Restoration has been elevated as an important strategy to reverse the decline of coastal wetlands worldwide. Current practice in restoration science emphasizes minimizing competition between outplanted propagules to maximize planting success. This paradigm persists despite the fact that foundational theory in ecology demonstrates that positive species interactions are key to organism success under high physical stress, such as recolonization of bare substrate. As evidence of how entrenched this restoration paradigm is, our survey of 25 restoration organizations in 14 states in the United States revealed that >95% of these agencies assume minimizing negative interactions (i.e., competition) between outplants will maximize propagule growth. Restoration experiments in both Western and Eastern Atlantic salt marshes demonstrate, however, that a simple change in planting configuration (placing propagules next to, rather than at a distance from, each other) results in harnessing facilitation and increased yields by 107% on average. Thus, small adjustments in restoration design may catalyze untapped positive species interactions, resulting in significantly higher restoration success with no added cost. As positive interactions between organisms commonly occur in coastal ecosystems (especially in more physically stressful areas like uncolonized substrate) and conservation resources are limited, transformation of the coastal restoration paradigm to incorporate facilitation theory may enhance conservation efforts, shoreline defense, and provisioning of ecosystem services such as fisheries production.shoreline defense | facilitation | coastal wetlands | wetland restoration D egradation of coastal ecosystems is occurring worldwide (1).Human-generated threats such as overharvesting, eutrophication, climate change, habitat destruction, and pollution have threatened these valuable ecosystems at local, regional and global scales (2-6). As these threats have intensified and combined, substantial declines in overall habitat coverage have occurred in almost all major coastal ecosystems, including those generated by key habitat-forming foundation species. For example, oyster reefs have declined by at least ∼85% (7), coral reefs by ∼19% (8), seagrasses by ∼29% (9), North American salt marshes by ∼42% (10), and mangroves by ∼35% (1). Because these ecosystems generate some of the richest biodiversity hotspots on Earth (11, 12), and provide critical services for human populations, including storm protection (13), fisheries production (2, 14, 15), and carbon storage (16, 17), conservation resources totaling over 1 billion US dollars have been spent globally in an attempt to halt and reverse the decline of foundation species in the coastal realm (18,19).A number of strategies have been used to conserve coastal ecosystems, including threat reduction, marine protected areas, buffer establishment, and international treaties. Habitat restoration, although in existence for many decades, has only recently been elevated as a global strategy for ...

Abstract:Coastal ecosystems have drastically declined in coverage and condition across the globe. To combat these losses, marine conservation has recently employed habitat restoration as a strategy to enhance depleted coastal ecosystems. For restoration to be a successful enterprise, however, it is necessary to identify and address potential knowledge gaps and review whether the field has tracked scientific advances regarding best practices. This enables managers, researchers, and practitioners alike to more readily establish restoration priorities and goals. We synthesized the peer-reviewed, published literature on habitat restoration research in salt marshes, oyster reefs, and seagrasses to address three questions related to restoration efforts: (i) How frequent is cross-sector authorship in coastal restoration research? (ii) What is the geographic distribution of coastal restoration research? and (iii) Are abiotic and biotic factors equally emphasized in the literature, and how does this vary with time? Our vote-count survey indicated that one-third of the journal-published studies listed authors from at least two sectors, and 6% listed authors from all three sectors. Across all habitat types, there was a dearth of studies from Africa, Asia, and South America. Finally, despite many experimental studies demonstrating that species interactions can greatly affect the recovery and persistence of coastal foundation species, only one-fourth of the studies we examined discussed their effects on restoration. Combined, our results reveal gaps and discrepancies in restoration research that should be addressed in order to further propel coastal restoration science.