Scaling Up ʻĀkoʻakoʻa

When we think of restoring coral reefs along the West Hawaiʻi Island coastline, most people think of caring for coral, promoting pono fishing practices, and reducing wastewater pollution. Those are all true and vitally needed.  We also need to recognize that our coral reef ecosystem, like others in Hawaiʻi and around the world, has been and will continue to be impacted by ever-warming summers and periodically destructive marine heatwaves. 

With each heatwave, corals bleach and die, and with that comes a weakening of the physical (carbonate) structure of the reef. In other words, a reef that is not actively growing its corals is actively falling apart and dissolving back into the ocean. Forces of coral growth must win over forces of coral decay in order for our reef to survive.

When we first envisioned ʻĀkoʻakoʻa, we knew that culture and communities would be our paramount focus, since the reef is only as important as its people who care for and rely upon it. Caring for the reef remains central to our program, but our science turns out to be the pathway to scaling the restoration processes needed to keep the forces of coral growth winning over the forces of coral decay. How do we achieve that goal?

From the beginning, we also knew that simply outplanting corals is too narrow a perspective. While that process is helpful for education, public awareness, and refining restoration approaches, it is unable to meet the challenges that face our reefs and simply can’t generate the self-sustaining “whole reef” future we all envision. To reach the scale of entire coastlines, we rely on our advanced reef diagnostics program. Driven by our airborne laboratory’s unique system for measuring coral growth and death along the entire coastline, we match these efforts with our field program supporting exploration of reef processes to harness and guide restoration of the reef as a whole.

From this diagnostics program, we know that nearshore currents and their seasonality are hugely influential and important. This includes the movement of biological slicks, the ribbon-like smooth features on the ocean surface along West Hawaii’s coastline that many confuse as boat wakes. We also know about land-based pollution, which negatively impacts our reef ecosystems and impedes restoration efforts. Finally, and most importantly, we know where corals give birth and where they settle along the West Hawaiʻi coastline. In fact, this is the critical combination needed to harness mother nature’s already well-established processes. Knowing how and when corals move empowers us to turbocharge the process over areas of reef far larger than can be approached using more traditional, site-specific restoration methods.

Our restoration approach, tested and rolled out in ʻĀkoʻakoʻa involves two integrated activities. First, our Reef Nurseries initiative expands from our past culturally-based site approach with high-tech knowledge of coral larval flow along the coastline. The result is a series of “Reef Nursery” sites where we reattach the largest corals that have broken off and decayed due to past marine heatwaves. These large corals are too big to bring into our nursery, yet if given a chance to recover in the water, they will produce billions of coral babies, “larvae”, each year. The Reef Nurseries are located to serve as coral larval “source” areas to support settlement “sink” areas down-current (think “downstream”) in areas that have been cut off from baby coral flow due to previous adult coral losses.

Our second restoration approach is called Targeted Larval Enhancement, and it builds upon the Reef Nurseries. This approach involves taking medium-sized sick corals from the same Reef Nursery sites, rehabilitating them in our coral nursery, and then integrating them into mass larval production in our facility. Our approach assists nature by boosting the natural reproductive cycles of corals. When too many corals on a reef die, the remaining individuals become too isolated to reproduce effectively, which is a primary reason why our reefs are struggling to recover on their own. This is where we step in to help.

Our process begins by simply selecting adult corals that demonstrate a natural resistance to warmer water. At the facility, we cross-breed these resilient corals to produce offspring that inherit this heat tolerance trait. Next, we collect eggs and sperm from these selected corals and raise billions of larvae in our nursery. Once they are ready, we transport them to our Reef Nursery sites that are already strategically located to serve a much larger area via nearshore current flow. By releasing the coral larvae in targeted areas, in high concentrations, we give them the best chance to survive to reproductive age, thus turbocharging the natural recovery process.

A key part of our strategy is called Assisted Larval Flow. In a healthy reef system, coral larvae can travel, which helps them mix and maintain robust populations over large areas. However, on degraded reefs like many in West Hawaiʻi, this natural process has been suppressed by past coral death, further hindering natural recovery. Using our understanding of currents along West Hawaiʻi, we rely on our Reef Nursery sites to maximize the effectiveness of future larval flow. By introducing large numbers of selectively bred larvae to our Reef Nurseries, we are achieving much more than just increasing coral numbers locally. We are strengthening the overall health and resilience of the entire reef, helping it better withstand future heatwaves and other climate-related challenges.

Fusion of our Reef Nurseries and Targeted Larval Enhancement is the science needed for the future of coral reefs, giving them the  best chance of winning the battle against climate change for years to come. ʻĀkoʻakoʻa is leading the effort, for our communities and as a demonstration to the world.

‍