Assessing coastal ecosystem services with ecosystem models, socioeconomic statistics and socialecological system’s understanding

Coastal seas consist of distinct yet closely connected ecosystems, including estuaries, shallow-water habitats, and tidal wetlands. These environments are among the most threatened in the world due to terrestrial nutrient and pollution inputs, human infrastructure developments, and rising temperatures and increased sea levels. At the same time, these areas provide a wide range of ecosystem services on which coastal communities and wider society depend, including coastal fisheries, coastal recreation, and the filtering of nutrients and remediation of pollutants. Assessing the variety of ecosystem services provided by coastal areas requires a mixed-methods approach. Here, we present an example from a large Baltic Sea lagoon, where ecosystem services are assessed using simulations from an ecosystem model and socio-economic statistics. These are complemented by conceptual mapping workshops, which helped us to better understand the area's social-ecological system and the perceived relevance of its ecosystem services. With a focus on coastal water quality and recreational values, we highlight and discuss how to address existing knowledge gaps (e.g. how the coastal filter functions), how to overcome difficulties in obtaining socio-economic data at the appropriate scale and how to account for diverging views on ecosystem services.