Farmed Coral Transplanting Project The Second Phase | General Incorporated Foundation - Okinawa Convention & Visitors Bureau Busena Marine Park Office

1. Formulation of farmed coral transplanting plan

2020 marked the 50th anniversary of Busena Marine Park. As a commemorative project for the milestone and one of the SDGs activities implemented by the Okinawa Convention & Visitors Bureau (OCVB), Busena Marine Park decided to formulate and implement a farmed coral transplanting plan in cooperation with the nonprofit organization Coral Okinawa, which works on coral preservation.

Busena Marine Park is a tourist facility managed and operated by OCVB, which was registered as an “Okinawa SDGs Partner” on February 1, 2021. OCVB clearly stated in the SDGs Plan submitted to the prefecture that it puts maximum effort to preserve the natural environment of Busena Marine Park.
OCVB was registered as the Okinawa SDGs Partner.

Since 2022, we and The Terrace Hotels Co., Ltd. have cooperatively conducted a coral transplantation project with the financial support of Aramco Asia Japan K.K. through the Okinawa Coral Reef Conservation Consortium.
In implementing this grant support, a project start-up report meeting was held in June 2022.

Okinawa Convention & Visitors Bureau Busena Marine Park supports the Sustainable Development Goals (SDGs.)

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Currently, many different organizations implement coral transplantation, but a standardized method or technique has yet to be established. It is not uncommon for monitoring research after transplantation to reveal a survival rate of 0%. However, there are cases where corals transplanted over 20 years ago have successfully grown and even reproduced. Busena Marine Park referred to past examples when deciding how, where, and what type of coral to transplant.
Additionally, the transplantation plan follows the “Okinawa Prefecture Coral Transplantation Manual” and “Japan Coral Reef Society: The Transplantation Guideline for Reef-Building Corals.”

Permission of Coral Transplantation

Since Busena Marine Park is designated as a marine park area by the natural park law, it is necessary to obtain permission from the prefectural governor when implementing a coral transplantation. Development within the marine park area is strictly restricted, and only acts related to academic research, restoration after natural disasters, and public welfare are allowed.

The Okinawa Kaigan Quasi-National Park - Marine Park Area

The marine park area is the waters separated by the line connecting 300 meters northwest of Cape Busena and 200 meters northwest of Cape Nakama, stretching from Kise in Nago City to Nakama in Onna Village.
About The Okinawa Kaigan Quasi-National Park - Marine Park Area

When implementing coral transplantation, simply placing coral seeds on the seafloor does not work. It is necessary to fix the coral using wire or to adhere it, including its base, using special glue.
According to the Natural Park Law, the wire and the base are considered artificial objects. Therefore, permission to "install artificial objects in the marine park area" from the prefecture is required.
Okinawa prefecture had not previously permitted anyone to install artificial objects for coral transplantation within the marine park area, including Busena Marine Park.
However, after continuous consultation with the Department of Environmental Affairs Nature Conservation Division of Okinawa Prefecture, permission was granted in February 2021.

We requested permission for the second phase transplantation from the Department of Environmental Affairs Nature Conservation Division of Okinawa Prefecture. The permission was granted again in January 2023. Additionally, we applied for “permission for new construction of structures and use of public property” from the Department of Civil Engineering and Construction Hokubu Regional Public Works Office and received permission in February 2023.

Selection of transplanting location

Coral is a highly sensitive creature; therefore, it cannot grow well under unsuitable conditions. The transplanting location must be selected carefully, considering multiple factors such as depth, water quality, water temperature, current direction, seafloor conditions, the presence of natural enemies, and more.

Additionally, the location must be easily accessible so that visitors can observe the corals in the future.
We have selected a transplanting location near the pier of the glass-bottom boat that meets the following conditions:

Conditions for the selection

The location is approximately 3 meters deep, close to the pier, and easy to access for transplantation and monitoring.
The seafloor is flat and rocky, which is ideal for coral transplantation.
There are nearby living coral reefs in good condition that demonstrate suitable conditions.
The presence of a current prevents coral bleaching due to high water temperatures during the summer.
There are few natural enemies of coral, such as Crown-of-thorn starfish, Coral-eating gastropods, and Parrotfish.

Source of “mother” coral and its type

The Okinawa Fisheries Adjustment Regulations prohibit the gathering, possessing, buying, and selling of reef-building corals. Therefore, legally cultured coral must be used for coral transplantation.
There are multiple facilities that culture coral in Okinawa, but we asked Sango Batake, which has excellent experience in coral preservation, to provide the mother coral of Plate Coral.

We collected and planted broken branches of the abundant Branched Montipora Coral found in Busena Marine Park that were carried away by waves.
However, it is necessary to obtain Approval of Special Collection to collect these pieces. After continuous consultation with the Fisheries Division of Okinawa Prefecture, permission was granted in November 2022.

We decided on transplanting coral species based on the following conditions.

It is a common species and has easily obtainable donor (mother) corals.
It can be obtained from the west shore of Okinawa main island to ensure genetic proximity to the corals already inhabiting the area.

It is cultured by a reliable farm.
There are past examples of successful transplantation of the species, and it has a high potential to survive after being transplanted to Busena Marine Park.

Plate CoralPavona decussata

Different from branched corals, it develops a thick plate-like vertical structure that is durable against physical impact such as strong waves. As a pioneer species, it starts growing in environments with hardly any other organisms, promoting the growth of other types of corals. There is an established method to nurture the seedlings, and there are many successful cases of transplantation in the past. It is one of the most resilient species for the high water temperatures in the summer.
Branched Montipora CoralMotipora digitata

Currently inhabiting species at Busena Marine Park has a high potential to survive after transplantation. Its vertically growing branches make it less susceptible to being covered by sand. It is possible to obtain a donor (mother coral) within Okinawa prefecture, and there is an established method to nurture the seedlings with many successful cases of transplantation in the past. It is relatively resilient to high water temperatures.

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The coral transplantation guideline of the Coral Reef Society states that "one should take maximum care to avoid genetic pollution of the coral reef ecosystem."
It is important not to introduce coral species that are not native to the area. Additionally, even when transplanting species that are already present in the area, special care must be taken if they are being transplanted from a remote location to prevent genetic pollution of the existing coral colonies."

2. Nurturing coral seedlings

The coral seedlings were nurtured at Sango Batake, a provider of the mother coral. Sango Batake is the largest coral farm in Japan that can culture up to 300 thousand coral seedlings at maximum. The facility implements coral transplantation by gathering natural corals based on special permission from the Okinawa prefecture and breeding them.

The Plate Coral seedlings were fixed on both Ryukyu limestone plates and simply installable coral implantation devices and then nurtured in the water tank of Sango Batake.

Report

For the second phase of transplantation (September 27, 2022), transplant project personnel prepared about 60 seedlings of Plate Coral.

Nurturing and preparing coral seedlingsThe following is the procedure for creating coral seedlings from donor (mother) corals.

Place pieces of coral cut from the donors on bases made of Ryukyu limestone and secure them using natural rubber. After being nurtured in this condition for a few months, the coral pieces will form membranes and adhere to the bases.

To minimize damage, the securing process was performed underwater quickly. When secured with natural rubber, the pieces of coral were placed on the bases in a way that maximizes their adhesive area.

3. Coral Transplantation Work

Method

While there are several methods for cultured coral transplantation, we tried two new methods, namely “transplantation using simply installable coral implantation devices” and “transplantation using mesh pots,” for the second phase transplantation in addition to the "glue method," which was adopted at the first phase.

Report

Two transplantation events took place during the second phase. On March 3, 2023, the transplantation was carried out using the "glue method" and "simply installable coral implantation devices." On March 21, 2023, the transplantation was carried out using ”mesh pots.”
Before entering the water, the participants received a briefing on coral transplantation. For safety reasons and to comply with time limitations, the transplantation position and procedure were carefully confirmed before the work began.

Transplantation work

Glue
Method
Transplantation using simply installable coral implantation devices
Transplantation using mesh pots

Step1

Enter the water from a pier at Busena Marine Park and carefully transport the coral seedlings to the transplantation site 30 meters offshore.
Step2

Remove any algae from the surface of the site using brushes, as they reduce the adhesion strength of the underwater glue.
Step3

After removing the algae, mix the glues quickly in the sea and apply the mixture to the base of the coral seedlings. The required amount of glue per seedling is approximately the size of a golf ball.
Step4

Adhere the coral seedlings to the seafloor using the underwater glue. It can be challenging to work in the water, but the workers should apply as much weight as possible to the seedlings to ensure proper adhesion. If the adhesion is not sufficient, adjust the position and use new glue to try again.

Step1

Enter the water from a pier at Busena Marine Park and carefully transport the coral seedlings to the transplantation site 60 meters offshore.
Step2

Confirm that no organisms are inhabiting the seafloor around the transplantation site and then place the simply installable coral implantation devices.
When installing, make sure that the devices adhere closely to each other with enough care to properly fix the Plate Coral.
Step3

Since the seafloor is uneven due to gravel and rocks, make a fine adjustment of the position so that the devices are settled well.

Step1

Collect pieces of the Branched Montipora Coral, which are broken by strong waves, at the spot 80 meters offshore where Branched Montipora Coral develops.
Step2

Place pebbles in mesh pots, then place pieces of Branched Montipora Coral on top.
To secure the coral, place additional pebbles on top. Carefully transfer the prepared mesh pots to the transplantation spots.
Step3

The transplantation is carried out at sandy spots where seagrass, such as sickle seagrass, thrives. Make indentations on the surface of the sandy seafloor and place mesh pots in them to prevent them from being moved by waves.

5. Record of corals’ growth

Monitoring the growth and survival rate of transplanted corals is critical.
To achieve this, Busena Marine Park conducts research at one week, one month, three months, six months, and one year intervals after the transplantation. Here are the results of this research.

5.Future goals and tasks for Busena Marine Park

The coral transplantation project at Busena Marine Park was launched to commemorate the park's 50th anniversary. Starting from the second phase (FY2022), we have been conducting the project in cooperation with The Terrace Hotels Co., Ltd. and with financial support from Aramco Asia Japan K.K. through the Okinawa Coral Reef Conservation Consortium.
To preserve the rich oceanic environment at Busena Marine Park, we will continue cooperation with businesses nearby and research institutes.

For over 50 years, Busena Marine Park has been a pioneer in marine tourism in Okinawa, sharing the beauty of the Okinawan ocean with both local residents and tourists. To continue fulfilling this role, we will drive activities related to the Sustainable Development Goals, such as the cultivated coral transplantation project