Towards an understanding of the spatial relationships between natural capital and maritime activities: A Bayesian Belief Network approach

Economic activities are dependent upon natural capital (NC), which are responsible for 'Ecosystem Services' (ES). Understanding dependencies on NC provides insight into the ecosystem's capacity to maintain and develop activities into the future. To determine 'NC dependencies', we present a framework linking maritime activities (bottom trawling, artisanal fisheries, aquaculture and tourism) to their demand for ES and further, to the NC components responsible for their production. The framework was operationalised using a spatially-explicit Bayesian Belief Network (BBN), using the Basque coast (SE Bay of Biscay) to illustrate our approach, in identifying trends in the strength and spatial distribution of NC dependencies. For example, benthic trawling was dependent on sedimentary habitats, with 'moderate' to 'high' dependency of 52% of the study area. The model can also extrapolate NC dependencies to a larger area where the activity currently does not operate, where benthic trawling was estimated to have higher utilisation of ES in deeper waters. When NC dependencies are combined with economic and legislative factors, the current spatial distribution of the activity can be explained, and the potential socio-economic impacts of management decisions could be predicted. The integrative approach contributes towards ecosystem-based spatial planning.