Indirect effects cause decline in ecosystem service delivery: a case study in the Barents Sea
Ecosystem services are important for the well-being of human societies. At the same time, the ecosystems providing the services are under constant pressure from anthropogenic activities, causing loss of biodiversity. Since all species are connected to each other via interaction networks, the loss of one species can trigger additional, secondary extinctions. However, the consequences of these secondary extinctions for ecosystem services are not known. Here we address this gap by coupling threats to species and their interaction networks, and these networks to ecosystem service provisioning. We use a highly resolved food web dataset of the Barents Sea, and simulate secondary extinctions using Bayesian networks. We explore a range of assumptions on how the loss of service-providing species translates to the disintegration of the services they provide. We find that activation of threats cause secondary extinctions of service-providing as well as supporting species which negatively affect ecosystem services, and that the magnitude of these effects are highly dependent on the sensitivity of consumers to resource loss as well as service robustness. We also show that the indirect effects from species interactions causes substantial decreases in service provisioning. Understanding the linkages between ecological threats, species interactions in ecological networks and ecosystem service provisioning will be an important tool for guiding management strategies for effective ecosystem service management.