Coral Recruitment Monitoring Project

Our scientists are trying to understand more about the corals in the Kwanini Marine Protected Area (KMPA). We wanted to know what makes corals settle and grow where they do? Are some species more competitive than others? What are the best conditions for corals to settle and grow? What makes them die off once they have become established? What are the threats to coral settlement and growth?

To regenerate a degraded coral reef, we need new corals recruits to settle in the damaged areas and grow to form a new reef. The reef in the KMPA at the Manta Resort has some areas degraded by human activities but are they slow to repair?

In a study of the resilience of coral reefs in the Pemba Channel in 2009, the International Union for Conservation of Nature (IUCN) suggested that one of the reasons for the lack of recovery is local stresses which may not prevent juvenile corals from settling but which may prevent them growing to a larger size. The question arises, what are the stresses that might lead to this lack of recovery. To answer this really important question we need to know something about how coral settles and how it grows.

We are pretty convinced that there are more fish inside our marine protected area than outside! We have resident schools of Trevally and Rainbow Runners of all size categories which are definitely on the increase. The fishermen seem to know it too and can regularly be seen fishing along the boundaries of the reserve. We have an excellent demonstration site to show the advantages of restricted access to small parts of the coastline.

Fortunately, we are in luck because the Manta Resort has an underwater room anchored to the sea bed by 4 large concrete blocks. It is in a sheltered location and the blocks make excellent monitoring sites so the juvenile corals on each block have been meticulously measured and photographed.

So far almost 100 juvenile corals (recruits) have been identified as they colonise these blocks, some just millimetres in size! The programme involves photographing and measuring the recruits every 6 months to see how they progress, how big they grow, what species are present, and when do they settle.

Answers to these questions might help us better understand why the degraded reefs in the Kwanini Marine Conservation Area are slow to regenerate. An underwater Sonde is also deployed on the site to giving daily readings of important sea condition such as temperature, salinity and oxygen levels.

Our next monitoring period will be in March 2019 – watch out for the results on the website in our documents downloads section!

If you go for a dive around the Underwater Room take a closer look at the blocks and see if you can spot our tiny corals! Ask your dive guide to point them out – they would be happy to help!