The coral reefs of the Western Indian Ocean are at high risk of collapse within the next five decades because of much ocean warming and overfishing, according to a latest study published today in the journal Nature Sustainability.
As per the IUCN Red List of Ecosystems criteria, coral reefs were assessed as ‘Critically Endangered in four of the sub regions (East and South Madagascar, the Comoros, and Mascarene Islands). It was listed ‘Endangered’ in West and North Madagascar and the Outer Seychelles. The study found rising seawater temperatures caused by climate change as the greatest threat to coral reefs in these island nations. In the remaining four sub-regions, in North Seychelles, and along the entire mainland East African coast from South Africa to Kenya, reefs were classified as ‘Vulnerable to collapse. Overfishing, by altering the ecology of reefs and promoting algal takeover, was found to pose the greatest overall threat in continental African countries.
CLEAR DATA
Lead author Dr. David Obura said that coral reefs are known to decline for quite some time and now it is precisely clear to what degree and why they decline. David Obura is the founding Director at Coastal Oceans Research and Development in the Indian Ocean (CORDIO East Africa) and Chair of the IUCN SSC Corals Specialist Group.
“This assessment reaffirms the urgency of the interlinked climate and biodiversity crises addressed by COP26 last month in Glasgow, and COP15 in a few months in Kunming. We need to take decisive action to address both global threats to corals from climate change, and local ones, such as overfishing,” he said.
Meanwhile, Senior Scientist and Programme Manager at CORDIO East Africa and a co-author of the study Mishal Gudka pointed out overfishing of top predators on all the reefs. “These results highlight the need to improve local fisheries management to ensure the health of reef systems and secure sustainable fish stocks, which support jobs for a quarter of a million people in the region,” he said.
DATA ANALYSIS
Director of the Centre for Society and Governance at IUCN Dr Radhika Murti said that the study was designed so that it can be applied to coral reefs around the world. “If the IUCN Red List of Ecosystems criteria can be applied to all coral reef regions around the world, we will have a clear and consistent picture of the status of these vital ecosystems globally and of the most urgent policy measures decision makers need to take,” she said.
The authors analysed data ranging as far back as 35 years as well as sea surface temperature projections 50 years into the future. Their study area included the east coast of continental Africa from Kenya to South Africa and east to the island states of Seychelles and Mauritius. In total, it comprised around 5% of the world’s coral reefs. The work was led by researchers from CORDIO East Africa. It also involved contributions from researchers across nine Western Indian Ocean countries and from more than 35 institutions.
