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  CDTS331: Exploring factors underpinning resilience and identifying avenues for restoration of maerl beds, a priority habitat for marine conservation

   Department of Biosciences

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  Prof Mike Allen, Dr J R Stevens, Dr Peter Robins, Prof Jason Hall-Spencer  No more applications being accepted  Competition Funded PhD Project (UK Students Only)

About the Project

Similar to reefs formed by colony-building hard corals, maerl (coralline algae) needs sunlight to photosynthesise and can aggregate to form dense biogenic habitats, known as maerl beds (Fig. 1), providing a 3-dimensional habitat on the seafloor. These beds are important nursery areas for fish and shellfish of commercial importance, e.g. cod, scallops; they have also been shown to sequester carbon at similar rates to salt marshes and seagrass beds. However, while listed as priority habitats under UK and European legislation, little is known about the reproduction and biology of these coralline algae. This knowledge is key to understanding the resilience of maerl-forming species to environmental and climate change, and for directing conservation actions to drive recovery and restoration of degraded maerl beds. This PhD will explore the environmental, biological and genetic factors that may be acting to drive degradation. Subsequently, we will look to propose management actions to remedy this situation, to halt decline and promote restoration.

Aims and Objectives

This project addresses key knowledge gaps in maerl biology and ecology: in reproduction, biology, resilience and diversity of maerl-forming species using a multidisciplinary approach, including aquarium experiments, microscopy and genomics.

Aquarium experiments will explore how light restriction (sedimentation), salinity (freshwater discharge) and temperature (ocean warming) affect the biology and reproduction of maerl. Microscopy will identify reproductive structures. This will enable follow-up studies of when and under what conditions maerl-forming algae reproduce sexually/asexually. The project will have access to recently developed genomic and eDNA resources for two maerl-forming species (Phymatolithon calcareum and Lithothamnion corallioides); this will allow investigation of the adaptability of maerl at a molecular level and assessment of organismal diversity within maerl beds using eDNA. In conjunction with our stakeholder partners, results will feed directly into the conservation, management and restoration of maerl beds. The student will have the opportunity to feed into the planning and execution of laboratory trials, and field assessments of diversity, including sample collection and eDNA surveys.


Training will be given in molecular genomics and eDNA analysis, field-based marine diversity sampling and assessment, and in the use of aquarium facilities at the Exeter Aquatic Resource Centre (ARC), allowing investigation of maerl growth patterns under differing environmental stressors. A visit to a partner laboratory in Spain will allow the student to learn the techniques required for accurate identification of algal reproductive structures.

Project Structure

The project will be supervised by Jamie Stevens, Exeter, Jason Hall-Spencer, Plymouth and Dr Magnus Axelsson, Natural England. The student will be based at Exeter (Streatham campus), with access to a fully equipped, modern molecular research laboratory and the Exeter Sequencing Service (allowing exploration of patterns of genetic differentiation between maerl populations); the team hold a large selection of maerl samples from different sites around England and Wales, which the student will be supported to supplement early in the project, providing opportunities for field work, and aquarium studies. The student will work with supervisors and stakeholder partners (Natural England and NRW) to feed project findings into national policies. 

Application deadline: 16:00pm (BST), 27th June 2024

Biological Sciences (4) Environmental Sciences (13) Geography (17) Politics & Government (30)

Funding Notes

Funded by the SuMMeR Doctoral Training Programme/Departmental funding

The CDT SuMMeR has funding available to appoint 2 successful candidates from the 4 projects being advertised. Candidates will be appointed on merit, based on their application documents and performance in interviews.

The CDT SuMMeR is not able to offer further UKRI-funded postgraduate studentships to international candidates due to the number of international candidates already recruited for this cohort. If you will need a student visa to study in the UK, unfortunately, you will not be eligible during this round of applications. 

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