Page 18 - LandscapeSA_115

ENVIRONMENTAL FEATURE

CORAL REEF RESTORATION

Known as tropical rainforests of the ocean, coral reefs are underwater cities

and although they occupy a very small percentage of the marine environment,
underwater ecosystems are home to 25% of earth’s marine life.

Mnemba Island coral reef restoration project

ike so many life-sustaining ecosystems, coral reefs are under with Marine Cultures, an NGO supporting small scale ecological
severe threat due to reef degradation, climate change, rising aquaculture conservation projects in Zanzibar. This partnership will
Lwater temperatures, sedimentation and human activities such as help to restore the ecological integrity of the Mnemba Island reefs,
destructive fishing practices, pollution, plastic waste, insensitive tourism protect the marine conservation area and support the sustainability
operations and coral mining. of local reef fisheries.

Coral reefs rely on sunlight and stable temperatures in order to grow, The Mnemba reef was selected as a living laboratory for the project and
which is why they are most commonly found in warm tropical waters, from an initial five coral tables used to cultivate the coral fragments,
which are also clear and shallow. When coral reefs become distressed there are now 22 and the nursery is set to almost double in size in the
by dramatic changes in their ecosystem (rise or drop in ocean coming year. Once the coral fragments have grown sufficiently, the
temperatures, extreme low tides or over- exposure to sunlight), they will successfully cultivated coral colonies will be able to be transplanted
expel the symbiotic algae that lives within their tissues, causing them to onto degraded reef sections of the Mnemba reef.
turn a stark white and leaving them vulnerable to disease. This is known
as coral bleaching and with prolongued algae loss and continued stress, The greater the variety of corals that are cultivated, the more chance
the coral will eventually die. there is that some species will show resilience as conditions and
pressures change. This will help to better conserve the ecosystem and
Coral reefs are 500 million years old but given the above-mentioned promote essential biodiversity in the restoration of the reefs.
threats, they are in danger of being lost permanently as they grow at an
average rate of only 2cm per year. The project also has funding to shape a community-owned artificial
reef structure as an alternate ecotourism site, which will reduce pressure
Coral reef restoration in Zanzibar on the Mnemba reef and support the newly transplanted corals. It will
Coral reef restoration can help span the gap between the present – also include the active participation of local communities and have far-
when existing coral populations are threatened with extinction – and a reaching benefits across research, education and the blue economy of
future ocean that is again hospitable to corals. Current work is showing Zanzibar.
that reef restoration is possible and by harnessing promising research
on ecological and genetic intervention strategies, restored reefs can Coral farming and outplanting
become more resilient. Corals are colonies of animals called ‘polyps’ and most reef-
building corals have polyps that live in symbiosis with algae called
In September 2021, the Oceans Without Borders Mnemba Island zooxanthellae. The algae live in the body of the polyp, providing it
community and conservation ranger team started a training course with food they produce by photosynthesis. By using small fragments

16 Landscape SA • Issue 115 2022