Pick Up Technologies


Coral Net

Katsunori Yamaki, Ph.D.
Environmental Engineering and
Bioengineering Group

Coral Conservation Initiatives

Kajima recognizes that addressing environmental issues, including climate change is a key management issue. The conservation and rehabilitation of coral reefs are one of the most important environmental issues.
Kajima is one of the oldest and largest Japanese general construction companies to have been involved in research and development on coral rehabilitation technology for more than 20 years.
Coral Net, Kajima’ s core coral rehabilitation technology, has been tested in Okinawa, Japan since 2003, and enables more stable coral rehabilitation than conventional technologies. The mesh-like structure of Coral Net reduces the accumulation of fine particles including red soil, which can cause stress to corals. Coral Net also allows suitable light and water flow, creating an enabling environment for natural settlement and growth of corals. The larvae of corals settle on the underside of the Coral Net, thus avoiding predation from organisms like crown-of-thorns starfish.

In order to effectively introduce technologies, such as Coral Net, for the conservation and regeneration of coral it is important to assess the marine environment in terms of time and space through on-site observations and the numerical oceanic simulation. The utilization of oceanic simulation allows for quantitative analysis of fluctuation in ocean currents, temperature, salinity, water quality, and other factors over a wide range and long period of time. Based on the simulation results, selecting suitable coral rehabilitation methods and implementation locations for the target marine area becomes possible.
Since 2023, Kajima’ s reef restoration project targeting coral reefs has expanded the implementation area in South-East Asia.

We will continue the research and development to apply its technology to coral reef restoration projects in Japan and around the world.

Key points!

Coral Net (Substrate to which coral larvae attach)


Concept and features of Coral Net


Biodegradable Coral Net (Plastic)
The Biodegradable Coral Net has been developed to preserve of coral reef ecosystems, and only the implanted coral remains after natural degradation within about 10 years.


Durable Coral Net (Stainless steel )
The Durable Coral Net is installed in concrete structures such as harbors. The Durable Coral Net can be stably installed even in environments with strong waves and currents.

Evaluation of marine environments suitable for coral growth using oceanic simulations

Decrease in water temperature and strong current during approaching typhoon.
Color: surface temperature, contour:atmospheric pressure vector: surface current velocity.

Calcification rate of coral reefs in Okinawa as a function of changes in the marine environment at coral habitable depths (shallower than 50 m).
During the day, coral photosynthesis is dominant, promoting calcification. In contrast, coral activity weakens at night when photosynthesis does not occur.


Application to Coral Reef in a Port
-Naha Port, Okinawa, Japan-

Application to Typhoon Damaged Coral Reefs
-Kerama Islands, Okinawa, Japan-

InCore Project
-Tangalan, Aklan Province, Panay Island, Philippines-

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