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News from our Resident Marine Biologist

Nyororo island

It wasn’t long ago that Nyororo Island was inhabited by between 500 and 700 fishermen, making it extremely difficult for the island to be actively protected. Since March 2007 all three islands on the western side of Mafia, Nyororo Island, Mbarakuni, Shungimbili (Thanda Island) and their surrounding waters, have been declared a Marine Reserve under the management of Marine Parks and Reserves Unit Tanzania and are actively protected today. The Marine Reserves are established as a no-take area, meaning that no fishing practices are allowed within the boundaries of the reserves. This provides the highest level of protection for the islands and their surrounding coral reefs. The Marine Reserves provide a refuge for endangered and commercial species, protect the coral reefs from destruction by human activities and provide a safe habitat for fish to reproduce and for juvenile fish to grow to adult size.

Coral bleaching and Indian Ocean Dipole

The Western Indian Ocean is suffering from a lot of coral bleaching at the moment and so are the reefs around Shungimbili Island. Corals have a symbiotic relationship with tiny algae, called zooxanthellae, that live inside the corals’ tissue. These algae provide the coral with energy from sugars produced via photosynthesis which is the main source of energy for the corals. The corals on their part provide a safe home for the algae. When corals get stressed, for instance, due to high temperatures or pollution, they start expelling these algae from their tissues. This leaves the transparent coral tissue as it is the algae that give the coral its colour. The transparent coral tissue shows the white skeleton underneath and the corals appear white or ‘bleached’. The current coral bleaching is linked to the persistent high seawater temperatures. The water temperature is currently still on 29 degrees Celsius whereas normally it would have gone down already this time of the year. This is likely to be caused by the positive Indian Ocean Dipole event of 2019/2020 which causes elevated sea temperatures in the Western Indian Ocean and increased rains in East Africa whereas the Eastern Indian Oceans is colder and dryer than usual. Hopefully now with the rainy season, the water temperatures will drop and the corals will recover.

Reef restoration

Thanda Island runs a small-scale coral nursery to assist the coral in growing faster and to stimulate reef recovery. It takes approximately one year for the coral fragments to grow to a size where they are ready for planting back on a reef or on an artificial reef structure. While this undoubtedly has aided the reefs surrounding Shungimbili Marine Reserve, the ultimate goal is to set up a large-scale reef restoration project with the support of the community of Chole Island, located in the Mafia Island Marine Park. This will provide jobs in coral conservation for the local community, helping to ensure the long-term recovery of the reefs near Mafia Island.

Photography: Temujin Johnson
Photography: Temujin Johnson

The nurseries and the transplantation at Shungimbili Island provide a great example for our guests to see reef restoration into practice, but in its current form, it is too small to make a significant difference on the reef. Jean de Villiers, the owner of Chole Mjini treehouse ecolodge and Kitu Kiblu responsible whale shark encounters, has an ambitious proposal to set up a large scale reef restoration project in Chole bay with the community of Chole Island. The project will provide jobs in coral conservation for the local community and educate them about marine conservation and could become a significant factor in the conservation and restoration of coral reefs in the Mafia Island archipelago.

Right now we have a once in a lifetime opportunity to start up a project like this as a result of the coincidence of three uncommon events.

1) A serious bleaching event has just happened/is still happening that has selected and is selecting for corals in Chole bay that are relatively heat tolerant.

2) Because of COVID-19, we have a period of about 6 months when scuba diving in Chole bay is at a standstill and scuba divers can be hired to do the work for a minimal wage.

3) Jean de Villiers is free and stuck in Mafia for the next 4 to 6 months because of COVID-19 so he will be able to personally train the divers and oversee the project.

The complete project is planned for a duration of 2 years and would require estimated funding of $50,000. After the first two years, the project is expected to be able to sustain itself and to continue with making a positive difference for the coral reefs in the area. Because of the unique situation at the moment, it would be a waste of valuable time to wait for the complete funding to be sourced. Therefore we are urgently looking for funding to cover the initial 4 months of the project. With around $14,000 the first 4 months could be funded and this will cover the setting up of a coral nursery for 10,000 found coral fragments which approximately 6 months later are expected to be ready to split into approximately 50,000 fragments, or being transplanted, or a combination of both. If you would be interested in supporting this promising project, please get in touch. The ocean and the coral reefs in the Mafia Island archipelago will be very grateful!

Above photos: Pictures of the beautiful reefs in Chole Bay (photography: Temujin Johnson)