Coral reefs are the rainforests of the sea. And yet, in Zanzibar they are diminishing at an alarming speed. In Mnemba, corals are now artificially re-grown.
Corals are critically important ecosystems hosting more than 25 per cent of all marine life. Their decline threatens local livelihoods, fisheries and tourism. The pressures on Zanzibar’s reefs mirror threats facing coral reefs around the world: increasing water temperatures resulting from climate change, tropical cyclones, destructive fishing practices, plastic waste and, last but not least, unregulated tourism.
The reefs adjacent to Mnemba Island and northern Unguja Island – a very popular snorkelling and diving spot - annually contribute an estimated one million dollars to the local economy via eco-tourism. However, the pressure on these reefs “has led to their rapid degradation, with live coral cover significantly reduced to only five per cent of the reef area”, says the environmental group “Ocean without borders”. A coral reef restoration project on Mnemba Island now includes a quite spectacular community-owned artificial reef site.
Tiny corals growing up like babies
The project kicked off in September 2021. An area near the original Mnemba Island Reef was selected as a living underwater laboratory for the project. In 15 so-called coral nurseries made of nets and frames new corals are re-grown. The “successfully cultivated coral colonies will soon be transplanted onto degraded sections of the Mnemba Reef”, the organisation announced. The experiment is comparable to a hair transplant for a bold guy.
At this crucial point some funding from the European Outdoor Conservation Association (EOCA) became available. Against several competitors worldwide 30,000 euro were awarded to the Zanzibar group of Dr Tessa Hempson, a marine biologist, diver and special representative of Mnemba owner andBeyond. The activist said: “We are thrilled to receive this important funding that will have far-reaching benefits across marine research and education in Zanzibar.”
More pressure by more hotels?
But what about the on-going pressure on the reef by ever expanding tourism on the island? Directly opposite the quiet Mnemba private island with its small barefoot luxury retreat , a large new hotel and villa project with more than 1000 beds are being built on mainland Zanzibar. “The andBeyond team together with the marine conservation department in Zanzibar are keeping a close eye on these developments to ensure no further negative environmental impact”, the company said.
The reef rebirth in Mnemba is one of the daily activities undertaken by “Oceans Without Borders”. Three days a week marine rangers go underwater to check on the coral nursery. It’s a scientific task almost like a space mission – but underwater. To create the artificial new colony, corals were collected from a variety of sites around Mnemba Island. The GPS location of every small part is recorded before it is glued with cement to the so-called coral table. To ensure healthy growth, algae is brushed off each coral piece. The fragments, a mix of different species ensuring genetic biodiversity, take between 25 and 40 weeks to grow into a transplantable coral colony.
Local reef custodians
A team of local marine rangers, headed by coordinator Nancy Iraba, collects the research data. School learners, young people, boat operators and fishermen have already been brought into the boat, so to speak. They learn about tending the underwater nursery, are involved in beach erosion surveys and spend plenty of interactive community time. The next phase of the project will create a full additional reef. Fishers, tour guides and school children will become local reef custodians – for a healthy sea in Zanzibar.
