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Catching a break at Malaekahana, on O‘ahu's windward coast.
Vol. 11, No. 3
June/July 2008

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Raising the Reef (Page 3)

More than two decades ago, the Waikiki Aquarium began systematically raising coral for use in its exhibits. In the early 1990s there was a growing concern about the sources of the coral displayed in public aquariums, which rely upon suppliers in places like Fiji, Indonesia and the Solomon Islands. Although there’s now a trend toward culturing corals and other organisms for the aquarium trade, back then much of the live coral was collected right off the reef. Aquariums had little idea where their coral came from or whether harvesting them harmed the reefs. “We’re probably unique,” Delbeek says, “in that we can say exactly which reefs all our corals come from in the wild. We even have the GPS coordinates for some of the species in our collection.”

Visitors to the aquarium can get a sense of how coral farming works in a special exhibit near the Hawaiian monk seals. Despite the prior reservations of marine biologists, who felt corals were too fickle and sensitive to raise in captivity, coral husbandry turns out to be fairly straightforward.

What we perceive as a single mass of coral is actually a colony of thousands or millions of individual organisms called polyps. In the hard or stony corals, these polyps remove calcium from sea water and secrete the skeleton most of us know as coral. Soft corals don’t grow this hard skeletal structure; instead, their polyp colonies coat rocks or dead coral stone and can resemble a mass of anemones. For both kinds of coral, one form of reproduction is asexual, the simple multiplication of polyps in the colony; thus all you need is one finger-size fragment—a “frag” in the trade—and you can grow a new colony, a genetic clone of the original.

The tanks of the aquarium’s coral farm are fabulously congested with colonies of both stony and soft corals. They grow surprisingly fast. Stony corals can grow as much as 8 inches a year. The impressive samples of purple-tipped staghorn coral that overshadow the giant clams in the Barrier Reef exhibit began as basketball-size chunks only a little more than two years ago. Now they’re shading out other corals, and Delbeek is considering replacing them with smaller pieces. Soft corals are even more prolific. “They grow like weeds,” Delbeek says.

Of course, it’s not as easy as it sounds. It turns out that there are a lot of things to know about growing coral. Lighting, for example, is critical. The Waikiki Aquarium is unusual because its tropical location means that natural light can be used for many of the exhibits. The climate is also a factor. “We can easily do exhibits outside,” Delbeek says. “Other aquariums really can’t. We can just dig a hole in the ground, where other facilities would have to spend millions.”

Delbeek also stresses the importance that water chemistry—calcium levels, alkalinity and pH—has on the health of coral. Part of the aquarium’s unusual success in growing coral might have to do with its extraordinary water, which comes from a saltwater well deep underground. After percolating through 80 feet of calciferous rock, the chemistry of the water is different from normal sea water. Then it’s vigorously aerated to remove excess carbon dioxide. The result is a perfectly clear fluid that one researcher calls “miracle water.” Its superior quality is so sought after that one of the benefits of membership at the Waikiki Aquarium is the privilege of bringing its water home for your private aquarium.

While most public aquariums now have a live coral exhibit, at the Waikiki Aquarium almost every display contains live coral. Except for a small amount of seed stock—frags carefully collected from around the tropical Pacific—all the coral on display at the aquarium was raised on the premises. But one of the principal functions of the aquarium’s coral husbandry program is to supply live coral to other institutions. “I’ve been here since 1995,” Delbeek says. “During that time, we’ve sent out more than 6,000 frags to other aquariums. There’s probably not one aquarium in America that we haven’t sent coral to.” Kathryn Harper, the aquarium’s director of community outreach, highlights the scale of the operation: “We could do this full time if we wanted—there’s enough demand.” The aquarium, which is owned by the University of Hawai‘i, cooperates closely with scientific institutions like the National Oceanic and Atmospheric Agency and the Hawai‘i Institute for Marine Biology. “Right now we’re working with scientists who need samples of genetically identical Hawaiian coral,” says Delbeek. “We also sent about 600 Acropora frags to an environmental consulting company doing research on the effects of crude oil on coral.” Concerns about human effects on coral reefs, like the ship grounding that wiped out nearly 20 acres of reef in ‘Ewa, lend impetus to the coral research at the aquarium.

“Now we’re working with rare Hawaiian corals,” says Delbeek. “That’s the direction we want to move in.” Among the more fascinating corals in his care is a small collection of deep-sea corals recently collected in the ‘Au‘au Channel off Maui. “These are Leptoseris,” Delbeek points out. “They were collected at more than 100 meters—the world’s deepest-occurring photosynthetic coral.” The aquarium is trying to grow this species out so that scientists will have enough material for their research. Another Hawai‘i species in the collection is Montipora dilitata. “This coral is believed to be only found in Kane‘ohe Bay,” Delbeek says. “It’s currently classified as a species of concern by NOAA, but it may soon be listed as endangered.”

Perhaps the greatest threat facing the world’s corals is the worldwide epidemic of coral bleaching thought to be associated with global warming. When exposed for an extended period to higher than normal temperatures, many corals will expel their zooxanthellae—the symbiotic algae that live within the polyps, produce their food and give them their color.

“Hawai‘i’s far enough north that we haven’t really been affected by frequent coral bleaching events yet,” says Delbeek. But eventually, Hawai‘i’s reefs will also face this threat. Hawai‘i’s corals are already under stress from pollution, human damage and invasive algae that choke out the sunlight. Part of the aquarium’s interest in expanding the coral farming project is to be able to restock wild populations of Hawaiian corals after a die-off. The aquarium has more than 100 species of stony coral alone, including several Hawaiian species. Although the current state of the world’s coral reefs is alarming, Delbeek says there’s still some room for optimism. “If the conditions are good, the coral comes back,” he says. “Last October, I was diving in the Solomon Islands and saw a section of reef that just ten years ago was all dead. Now it’s completely covered with living coral.”

That resilience is crucial to the aquarium’s vision to become a kind of seed bank. And maybe one day, in addition to supplying coral to the public aquariums of the world, the pullulating colonies of coral in this improbable farm will help save the fragile reefs of Hawai‘i. HH