Kelp forests cover 25% of global coastlines and are considered some of the most productive habitats on Earth. They provide a complex 3D habitat supporting high levels of diversity and provide ecosystem services to human society. They are increasingly threatened by stressors such as ocean warming, eutrophication and over-exploitation.
Globally, sea urchins are considered important consumers of kelp exerting top-down control affecting kelp distribution, abundance and composition. Urchin abundance and impacts have increased globally due to anthropogenic pressures such as over-fishing and climate induced range shifts. Where urchin densities exceed a threshold, their grazing activities lead to the formation of extensive barrens, which are less productive, less biodiverse and less structurally complex habitats. It had been thought that urchin grazing did not control kelp forests in the UK, however, recent surveys suggest that urchin barrens exist in kelp forests along the UK North Sea coastline. Urchin abundance here is an order of magnitude higher than similar locations around the UK, posing the question ‘What is the impact of urchins on North Sea kelp forests and what drives barren formation?’
Brief methodology: 1. Estimate urchin barren extent and persistence, urchin density (and size) and kelp depth limit. 2. Undertake surveys of kelp forests in different environmental contexts to identify the physical and biological drivers leading to urchin barren formation. 3. Perform manipulative experiments to investigate the resilience of barren areas. 4. Estimate relative rates of urchin omnivory between areas with and without barrens.
This is a CASE funded project with Natural England. The student will gain skills in experimental design, photogrammetry, field and laboratory techniques, including stable isotope approaches, statistical and ecological modelling.
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