The coral reef is an area of primary production that cultivate ecosystems with high biodiversity, and it is also an important area as tourism resources. However, many of the coral reefs around the world tend to decline because of rising seawater temperature caused by global warming.
Meanwhile, the upsizing of ships has become a global trend along with the increase in demand for logistics, so dredging of routes and construction of harbors and fish ports are increasingly important. As a result, coral reef area came to be directly changed and coral growth came to be indirectly influenced by the coastal area development.
For these reasons, in Japan, as a measure to avoid, reduce or compensate for the influence on ecosystems in the development of coral reef, we have been developing coral reef propagation technology. Here we introduce the efforts of coral propagation technology and report on the result.
Our development of coral propagation technology began with producing a large number of juvenile corals by sexual reproduction. In the period from 2006 to 2008, we succeeded in producing about 30,000 juvenile corals in aquariums on land.
In addition, we developed an artificial foundation for efficiently transplanting a large number of juvenile corals, and made it possible to efficiently transplant about 200 juvenile corals per person in a day’s work. Now, since the survival rate of coral one year after transplantation is as high as 80 %, we believe that our technology has been mostly established.
However, the technology to produce juvenile corals in aquariums on land is costly, so we are currently undertaking the development of technology that can produce a large number of juvenile corals at a far lower cost. For that purpose, we developed equipment that is capable of collecting, rearing, and seeding natural coral larvae in situ. With this equipment, it is possible to produce corals at a considerably lower cost compared with the method of producing juvenile corals in aquariums on land, and to transplant a large amount of juvenile corals.