At the edge of the reef on Molokaʻi's east end, Kaʻiku Kaholoaʻa is researching the thermal tolerance of corals.
“For colony 17, we have that stark white bleaching. It’s a clear five,” he tells volunteer researcher Carly Kajiwara, as she ranks results in a notebook. “This is a major sensitive coral to heat.”
Under a makeshift tent, an intricate network of tubes and cords connects a series of coolers. Kaholoaʻa and his small team of research volunteers are peering at chunks of coral they have carefully labeled.
“What that tells us is that this coral, this colony that we pulled off the reef, is actually really susceptible to climate change, and that when those heat waves come in the future out there in the wild, this individual wouldn’t do as good,” Kaholoaʻa explains.
That reaction to rising water temperatures is called coral bleaching.
Volunteer Kanoe Aiu, a fellow Stanford student from Hawaiʻi, explains how she and volunteer Nichole Ishii are grading coral samples based on color.
“We're just going through and giving visual bleaching scores from one to five. So one is a coral that looks healthy and has all of its color,” she says. “A five is a coral that doesn't have any color anymore.”
Over six days, heaters in the tanks incrementally bring water temperatures up during set periods each day to mimic low tide and midday heat.
“The most that they experience is 37 degrees [Celsius] and in Fahrenheit, that is 98.6, so it's really hot water — like saimin water,” laughs Kaholoaʻa. “But what we found is that some corals are actually surviving throughout the entirety of the experiment. It's very low, but some of them are really resistant, and that's what we wanted to capture.”
They’re testing about 1,000 samples from 25 sites on Maui and Molokaʻi that they collected in accordance with scientific gathering regulations during dive sessions. Half of the samples are kept at control temperatures for accuracy and comparison.
“[A score of one] is as happy as it gets, and a five will look totally white,” says Aiu, holding up a sample they’re examining. “If you look inside the polyps, there won't be any dots of color. So this one, I see a little bit of color still inside the polyp, it looks a little darker than the surrounding tissue. So I would probably give this one a four.”
Kaholoaʻa's research centers around the idea of thermal tolerance, or how much heat a coral can withstand before bleaching.
“The really cool part is that thermal tolerance is genetic,” he says. “The fact that thermally tolerant parents produce thermally tolerant keiki is a really important deal, because this means that coral populations have the potential to acclimate and build a resistance to climate change conditions.”
Coral colonies spawn by releasing eggs and sperm simultaneously, based on the lunar cycle. Where they end up is what’s especially interesting.
“These larvae, is what we'll call them, drift around in the currents, wherever they go, and they're the ones that actually create our new reefs,” explains Kaholoaʻa.
The larvae can stay alive for up to 40 days, traveling great distances.
Testing a theory
Based on the work of previous researchers tracking those coral larvae, Kaholohaʻa wants to prove a theory.
The Olowalu reef in West Maui is believed to be a mother reef, or a genetic origination point for spawning neighboring reefs.
“We found that Olowalu harbors lots of thermally tolerant corals, so it already has that potential to be a critical reef area.”
Along with other areas of Maui, Kaholoaʻa theorizes it is also a mother reef of the extensive Kawela Reef Track on Molokaʻi's south shore. Genetic testing from the samples he’s taking on Maui and Molokaʻi will confirm whether or not the theory is true.
Genetic testing takes time — and money. Kaholoaʻa says it might be as long as two years before he gets back the results, in part because of financial challenges with federal research funds being cut. But that’s not stopping him from pressing ahead.
“What we're doing is finding those thermally tolerant reefs, those areas with a lot of thermally tolerant corals, but ultimately those highly connected reefs,” he says. “Our goal is finding those combination ‘aliʻi reefs’ that have both thermally tolerant corals — a lot of them — and will seed future reefs across Maui Nui and maybe even Oʻahu.”
Ultimately, he hopes his research could lead communities to seek designations as marine protected areas, shown to be heat-tolerant mother reefs — bringing greater resilience to coral of the future.
He says those designations need to be created by Hawaiians, for Hawaiians.
“My job is to help you, all you community members, know what reefs you have on your island is most important, and share that information with you and your leaders,” he says. “Your job is to decide if you want to protect your areas, and if so, how you want to protect those areas.”
Inspiring Hawaiians in science fields
Rising ocean temperatures are just one factor among many negatively affecting reef health. Other impacts can come from sedimentation and runoff, overfishing and irresponsible human behaviors like trampling delicate corals. A mauka to makai approach is important to creating a healthier ecosystem for coral, Kaholoaʻa says.
Born on Molokaʻi, Kaholoaʻa grew up with a close connection to the ocean and its cultural significance. Marine science became the link that tied his cultural connections to his desire to protect Hawaiʻi's reefs. He says learning to dive and practicing a sustainable lifestyle at Moʻomomi with his ʻohana is also where he first saw coral bleaching and was taught about the concept in middle school.
After graduating from high school on Oʻahu, Kaholoaʻa got his bachelor’s in molecular biology and is now a doctoral candidate at Stanford University. As part of his work at Stanford’s Palumbi Lab, he had the opportunity to travel to other small coastal communities around the world to see their coastal conservation methods.
Now two months into the field work portion of his dissertation, he’s sharing his research with communities on Maui and Molokaʻi. Presentations have been supported by local organizations like ʻĀina Momona, Marine Institute Maui Ocean Center, Kipuka Olowalu and The Nature Conservancy.
Kaholoaʻa says he hopes one day to be a role model for Native Hawaiian youth in science, because he didn’t see that representation growing up.
“Whenever I dreamed about being a scientist, I imagined being an old white guy on an old boat doing specific things,” he says. “It just never occurred to me that I could be an old Hawaiian guy in a wa’a, doing my work.”
He hopes to do just that as he fulfills his goal of coming home to become a University of Hawaiʻi professor in molecular biology — though admits he struggles with "imposter syndrome."
“I feel like I can make a huge difference in the next generation, just serving as a Native Hawaiian role model in science — letting our keiki see that if you want to be a scientist, this is what a Native Hawaiian scientist looks like,” he says. “It's just in the middle of the surfing and the paddling, you just got to work on protecting your oceans and your community.”
In the meantime, he hopes his research can help Hawaiians "understand that these different communities are actually very much connected through their coral reefs."
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