Managing for cumulative impacts in ecosystem-based management through ocean zoning

Multiple activities affect the marine environment in concert, yet current management primarily considers activities in isolation. A shift towards a more comprehensive management of these activities, as with recent emphasis on ecosystem-based approaches to management, requires a means for evaluating their interactive and cumulative impacts. Here we develop a framework for this evaluation, focusing on five core concepts: (1) activities have interactive and cumulative impacts, (2) management decisions require consideration of, and tradeoffs among, all ecosystem services, (3) not all stressors are equal or have impacts that increase linearly, (4) management must account for the different scales of activities and impacts, and (5) some externalities cannot be controlled locally but must be accounted for in marine spatial planning. Comprehensive ocean zoning provides a powerful tool with which these key concepts are collectively addressed.