Healthy coral reefs are some of the most biologically important and economically valuable ecosystems on the planet. Hawaiʻi’s nearshore coral reef ecosystems are home to many species unique to Hawaiʻi, have a special place in Native Hawaiian cultural traditions, and provide food, jobs, coastal protection, and other valuable goods and services to millions of residents and visitors.
Coral reefs in Hawaiʻi and around the globe are increasingly threatened by climate change, pollution, coastal development, overfishing, and other stressors. In response, in 2016, the State Division of Aquatic Resources (DAR) committed to effectively managing 30 percent of nearshore waters for healthy coral reefs, sustainable fisheries, and local communities by 2030 under the Holomua: Marine 30-by-30 Initiative.
Holomua means “to go forward,” and DAR aims to work with communities to improve nearshore waters and marine resources for present and future generations. The Holomua Initiative focuses on developing and strengthening the essential components of effective management, including development of a resilient marine managed area network, statewide fisheries rules, outreach and enforcement strategies, restoration, and monitoring. Driven by community input on management priorities, DAR will incorporate the best readily available science and cultural advice to achieve the Holomua Initiative’s goals.
“It became clear that we could assist coral reef management and restoration activities in Hawaiʻi by supporting data collection on three fronts: where coral reef resources exist, the current status of those resources, and how reefs may change as a result of climate change and other stressors over time,” said Charlotte Hudson, project director of the Lenfest Ocean Program. “This is a truly collaborative effort bringing together scientists using novel technologies, the Division of Aquatic Resources and other management bodies, and partners like The Nature Conservancy Hawaiʻi.”
Understanding the current condition of Hawaiian reefs statewide is critical for identifying the locations where management efforts might be most effective. Managers and communities require information at different scales, including details on corals across the entire archipelago, as well as data at the island and community levels. Maps have an important role in delivering this information. However, mapping coral reef ecosystems is a complex task and there are a variety of techniques, each with different strengths and limitations in terms of the level of detail provided and the geographic area covered.
To complement existing mapping efforts and collect high-resolution data statewide, the Lenfest Ocean Program began conversations with Arizona State University’s Greg Asner, and other partners, to launch a project in 2019 to map Science to Support Coral Reef Management in Hawaiʻi’s coral reefs. Asner’s Center for Global Diversity and Conservation Science uses an airplane-based laboratory to collect large amounts of data about the condition of natural resources.
“We undertook the most high-resolution statewide aerial mapping effort to determine where corals currently live in Hawaiian waters to support efforts by partner organizations, identify more cost-effective management and restoration activities, and enhance public engagement,” Asner said.
Using airborne remote sensing, artificial intelligence, and other tools Asner and his team generated a detailed, bird’s-eye view of the geographic distribution of live and degraded coral down to 50 feet below the ocean’s surface across the entire archipelago - more than 750 miles of coastline.
“Our new approach also pointed to areas where corals were more resilient to stressors. Resource managers and communities can use this information to collectively target their coral reef management efforts,” Asner points out.
Exploring how coral reefs may change in a dynamic ocean and with equally dynamic stressors, such as more frequent climate change-driven marine heatwaves, is a key question managers and communities must address when making decisions about coral reef management and restoration activities. Research led by Jeffrey Maynard, director of SymbioSeas and in collaboration with The Nature Conservancy’s Hawaiʿi Marine Program, will help provide answers. With support from the Lenfest Ocean Program, Maynard launched the research project in 2020 to model and map coral reef vulnerability and resilience to multiple threats, including ocean warming.
“The project goals are to assess the relative vulnerability of coral reefs to climate change for each island and archipelago-wide, understand the drivers of vulnerability, and identify actions managers can take to reduce climate vulnerability,” Maynard said. “Over the next year, we will use climate models, coral bleaching data, and other information to predict which coral reefs are likely to decline over time because of warmer sea surface temperatures.”
The team will examine the mapping data along with ecosystem data from long-term monitoring efforts by the state and partners, which includes characteristics like macroalgae coverage, herbivorous fish biomass, and the physical characteristics of the reef, to assess resilience to climate change and identify the location of Hawaiʻi’s most resilient coral reef ecosystems. These details will then be combined with data on reef fishing, invasive species, and sediment pollution to examine vulnerability to the impacts of climate change.
In other words, if the purpose of Asner’s project is to provide diagnostic information about coral health, this project will complement that effort by providing prognostic, or predictive, information.
“Our team and local partners can then identify areas and actions where protecting reefs, improving the abundance of herbivorous fish communities, and focusing reef restoration efforts can be most successful,” says Kim Hum, Marine Program Director for The Nature Conservancy in Hawaiʻi. “Combined with the maps provided by Dr. Asner’s lab, local community knowledge, and data from in-water surveys, this information can help the state and partners most effectively target their management and restoration efforts under the Holomua Initiative.”
Ultimately, the new, high-resolution coral reef maps and information on coral vulnerability and resilience to climate change and other stressors will paint a clearer picture of the state’s coral reef resources. This will be useful as managers and communities continue to implement Hawaiʻi’s Holomua: Marine 30-by-30 Initiative, as well as statewide coral reef restoration efforts.