The ecosystem stack
A 30-arc-second grid, cells about a kilometre across, is laid over the site. The ecosystem functional groups of the IUCN Global Ecosystem Typology are stacked in every cell, each at its true depth on ETOPO and GEBCO bathymetry.
Species and condition
A habitat crosswalk links 31 functional groups to more than 17,000 IUCN Red List taxa, narrowed to those recorded in the site’s region. Population trends and threat status give stability; human pressure, weighted by each species’ sensitivity, gives fragility. Together they give resilience.
Honest uncertainty
Every MBCU carries an uncertainty band built from four sources: Red List data quality, species expected but not yet confirmed, data-deficient species and model error. Every run also states its minimum detectable effect: the smallest real change the system can tell apart from noise.
Verification in the field
Observations are matched to the desk inventory through the World Register of Marine Species. Each confirmed species narrows the band, and not seeing a species is never counted as its absence. Field methods: environmental DNA, baited cameras, dive transects and passive acoustics.
A counterfactual
MRV builds matched controls: areas in the same country with the same mix of ecosystems, outside the protected area. Both sides are designed to be re-scored as new pressure data arrive, so gains can be credited to protection rather than chance.
