Significance: Oceans and coasts provide people with diverse benefits, from fisheries that sustain lives and livelihoods to recreational opportunities that generate tourism. However, translating appreciation of these benefits into changes in management and policy is not trivial. We report on a ground-breaking effort to use ecosystem-service values and models within a coastal planning process. By accounting for spatial variation in the influence of human activities on services, our results allowed stakeholders and policymakers to refine zones of human use, reduce risk to ecosystems, and enhance delivery of multiple ocean and coastal benefits. Application of our approaches and tools will enable planners worldwide to bring ecosystem-service science to bear on real-world decisions, thus directing actions that protect ecosystems and their benefits for people.

Much of the United States’ critical infrastructure is either aging or requires significant repair, leaving U.S. communities and the economy vulnerable. Outdated and dilapidated infrastructure places coastal communities, in particular, at risk from the increasingly frequent and intense coastal storm events and rising sea levels. Therefore, investments in coastal infrastructure are urgently needed to ensure community safety and prosperity; however, these investments should not jeopardize the ecosystems and natural resources that underlie economic wealth and human well-being. Over the past 50 years, efforts have been made to integrate built infrastructure with natural landscape features, often termed “green” infrastructure, in order to sustain and restore valuable ecosystem functions and services. For example, significant advances have been made in implementing green infrastructure approaches for stormwater management, wastewater treatment, and drinking water conservation and delivery. However, the implementation of natural and nature-based infrastructure (NNBI) aimed at flood prevention and coastal erosion protection is lagging. There is an opportunity now, as the U.S. government reacts to the recent, unprecedented flooding and hurricane damage and considers greater infrastructure investments, to incorporate NNBI into coastal infrastructure projects. Doing so will increase resilience and provide critical services to local communities in a cost-effective manner and thereby help to sustain a growing economy.

Indirect facilitation can occur when a species positively affects another via the suppression of a shared competitor. In giant kelp forests, shade from the canopy of the giant kelp, Macrocystis pyrifera, negatively affects understory algae, which compete with sessile invertebrates for space. This raises the possibility that giant kelp indirectly facilitates sessile invertebrates, via suppression of understory algae. We evaluated the effect of giant kelp on the relative abundance of algae and invertebrates by experimentally manipulating kelp abundance on large artificial reefs located off San Clemente, California, USA. The experiments revealed a negative effect of giant kelp on both light availability and understory algal abundance and a positive effect on the abundance of sessile invertebrates, which was consistent with an indirect effect mediated by shade from the kelp canopy. The importance of these processes to temporal variability in benthic community structure was evaluated at 16 locations on natural reefs off Santa Barbara, California, over an eight‐year period. Interannual variability in the abundance of understory algae and in the abundance of sessile invertebrates was significantly and positively related to interannual variability in the abundance of giant kelp. Analysis of these observational data using Structural Equation Modeling (SEM) indicated that the magnitude of the indirect effect of giant kelp on invertebrates was six times larger than the direct effect on invertebrates. Results suggest that the dynamics of this system are driven by variability in the abundance of a single structure‐forming species that has indirect positive, as well as direct negative, effects on associated species.