Sustainability threshold for multiple ecosystem services in the Venice lagoon, Italy

One of the biggest challenges for ecosystem services (ES) science is to make the concept operational for decisionmaking purposes. The capacity to understand the long-term sustainability of multiple ES is still limited, while being highly needed to improve the management of natural resources. This work aims to use ES, and particularly the assessment of their capacity and flow, to explore the sustainability of the ES provision in the coastal socialecological system of the Venice lagoon, Italy, by adopting a spatially explicit approach. By applying multivariate analysis on the ES maps, a zonation is derived which reflects the different bundles of ES in the lagoon. A new approach to analyze the ES bundles is presented, which determines their degree of sustainability. Building on the rationale that not all combinations of ES are desirable for the long-term maintenance of ES capacity, a 'sustainability threshold' for multiple ES is proposed. This threshold corresponds to a balance between ES capacity and flow, and to a balance between the flow of regulating ES and the flow of ES mediated by human activities. The results show that about 53% of the lagoon's surface is exploited to a level that falls beyond the 'sustainability threshold' and thus should be considered in an unsustainable condition. This reveals the need to intervene to change the patterns of ES uses in some areas of the lagoon, to enjoy the benefits offered by the ecosystem without impairing its capacity to provide them. Some potential directions for change are discussed, moving towards a more sustainable management of the lagoon social-ecological system.