences of the USA 108:17230–17233
Fabricius K, et al. (2012) Effects of terrestrial runoff on the ecology of corals and coral reefs: review and synthesis. Marine Pollution Bulletin 65:320-332
Fong P, et al. (1994) Nutrient concentration in tissue of the macroalga enteromorpha as a function of nutrient history-an experimental evaluation using field microcosms. Marine Ecology Progress Series 106:273-281
Burkepile DE, et al. (2013) Nutrient supply from fishes facilitates macroalgae and suppresses corals in a Caribbean coral reef ecosystem. Scientific Reports 3:1493

How good is research at Lancaster University in Earth Systems and Environmental Sciences?

FTE Category A staff submitted: 44.90

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