Looking now at the Indian Ocean from the island of Mnemba, it’s hard to believe that just three years ago the stunning coral reef that surrounds this part of Tanzania’s Zanzibar archipelago was dying.
Under threat from climate change, overfishing and other human activities, islanders faced the loss of their livelihoods and the prospect of moving completely.
Eager to save the colorful, oval-shaped reef, which lies quite close to the coast and is about 7 km (4.3 miles) long, communities on the small island embraced a conservation project that managed to restore some of what was lost. .
The initiative also aims to protect the reef, which is known worldwide for its beauty, in other ways.
The water is so clear that the reef, which lies 10 m (32 ft) below the surface, appears almost within touching distance.
But a few years ago, locals started to notice how stressed the coral looked — part of this was due to climate change, which brought warmer sea temperatures.
Coral may look like a plant, but it’s a kind of animal – actually several tiny creatures called polyps. They grow very slowly and form a hard outer shell by extracting salt from seawater, then fuse together to form what we call colonies.
Reefs are sometimes called “rainforests of the sea” because they create ecosystems that support a wide variety of marine life.
But when the water heats up a few degrees more than normal, it causes the coral to expel the colorful algae that live inside and provide nutrients. As the algae leaves, the coral disappears, becomes bleached and eventually dies.
Dynamite used by fishermen has also killed coral, as has the volume of tourist boats and unregulated divers causing damage to the reef.
Mnemba Island fishmonger Juma Mshindan says it was clear something was very wrong: “There is a significant difference in the availability of fish then compared to now. In the past, fish were abundant.”
Sustainable tourism group &Beyond and nonprofit Africa Foundation began collaborating with islanders in September 2021 to help resolve some of these issues.
Underwater nurseries have been created using steel mesh tables, where coral fragments are grown to be replanted on the coral reef.
They are cared for and fed by local divers who have been trained as rangers.
It takes about two or three months for a coral colony to form and then the rangers take them to the reef.
The results so far are encouraging, with 80% coverage restored in the so-called “home reef” that surrounds the island.
“It’s as if they grew up on their own,” says ranger Hija Uledi.
“We restored the reef and you can’t tell the difference. Now they have fish around. The work is great and many species can be seen.”
Conservationists have also created artificial reefs – steel and stone structures that have been placed about 3km from the island and where rangers also plant newly grown corals in the nurseries.
The aim is to help replenish marine life – which benefits fishermen and has also become a destination for snorkelers and divers.
Dr Camilla Floros, lead scientist for the Africa Foundation’s Oceans Without Borders programme, says the ongoing restoration scheme is careful to work with the right materials – learning from past mistakes around the world.
“When artificial reefs were in their infancy, people used the wrong materials, like tires, to try to create them, which is not the right approach,” she says.
The success of the regeneration work around Mnemba Island is due to the support of the local community, acknowledges Dr Floros.
“Whenever we have a new initiative, we discuss it with them and get their buy-in,” she says.
Atuwa Omar is a local resident who was involved in the restoration. Before taking on the ranger role, the 24-year-old was at home looking after her young son.
“Being a ranger on this project on Mnemba Island not only allows me to provide food for my family, but also supports my son’s education,” she says.
Although Ms. Omar admits that it has not been easy for her as she is the only woman working on the project.
She has faced conservative attitudes from some who don’t want women involved – but she says such challenges have been worth it.
Conservation groups have been working hand in hand with local authorities and the seas around Mnemba have been designated a protected area by the government of Zanzibar, a semi-autonomous part of Tanzania, in 2022.
This means that measures can now be taken to limit the damage caused by tourists and fishermen.
Bakari Jaha, coordinator of the Africa Foundation Zanzibar, points to the amount of tourist traffic that used to visit the house reef.
“Initially, the area faced significant pressure from tourism, with 200 boats carrying at least 400 guests entering an area of just 200 square meters,” he says.
“To preserve the area, the government, together with &Beyond and the Africa Foundation, decided to limit the number of visitors to 80.”
In the past, visitors paid $3 (£2.40) – this cost has now increased to $25.
“This approach not only improved environmental preservation, but also increased revenue,” says Jaha.
Fishing has also been suspended around the house reef while it is being restored.
“We saw positive changes. Illegal practices such as the use of dynamite have decreased and fishermen have become more knowledgeable about sustainable fishing methods,” says fisherman Mshenga Ally.
The Zanzibar government says it is so encouraged by the success of the Mnemba restoration project that it plans to expand it to other threatened areas.
“The government has identified 14 areas with undamaged reefs and others with damaged corals and we are planning to preserve them,” said Dr. Makame Omar Makame, director of the Zanzibar Marine Department.
“We placed buoys so that people can be careful, understanding that fishing activity is not permitted in that location.”
The pressures on Zanzibar’s reefs reflect the threats facing coral reefs around the world. Those involved in the Mnemba project say that although they cannot stop the warmer sea currents, they hope their efforts can help other threatened areas.
“The relationship between the sea and corals is crucial to the health of the oceans. We have witnessed coral regeneration, even at significant depths,” says Jaha.
“We are allowing sea conditions to restore the reefs to their original state.”
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