Hong Kong has a long coastline and as many as 84 species of hard corals; one tenth of the total number of reef-building corals in the world. Corals are known as the "tropical forests" of the ocean as they provide complex microhabitats for many marine species to shelter and breed, enriching the marine ecology.
However, corals are very vulnerable to adverse impacts and require high water quality. Slight changes in sea water temperature, salinity or clarity can lead to their bleaching or even their death. Observations made by our divers reveal that the number of hard corals and their related ecosystems have been decreasing in recent years. For example, at Double Island, Sai Kung, the coral population has declined by up to 80% in the last decade. There are various reasons for this reduction, including global warming, pollution, net fishing and leisure water sports, which all affect corals to different degrees.
As hard corals grow and recover rather slowly, they are hard rebuild from damage through natural regeneration alone. However, artificial transplants can accelerate their recovery. Places around the world such as Taiwan, Malaysia and Singapore have all succeeded in artificial transplantation.
The first step of artificial coral transplantation is to collect suitable corals from other areas. In order not to harm the original coral colonies, divers will only collect coral fragments that have fallen off due to a variety of reasons such as typhoon damage. Divers will check the health status and species of the coral fragments, and transplants can be conducted upon suitability being confirmed. As corals can reproduce asexually, when divers fix the coral fragments in suitable target growing locations, the fragments will grow slowly and achieve restoration eventually.
Green Power working with Eco-education & Resources Centre and a group of local divers, carried out artificial coral transplant in June 2014. The present stage is rather experimental, focusing near Double Island. 1,500 square metres of hard corals are expected to be restored in 5 years.2021