Dataset: Integrating ecosystem services into shellfish reef restoration and coastal policy: insights from a global synthesis

METHODS This systematic review aimed to synthesize global empirical evidence on the ecosystem services provided by natural and restored shellfish ecosystems, the restoration practices supporting them, and the extent to which these services are integrated into policy and governance frameworks. We conducted a systematic evidence synthesis following the ROSES (Reporting Standards for Systematic Evidence Syntheses) guidelines (Haddaway et al., 2018). The search was carried out in the Web of Science Core Collection, covering all years indexed up to December 2024. We used the Boolean query: ("ecosystem service*" OR "ecological function*") AND ("mollusk bank*" OR "shellfish reef*" OR "bivalve bed*" OR "shellfish*") This search returned 352 records. Records were screened in two stages: title and abstract, and full text. We applied predefined inclusion and exclusion criteria (Table S1), ensuring studies (i) explicitly evaluated ecosystem services (ES) from natural or restored shellfish reefs/banks, (ii) employed recognized ES classification frameworks (MEA, 2005; TEEB, 2010) or reported ES metrics, (iii) provided empirical evidence (quantitative or qualitative), and (iv) discusses implications for, or mentions policy, or restoration. We excluded papers focused exclusively on aquaculture, non-bivalve ecosystems (e.g., coral reefs, mangroves, seagrasses), or non-empirical contributions such as opinion pieces and conceptual essays. Screening and data extraction were independently verified by two reviewers to ensure consistency. A random 10% of records were double-checked for coding accuracy, and any discrepancies were resolved through discussion. After screening, 151 studies were retained for analysis (See Supplementary Material 1: Fig. S1 and Tables S1–S2 for a summary of the inclusion and exclusion criteria and the ROSES reporting elements). Inclusion/Exclusion Criteria Table S1. Inclusion and exclusion criteria for the systematic review of ecosystem services (ES) provided by shellfish banks. The table outlines the specific criteria used to evaluate studies based on relevance, methodology, scope, and policy significance, ensuring the inclusion of studies that focus on the socio-ecological and economic significance of shellfish ecosystems while excluding those that do not meet the set objectives. Criterion Inclusion Exclusion Topic Relevance Studies evaluating specific ecosystem services (ES) of shellfish banks/reefs (e.g., oysters, mussels, clams). Studies focusing on general marine ecosystems without specific reference to shellfish banks/reefs. Research addressing the socio-ecological, economic, or environmental significance of shellfish reefs. Studies on aquaculture or fisheries with no link to ecosystem services of natural/restored shellfish banks. Studies identifying shellfish reefs as nature-based solutions (NBS) or contributors to ecosystem resilience. Papers unrelated to ecosystem services, restoration, or conservation of shellfish banks. Frameworks and Methodologies Uses established ES classification frameworks (MEA 2005, TEEB 2010). Papers without use of recognized frameworks for ES classification. Provides quantitative or qualitative evidence of ES (e.g., economic valuation, biodiversity, water quality). Lacks empirical evidence or data-driven conclusions (e.g., opinion pieces, speculative papers). Geographical Scope Studies from any region with relevant socio-ecological or economic context. None (unless region is irrelevant to shellfish ecosystem services). Study Type Peer-reviewed articles, systematic reviews, or reports providing empirical data. Opinion pieces, editorials without specific data or analysis. Studies explicitly evaluating specific ES (e.g., nutrient cycling, habitat provision, food provision). Studies with a generalized focus, lacking detailed or specific analysis of ES for shellfish banks. Irrelevant Topics Relevant to natural or restored shellfish banks/reefs and their ecosystem services. Research focusing solely on non-bivalve ecosystems (e.g., coral reefs, seagrasses, mangroves). Policy/Restoration Relevance Discusses policy implications, restoration, or conservation measures for shellfish ecosystems. No mention of policy recommendations, restoration, or conservation approaches. *With the inclusion and exclusion analysis, they were reduced to 151 records. Table S2. ROSES summary table for the systematic evidence synthesis of ecosystem services provided by shellfish ecosystems ROSES Element Description Title Ecosystem services and policy linkages in natural and restored shellfish ecosystems: a global systematic evidence synthesis Type of review Systematic evidence synthesis (quantitative + qualitative) Primary question What types of ecosystem services are provided by natural and restored shellfish ecosystems, what restoration practices and policy instruments support them, and how are these patterns distributed globally? Rationale To synthesize empirical evidence on ecosystem services (ES) associated with shellfish reefs/banks and to examine how restoration practices and policy frameworks contribute to their delivery and recognition. Frameworks used Millennium Ecosystem Assessment (MEA 2005); TEEB 2010; IPBES 2018. Search strategy Web of Science Core Collection (all years ≤ Dec 2024). Search string: (“ecosystem service*” OR “ecological function*”) AND (“mollusk bank*” OR “shellfish reef*” OR “bivalve bed*” OR “shellfish*”). Date of search January 2025 Total records retrieved 352 Databases searched Web of Science Core Collection (SCIE, SSCI, AHCI, ESCI) Screening stages (1) Title and abstract screening; (2) Full-text screening. Screening tools Manual screening in EndNote and Excel templates following ROSES workflow. Inclusion criteria Studies explicitly evaluating ES in natural/restored shellfish reefs/banks; use of recognized ES frameworks (MEA, TEEB, IPBES) or metrics; empirical evidence (quantitative or qualitative). Exclusion criteria Aquaculture-only focus; non-bivalve ecosystems (e.g., coral reefs, mangroves, seagrasses); non-empirical papers (e.g., opinions, conceptual essays). (Full details in Table S1). Final sample size 151 studies retained after screening. Data extraction fields (1) Study context (year, country, scale, ecosystem type); (2) Ecosystem services (category, sub-services, metrics); (3) Restoration practices (approach, techniques, objectives, monitoring); (4) Policy variables (instrument type, scale, function, stakeholders). Data synthesis methods Descriptive and comparative analyses of temporal, geographic, and thematic patterns; visualizations via barplots, heatmaps, and Sankey diagrams (linking restoration–ES–policy). Software used R v 4.5.1 (R Core Team, 2023); packages tidyverse, ggplot2, networkD3. Bias assessment Transparent screening by two reviewers; standardized coding scheme. Geographic coverage Global – studies spanning > 90 countries across all continents (Fig. 2). Outputs produced Figures 1–9 (temporal trends, geographic distribution, ES frequencies, restoration approaches, policy integration); Tables S1–S5 (detailed metadata). Limitations Restriction to Web of Science may exclude grey literature; language bias possible (English-only search). Data and code availability All extracted datasets, metadata, and R scripts available at [repository DOI placeholder]. AI usage statement No AI tools used for data extraction or analysis; AI assisted only in language editing per journal guidelines. Reporting standard compliance Complies with ROSES 2022 checklist for systematic reviews (Haddaway et al., 2018). Spatial Scale Table S3. Classification of spatial scales in the reviewed articles. The table presents the classification of spatial scales applied in the reviewed studies, based on the geographical extent considered in each analysis. Spatial Scale Definition Local scale Studies focused on site-specific or small-area assessments, typically limited to a single reef, bay, or community-level setting Regional scale Studies encompassing multiple sites or broader geographical units such as estuaries, coastal regions, or administrative areas Global scale Studies or reviews addressing international contexts, cross-regional comparisons, or global initiatives related to shellfish reef restoration (e.g., the Native Oyster Restoration Alliance, NORA) Ecosystem Type Table S4. Classification of Shellfish-Specific Ecosystems. This table categorizes shellfish-specific ecosystems based on dominant species and habitat type, including oyster reefs, mussel beds, clam beds, scallop habitats, cockle beds and mixed bivalve reefs. When no ecosystem type was specified, it was recorded as “shellfish general”. It provides a framework to systematically evaluate ecosystem services, restoration practices, and policy relevance for each ecosystem type. Ecosystem Type Subcategory Description Oyster Reefs Crassostrea (Eastern oyster reefs) Reefs formed by Crassostrea species, e.g., Crassostrea virginica (Eastern oyster). Ostrea (Native European oysters) Reefs formed by Ostrea species, e.g., Ostrea edulis (European flat oyster). Mussel Beds Mytilus (Blue mussel beds) Beds dominated by Mytilus species, e.g., Mytilus edulis (blue mussel). Perna (Green-lipped mussel beds) Beds dominated by Perna canaliculus (green-lipped mussels). Clam Beds Hard clam beds Habitats with dense populations of hard clams, e.g., Mercenaria mercenaria. Geoduck clam habitats Habitats dominated by geoduck clams, e.g., Panopea generosa. Scallop Habitats Habitats where scallops, e.g., Pecten maximus, form dense aggregations. Cockle Beds Habitats dominated by dense populations of cockles (family Cardiidae), e.g., Cerastoderma edule (common cockle). Mixed Bivalve Reefs Shellfish habitats featuring multiple bivalve species coexisting. Ecosystem Services Table S5. Overview of the ecosystem services classification and grouping applied in the systematic review. The table presents the classification of ecosystem services following the Millennium Ecosystem Assessment (MEA, 2005) framework and the grouping of each service recorded across the 151 reviewed studies. ES Category ES grouped Specific ES mentioned Supporting Biodiversity biodiversity, biodiversity support, ecological carrying capacity, energy transfer between trophic levels, food web support, food web structure, maintaining nursery populations, nursery, provisioning nutritionally valuable prey. Habitat provision bioengineering, ecosystem engineering, foraging habitat, habitat complexity, habitat creation, habitat enhancement, habitat formation, habitat provision, habitat provisioning, habitat heterogeneity, landscape and habitat diversity. Nutrient cycling benthic–pelagic coupling, biogeochemical cycling, enhancement of productivity, nitrogen regeneration/excretion, nutrient cycling, nutrient regeneration, perturbation and alteration of sediment properties, primary production, sediment biogeochemistry alterations. Regulating Water quality heavy metal absorption, pollutant removal, removal of contaminants, sediment stabilization, toxin removal, turbidity reduction, water clarification, water clarity, water filtration, water purification, water quality Nutrient removal biodeposition, burial of biologically important element, denitrification, eutrophication control, eutrophication mitigation, nitrogen cycling, nitrogen removal, nutrient removal, nutrient uptake, phosphorus removal, reduced risk of eutrophication, sequestration of nitrogen, seston depletion. Coastal protection coastal protection, coastal resilience, erosion control, erosion protection, flood protection, mitigation debris movement, mitigation of storm surge, reduced erosion, shoreline erosion prevention, shoreline erosion reductions, shoreline protection, shoreline stabilization, stabilize foreshores, stabilizing shorelines, storm surge protection, vertical accretion, wave energy dissipation Climate regulation carbon removal, carbon sequestration, climate change mitigation, climate regulation, sequestration of carbon Biological regulation biological control prevention, disease regulation, pathogen removal, removal pathogens Provisioning Food provision food provision, food production, provision of food, food provide, food sources, fisheries, seafood, seafood supply, seafood production, production of harvested species, aquaculture, wild animals for nutrition, bivalve harvest, bivalve fisheries, shellfish for food, shellfish meat, fishery output, clam production, fish production, fish productivity, shell fishing, oyster harvest, seafood industries, commercial fishery, shellfish harvests, food security, mariculture, meat Seed and larvae supply brood stock oyster population enhancement, shellfish seeds, shellfish larvae, spat, shellfish spat Raw materials provision of material, shell, shell extraction, shell production, ornamental materials, ornaments, shell by-products, poultry grit, construction material, mineral resource, shell substrate, building materials, jewelry, shell aggregate Genetic resources genetic resources Cultural Recreation adventure, challenge, ecotourism, food tourism, leisure, recreational fishing, recreational harvesting, recreation, tourism Aesthetics and inspiration aesthetic appeal, aesthetic appreciation, biodiversity appreciation, freedom, inspiration, ornamental use Heritage and Identity bequest value, contribution to community, culture, cultural activities, cultural continuity of traditional food gathering, cultural heritage, cultural practices, cultural services, cultural shellfish gathering, cultural symbology, cultural value, cultural value of biodiversity, existence value, family heritage, harvesting culturally valued food species, harvesting traditions, heritage, historical harvest, identity, indigenous and colonial use, local history, non-commercial family harvesting, past experiences, responsibility of care – environment, responsibility of care – husbandry, responsibility of care/bequest, sense of attachment to nature, sense of place, spiritual and religious, spiritual and symbolic, spiritual experience heritage, spiritualism, symbolic meaning, symbolic values Education art, educational use, intellectual valor, knowledge, public awareness, research, science, scientific research, skills Well-being well-being, community engagement, independence, job satisfaction, lifestyle, mental health, physical health, pride, relationship with nature, safety, security, security and reliability, sense of belonging, sense of pride, sense of purpose, shared experiences, social bonds, social capital, therapy, transformation, livelihoods Restoration Table S6. Overview of the restoration classification scheme applied in the systematic review. The table presents the categories and operational definitions used to classify restoration-related aspects, including restoration objectives, approaches, specific restoration categories, and monitoring practices reported in the reviewed literature. Characteristics of the Restoration Category Definition Restoration Objectives Habitat Restoration Restoration focused on recreating or enhancing natural shellfish habitats (e.g., oyster reefs, mussel beds). Biodiversity Enhancement Efforts aimed at improving species richness and abundance in restored habitats. Ecosystem Function Recovery Targeting restoration of key ecosystem services (e.g., water filtration, nutrient cycling). Coastal Protection Projects designed to use shellfish banks as natural breakwaters to reduce coastal erosion and storm impacts. Restoration Approach Passive Natural recovery processes occur without direct human intervention, relying on the removal of stressors or protection measures. Active Direct human actions are implemented to accelerate or enhance ecosystem recovery (e.g., substrate addition, species reintroduction, or habitat engineering). Hybrid Combination of passive and active strategies, where initial interventions support or complement natural recovery processes. Specific Restoration Category Substrate addition Deploying hard and heterogeneous substrates (e.g., cultch, shells, rocks, artificial reefs) to promote shellfish settlement and growth. Reef seeding Introducing juvenile shellfish or larvae to establish or enhance populations. (e.g., adding spat or larvae) Habitat engineering Modifying physical or hydrological conditions (e.g., altering flow, sediment, or shoreline structures) to create suitable conditions for restoration. Community engagement Active participation of local communities in the design, monitoring, and implementation of restoration (e.g., participatory restoration programs) Hybrid Methods Combining natural and engineered approaches (e.g., co-deployment of seagrass and oyster reefs for mutual benefits). Stressor removal Reduction or elimination of pressures limiting natural recovery (e.g., fishing restrictions) Habitat protection Safeguarding existing habitats to enable natural regeneration (e.g., MPAs) Pollution control Reducing nutrient or contaminant inputs to improve environmental conditions. (e.g., reducing nutrient runoff) Biodeposition-Based Approaches Using shellfish biodeposits to enhance sediment organic content and promote habitat growth. Biodeposition approaches primarily rely on natural processes (e.g., the natural filtration and deposition of organic material by shellfish) to enhance sediment organic content and promote habitat growth. Monitoring Performance Metrics Defining and measuring success through biological (e.g., shellfish density), ecological (e.g., biodiversity), and socio-economic indicators. Adaptive Management Implementing flexible strategies informed by ongoing monitoring results. Citizen Science Engagement of local communities and volunteers in monitoring and restoration activities. Nature-Based Solutions Table S7. Classification of Nature-Based Solutions (NbS) types applied to shellfish beds. The table presents the classification of NbS types in which shellfish beds were discussed as nature-based solutions for climate mitigation or resilience building. Natura-Based Solutions Definition Climate Mitigation Using shellfish reefs to sequester carbon and mitigate ocean acidification through biogenic calcification and habitat enhancement Coastal Protection Increasing coastal resilience to environmental changes, including sea-level rise, erosion, and storm impacts, through the physical structure and wave attenuation capacity of reefs. Water Quality Improvement of water conditions through the filtration capacity of shellfish and associated biogeochemical processes. Remove Nutrients Reduction of nutrient loads (e.g., nitrogen, phosphorus) from the water column via biofiltration and biodeposition processes Policy Table S8. Overview of the policy classification scheme applied in the systematic review. The table presents the categories and operational definitions used to categorize policies according to their thematic focus (policy area), primary function or objective, and type of policy instrument mentioned in the reviewed literature. Characteristics of the Policy Category Definition Type of Policy Instrument Regulatory Measures Laws and regulations protecting shellfish habitats (e.g., marine protected areas, harvesting restrictions). Market-Based Instruments Incentives like tax breaks or subsidies for restoration and conservation projects. Certification Programs Ecosystem service certification or eco-labels (e.g., for sustainable fisheries or aquaculture practices). Governmental Program/Initiative Strategic initiatives and plans for the management and/or restoration of ecosystems, resources, or productive sectors promoted by local governments. (e.g., species management plans, restoration plans, National Shellfish Initiative (EE.UU.)) Framework Policy Policy that defines broad principles, goals, and guidelines to guide and coordinate the actions of governments, institutions, and actors. (e.g., United Nations Decade on Ecosystem Restoration, EU Biodiversity Strategy for 2030, Kunming–Montréal Global Biodiversity Framework) Management approaches or frameworks Integrated approaches and tools guiding the sustainable use and governance of marine and coastal resources (e.g., Marine spatial planning (MSP), ecosystem-based management (EBM)) Policy Frameworks International Agreements Global agreements like the Convention on Biological Diversity (CBD) or IPBES (Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services). Regional Policies Policies specific to regions, such as EU Marine Strategy Framework Directive or U.S. Clean Water Act. Local Legislation Community-driven policy initiatives or state-level regulations targeting restoration. Thematic Area (Policy Focus) Fisheries and Aquaculture Policies on resource use and sustainability, including aquaculture leases, fishing quotas, and food safety regulations. Habitat and Biodiversity Instruments for habitat and species conservation, such as MPAs, restoration programs, and biodiversity protection frameworks. Environmental Quality Policies ensuring ecosystem integrity through water quality standards, nutrient control, and pollution or emission regulations. Management and Governance Integrated approaches for marine and coastal management, including Marine Spatial Planning (MSP), Integrated Coastal Zone Management (ICZM), Ecosystem-Based Management (EBM), and community or indigenous governance. Policy Function (Objective/Purpose) Conservation Policies aimed at maintaining or protecting ecosystems, species, or ecological functions from degradation or loss. Restoration Policies designed to recover or enhance degraded habitats and ecosystem services through active or passive measures. Regulation Legal or administrative mechanisms establishing rules, standards, or restrictions to control human activities and resource use. Incentives Economic or social instruments (e.g., subsidies, compensation schemes, market mechanisms) that promote sustainable practices or conservation actions. Planning Strategic and spatial frameworks guiding the allocation, management, and use of coastal and marine resources (e.g., MSP, ICZM). Participation Mechanisms that involve stakeholders and communities in decision-making, governance, and implementation processes. Stakeholder Involvement Public Engagement Mechanisms for including citizens, NGOs, and communities in policy formulation. Private Sector Engagement Encouraging industries (e.g., fisheries, tourism) to invest in restoration and sustainable practices Indigenous Participation Recognizing and incorporating Indigenous knowledge and rights in conservation efforts Engagement Methods Public Consultation Mechanisms to collect opinions and feedback from stakeholders or the public. Engagement is mainly consultative, and input informs but does not determine decisions. (e.g., public consultation processes, oral hearings, appeals processes, expert panels, interviews) Participatory Interaction Two-way processes that foster dialogue, learning, and collaboration among stakeholders, helping refine policies and integrate diverse knowledge. (e.g., workshops, stakeholder committees, early engagement, community relationship-building) Co-management Collaborative and power-sharing arrangements where stakeholders jointly design, implement, and/or manage initiatives. (e.g., co-development of management goals and schemes, partnerships, citizen science programs, cooperative fishery management)