Towards a robust assessment of ecosystem services provided by kelp habitats: a case study from Plymouth Sound, southwest UK

Background and Aims Kelps are distributed across more than a quarter of the world’s coastlines, where they serve as foundation organisms and support high levels of biodiversity and primary productivity. They are increasingly threatened by a range of anthropogenic stressors and given their significant ecological and socioeconomic value there is a pressing need to better understand the structure and functioning of these forests, and their role in underpinning and providing ecosystem services. However, robust quantitative assessments are mostly lacking and certain services remain underexplored, which hinders evidence-based approaches to management, restoration and protection. Methods We focused on Laminaria hyperborea forests in and around Plymouth Sound (southwest UK) as a model region to present a robust quantification of four key ecosystem services spanning provisioning (fisheries), regulating (climate through carbon storage) and supporting (habitat creation and biodiversity). Data were collated from a range of sampling techniques and approaches, including diver-based collections and deployment of baited remote underwater video (BRUV) systems. Key Results Our survey data showed that kelp forests consistently support very high levels of biodiversity and carbon standing stock and provide stable and extensive habitat for a variety of fishes and mobile macrofauna species, some of which have socioeconomic value. While ecological structure differed amongst survey sites, all kelp forests underpinned critical ecosystem services by supporting biodiversity, assimilating carbon and providing fisheries habitat. Conclusions High-resolution survey data highlight the socioeconomic importance of kelp forests along temperate wave-exposed coastlines. Improved monitoring and targeted management and conservation of these habitats is needed to safeguard ecosystem service delivery in the face of multiple anthropogonic stressors, notably ocean warming, decreased water quality and fishing activities.