Photographs by Daniel Sullivan
Restoring Honolua Bay
In May 2025 at Māʻalaea Harbor, six divers and two snorkelers from Maui Ocean Center and the Marine Institute at Maui Ocean Center (MOCMI) loaded 246 coral fragments onto a boat bound for Honolua Bay on Maui’s west side. The fragments came from four species; crews had collected them from broken colonies at Honolua and kept them alive in a Māʻalaea nursery.
Their return began with a yacht on coral.
In February 2023, the yacht Nakoa broke loose from its mooring and grounded at the north end of Honolua Bay, just outside the Honolua-Mokulēʻia Bay Marine Life Conservation District. It sat in shallow water for nearly two weeks. State of Hawaiʻi divers later measured more than 19,000 square feet of damaged coral and reef live rock.
The damage at Honolua came on top of pressures already reaching Maui’s reefs: warming water, runoff, sediment, pollution and coastal development. Across Maui, various organizations are coming together to protect the ecosystems offshore. At Māʻalaea, MOCMI staff and volunteers keep coral alive in nursery tanks. Along leeward Maui, reef monitors fill sample bottles, divers pull fishing line from coral and researchers lower speakers beneath buoys.
After crews removed Nakoa from the reef, two Maui Ocean Center coral specialists helped the nursery team collect damaged coral colonies for rehabilitation.
In the nursery, which uses saltwater pumped from Māʻalaea Bay, staff trimmed the Honolua colonies into fragments and glued them to aragonite plugs. They cleaned algae with dental picks so light could reach living tissue. Staff target-fed some corals a daily blend of algae, spirulina, fish, oysters, mussels and krill. For 26 months, the nursery team cleaned, fed and checked the coral every day.
During the final month before outplanting, staff moved the fragments under filtered outdoor sunlight to help them transition back into the ocean. Back in Honolua Bay, two dive teams attached them in a 36-foot-wide zone near the shallower area where crews had collected them.
The outplanting didn’t erase the yacht scar. It put living coral back on the reef where the broken colonies had come from. If the fragments survive, they can grow across the reef surface and add structure to part of the damaged zone.
“We feel it’s a privilege and honor to do this work on behalf of the community of Maui,” said Dustin Paradis, MOCMI’s executive director. “Honolua is a very special place for many reasons, and we hope this effort can provide some healing and closure for the community.”
MOCMI operates Maui’s only land-based coral-restoration nursery, where staff and volunteers care for coral fragments in tanks before outplanting. Its state special activities permit allows the institute to respond to coral-damage incidents. Maui Ocean Center provides nursery space and infrastructure.
The nursery sits beside Māʻalaea Bay, where runoff has troubled coral for decades.
Tracking Water Quality
Hui O Ka Wai Ola is a water-quality monitoring program co-managed by Maui Nui Marine Resource Council (MNMRC), The Nature Conservancy and West Maui Ridge to Reef Initiative. Since 2016, the program has collected and analyzed more than 5,500 samples from 58 sites.
On sampling days, trained volunteers gather water at knee depth, check turbidity with an onsite meter and keep nutrient samples cold for lab testing. Turbidity shows how murky the water is; nitrates can point to fertilizers, wastewater or other land-based pollution.
Māʻalaea Harbor opens into Māʻalaea Bay on Maui’s south-central coast, below dry slopes cut by gulches. After heavy rain, runoff carries soil and pollutants downhill toward South Maui reef flats. Sediment clouds the water, blocks sunlight and can coat living coral.
In 1972, researchers described Māʻalaea’s reef as striking for its coral diversity and rare species. As late as 1993, estimated coral cover near the site was 50-75 percent. By the time of later monitoring, cover there had fallen to about 8 percent. State summaries described a degraded reef overgrown by algae, with poor fish stocks.
Hui O Ka Wai Ola’s 2016-2025 report recorded high turbidity and nitrate levels across leeward Maui, including Māʻalaea Harbor to South Kīhei. It also flagged brown water from coastal erosion and storms from Māʻalaea to North Kīhei, where nitrates ranked second only to Cove Park.
Since 2023, MNMRC crews have repeated South Maui surveys of coral, fish and invertebrates. At Māʻalaea, those surveys show which corals remain, which fish use the reef and whether conditions change as upstream projects continue.
Coral as Ancestor
Scientists count coral in fragments, cover, survival rates and water-quality readings, but in Hawaiʻi the story reaches farther back. In the “Kumulipo,” the ancestral Hawaiian creation chant, coral, or koʻa, appears near the beginning of life – not only as reef structure, but as ancestor.
“Coral polyps, they’re one of our oldest ancestors and unfortunately, we failed them to a certain degree,” Dane Maxwell, Maui Ocean Center’s cultural advisor, says in the documentary film Coral Guardians.
The chant begins in darkness, then birth: Kumulipo, Pōʻele, the coral polyp, the coral. Sea cucumbers, sea urchins, oysters, limpets and other sea life follow in the chant, generation by generation. Coral isn’t a metaphor added later. It is there at the start.
Building Reef Habitat
At Keawakapu Beach in Kīhei, the next piece is concrete – literally.
MOCMI and the State of Hawaiʻi Division of Aquatic Resources, or DAR, are attaching nursery-grown corals to old concrete blocks at the Keawakapu Artificial Reef.
Some have been there for decades. The added coral is meant to attract fish, build habitat and test methods that could inform future erosion and shoreline protection. Staff plan to attach more corals later in 2026 or early 2027.
Farther south at Keoneʻōʻio, also known as La Perouse Bay, Pacific Whale Foundation divers surface with coils of fishing line, hooks and lead weights. Some line settles over coral like a net, gathers algae and keeps herbivores from grazing. Pacific Whale Foundation says its cleanup program has removed more than 4,100 pounds of debris from the reef and estimates about eight tons remain.
Mapping Maui’s Mother Reefs
At ʻOlowalu in West Maui, Kaiku Kaholoaʻa is studying how coral larvae travel by current to other reefs across Maui. Kaholoaʻa, a Native Hawaiian from Molokaʻi pursuing a doctorate at Stanford University, uses genetics to trace where larvae go after spawning.
During spawning, coral colonies release eggs and sperm into the water, often in synchronized pulses tied to seasonal and lunar cues. Fertilized eggs become larvae, which drift by current until they find a hard surface to settle and begin new colonies. Survival depends on timing, current, water conditions and a clean place to land.
Kaholoaʻa’s research helps show which reefs may seed others across Maui Nui. Researchers call them source reefs, or mother reefs; other reefs “self-recruit,” meaning most larvae settle where they began. Scientific connectivity models identify ʻOlowalu as one of those source reefs, able to send larvae toward damaged reefs across Maui.
Kaholoaʻa’s coral genetics research also looks for heat tolerance. His dissertation uses genetics to identify connected reefs across Hawaiʻi and sites where corals are more likely to survive warm water. In lab experiments, researchers test Maui Nui fragments in warm water, then watch which survive.
The results help identify reefs to protect first. Kaholoaʻa said even heat-tolerant reefs still need protection from overfishing, pollution and other stressors; some may carry genes that help other reefs survive warmer water.
After earning his doctorate, Kaholoaʻa plans to return to Hawaiʻi and continue his research before eventually becoming a professor at the University of Hawaiʻi at Mānoa so he can “uplift other Native Hawaiians interested in marine science.”
ʻOlowalu is also part of MOCMI’s heat-tolerance research. There, the institute and the Hawaiʻi Institute of Marine Biology’s Coral Resilience Lab are testing how corals respond to warmer water, Paradis said.
“This challenge to restore and protect our reefs requires not only ingenuity, but also a team effort,” he said.
Listening for Reef Recovery
Beneath six buoys in Maui waters, speakers play fish croaks, purrs and grunts mixed with the crackle of snapping shrimp. Those sounds are common in healthy reef soundscapes. Researchers are testing whether coral larvae use those cues when choosing where to settle.
Scientists from Woods Hole Oceanographic Institution, or WHOI, based in Woods Hole, Massachusetts, have studied coral acoustics on Maui for the past two years. In earlier research, WHOI found that broadcasting the soundscape of a healthy reef can encourage coral larvae to settle at higher rates, though researchers caution that sound is only useful if the larvae settle where they can survive.
On Maui, the test began in nursery tanks at Maui Ocean Center. In summer 2024, WHOI researchers used five coral species in the nursery. In summer 2025, they moved offshore, placing five buoys along the south coast and one on the west side to play recordings from a healthy reef.
The acoustics project also includes Maui Ocean Center, DAR and NOAA’s Hawaiian Islands Humpback Whale National Marine Sanctuary. Researchers will compare the sound-enriched sites with control sites that play no reef recordings, measuring whether the sound of a healthy reef helps new coral find a place to settle.
Whether it starts as a larva or nursery fragment, coral needs attachment, light, clean water, space and time.
At Honolua, the 246 fragments are back in surge and sunlight, attached near the original scar. MOCMI staff will watch for attachment, clean tissue, new growth and algae overgrowth. If the fragments hold fast, living coral can begin covering damaged reef, one edge of new growth reaching over the broken place.
