A cumulative impact assessment on the marine capacity to supply ecosystem services.

Ecosystem services link the status of biodiversity and its functioning to societal goods and benefits contributing to human wellbeing. As such, they can play a key role in preserving the environment and managing natural resources and ecosystems to conserve nature's contributions to people. Identification of the main threats acting on the natural environment, and how these may impact its capacity to supply ecosystem services, is fundamental to the maintenance of these services. To that end, we present a novel approach based on a cumulative impacts assessment that 1) covers all relevant human activities and their pressures, 2) links impacts to the biotic groups that make up biodiversity and 3) provides an estimation of the Service Supply Potential based on the functioning of these biotic groups. Key proxy metrics to estimate this Service Supply Potential were identified from a literature review and quantified using a food web model (Ecopath with Ecosim). In addition to this quantitative information, the assessment of the capacity to supply ecosystem services was supplemented with expert judgement-based information to reflect the societal preferences that drive the allocation of human capital and turn these services into societal goods and benefits. As a proof of concept, the method was applied to the North Sea ecosystem. Results showed that, overall, the capacity of the North Sea to supply Cultural ecosystem services was most threatened, with an average potential decline of 50 % compared to an undisturbed situation. This was followed by the Provisioning ecosystem services with 46 % and the Regulation & Maintenance with 38 %. The main anthropogenic threats (excluding climate change) to the North Sea capacity to supply ecosystem services come primarily from fishing contributing to 51 % of the overall threat. Of the remaining 18 sectoral activities another 23 % was contributed by mining, non-renewable energy, tourism, and agriculture.