‘Coral reefs in western Indian Ocean run the risk of collapse’

NAIROBI: Rising sea temperatures and overfishing threaten coral reefs in the western Indian Ocean with complete collapse in the next 50 years, according to a groundbreaking study of these marine ecosystems.

The findings, published in the journal Nature Sustainability on Monday, warned that reefs along the eastern coast of Africa and island nations like Mauritius and Seychelles faced a high risk of extinction.

For the first time, researchers were able to assess the vulnerability of individual reefs across the vast western reaches of the Indian Ocean, and identify the main threats to coral health.

They found that all reefs in this region faced “complete ecosystem collapse and irreversible damage” within decades, and that ocean warming meant some coral habitats were already critically endangered.

“The findings are quite serious. These reefs are vulnerable to collapse,” lead author David Obura, founding director at CORDIO East Africa, a Kenyabased oceans research institute.

“There’s nowhere in the region where the reefs are in full health. They’ve all declined somewhat, and that will continue.”

The study, co-authored with the International Union for Conservation of Nature, assessed 11,919 square kilometres of reef, representing about five percent of the global total. Reefs fringing picturesque island nations like Mauritius, Seychelles, the Comoros and Madagascar - popular ecotourism destinations heavily reliant on their marine environment - were most at risk, researchers said.

Coral reefs cover only a tiny fraction - 0.2% - of the ocean floor, but they are home to at least a quarter of all marine animals and plants.

Besides anchoring marine ecosystems, they also provide protein, jobs and protection from storms and shoreline erosion for hundreds of millions of people worldwide.

Obura said healthy reefs were “very valuable” and their loss would prove “a double whammy”.