Pink sea fans (Eunicella verrucosa) as indicators of the spatial efficacy of Marine Protected Areas in southwest UK coastal waters

Globally, the need to identify and establish integrated and connected systems of Marine Protected Areas (MPAs) is becoming increasingly recognised. For best practice, these networks need to be planned and assessed against multiple criteria. However, building a sound evidence base to support decision-making processes is complex, as well as fiscally and logistically challenging. Recent studies have demonstrated the utility of integrating ‘citizen science’ data into mainstream scientific analysis, particularly where broad-scale spatial patterns of distribution are required. In UK waters, the pink sea fan (Eunicella verrucosa) is a nationally protected slow growing, cold-water coral, and is a representative species of reef features that provide habitat for many other sessile species. However, this species is vulnerable to physical impact and loss of suitable substratum, and is likely highly vulnerable to bottom-towed fishing gears. In this study, data from a volunteer-based marine survey programme (‘Seasearch’) are analysed with the aim of describing the spatial distribution and relative abundance of pink sea fan colonies throughout southwest UK coastal waters. The congruence between pink sea fans and the extant southern UK MPA network is reported, and the current threat from Bottom-Towed Gear (BTG) to pink sea fan dominated reefs, that have historically lacked protection, is quantitatively assessed. This analysis reveals that protection of this and other benthic species has been increased by management of previously ‘open access’ MPAs. Nonetheless, areas of pink sea fan habitat and their host reef systems exist outside extant protected areas in southwest UK seas, and as such are potentially at risk from bottom-towed fisheries. This analysis demonstrates the utility of well-organised citizen science data collection and highlights how such efforts can help inform knowledge on broad scale patterns of biodiversity.