Factors limiting marine connectivity at a species' range edge - the case of the pink sea fan, Eunicella verrucosa

The pink sea fan, Eunicella verrucosa, is IUCN red-listed and protected in UK waters. It is a Protected Feature and central to the designation of many MCZs in southwest England (2013, 2016). Understanding the diversity and connectivity of this species is vital for its conservation and for identifying future candidate MCZs (Natural England, 2016). This project will investigate oceanographic pathways, barriers to gene flow, and the role of natural selection in genetic differences between populations at the species' range edge. E. verrucosa is a broadcast spawner, with larvae dispersed by ocean currents, yet little is known about its larval biology-such as time in the water column or resilience to thermal stress. We will use modelling, and aquarium experiments to examine factors contributing to limited recruitment at range edges, including heat stress, spawning timing, larval survival, and pelagic larval duration. These insights will help parameterise oceanographic models, grounded in high-quality physical (currents, temperature) and biological (population distributions, larval traits) data. A sensitivity framework will place dispersal/connectivity results within natural variability and model uncertainties. We hold a large collection of tissue samples from the northeast Atlantic and western Mediterranean. Crucially, we have permission to work with NRW staff to sample recruits at Skomer Marine Reserve in Wales. A key objective is to determine whether low recruitment at Skomer is due to poor connectivity, selection (e.g. winter temperatures), or Allee effects - were sparse adult populations limit fertilisation success. Results will be compared to Lundy, a site with stronger connectivity to core populations. We will apply whole genome sequencing to identify SNPs and structural variations linked to geography or selection. This interdisciplinary project offers postgraduate training in molecular genetics, oceanographic modelling, and aquarium work, producing results to inform UK marine policy via our CASE partner Natural England and associate partner Natural Resources Wales. By advancing our understanding of genetic structure and connectivity, this work will enhance conservation strategies and support the resilience of marine ecosystems in the face of climate change.