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Her time in the underwater wasteland has gotten easier these days for coral research diver Lindsey Kramer.
Stationed in Kailua-Kona — ground zero for the worst recorded coral bleaching in state history in 2014 to 2016 — Kramer wept when she first witnessed the trails of telltale mucus drifting from pillared colonies that were 500 years in the making.
Some 80 percent of cauliflower corals are dead off West Hawaii. Gigantic colonies of mounding coral have succumbed — to the tune of 93 percent. As these structures disintegrate in slow motion, scientists worry the dead masses of calcium carbonate will break off and roll around, pulverizing the surviving corals.
But in the immediate aftermath of the bleaching — if you don’t look too hard at the devastation sleeping under the algae — you could almost pretend things are back to normal. Once bleached like bone, some 50 percent of the coral has recovered off West Hawaii, the state Division of Aquatic Resources determined last year.
“You kind of get used to coral mortality. It’s not quite so raw now,” said Kramer, who heads up the volunteer Eyes of the Reef Hawaii network for the island.
In the soul-searching that follows a disaster of this scale, scientists are now trying to determine what lessons can be learned from the survivors so that reefs stand a better chance in the future.
It’s what you do when faced with extreme but plausible scenarios like the wholesale loss of the earth’s reefs by mid-century as ocean warming churns out of control.
“A lot of it has to do with fighting the feeling of inevitability, like ‘it’ll all be gone,'” said Bill Walsh, a biologist with the state Division of Aquatic Resources. “Those are projections. What’s unique about this event is that we have caused it, but we’re here and we can do something about it.”
On the bright side, half of the coral survived the bleaching, and there are stellar performers out there, Walsh noted. He was talking about two particular species found off West Hawaii that hardly suffered at all under the thermal fluxes that killed off fields of their neighbors.
Start with Acropora gemmifera. The coral has been identified nowhere in the Main Hawaiian Islands except for a patch near Keauhou. When water temperatures well above 80 degrees whitened corals on both sides, the Acropora pulled through largely intact.
“They may have been stressed, but as far as we can tell there wasn’t much mortality,” Walsh said.
Scientists have no idea how the sturdy coral — found in parts of the Northwestern Hawaiian Islands — came to take up residence here, or how to account for its toughness.
“We need to be thinking outside the box on how we can stabilize reefs now and make them strong enough to face a future that is warmer and more acidic.” — Ruth Gates, Hawaii Institute of Marine Biology
The second survivor is an uncommon plate and pillar coral found off Makalawaena north of Kailua-Kona. Survey divers finned their way through a single valley of Porites rus in October 2015. They wrote off the area, about a third the size of a football field, as bleached and dead.
“We came back in February of 2016 expecting it to all be dead,” Walsh said. “But there was 97 percent recovery of this particular species. It’s the most optimistic story line we have.”
This resilience is now guiding conversations about coral and the future of the reefs.
“What doesn’t kill you makes you stronger,” Walsh said. “If there is a bleaching event and the coral can make it through, it’s more likely to make it through future events and the offspring will presumably have some genetic advantage. But that remains to be seen.”
At the Hawaii Institute of Marine Biology, Ruth Gates is trying to take those concepts to the bank. As a lead researcher and director of the institute, she is working to breed coral that can withstand a heavy thermal punch.
But engineering is no substitute for good stewardship or abandoned conservation measures of the past, scientists caution.
“We don’t want just one species out there; we want all of our species healthy,” Kramer said.
Within weeks, the state is expected to release a recovery plan for Hawaii reefs. The plan is based on the suggestions of more than 140 coral experts around the globe, whose input has been refined by a group of Hawaii-based stakeholders who — in part — offer a reality check about what can actually be accomplished.
“One of the highest things on the list is to keep sediments and pollution out of the ocean,” Walsh said. “What happens on land is critical to what happens in the ocean, especially in a stressed environment.”
Other steps will include establishing a network of areas where herbivorous fish are protected, allowing them to live in peace while grazing on coral-smothering algae.
Introducing resistant corals like those found at Keauhou and Makalawaena will also be on the table. Ultimately, it will be up to the state to decide which suggestions to act upon.
Other scientists are racing for answers as well. The Nature Conservancy is conducting surveys on West Hawaii reefs to try to determine where resistant species are located and why they are doing better than other corals.
While it’s exciting to identify hardy residents like Acropora and Porites, healthy ecosystems depend on multiple coral species, sizes and growth forms, said Chad Wiggins, the island’s marine program director for The Nature Conservancy, in an email.
“Regarding the potential for ether species to be building blocks for future reefs, I might recommend caution for the foreseeable future,” Wiggins said. “Neither is currently a dominant coral on reefs in Hawaii and the Acropora genus which is dominant at reefs like Palmyra and Papahanaumokuakea, is relegated to a very narrow geography — a single reef.”
Gates agreed that selective breeding can’t take the place of intelligent conservation.
“It is critical to maintain our pace trying to take care of local problems like sediments and nutrients and pollution coming in,” she said. “Coral treated well will do well going into a bleaching event.”
The caveats don’t detract from the promise of Gates’ work to generate a super-coral in hopes it can one day be planted on a massive scale.
“We need to be thinking outside the box on how we can stabilize reefs now and make them strong enough to face a future that is warmer and more acidic,” she said.
Gates successfully bred thermally tolerant coral last year. Her research involves subjecting coral to artificial high temperatures and selecting and breeding the most tolerant survivors. This genetic “directing” has gone on for centuries as humans created superior crops, animals and trees, Gates pointed out.
Coral reproduce annually, and within a few years Gates expects to have answers on whether this super-coral can indeed be realized. She also expects to know if the project can be scaled up to the size of an entire reef.
“What happens next? Can they reproduce and will they repopulate the reef?” Gates said. “There is still a lot of science to be done and we really don’t have a lot of time to mess about.”