On Zanzibar our first coral restoration projects were launched in 2012 together with the Swiss NGO marinecultures.org . We focused our activities in the lagoon in the Southeast of Zanzibar i.e. the area between the shore and the barrier reef. The barrier is approximately 2 kilometers away from the shore.
The lagoon has been hit hard by mostly climate change and overfishing. We decided to restore the reef by out-planting corals on natural substrate that had lost most of his coral cover. The corals were all farmed in our coral farm in Jambiani, see below how this works.
From 2012 the farm grew from 10 to 40 coral tables in 2017. The tables are at a depth of 8 meters and each table holds about 500 coral juveniles. Weekly about 180 coral juveniles where out-planted during the last years of the partnership, giving the area a significant supply with healthy new settlers. Over the years we developed a procedure together for coral farming and coral reef restoration that we both use in other regions as a guideline.
After almost 10 years of fruitful collaboration we ended the collaboration in order to to be able to initiate conservation projects elsewhere. But not after safeguarding marinecultures would be able to continue the operation. We left them with a completely renovated boat and an efficient organization and Marinecultures found durable funding by turning coral restoration training into a business model. For instance, income is now generated thru organizing training sessions in coral restoration with hotel staff in the area. A double win because the area of restoration is seriously expanded this way.
We are still in touch with the Jambiani team and will keep in touch the coming years to monitor the restoration project and see how our out-plants are doing.
How do we do coral farming and out-planting?
Corals are colonies of animals called ‘polyps’. Most ‘reef-building corals (i.e. hard corals) have polyps that live in a symbiosis with algae (i.e. plants) called the Zooxanthella. The algae live in the body of the polyp providing the polyp with food (see What are corals ). By using small fragments of a coral colony and planting these fragments somewhere else, we can give the colony a new living environment in which it can multiply and further grow. We have a special technique for this.
Coral farming and reforestation:
1st – on the reefs we look for pieces of coral that have broken off naturally by waves, storms, etc. These so-called ‘corals of opportunity’ we cut into smaller coral fragments.
2nd - a coral fragment is placed on a cement plug which is put on a nursery bed on the sea floor. We have about 40 beds, these coral nurseries we call the ‘coral farm’.
3rd - after approximately 4-8 months the corals in the nurseries have grown sufficiently. During the entire process our coral divers regularly clean the Juvenile Corals and the nursery beds: removing algae, sediment and predators like the Drupella snail or Crown of Thorns starfish.
4rd – in the meantime we select substrate to plant the coral plugs. We either plant the corals in existing reefs that have (partly) lost their corals, or we use artificial reef structures.
5th - the Juvenile Corals are moved carefully to the out-plant area. The plugs with the Juvenile Corals are inserted in holes that we drilled in the substrate and they are firmly fixed with cement. Another technique is to use specially made springs that push the coral fragments down on the substrate. The springs are connected into the substrate with a nail.
6th - we check the first weeks to see whether the plugs remain fixed on the substrate and clean the corals if necessary. After that it’s waiting for our new reef!
Some corals grow relatively fast, others slow. We try to make a natural reflection of the coral ecosystem in the area. The mix of planted corals is based on the example nature gives us. To farm and transplant genetic diversity within one coral species is of extreme importance. We safeguard this by our procedures that describe how to find corals and how to out-plant them. We keep abreast of new research on these issues to keep on fine-tuning the work method.
See for a more detailed description of this project: Coral reforestation procedure CRC, July 2020.