PhD Studentship: Seagrass as a Natural Defence: Microbiomes, Pathogens and Coastal Water Quality in the Face of Environmental Change

Seagrass meadows provide vital ecosystem services, but their potential to reduce harmful waterborne bacteria remains largely unexplored. We ask whether Zostera marina reduces the abundance or persistence of bacterial pathogens in coastal waters, whether its associated microbiome contributes to this effect, and how these interactions respond to environmental change and episodic pollution. Resolving these questions could reveal an overlooked contribution of seagrass and its restoration to coastal water quality and further understand how this vital coastal habitat responds to multiple stressors. The project will uniquely link field observations with mechanistic experiments under controlled conditions. Building on preliminary cultivation trials and expertise across the partnership, the researcher will optimise Z. marina cultivation in bespoke recirculating mesocosms within Exeter’s Containment Level 2 Global Meteorological Simulator (GMS). The GMS will provide a highly controlled environment for manipulating environmentally relevant bacterial pathogens alongside key aquatic conditions identified through field studies. Experiments will examine pathogen persistence with and without seagrass and test responses to gradual environmental change and acute water-quality perturbations. Quantitative microbiology and profiling of leaf, root and rhizosphere microbiomes will investigate underlying mechanisms. Field studies across contrasting seagrass environments will test laboratory-derived relationships under natural conditions and generate new hypotheses for controlled experiments. The researcher will gain interdisciplinary training in seagrass cultivation and field ecology, pathogen microbiology, microbial community analysis, mesocosm experimentation, experimental design, data analysis and scientific writing. Findings will shape subsequent field and laboratory studies, enabling the researcher to develop their own questions and experimental directions with supervisory support. The team combines complementary expertise in pathogen ecology and controlled-environment experimentation (Exeter-Streatham), seagrass field ecology and water quality (Exeter-Penryn), seagrass conservation, cultivation and restoration (Ocean Conservation Trust), and marine pollution and biogeochemistry (PML). These closely connected capabilities, alongside established regional water-sector partnerships, provide a distinctive field-to-laboratory framework for addressing this unresolved problem.