Coral Reefs and

Climate Change

Climate Vulnerability in the Comoros Archipelago

The Comoros islands are a poorly known volcanic chain of islands in between Mozambique and Madagascar in the ‘hotspot’ of coral reef biodiversity for the Western Indian Ocean. They still possess some beautiful areas of coral, but are threatened because of the combined effects of over-fishing, sedimentation from deforestation on land, coral mining and coral bleaching.

Also being a densely populated, developing island nation, there is an extremely high reliance on coral reef resources, meaning that marine conservation is essential for both the marine environment and the local population.

CORDIO sent an expedition to the smallest island, Mohéli, in late 2016 to assess the health and resilience of the reefs in the nation’s only MPA, Parc National de Mohéli (PNM), to climate change and human threats. This was done using SCUBA based methods. The results have just been published in the journal of Marine Pollution Bulletin. The study was conducted by Benjamin Cowburn, Melita Samoilys and David Obura funded through WWF Madagascar.

The study found a range of reef conditions, including healthy-looking reefs offshore and resilient reefs inshore, but others that appeared to be very degraded. Highly variable conditions included:

  • live coral cover ranging between 6% and 60%
  • target fishery species biomass ranging between 20 and 500 kg per ha.

This information was provided to local park management in the form of management report just after the fieldwork. The findings indicate different vulnerabilities for the different reef conditions and provide crucial information to better advise the sustainable management of the reefs in this remote archipelago.

The study concludes that climate impacts to date appear moderate and local human pressures are not having a major impact on components of reef health and recovery, suggesting these reefs are relatively resilient to the current anthropogenic stresses that they are experiencing.