Nosy Be

Raw observed numbers

• Coral cover: 27% (survey Sep 2024, GCRMN Western Indian Ocean transect)
• Bleached: 16%
• Recent mortality: 6%
• East Africa — observed condition reflects the thinning regional pattern.

Raw thermal numbers

• NOAA CRW alert level: No stress
• Degree Heating Weeks: 6.2 °C-wk
• SST anomaly: +0.7 °C

How we summarise this

Observed coral cover, bleaching, and mortality come from named in-situ surveys with a stated date and method — they describe one snapshot of one reef and do not extrapolate to neighbouring sites. Current thermal stress is satellite-derived from NOAA Coral Reef Watch at ~5 km resolution; it indicates risk, not observed coral damage. We deliberately separate observed condition, current thermal stress, and projection — and we never publish a projection without a documented model and uncertainty.

Sources

• Global Coral Reef Monitoring Network — GCRMN / ICRI
• NOAA Coral Reef Watch — U.S. National Oceanic and Atmospheric Administration
• AIMS Long-Term Monitoring Program — Australian Institute of Marine Science
• Atlantic and Gulf Rapid Reef Assessment — AGRRA Program / Perry Institute for Marine Science
• NOAA National Coral Reef Monitoring Program — NOAA Coral Reef Conservation Program
• Reef Check — Reef Check Foundation
• NOAA CoastWatch / OceanWatch — NOAA NESDIS / STAR
• Allen Coral Atlas — Arizona State University Center for Global Discovery and Conservation Science
• Great Barrier Reef Marine Park Authority — Australian Government
• International Coral Reef Initiative — ICRI Secretariat
• Reef Life Survey — Reef Life Survey Foundation
• NASA PO.DAAC — NASA Jet Propulsion Laboratory / Caltech
• Copernicus Marine Service — Mercator Ocean International for the European Union
• NASA Ocean Color (OB.DAAC) — NASA Goddard Space Flight Center / Ocean Biology Processing Group
• Argo float network — International Argo Program / UCSD
• CoralWatch — University of Queensland
• IMOS / AODN — Integrated Marine Observing System / Australian Ocean Data Network
• WRI Reefs at Risk Revisited — World Resources Institute
• Ocean Health Index — OHI partnership (Conservation International + UCSB + NCEAS)
• IPCC Special Report on the Ocean and Cryosphere (SROCC) — Intergovernmental Panel on Climate Change
• GOA-ON — Global Ocean Acidification Observing Network — GOA-ON Secretariat + IOC-UNESCO
• HAEDAT — Harmful Algae Event Database — IOC-UNESCO Intergovernmental Panel on Harmful Algal Blooms
• NCEI Marine Microplastics — NOAA National Centers for Environmental Information