Active restoration is becoming an increasingly important conservation intervention to counteract the degradation of marine coastal ecosystems. Understanding what has motivated the scientific community to research the restoration of marine coastal ecosystems and how restoration research projects are funded is essential if we want to scale-up restoration interventions to meaningful extents.Here, we systematically review and synthesize data to understand the motivations for research on the restoration of coral reefs, seagrass, mangroves, saltmarsh, and oyster reefs. We base this analysis off a published database of marine restoration studies, originally designed to estimate the cost and feasibility of marine coastal restoration, derived from mostly scientific studies published in peer-reviewed and some grey literature. For the present study, the database was updated with fields aimed at assessing the motivations, outcomes, and funding sources for each project. We classify restoration motivations into five categories: biotic, experimental, idealistic, legislative, and pragmatic. Moreover, we evaluate the variables measured and outcomes reported by the researchers and evaluate whether projects adhered to the Society for Ecological Restoration’s (SER) standards for the practice of ecological restoration. The most common motivation of the scientific community to study restoration in marine coastal ecosystems was experimental i.e. to seek experimental data to answer ecological research questions or improve restoration approach, as expected since mostly peer-reviewed literature was evaluated here. There were differences in motivations among the five coastal ecosystems. For instance, biodiversity enhancement was the most common case for a biotic motivation in mangrove restoration projects. The most common metrics evaluated were growth/productivity, survivorship, habitat function, physical attributes and reproduction. For most ecosystems, ecological outcomes were frequently reported, with socio-economic implications of the restoration rarely mentioned, except for mangroves. Projects were largely funded by governmental grants with some investment from private donations, non-governmental organizations, and the involvement of volunteers. Our findings and database provide critical data to align future research of the scientific community with the real social, economic and policy needs required to scale-up marine coastal restoration projects.

The database of Bayraktarov et al. (2016) which included publications up to 2014, was expanded for the present study using the following methods: The database was updated to include publications until 2018. This involved a systematic literature search using Web of Science (Core collection; Thomson Reuters, New York, New York, U.S.A.) and Scopus (Elsevier, Atlanta, Georgia, U.S.A.) and the title search terms ‘(ecosystemA* OR ecosystemB*) AND restor*’, as well as ‘(ecosystemA * OR ecosystemB*) AND rehab*’. The terms ecosystemA and ecosystemB were used as placeholders for two different words describing the same ecosystem (e.g., coral and coral reef, mangrove and mangal, saltmarsh and salt marsh, shellfish and oyster). For consistency with Bayraktarov et al. (2016), An EndNote (Version X8.1; Thomson Reuters.) search was then performed within the full text using the search terms ‘(cost* OR feasib* OR surviv*)’. Additional information was gathered by following citations, personal communications, and inspecting diverse restoration databases and webpages. Reports included in the database were mostly from the published literature but also included some information from webpages and personal communications. English was the primary language in which the restoration projects were described with a few exceptions in Spanish. The updated database consisted of 275 studies of which 64% were scientific papers published in journals and 36% included other reports (e.g. books, book chapters, conference proceedings, reports, webpages, and personal communication).

This database represents the core part of the synthesis paper "Priorities and motivations of marine coastal restoration research". It contains information on cost and success of restoration projects worldwide described by the published literature, some grey literature and a few personal communications. This database is an update of the database "The cost and feasibility of marine coastal restoration" which captured information on the restoration of coral reefs, seagrass, mangroves, saltmarshes, and oyster reefs until November 2014. The update involves data extracted from the literature published until March 2018, data on motivations to carry out the restoration projects, information on whether the Standards for Ecological Restoration were followed by the projects, the category of the outcome reported and the variables measured to report on the project success. All economic values were updated with the newest data provided by The World Bank (March 2019). The restoration database with sections on coral reefs, seagrass, mangroves, saltmarsh and oyster reefs, contains the full reference, general information about the publication and project, the restoration action undertaken, species involved, location, a description on the type of cost reported, information on funding sources, project duration (in years), the area restored in hectare (ha), the converted restoration cost in 2010 US$ ha-1, feasibility information (including reasons for success or failure), and restoration success in terms of % survival of restored organisms. We accounted for pre-transplant (i.e. survival of coral spat/larvae in culture before rearing them in nursery or out-planting), transplant (i.e. survival of coral fragments during nursery period), post-transplant (i.e. survival of coral fragments after out-planting to the reef) survival as well as for the overall survival averaged over the former three categories for the coral reef section. See ‘Methods’ of the publication for a detailed database description for a detailed summary of the database information.