Assessing Future Marine Ecosystem Service Values : Value-Pluralism and Non-Additive Effects of Multiple Interacting Stressors

The marine environment is increasingly threatened by multiple anthropogenic stressors, and the future of marine ecosystem services is at stake. To ensure that biodiverse marine ecosystems and related services are preserved, marine management should be robust to uncertainty in the combined effects of multiple stressors. Furthermore, it is important that plural values and diverse human-nature relationships are adequately represented in marine environmental valuation. This study couples ecosystem modelling with a novel valuation framework to estimate changes and temporal dynamics in marine ecosystem service values in different scenarios of anthropogenic stress (including climate change, pollution, nutrient runoff, and fishing) and interactions between stressors. The new valuation framework allows harnessing multiple valuation methods and representing plural values associated with the marine environment. Through the innovative combination of the two methodologies, this study explores the effects of non-additive interactions between stressors on marine ecosystem service values. The results show that failing to account for different types of interactions between stressors may lead to unexpected results. We observed both linear and nonlinear effects of synergy on marine ecosystem service delivery/value. Additionally, we demonstrated novel insights to temporal value dynamics and trade-offs between stakeholder groups. We showed that increased synergy between stressors likely increases volatility in the value of fisheries over time. Further, we found that the effects of ecosystem change were unequally distributed amongst different groups of fishers, and that the magnitude of these inequalities significantly differed depending on whether non-additive interactions were included. This study is a step towards marine management which is robust to uncertainty in the combined effects of multiple stressors and also takes plural values into account