10/8/24 – The West Hawaiʻi Coral Restoration Program

In the past, DAR’s coral restoration work in West Hawaiʻi has been mostly limited to responding to physical damage events like ship groundings, anchor damage, and dislodgement from boat moorings. The newly formed West Hawaiʻi Coral Restoration Program (WHCRP) provides DAR with additional staff that can now not only respond to physical damage to the reef but also dedicate time and resources to conduct active coral restoration projects along the west coast of Hawaiʻi Island. This program will focus on designing and testing coral restoration methodologies in Kealakekua, Kahaluʻu, and Keauhou after consulting with community leaders from these areas. Staff will also work to remove at-risk corals from man-made structures such as day-use moorings, seawater intake pipes at NELHA, and off-shore fish mariculture pens and outplant them onto nearby reef substrates. Lastly, DAR is working in collaboration with Arizona State University (ASU) to test and operate a land-based coral nursery in the HOST park. The WHCRP will integrate these diverse coral restoration activities to develop comprehensive recommendations for best practices tailored to the unique reef conditions of the west coast of Hawaiʻi.

One of DAR’s key restoration sites is located within Kealakekua Bay. Restoration staff regularly join community meetings to discuss restoration planning and implementation. The restoration design that was created with help from community leadership involves reattaching corals of opportunity (COOs – dislodged corals) back to the reef to increase their chances of surviving long-term. Restoration and control plots will be mapped and monitored over the next several years to begin assessing what methods have the most success at each specific site.
 
1-month-old coral

1-month monitoring of a transplanted coral of opportunity (knocked off the reef) growing over the cement adhesive.

Rubble zones can also be a challenge for restoration efforts. These areas are typically unfavorable environments for coral recruits because of the poor structural integrity. DAR is conducting rubble stabilization tests utilizing basalt and galvanized steel mesh within Kealakekua Bay. The goal for this mesh is to hold the rubble in place and allow for natural recruits and coral fragments to re-establish a sturdy reef structure. Divers will return to these stabilization areas to attach COOs to the mesh to further the recovery of the reef substrates. Preliminary observations of the mesh show signs of great stability.

basalt and steel mesh

1-month monitoring of basalt (left) and galvanized steel (right) mesh secured to a rubble zone within Kealakekua Bay.

Another source of corals for restoration use are man-made structures.  The west coast of Hawai‘i Island has numerous moorings often decorated by cauliflower and antler corals (Pocillopora meandrina and P. grandis, respectively). Removal from mooring lines becomes necessary when the added weight of the corals compromises the functionality of the mooring, or when the line itself has to be replaced as a part of regular mooring maintenance. In the past 5 months DAR staff have conducted 4 separate coral removal events within Makako Bay and Kohala in anticipation of mooring maintenance. Some of the corals were transplanted immediately, while others were brought back to the land-based nursery for husbandry research. In September, some of those nursery corals were returned to Makako Bay (where they originated) and reattached to the reef using different adhesives: marine epoxy and cement. These corals will be periodically monitored to determine which reattachment method is most suitable for these transplants.

mooring line with corals

Mooring line in Makako Bay overgrown with Pocillopora corals.

DAR staff have been working with Arizona State University (ASU) to build and operate the first large scale land-based coral restoration nursery on Hawaiʻi Island. The Ridge to Reef Restoration Center (3RC) was officially opened in April 2024 and has been running continuously ever since. Of the 72 raceways on-site, 8 currently contain corals from different regions throughout the west coast of Hawaiʻi Island. These corals are being used for sexual reproduction, asexual propagation, gene banking, and thermal tolerance research. DAR staff are building and maintaining databases to track coral collections, nursery holdings, outplanting, and monitoring.

restoration center

Ridge to Reef Restoration Center (ASU land-based coral nursery – collaboration with DAR)

DAR is partnering with various organizations and community groups to explore and monitor different coral restoration techniques. This collaborative effort is crucial for gathering diverse insights and improving restoration practices.  Initial efforts include reattaching coral fragments (COOs) and corals growing on man-made structures. This method is not only cost-effective but also a practical first step in rehabilitating damaged reef areas. Testing rubble stabilization techniques is particularly important for addressing “dead zones,” areas that are typically avoided in restoration planning due to their challenging conditions.  Collaborating with ASU to enhance land-based coral restoration techniques, such as fragmentation and sexual reproduction, is a forward-thinking strategy towards larger-scale restoration efforts. This approach aims to increase the capacity for growing coral tissue in controlled environments, which can then be used for active restoration on the reef.  The WHCRP is working to broaden the scope of coral restoration efforts across the west coast of Hawaiʻi Island. This expansion aims to increase the impact of restoration activities and support the recovery of coral reef ecosystems.