Western Indian Ocean

Countries included

Somalia, Kenya, Tanzania, Mozambique, South Africa, Mauritius, Madagascar, Comoros, Seychelles, La Réunion (France)


Swaleh Aboud
Researcher/Analyst CORDIO East Africa

Regional Context

Importance of coral reefs

The Western Indian Ocean (WIO) region comprises almost 6% (about 15,180 km2) of the total global area of coral reefs, and the region is a globally important hotspot for coral reef biodiversity.


The coral reef monitoring in the Western Indian Ocean (WIO) has been undertaken using the umbrella of the Global Coral Reef Monitoring Network (GCRMN) and the Nairobi Convention’s Coral Reef Task Force (CRTF), since the late 1990s. The CRTF was constituted by a decision of the Nairobi Convention in 2001, with a representative from each country.

Traditionally, the southwest Indian Ocean islands (SWIO) and the mainland East Africa nodes of the GCRMN have operated independently, but in the last decade, these have been integrated more closely through the CRTF. This effort is supported through projects in the Marine Programme of the Indian Ocean Commission – the ISLANDS Project (2009-13) and Biodiversity Project (2014-2018).

Keys numbers


Total area of coral reefs (km2)


Proportion of the world’s coral reefs


Countries with coral reefs


Marine Ecoregions of the World (MEOW) (i)

(i) Marine Ecoregions of the World (MEOW) is a biogeographic classification of the world’s coasts and shelves (Spalding et al., 2007).

Key figures from the 2020 report

Hard coral cover

Algae cover


  • 2021WIO Global Coral Reef Monitoring Network Data Training Course 
  • 2019Expert meeting of WIO Coral Reef Task Force/GCRMN regional network, 11th WIOMSA Scientific symposium, 5 July 2019, Mauritius
  • 2017Special Session: “2017 WIO Post-bleaching Assessment and Monitoring Sustainability”, 10th WIOMSA Scientific Symposium, Tanzania Report 
  • 2016Webinar, Reef Resilience Network,
    Overview of the 2016 WIO Bleaching Event & Discussion on Bleaching Management Plan
  • 2016Webinar, Reef Resilience Network,
    Preparing for Coral Bleaching in the Western Indian Ocean
Francesco Ungaro | Unsplash
Francesco Ungaro | Unsplash


Regional reports and guidelines from the Western Indian Ocean