Gazing out over the Indian Ocean from Mnemba Island, it’s astonishing to think that just three years ago, the vibrant coral reef around this part of Tanzania’s Zanzibar archipelago was dying. The reef faced severe threats from climate change, overfishing, and human activities, putting the islanders’ livelihoods at risk and possibly forcing them to relocate.
Determined to save the colorful, oval-shaped reef close to shore, the local community embraced a conservation project that has managed to restore some of the lost beauty. This initiative also aims to protect the reef, renowned worldwide for its splendor.
The water is so clear that the reef, lying 10 meters (32 feet) below the surface, appears almost within reach. However, a few years ago, locals noticed the coral was stressed, partly due to warmer sea temperatures caused by climate change. Coral, while resembling plants, are actually tiny creatures called polyps that grow slowly, forming hard shells by extracting salt from seawater and fusing into colonies.
Reefs are often called the “rainforests of the sea” because they support diverse marine ecosystems. However, when water temperatures rise, the coral expel the colorful algae that provide nutrients, leading to bleaching and death. Additionally, dynamite fishing and unregulated tourist activities were damaging the coral.
Fishmonger Juma Mshindan observed a stark decline in fish availability, a clear sign of trouble. In response, the sustainable tourism group &Beyond and non-profit Africa Foundation began collaborating with islanders in September 2021. They established underwater nurseries using steel-mesh tables to grow coral fragments, which local divers, trained as conservation rangers, then replant on the reef.
This project has shown promising results, with 80% of the “house reef” around the island restored. “It’s like they have grown by themselves,” says conservation ranger Hija Uledi. “We have restored the reef, and you can’t tell the difference. Now there are fish around. The work is great, and many species can be seen.”
Artificial reefs made of steel and stone were also created 3 km off the island, where newly grown coral from the nurseries is planted, benefiting marine life and becoming attractions for snorkelers and divers.
Dr. Camilla Floros of Africa Foundation’s Oceans Without Borders programme emphasizes the importance of using the right materials for artificial reefs, learning from past mistakes. The success around Mnemba Island is largely due to community support, with new initiatives always discussed with locals.
Local resident Atuya Omar, who joined as a conservation ranger, shares how the project has helped her provide for her family and support her son’s education, despite facing conservative opposition as the only woman in the project.
The conservation efforts, supported by local authorities, led to the designation of the seas around Mnemba as a protected area by the Zanzibar government in 2022. This allows measures to limit damage from tourism and fishing. Restrictions on tourist numbers and increased fees have improved both environmental preservation and revenue.
Fishing has been suspended around the house reef, leading to positive changes. Illegal practices have decreased, and fishermen have become more aware of sustainable methods. Inspired by the Mnemba project’s success, the Zanzibar government plans to expand it to other threatened areas.
The pressures on Zanzibar’s reefs reflect global threats to coral reefs. Those involved in the Mnemba project hope their efforts can serve as a model for other areas at risk. “The relationship between the sea and coral is crucial for ocean health. We’ve witnessed corals regenerating, even at significant depths,” says Mr. Jaha. “We are allowing sea conditions to restore the reefs to their original state.”
