Overview
How this pathway works
Blue carbon refers to the organic carbon captured and stored by coastal and marine ecosystems - principally mangrove forests, seagrass meadows, and tidal salt marshes. These three ecosystem types are responsible for approximately half of all carbon burial in ocean sediments despite covering less than 0.5% of the ocean floor. Their extraordinary carbon density relative to area arises from a combination of high productivity, year-round growth in tropical and subtropical systems, and the near-anaerobic conditions of their waterlogged soils that suppress the microbial decomposition of organic matter - allowing carbon to accumulate in sediment layers stretching back thousands of years.
Under TNS v1.0 Annex F, blue carbon projects earn Teravent Nature Credits (TNCs) either by preventing the conversion of intact coastal wetlands - thereby avoiding the catastrophic release of their ancient legacy carbon stocks - or by actively restoring degraded coastal systems to re-establish sequestration and halt ongoing emissions. The distinction between conservation-based and restoration-based accounting is fundamental to Annex F: conservation projects primarily prevent emissions from disturbed sediments, while restoration projects primarily generate new sequestration credits as vegetation and soils recover.
Three ecosystem-specific methodology codes are approved under Annex F. BLC-M01 covers mangrove conservation and restoration; BLC-M02 covers seagrass meadow conservation and restoration; and BLC-M03 covers tidal salt marsh conservation and restoration. All three share a common requirement for tidal hydrology assessment, soil organic carbon depth profiling, and non-CO₂ GHG accounting - distinguishing Annex F from all terrestrial nature-based pathways.
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Class II - Ecological permanence. All credits under TNS Annex F carry Class II Ecological permanence, reflecting the multi-century carbon storage horizon of intact coastal wetland soils. The primary permanence risk is hydrological disruption - drainage, impoundment, or sea-level change altering the waterlogged conditions that suppress decomposition. Buffer pool contributions of 15–30% apply, with the specific rate determined by the NPRR at validation, which includes tidal connectivity, storm surge exposure, land tenure security, and sea-level rise trajectory as explicit risk factors.
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Non-CO₂ GHG accounting is mandatory. Coastal wetlands produce methane (CH₄) and nitrous oxide (N₂O) under natural conditions - primarily from tidal channels, unvegetated mudflats, and areas of seasonal salinity fluctuation. These emissions must be quantified and deducted from gross CO₂ sequestration or avoided-emission benefits. For mangrove and salt marsh projects with salinity above 18 ppt, CH₄ emissions are typically low and may be de minimis. Seagrass meadows in freshwater-influenced systems require a full non-CO₂ assessment. The net GHG balance - CO₂ benefit minus CH₄ and N₂O - must be positive for credit issuance.
Ecosystem Coverage
Three coastal ecosystem types
TNS v1.0 Annex F covers three distinct coastal ecosystem types, each with its own ecology, carbon pool structure, and monitoring requirements. A project may span multiple ecosystem types within the same project boundary, but each ecosystem type must be accounted separately using its applicable BCL methodology code and carbon pool framework.
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Mangroves
BLC-M01 · TNS Annex F
Carbon Storage
800–6,000 tCO₂e/ha in soil
Soil Depth
To full depth or 3 m minimum
Biomass
Above + belowground required
Key Risk
Drainage, aquaculture, timber
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Seagrass Meadows
BLC-M02 · TNS Annex F
Carbon Storage
140–2,400 tCO₂e/ha in soil
Soil Depth
To full depth or 1 m minimum
Biomass
Belowground rhizomes primary
Key Risk
Turbidity, boat damage, eutrophication
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Salt Marshes
BLC-M03 · TNS Annex F
Carbon Storage
200–3,500 tCO₂e/ha in soil
Soil Depth
To full depth or 2 m minimum
Biomass
Below ground dominant; AGB optional
Key Risk
Ditching, grazing, sea-level rise
Governing Standard
TNS v1.0 - Annex F
This pathway is governed exclusively by the Teravent Nature-Based Carbon Standard (TNS v1.0). All requirements - additionality, soil carbon depth profiling, non-CO₂ GHG accounting, tidal hydrology assessment, MRV, permanence risk, and credit issuance - are defined within TNS v1.0 and Annex F.
TCR›
TNS v1.0›
Annex F - Blue Carbon›
BLC-M01 through BLC-M03
M02
Threat-based additionality for conservation projects · Three-test additionality for restoration · FPIC mandatory on all coastal community land
M03
Soil organic carbon depth profiles to full depth or minimum ecosystem depth · Non-CO₂ GHG (CH₄, N₂O) measured and deducted · Tidal hydrology index required
M04
Class II Ecological permanence · Buffer pool 15–30% · NPRR includes sea-level rise, storm surge, tidal hydrology, land tenure, and coastal development risk
M05
Biodiversity Impact Assessment mandatory · Fisheries co-benefit monitoring strongly encouraged · FPIC required for all coastal communities with traditional access rights
M06
30-year initial crediting period + renewals · Conservation baseline: historical loss rate from remote sensing · Restoration baseline: degraded ecosystem soil carbon stock at time of intervention
M07
TNC serial: TCR–TNS–BLC–[Country]–[ProjectID]–[Vintage]–[Unit] · Conservation and restoration credits may be separately serialised within the same project boundary
Teravent Nature Credit - Serial Number Format (TNS Annex F)
TCR
–
TNS
–
BLC
–
IN
–
00256
–
2025
–
000001
Methodologies Accepted
Three approved ecosystem methodologies
TNS v1.0 Annex F approves three blue carbon methodology codes - one per coastal ecosystem type. Each methodology supports both conservation-based accounting (avoided emissions from protecting intact systems) and restoration-based accounting (new sequestration from recovering degraded systems). Projects may combine both activity types within a single boundary, but the two accounting tracks must remain separate throughout the crediting period.
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Conservation vs. restoration accounting: Conservation projects demonstrate an active threat to the ecosystem and quantify the avoided emissions from preventing conversion - using historical deforestation/degradation rates from satellite time-series as the baseline. Restoration projects quantify the difference between degraded baseline carbon stocks and the recovering ecosystem stocks over time. The distinction is methodologically critical - mixing accounting frameworks within a stratum is not permitted under Annex F.
Mangroves are intertidal forests occurring at the land-sea interface in tropical and subtropical coastlines. They are the most carbon-dense blue carbon ecosystem - their deep, anaerobic soils can store 800–6,000 tCO₂e/ha, dwarfing the carbon density of all terrestrial forest types. Globally, mangroves are being converted at rates of 0.5–1.0% per year - primarily to aquaculture ponds, rice paddy expansion, and coastal development - releasing their enormous soil carbon stocks as CO₂ and CH₄ when drained. BLC-M01 conservation projects must document an active deforestation threat using minimum 10 years of satellite time-series and demonstrate legal protection or community stewardship strong enough to address that threat. Restoration projects must demonstrate that tidal hydrology has been re-established - the primary control on mangrove recovery - before substantive soil carbon credits can be issued.
Permanence
Class II · Ecological
Buffer Pool
20–30% (by NPRR)
Soil Depth
Full depth or 3 m minimum
Biomass Pools
AGB + BGB required; DOM where material
CH₄ Accounting
Required - de minimis if salinity >18 ppt
Hydrology Req.
Tidal connectivity confirmed before restoration credits
Key Monitoring Indicators
- Mangrove extent and canopy cover - annual satellite mapping (Sentinel-2, Planet, or SAR) across full project boundary
- Soil organic carbon profiles at permanent plots - 10 cm increments to full depth or 3 m; dry combustion CHNS analysis; every 5 years
- Aboveground biomass at permanent plots - DBH and height by species using mangrove-specific allometrics; every 3 years
- Belowground root biomass - root core sampling to 30 cm at permanent plots; every 5 years
- Tidal hydrology - water level loggers at minimum one per 50 ha; confirms tidal inundation frequency and duration (critical for restoration projects)
- Porewater salinity and redox potential at permanent plots - confirms anaerobic conditions preserving soil carbon; every 3 years
- CH₄ flux - static chamber measurements at tidal creek margins and mudflats; minimum quarterly; deducted from gross CO₂ benefit
- Deforestation threat evidence update - annual satellite review confirming threat status unchanged and conservation measures effective
Seagrass meadows are subtidal and intertidal flowering plant communities found in sheltered coastal and estuarine environments worldwide. Although their aboveground biomass is modest compared to mangroves, their rhizome-rich sediments accumulate organic carbon for thousands of years under reduced oxygen conditions. Seagrasses are declining globally at approximately 7% per year - primarily from poor water quality (turbidity, eutrophication), boat propeller scarring, and coastal development. The primary challenge for seagrass carbon accounting is attribution: unlike mangroves, which are visually distinct and remotely detectable, seagrass carbon stocks are highly spatially heterogeneous and require diver surveys or underwater ROV mapping combined with sediment coring for reliable quantification. Conservation projects must demonstrate that active threat is reducing or will reduce seagrass extent or density without intervention. Restoration projects are limited to sites where the original seagrass loss cause has been controlled - turbidity reduction, nutrient load reduction, or boating restriction.
Permanence
Class II · Ecological
Buffer Pool
20–30% (elevated - fragility)
Soil Depth
Full depth or 1 m minimum
Mapping Method
Diver transects, UAV, or multibeam sonar
CH₄ Accounting
Required - elevated risk in fresh/brackish water
Restoration Gate
Causative stressor must be confirmed as controlled
Key Monitoring Indicators
- Seagrass meadow extent - annual diver transect surveys or UAV/multispectral mapping of intertidal areas; every 3 years for subtidal areas
- Species composition and shoot density at permanent monitoring sites - minimum 5 permanent quadrat stations per stratum, surveyed annually
- Belowground biomass - rhizome and root core sampling at permanent sites to 1 m depth; every 5 years
- Sediment organic carbon profiles at permanent sites - 2 cm increments to 1 m depth; CHNS analysis; every 5 years
- Water quality indicators - turbidity (NTU), dissolved inorganic nitrogen, phosphate, and chlorophyll-a at permanent monitoring buoys or sampling stations; minimum monthly
- CH₄ flux from sediments - aquatic equilibration or benthic chamber sampling at permanent stations; minimum quarterly
- Threat documentation - water quality trend analysis and any boating or anchoring restriction enforcement records annually
Tidal salt marshes are grass and herbaceous plant communities colonising sheltered intertidal zones in temperate and high-latitude coastlines. Their carbon storage in deep, anaerobic peat-like sediments can approach or exceed mangrove soil stocks in cold, productive systems. Salt marshes have been historically drained and converted for agriculture across Europe, North America, and Australia - with the drainage of their soils triggering rapid oxidation of their ancient carbon stores. Restoration of salt marshes is achieved primarily by hydrological re-inundation - removing drainage infrastructure (tide gates, ditches, bunds) to restore tidal flooding - which rapidly re-establishes anaerobic conditions that halt soil carbon loss and begin new accumulation. BLC-M03 restoration projects must demonstrate that tidal hydrology has been restored before claiming soil carbon sequestration credits. Conservation projects must demonstrate an active drainage or conversion threat.
Permanence
Class II · Ecological
Buffer Pool
15–25% (by NPRR)
Soil Depth
Full depth or 2 m minimum
Hydrology Restoration
Tidal re-inundation confirmed before sequestration credits
N₂O Accounting
Required - elevated in brackish and N-enriched marshes
Key Co-benefit
Coastal flood attenuation, fisheries nursery
Key Monitoring Indicators
- Marsh vegetation extent and species composition - annual aerial or satellite mapping; diver or quadrat surveys at permanent transects
- Tidal hydrology at permanent water level gauges - confirms inundation frequency and duration; monthly data download minimum
- Soil organic carbon profiles to full depth or 2 m - 2 cm increments; CHNS and bulk density at each increment; every 5 years at permanent plots
- Soil surface elevation change - surface elevation tables (SET) at permanent stations to measure accretion and subsidence; annually
- CH₄ flux from sediment surface - static chamber measurements in vegetated and unvegetated marsh zones; minimum quarterly; de minimis check for saline systems
- N₂O flux - static chamber measurements, particularly in nitrogen-enriched estuaries; minimum quarterly; deducted where material
- Porewater salinity at permanent plots - confirms tidal connectivity and anaerobic conditions; every 3 years
- Coastal threat documentation - drainage infrastructure status, adjacent land use change, any sea wall or infrastructure modification; annually
Carbon Pool Accounting
What must be measured
Blue carbon accounting differs fundamentally from terrestrial pathways in two respects: soil organic carbon in coastal wetlands is the dominant pool by a very large margin - typically 80–95% of total ecosystem carbon - and non-CO₂ GHGs (CH₄ and N₂O) must be deducted from gross CO₂ benefits in all methodologies. The deep soil profiles required under Annex F are the most demanding sampling requirement of any Teravent pathway.
Required - Primary
Soil Organic Carbon (SOC) - Deep Profile
The dominant carbon pool in all blue carbon ecosystems. Profiled to full soil depth or the ecosystem minimum (3 m mangroves, 1 m seagrass, 2 m salt marsh). Sampled using Russian peat corer or vibracorer at 2 cm resolution per increment. Dry combustion CHNS analysis with bulk density measurements at every depth increment. Every 5 years at permanent plots. This is the most analytically intensive pool in the Teravent registry.
Required - Mangroves only (BLC-M01)
Aboveground Biomass (AGB)
Living mangrove tree biomass - stems, branches, leaves. Estimated from DBH measurements at permanent plots using mangrove-specific allometric equations. Required for BLC-M01 where mangrove stands are of creditable age and stature. Typically contributes 5–20% of total ecosystem carbon stock. AGB is not a material pool in seagrass (BLC-M02) or salt marsh (BLC-M03) systems and is excluded from those methodologies.
Required - All methodologies
Belowground Biomass (BGB) - Roots & Rhizomes
Live roots and rhizomes in the soil column. In seagrass systems (BLC-M02), belowground rhizome mass is the dominant biomass pool. Measured by root core sampling to 30 cm at permanent plots every 5 years. IPCC root-to-shoot ratios or published ecosystem-specific values accepted where direct measurement is not possible.
Required - Deduct from gross benefit
Methane (CH₄) Emissions
Blue carbon sediments produce CH₄ under anaerobic conditions - primarily at tidal channel margins, unvegetated mudflats, and low-salinity zones. Measured by static chamber gas sampling (minimum quarterly) with GC analysis. Converted to CO₂-equivalent using GWP₁₀₀ = 28. Where salinity is consistently above 18 ppt, CH₄ emissions are typically de minimis (<1% of gross CO₂ benefit) and may be excluded with VVB approval.
Required where material
Nitrous Oxide (N₂O) Emissions
N₂O is produced at the aerobic-anaerobic interface in nitrogen-enriched sediments. Material in salt marshes receiving high nitrogen load from agricultural or urban runoff (BLC-M03) and in freshwater-influenced seagrass systems (BLC-M02). Measured by static chamber sampling at minimum quarterly intervals. GWP₁₀₀ = 265. Where total inorganic nitrogen in porewater is below 50 µmol/L, N₂O may be excluded as de minimis with VVB acceptance.
Excluded
Dead Organic Matter & Dissolved OC
Woody debris (DOM) in mangrove systems is typically small relative to soil carbon stocks and is excluded for simplicity unless a VVB-approved site-specific assessment demonstrates materiality above 5% of total ecosystem carbon. Dissolved organic carbon exported to adjacent waters is not credited - this export is already accounted for within the soil carbon measurement framework, which measures what remains in the sediment.
Non-CO₂ GHG Accounting Framework
Methane - CH₄
When to assess and when to exclude
All blue carbon projects must conduct a preliminary CH₄ assessment at validation. Where porewater or surface water salinity exceeds 18 ppt across the project area, CH₄ may be deemed de minimis and excluded from ongoing monitoring with VVB approval. Projects in mixed freshwater-marine systems or with documented brackish zones must conduct quarterly static chamber measurements throughout the crediting period and deduct CH₄ as CO₂-equivalent from gross credits.
GWP₁₀₀ = 28 · Static chambers minimum quarterly · De minimis threshold: <1% of gross CO₂ benefit
Nitrous Oxide - N₂O
Nitrogen-enriched systems require full assessment
N₂O is most significant in salt marshes receiving agricultural runoff (BLC-M03) and nutrient-enriched seagrass systems (BLC-M02). The preliminary nitrogen assessment at validation compares porewater total inorganic nitrogen against the 50 µmol/L de minimis threshold. Projects in estuaries with documented high nitrogen loads must conduct quarterly chamber measurements. For restoration projects, N₂O emissions may be temporarily elevated during the first 2–3 years of hydrological restoration - this transition period must be monitored and deducted.
GWP₁₀₀ = 265 · De minimis if TIN < 50 µmol/L · Transition period monitoring mandatory
MRV Confidence
Measurement, reporting
& verification
Blue carbon MRV has a distinctive profile - mangrove extent detection by satellite is very high confidence, but soil carbon quantification at depth is the most technically demanding field measurement in the Teravent system. Seagrass mapping is the least mature of the three ecosystem MRV frameworks. Non-CO₂ GHG attribution remains a frontier measurement challenge across all three ecosystem types.
Mangrove Extent - Remote SensingVery High
Deep Soil Carbon ProfilingHigh
Seagrass Mapping & CoverageMedium–High
Non-CO₂ GHG Flux MeasurementMedium
Permanence ConfidenceHigh
Additionality - Conservation ThreatHigh
🔬 Soil Carbon Sampling Standard - TNS Module 3 · Blue Carbon
Blue carbon soil carbon profiles are the most analytically demanding measurements in the Teravent system. Permanent sampling plots must be established at minimum one per 20 ha of project area, stratified by ecosystem type and degradation level. Coring must use a Russian peat corer (for organic-rich sediments) or vibracorer (for mineral sediments) to achieve the minimum required depth without compaction - core compaction must be measured and corrected. Sub-sampling at 2 cm intervals is required for the top 30 cm; 5 cm intervals accepted from 30 cm to maximum depth. Each sub-sample requires bulk density measurement by volume and dry mass, and CHNS analysis at an ISO/IEC 17025 accredited laboratory. All depth profiles, bulk density records, and CHNS results must be archived for the full project lifetime plus 10 years.
Additionality
Demonstrating additionality
Additionality for blue carbon projects differs between conservation and restoration activity types. Conservation projects rely primarily on a threat-based additionality framework - demonstrating that the ecosystem faces a credible deforestation or degradation threat that would occur without the project. Restoration projects use the standard three-test additionality framework.
1
Conservation: Threat-Based Additionality
Conservation projects must demonstrate that the coastal ecosystem faces a credible, documented threat of conversion or degradation that would occur in the project's absence. Acceptable threat evidence includes: a documented historical deforestation rate from satellite time-series of minimum 10 years showing active mangrove loss at the site or in the surrounding landscape; a specific conversion threat such as an aquaculture or coastal development permit; or a regional deforestation rate exceeding 1% per year within 50 km of the project boundary. The threat must be real, proximate, and plausible - not a remote speculative risk. Conservation projects must also demonstrate that the legal protection or community stewardship mechanism provided by the project is not already in place and effective absent carbon finance.
2
Restoration: Financial Additionality
Restoration projects apply the standard financial additionality test - carbon revenue must be necessary for the restoration programme to be economically viable. Blue carbon restoration is typically expensive: tidal hydrology restoration may require removal of tide gates, dam infrastructure, or extensive drainage networks; seagrass restoration requires specialised diving teams and intensive water quality management. An investment analysis must demonstrate that the restoration costs - hydrological engineering, planting, monitoring, VVB verification - exceed the non-carbon revenues from alternative coastal management approaches without carbon finance. Community-led restoration programmes may demonstrate financial additionality through documented absence of alternative funding sources.
3
Common Practice Test
For conservation projects, the common practice test assesses whether comparable coastal ecosystems in the same jurisdiction are being voluntarily protected without carbon finance. In most blue carbon geographies - India, Southeast Asia, West Africa, Pacific Islands - voluntary protection of mangroves without carbon revenue or equivalent government support is not common practice, particularly where aquaculture expansion pressure is active. For restoration projects, the test confirms that blue carbon restoration at the scale and technical standard required by Annex F is not common practice in the project geography. The 20% voluntary adoption threshold applies to both activity types.
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Government-declared protected areas: Coastal ecosystems located within formally declared government protected areas - national parks, marine reserves, wildlife sanctuaries - require special treatment under the additionality framework. The project must demonstrate that the legal protection alone is insufficient to address the threat (i.e. the protection is poorly enforced or inadequately resourced) and that carbon finance is adding substantive additional protection beyond what the legal designation provides. Paper parks with demonstrated ongoing deforestation can pass this test; well-managed protected areas with low historical deforestation rates typically cannot.
Leakage Assessment
Leakage types & deductions
Blue carbon leakage analysis must assess both activity-shifting (displaced aquaculture or timber harvest moving to adjacent unprotected coastline) and ecological leakage (hydrological changes within the project boundary affecting adjacent coastal systems). Market leakage is generally not applicable to blue carbon projects.
Activity-Shifting Leakage
Displaced Aquaculture & Timber
Where conservation projects prevent aquaculture pond development or timber harvesting, these activities may shift to adjacent unprotected mangrove or coastal areas. A spatial analysis of the coastline within 50 km of the project boundary must assess the risk of activity displacement. Where adjacent mangrove areas have comparable aquaculture development pressure, a leakage deduction of 5–20% of gross credits applies, determined by the spatial leakage model accepted at validation.
Default: 10–20% for mangrove conservation · 5% for salt marsh and seagrass
Ecological Leakage
Hydrological Boundary Effects
Restoration of tidal hydrology within the project boundary may alter sediment transport, salinity gradients, and tidal flow patterns in adjacent areas. Where hydrological modelling indicates that restoration activities may accelerate erosion or reduce sedimentation in adjacent unprotected wetlands, an ecological leakage deduction must be assessed. For most tidal restoration projects the effect is positive (improved sediment supply to downdrift marshes), but projects involving substantial embankment removal in energetic coastal settings must assess this carefully.
Assessed case-by-case · Typically de minimis for smaller restoration projects
Upstream Input Leakage
Restoration Infrastructure GHG
GHG from construction activities - tide gate removal, excavation of drainage ditches, coastal engineering - must be quantified and deducted where material. For most blue carbon restoration projects these are de minimis (below 2% of gross carbon benefit over the crediting period). Where significant concrete or steel infrastructure is installed, a one-time embodied carbon calculation per TLP v1.0 must be included in the project lifecycle GHG assessment.
De minimis threshold: 2% · Typically <1% for nature-based tidal restoration
Hydrological Connectivity Risk
Baseline Emissions from Adjacent Areas
Where the project boundary abuts drained or converted coastal land, the drainage of soils outside the project boundary may continue to contribute emissions. The project accounts only for carbon within the project boundary - adjacent areas are not credited or debited. However, where project restoration activities physically block drainage from adjacent degraded land, causing unintended waterlogging or flooding outside the boundary, this must be disclosed and any community or landowner impacts mitigated and documented.
Managed through boundary definition · Adjacent impacts must be disclosed
Permanence & Non-Permanence Risk
Buffer pool & reversal risk
Blue carbon projects carry Class II Ecological permanence. The dominant permanence risks are hydrological in nature - drainage infrastructure failure, tidal creek diversion, or sea-level-rise-driven marsh drowning - rather than the fire and pest risks that dominate terrestrial nature-based projects. Sea-level rise trajectory is a mandatory NPRR input for all Annex F projects and must be based on IPCC AR6 regional projections for the project location.
| Methodology |
NPRR Rating |
Buffer Pool Rate |
Primary Reversal Risks |
| BLC-M01 Mangrove Conservation |
Medium–High |
20–30% |
Aquaculture encroachment; storm surge damage; land tenure loss; sea-level rise outpacing sediment accretion |
| BLC-M01 Mangrove Restoration |
Medium |
18–25% |
Tidal connectivity disruption; juvenile mortality in first 5 years; cyclone damage; sediment deficit in subsided areas |
| BLC-M02 Seagrass Conservation |
High |
25–30% |
Water quality deterioration; elevated turbidity events; extreme heat events; boat damage; eutrophication |
| BLC-M02 Seagrass Restoration |
High |
25–30% |
Stressor recurrence; turbidity increase; poor transplant survival; extreme temperature events |
| BLC-M03 Salt Marsh Conservation |
Medium |
15–22% |
Drainage re-establishment; sea-level rise exceeding accretion; storm surge soil disturbance; grazing reintroduction |
| BLC-M03 Salt Marsh Restoration |
Low–Medium |
15–20% |
Tide gate failure; grazing pressure; pioneer species establishment failure in first 3 years |
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Sea-level rise mandatory assessment: All Annex F projects must include a sea-level rise vulnerability assessment based on IPCC AR6 RCP 4.5 projections (or higher where locally appropriate) at validation. Where projected sea-level rise exceeds local sediment accretion rates by year 30 of the crediting period, the NPRR must reflect this risk with an elevated buffer contribution. Projects in areas with documented sediment deficits - particularly those adjacent to rivers with reduced sediment loads from upstream dams - must submit an accretion-rate measurement programme as part of the monitoring plan.
Eligibility Requirements
Key registration criteria
All of the following must be satisfied for registration under TNS Annex F. Methodology-specific requirements (tidal hydrology assessment, salinity profiling, seagrass mapping protocols) are detailed in the individual BLC-M code specifications within Annex F.
✓
Ecosystem type confirmed as mangrove, seagrass meadow, or tidal salt marsh by an independent coastal ecologist - a site ecology assessment must be submitted with the PDD documenting species composition, tidal connectivity, soil type, and ecosystem health indicators
✓
Baseline soil organic carbon profiles established at permanent sampling plots before project activities commence - minimum one plot per 20 ha, profiled to full depth or ecosystem minimum, with CHNS and bulk density analysis at accredited laboratory
✓
Tidal hydrology assessment completed at validation - tidal range, inundation frequency, salinity profile, and water table elevation documented; tidal connectivity confirmed as functional (or restoration plan to restore it submitted for degraded sites)
✓
Non-CO₂ GHG preliminary assessment conducted - porewater salinity and nitrogen measured across the project boundary; CH₄ de minimis determination documented where salinity exceeds 18 ppt; N₂O de minimis determination where porewater TIN below 50 µmol/L
✓
Additionality demonstrated per activity type - conservation projects: documented active threat with 10-year satellite time-series; restoration projects: three-test standard additionality with financial additionality analysis for restoration costs
✓
Sea-level rise vulnerability assessment completed per IPCC AR6 regional projections - results incorporated into NPRR and buffer pool determination; sediment accretion rate programme submitted where sea-level rise risk is elevated
✓
Biodiversity Impact Assessment mandatory - baseline coastal biodiversity survey (mangrove fauna, seagrass fauna, fish assemblages, bird use) completed by qualified coastal ecologist before project activities; monitoring plan specifying post-project survey frequency submitted
✓
Free, Prior and Informed Consent (FPIC) obtained from all coastal communities with documented traditional fishing, aquaculture, or resource access rights within the project boundary - consent must cover both carbon project activities and any access restrictions
✓
Leakage spatial analysis completed - 50 km coastal buffer zone assessed for comparable ecosystems at risk of receiving displaced aquaculture or timber pressure; leakage deduction rate determined and justified in PDD
✓
Land and coastal tenure secure for full crediting period - government-issued concession, community title, customary rights agreement, or long-term lease of minimum crediting period duration; no unresolved coastal boundary disputes affecting more than 5% of project area
Co-Benefits & SDGs
Sustainable Development
Goal alignment
Blue carbon projects deliver an exceptionally broad co-benefit profile anchored by fisheries, coastal resilience, and biodiversity. Mangroves serve as nursery grounds for tropical fisheries supporting hundreds of millions of people; seagrass meadows are the primary habitat for dugong, green turtle, and numerous commercially important fish; salt marshes provide coastal flood attenuation that protects vulnerable coastal communities. Nine SDGs are tracked across Annex F projects.
SDG 14 · Life Below Water
SDG 13 · Climate Action
SDG 15 · Life on Land
SDG 1 · No Poverty
SDG 2 · Zero Hunger
SDG 6 · Clean Water
SDG 11 · Sustainable Cities
SDG 3 · Good Health
SDG 8 · Decent Work
Biodiversity+
Coastal wetlands support extraordinary biodiversity - mangroves host 341 bird species and are nursery grounds for 70% of tropical fish species. Projects achieving verified net positive biodiversity outcomes - demonstrated by annual fauna and flora surveys at validation and each 5-year verification - are eligible for Biodiversity+. Blue carbon projects are among the most frequently awarded Biodiversity+ label holders in the Teravent registry.
Fisheries+
Projects demonstrating quantified fisheries productivity improvement - measured by fish assemblage surveys, invertebrate biomass estimates, or community catch data - are eligible for the Fisheries+ co-benefit label. Annual fisheries monitoring coordinated with local fishing communities is required. Fisheries+ is a blue carbon-specific label unique to Annex F and Annex G (Peatland) projects with adjacent fisheries connections.
Coastal Resilience+
Mangrove and salt marsh projects demonstrating verified coastal protection value - measured by wave attenuation modelling, community flood event reduction records, or storm surge buffer assessment - are eligible for Coastal Resilience+. Projects in areas with documented cyclone or storm surge exposure and vulnerable coastal populations are priority candidates for this label.
Livelihoods+
Projects generating verified income improvements for coastal fishing or aquaculture communities through improved fisheries productivity, community-run ecotourism, or sustainable non-timber coastal products - with documented income data verified annually - are eligible for Livelihoods+. Community benefit-sharing arrangements distributing a portion of carbon revenues directly to fishing households must be documented and independently verified.
Priority regions: India (Sundarbans - world's largest mangrove forest; Andaman & Nicobar Islands; Gulf of Kutch mangroves; Kerala backwater seagrasses; Chilika Lake seagrass meadows), Southeast Asia (Indonesia - world's largest mangrove area; Philippines; Vietnam Mekong Delta), Pacific Islands (Fiji, Solomon Islands, Papua New Guinea - high-biodiversity mangrove and seagrass systems), South Asia (Bangladesh Sundarbans, Sri Lanka mangroves), East Africa (Tanzania, Mozambique, Kenya - rapidly degrading mangrove coastlines with strong community co-benefit potential), and Australia (Queensland and Northern Territory mangroves and seagrass meadows supporting dugong populations).
