Natural capital accounting for mangrove ecotourism: a framework for valuing ecosystem services and sustainable business development
Abstract
Although mangroves occupy only 147,000 km² -less than 1% of all tropical forest area -their value to the 2.4 billion people living within 100 km of the coast cannot be overstated (UNEP, 2024;Leal and Spalding, 2024). Mangroves store on average 394 t C ha ⁻¹ , exceeding 650 t C ha ⁻¹ in some sites, and deliver coastal-protection benefits valued at US$855 billion over the coming century, sheltering some 15 million people from annual flooding (Menéndez and Beck, 2024;Menéndez et al., 2020). Yet between 1996 and 2020 a net loss of 5,245 km² occurred, with aquaculture, oil-palm and rice cultivation accounting for 43% (Bunting et al., 2022). The broader tourism-environment-economy nexus is similarly complex; in transition economies a significant long-run association between tourism growth and CO₂ emissions has been documented (Qodirov et al., 2024).Ecotourism is among the highest-value, lowest-impact uses of mangrove systems. At least 3,945 mangrove-based tourism sites have been identified across 93 countries, with global visitation plausibly in the tens to hundreds of millions and economic impacts in the billions of dollars annually (Spalding and Parrett, 2019); the Sundarbans alone contribute an estimated US$53 million yr⁻¹ to the Bangladeshi economy (Nobi et al., 2021).The crux is that very little of this activity is visible in the financial systems that allocate capital. Mangrove ecosystems are treated either as costless inputs or as residual land assets in standard accounting, and ecological-economic analyses tend to cover restricted service sets without connecting to business decision-making (Brander et al., 2012;Himes-Cornell et al., 2018). This invisibility is not neutral: global finance flows working against nature now exceed US$7 trillion, against just US$200 billion directed to nature-positive activities (UNEP, 2023).Against this backdrop, we propose the MENCA-ET (Mangrove Ecosystem Natural Capital Accounting for Ecotourism) framework to help operators and other stakeholders recognise and integrate the full value of mangrove ecotourism. The timing is favourable: SEEA-EA was internationally endorsed in 2021 (United Nations, 2021); TNFD released its final disclosure recommendations in 2023 (TNFD, 2023); IFRS S1/S2 was launched by the ISSB in 2023 (ISSB, 2023); the revised GRI 101: Biodiversity becomes mandatory in 2026 (GRI, 2024); and the Gold Standard published a mangrove-specific methodology in 2024 (Gold Standard, 2024).This study is a structured integrative narrative review, an approach considered appropriate when the aim is to synthesise mature, heterogeneous bodies of literature and to propose a new conceptual framework rather than to test a hypothesis (Torraco, 2005;Snyder, 2019). To increase replicability -a concern raised in peer review of earlier framework articles in this field -we applied an explicit, pre-specified search and screening protocol, summarised below.Three bibliographic databases were searched: Web of Science Core Collection, Scopus, and Google Scholar. Because Google Scholar does not support the structured, field-based queries available in the other two databases and returns a large volume of lower-precision records, Google Scholar screening was limited to the first 200 results ranked by relevance per query, a point beyond which returned records were no longer thematically relevant. The search covered the period January 2000 -March 2026. Search strings combined four conceptual blocks with Boolean operators:Mangrove block: "mangrove*" OR "blue forest*" OR "coastal wetland*".Accounting/valuation block: "natural capital accounting" OR "SEEA" OR "ecosystem service valuation" OR "TEEB" OR "TEV" OR "benefit transfer".• Finance/disclosure block: "TNFD" OR "IFRS S1" OR "IFRS S2" OR "GRI 101" OR "blue carbon" OR "blue bond*" OR "payment for ecosystem services".• Tourism block: "ecotourism" OR "nature-based tourism" OR "community-based tourism".For the purposes of this review, grey literature was defined as authoritative documents not Mangrove Alliance). Reference-list and citation-chain searches were used to identify additional sources missed by the primary queries.Inclusion criteria: (i) document type -peer-reviewed empirical or conceptual articles, authoritative grey-literature reports, or international standards; (ii) time period -published between January 2000 and March 2026; (iii) thematic relevance -addressing valuation, accounting, finance, governance, or business models for mangrove ecosystems or directly transferable adjacent systems (seagrass, salt-marsh, coastal NbS); (iv) language -written in English; and (v) methodological contribution -providing replicable methodology, quantitative estimates, normative recommendations, or operational protocols. The minimum thematicrelevance threshold required a record to engage substantively with at least one of the four conceptual blocks (mangrove; accounting/valuation; finance/disclosure; ecotourism) rather than to mention a relevant term only in passing; records meeting an incidental keyword match alone were excluded at title/abstract screening. The four primary screening dimensions were therefore time period (January 2000 -March 2026), language (English), document type (peer-reviewed articles, authoritative grey literature, or international standards), and minimum thematic relevance (substantive engagement with at least one conceptual block).Exclusion criteria: (i) studies on non-coastal forest carbon without transferable methodology; (ii) opinion pieces without supporting analysis; (iii) duplicate records; (iv) studies whose full text could not be retrieved; (v) records older than 2000, except for foundational sources retained for theoretical lineage (e.g., Costanza et al., 1997;TEEB, 2010).From 312 records initially identified (Web of Science n = 94; Scopus n = 137; Google Scholar n = 60; grey literature n = 21), 47 duplicates were removed. Title/abstract screening excluded 173 records as out-of-scope, leaving 92 for full-text appraisal. Forty-one were further excluded for failing the criteria above, yielding 51 sources retained for in-depth synthesis.Methodological quality of empirical sources was appraised against the Critical Appraisal Skills Programme (CASP) checklists, adapted for environmental-economic studies; standards documents were appraised by recency, issuing authority, and adoption status. The full identification, screening, eligibility, and inclusion process is summarised in the PRISMA flow diagram (Figure 1).Synthesis was thematic. Each retained source was coded against five conceptual blocks (inputs; mechanisms; outputs; moderators; risks) using a structured matrix; convergent and divergent findings were then triangulated to construct the MENCA-ET framework presented in Section 4. We acknowledge that 51 retained sources is a focused rather than exhaustive corpus;this reflects a deliberate choice to anchor the framework on authoritative standards, recent (post-2020) syntheses, and well-documented empirical cases, rather than on a broader but lower-quality set. The protocol allows for the corpus to be extended transparently in subsequent updates.Framework synthesis procedure. Framework components were derived from the coding matrix in three steps. First, each source was assigned to one or more of the five conceptual blocks using a structured coding form. Two members of the author team independently coded a 10% random subsample to verify inter-rater consistency; any discrepancies were resolved through consensus discussion, and the agreed coding conventions were then applied to the full corpus.Second, a frequency and convergence analysis identified candidate components: a component was retained if it appeared in the coding of ten or more sources and was corroborated by at least one authoritative standard (SEEA-EA, TNFD, IFRS S1/S2, GRI 101, or Verra VM0033). Third, triangulation against those standards confirmed or rejected candidates and assigned each to its block. The five inputs (I1-I5) correspond to the five SEEA-EA accounting domains adapted for ecotourism: extent, condition, flows, ecosystem-service values, and governance/reporting metrics.The seven mechanisms (M1-M7) were derived by cross-tabulating the five input blocks against seven functional categories in the retained standards literature (valuation, carbon finance, community accounting, biodiversity levies, integrated reporting, digital MRV, and adaptive finance), with each populated cross-tabulation cell yielding one mechanism. The five moderating conditions (C1-C5) were pre-specified from the LMIC governance and capacity-building literature before coding began; the four limiting risks (R1-R4) emerged inductively but were retained only where they appeared in at least eight sources. The full coding matrix is available from the corresponding author on request. The five cases were selected to represent maximum variation across the two governance As above (same national framework)M1 (nascent), M3(nascent)CBT biophysical integration; model for participatory SEEA-EA condition account under M3The SEEA-EA, adopted by the UN Statistical Commission in March 2021, is the world's first international accounting standard providing guidance on the extent, condition, benefits, and trillion yr⁻¹ in current prices (Costanza et al., 1997(Costanza et al., , 2014)). The value of mangrove ecosystem services has been estimated across a wide range -US$5.75-126,444 ha⁻¹ yr⁻¹ -depending on context and methodology (Brander et al., 2012;Himes-Cornell et al., 2018).valueMangroves sequester atmospheric carbon up to ten times faster than mature tropical forests, accumulating on average 1,000 t C ha⁻¹ when soils are included (UNEP, 2024;Howard et al., 2017). Two operational standards are now well established: Verra VM0033 v2.1 (Verra, 2023) and the Gold The framework integrates the elements above into a structure of five inputs, seven integration mechanisms, two output pathways, five moderating conditions, and four limiting risks.The five inputs are: I1 ecosystem extent and condition; I2 ecotourism flows; I3 blue-carbon stocks and fluxes; I4 community livelihoods; and I5 sustainability reporting metrics. These pass through seven integration mechanisms (Table 2) to produce two co-equal output pathways. Pathway P1 captures improved ecosystem-service valuation and finance for restoration and conservation;Pathway P2 captures sustainable business development in mangrove ecotourism with positive community impact. The framework speaks directly to sustainability strategies pursued by tourism firms, where competitiveness depends jointly on financial, environmental, and social performance (Yuldashev et al., 2026). Figure 2 provides the consolidated visualisation.Table 2 summarises the seven mechanisms, their accounting/financial tools, the ecosystem service each captures, the ecotourism application, the evidence level, and an illustrative case. Four risks recur in the literature and threaten the framework if unmitigated (Figure 2 Four pressures make MENCA-ET timely. (Toyirova et al., 2025).A central practical concern with the framework is that the costs of TNFD-and IFRSaligned reporting may be prohibitive for small-scale ecotourism operators in LMICs, even where Mechanism M2 (blue-carbon revenue) is well-established. We respond with a three-tier compliance pathway that distributes the compliance burden in proportion to operator capacity rather than imposing uniform requirements.Tier 1 (micro-operator; <US$100,000 annual revenue). Reporting is limited to a singlepage disclosure of dependencies and impacts using the TNFD LEAP-light template, populated from openly licensed sources (Global Mangrove Watch v4.0; ARIES for SEEA Explorer; national SEEA-EA accounts where available). Verification is internal. There is no obligation to produce IFRS S1/S2 disclosures.Tier 2 (small operator; US$100,000-1 million). Operators produce a TNFD-aligned report using a destination-level shared template prepared by the destination management organisation (DMO) or relevant Community Forest Association. IFRS S1/S2 disclosures are produced on a "comply or explain" basis, with sector exemptions for cost-prohibitive line items.Third-party assurance is limited to material items only.disclosures with independent assurance, GRI 101 line items, and biodiversity-credit integrity attestations.Three cost-sharing instruments make this pathway viable. First, destination-level shared services -a single TNFD-aligned account produced by the DMO and apportioned across operators -reduce per-operator overhead by an order of magnitude relative to bespoke reporting.Second, an earmarked tourism levy (M4) cross-subsidises Tier 1 disclosures from Tier 3 visitor flows. Third, blue-carbon revenue (M2) finances the marginal compliance cost of Tier 2 operators;in the Mikoko Pamoja case, where ~US$200,000 has been channelled to community development from ≥8,000 t CO₂ yr⁻¹ (Sundara, 2023), even a 10% earmark for reporting infrastructure is sufficient to fund Tier 2 compliance for the affiliated community-level enterprises. The framework therefore does not treat M5 as an obligation that local communities must absorb at their own expense, but as a service whose marginal cost is internalised within the framework itself.Transaction-cost analysis. The cost rationale for the tiered model is grounded in transaction-cost theory. Standalone TNFD-aligned reporting entails three categories of transaction costs for a small-scale operator: (1) search and information costs (learning the LEAP methodology;acquiring openly licensed GIS and remote-sensing data; understanding IFRS S1/S2 requirements);(2) negotiation and verification costs (contracting a third-party assurer; registering credits and operators. This framing connects the tiered pathway directly to the institutional economics that underpins the governance analysis in Section 5.3. compliance cost of US$3,000-8,000 on the shared-services model with surplus. Under a downside scenario at the voluntary market floor of approximately US$6.34/tCO₂e (as reported in Section 3), the same project yields ~US$50,720 gross revenue; a 10% earmark of ~US$5,000 may be insufficient at the high end of the Tier 2 cost range. This confirms that the tiered pathway is robust only when all three cost-sharing instruments operate simultaneously: shared services reducing the base cost, M2 earmarking providing the primary subsidy, and the M4 levy closing any residual gap. Formal sensitivity analysis using primary cost data and the full blue-carbon price range (US$6.34-US$29.30/tCO₂e) is warranted in the empirical validation work identified in the research agenda (Section 6).The Tahiry Honko project in Madagascar -where carbon-credit certificates could not be issued because national policy did not permit the transfer of carbon rights to community implementers (Hejnowicz et al., 2024) -is the paradigmatic case of the misalignment we address here. Mangrove ecotourism cannot serve as a tool for community empowerment if the underlying carbon and ecosystem-service rights remain ambiguous or are appropriated by the state for NDC accounting without flow-back to the communities that secure the asset. We therefore propose four concrete steps through which MENCA-ET can bridge the gap between national carbon claims and community tenure rights to make community-held accounts bankable:1.Legal transfer of carbon rights to communities. Statutory reform is required so that carbon rights over community-managed mangroves are vested in the relevant Community Forest Association (or analogous co-management body), with a defined revenue-sharing schedule for any state participation. Adjustments to NDC accounting can be made through Article 6.2 corresponding adjustments so that the same tonne is not claimed in both ledgers.2. FPIC at all LEAP steps. Free, Prior, Informed Consent must be operationalised not only at project initiation but at each of the four LEAP steps (Locate, Evaluate, Assess, Prepare), with documented community sign-off as a registration requirement for credits and disclosures under MENCA-ET.Bankable community ledgers (M3). Participatory SEEA-EA condition and extent accounts, maintained by Community Forest Associations and verified against Global Mangrove Watch alerts, function as the underlying ledger against which credits (M2, M4) and concession financing (M7) are issued. The ledger is the bridge: it makes community-held accounts visible to financiers while preserving plural valuation.NDC-community settlement protocol. A standardised protocol is needed by which the national authority and the relevant community body settle the apportionment of mitigation outcomes ex ante -for example, a default 70/30 community/state split for ITMO transfers from community-managed mangrove projects, subject to renegotiation. Without this protocol, even legally transferred carbon rights are practically unusable.These four steps require coordinated action by national statistical offices, environment ministries, finance ministries, tourism authorities, and standard-setters. MENCA-ET does not legislate them, but specifies them as the institutional moves through which Pathway P2(community-operator outcomes) becomes operational rather than aspirational.Comparative institutional analysis. The four steps proposed above are grounded in aComparative Institutional Analysis (CIA) approach drawing on Ostrom's Institutional Analysis and Development (IAD) framework (Palomo and Hernández-Flores, 2019;Slobodian et al., 2022) to evaluate carbon rights, tenure, FPIC, and Article 6 governance structures across the five casestudy is a test ex the be to in the of the ranked by and with SEEA-EA LMIC and to over analysis of mangrove ecotourism that blue-carbon revenue community and value for and M4 through the SEEA process under ecotourism MENCA-ET entails TNFD-aligned reporting on a tiered pathway and that ecosystem-service research on management economic and social performance can be when reporting integration is in from the and 2026), while work on sustainable in tourism provides a for accounting 2026). and accounts, them to and mangrove in and national accounts (Menéndez and Beck, 2024). (ISSB, TNFD, guidance and on of tourism and carbon communities and in MENCA-ET as not FPIC across all LEAP and secure tenure rights that make community-held accounts First, the economic contribution of mangrove ecotourism is in standard accounting and that invisibility is a of mangrove The to make this contribution visible are available Verra the Gold Standard, TNFD, IFRS S1/S2, GRI 101, and the MENCA-ET specifies an structure for to the five moderating conditions are and the four limiting risks are Third, for mangrove ecotourism to function as a accounting must from a to one of community community-held accounts, in tenure rights, FPIC at all LEAP and a settlement protocol between and community The framework presented is as a structure rather than a subsequent empirical work in the five LMIC sites identified in which mechanisms transfer and where the framework to be