PhD: A balancing act in coral reefs: how stoichiometry creates resilience in tropical reef systems
Lyell Centre, Heriot-Watt University
Ocean Sciences (OS)
Supervisors: Drs Heidi Burdett (Lyell Centre), Alex Poulton (Lyell Centre), Nick Kamenos (University of Glasgow) and Dan Exton (Operation Wallacea – CASE partner)
Deadline for applications: Friday 8th January 2021 at 5pm (GMT)
Project description: Coral reefs are one of the most biodiverse ecosystems on Earth. The ecosystem services they provide, including coastal protection, tourism, food security and medical derivatives, are valued at over $100 billion annually. However, around the world coral reefs are facing increasing pressure from direct human activities such as coastal development and pollution, as well as rapidly altering environmental conditions as a result of climate change. These pressures can cause degradation of coral cover, proliferation of algal growth and ultimately a complete ecosystem shift and loss of the reef habitat. Physiological resilience to these pressures, at the organism to community scale, is crucial for the future survival of coral reefs.
Paradoxically, despite being highly productive and supporting diverse marine ecosystems, coral reefs thrive in low-nutrient environments thanks to efficient nutrient recycling and retention. How they maintain the ratio between the basic elements of life (e.g. carbon, nitrogen, calcium) may therefore be fundamental to how coral reefs respond to environmental change. This so-called “ecological stoichiometry” has a long history of research within the open ocean, but the cycling of nutrients and balance of elements within coral reef systems remains largely unknown. Recent work by the supervisory team suggests that corals, and other calcifying organisms, can exhibit a wide range in C:N ratios, suggesting that the stoichiometry of a coral reef system may be highly dynamic in response to environmental change.
The aim of this project is to quantify the variability of elemental stoichiometry within the coral reef system and to identify the environmental drivers controlling this variability. Given their uncertain future, this information will provide a foundation for predicting coral reef resilience, and place these ecosystems within the wider context of global biogeochemical cycling.
The PhD student will have the opportunity to collect coral reef and water samples from multiple sites within the Caribbean (SCUBA diving is optional) for stoichiometric analysis. Sampling surveys will be conducted at the organism to community scale and combined with advanced ecological survey techniques (e.g. 3D habitat modelling) and historical biodiversity data to enable a mechanistic understanding of stoichiometric dynamics within the reef. This could be conducted in the laboratory should Covid-19 travel restrictions still be in place; physical distancing in the field and off-peak visits will also be possible. Innovative mass spectrometry technologies available at the Lyell Centre will also enable stoichiometric partitioning at the organism-level, e.g. between lipids and carbohydrates. 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.
Eligibility & application: This project is competition-funded through the NERC Iapetus2 DTP. Full details on the studentship can be found here: https://heidiburdett.wordpress.com/2020/11/15/phd-a-balancing-act-in-coral-reefs-how-stoichiometry-creates-resilience-in-tropical-reef-systems/