Waikíkí Aquarium researchers are maintaining a haven for rare coral from Hawaii waters at their oceanside laboratory. With the potential for repopulating a devastated habitat, the aquarium is calling it an ark for the delicate reef-building creatures.

"Our ultimate aim is to have a reference collection of all threatened Hawaiian species. Then, if there's any disaster in the wild, the species won't be extinct," said Andrew Rossiter, the aquarium's director.

One dozen species are on board, and plans are under way to add three more.

One-third of the world's estimated 2,200 coral species are struggling for survival, according to a survey published last year by the Global Marine Species Assessment. A decade earlier, the survey found that 2 percent were in trouble.

An environmental group is now seeking to add 83 coral species — including nine in Hawaii — to the endangered species list. The National Oceanic and Atmospheric Adminstration must respond within the next three months to a petition filed last week by the Center for Biological Diversity, based in Tucson, Ariz. And NOAA must decide within a year whether listings are warranted.

Two of the corals on the petition — Montipora dilatata (irregular rice coral or Hawaiian reef coral) and Cyphastrea agassizi (Agassiz's coral) are in the aquarium's ark.

TOO FRAGILE TO HANDLE

Coral — calcium skeleton encased in a thin tissue, essentially — simply cannot be handled without inflicting damage, said Richard Klobuchar, a researcher at the Waikíkí Aquarium. And if the animal fails to thrive, entire underwater ecosystems can collapse.

"A lot of the life around the Islands comes originally from these reefs — from the corals that are out there," Klobuchar said. "Without those structures, you're going to start losing animals" that live, graze and hide there.

Klobuchar said coral destruction can have a cascading, detrimental effect on reef habitat, "working its way up the chain" from larval fish to schools of silvery jacks and sharks.

The idea for the ark surfaced about a decade ago, when mass bleachings of M. dilatata in Käneohe Bay wiped out many colonies. Researchers brought fragments of the remaining three colonies to the aquarium for safekeeping and captive propagation efforts.

"The corals can grow very fast in ideal conditions," Klobuchar said.

This ability to bounce back after contending with threats ranging from polluted steam runoff to reef tourism offers researchers hope that the humble, brownish Hawaii coral has a future.

The ark is a flow-through vessel that feeds coral with a constant supply of fresh, low-nutrient seawater — free of predators and parasites — under natural light. The 600-gallon tank is not open to the public, but as the coral grows, cuttings are pulled from it for various exhibit tanks.

The ark is similar in setup to the aquarium's coral farm, which was launched about three decades ago as a fragment tank, and quickly grew into a 1,000-gallon public exhibit for South Pacific coral. Researchers have used the farm to develop a method for propagating small fingers of coral and growing it — at rates of up to 8 inches a year — into healthy coral heads.

Pieces of the South Pacific coral head are shared with researchers around the world. And corals from the farm are included in almost every aquarium exhibiting coral in the United States. Housing a total of 127 species of South Pacific and Hawaiian coral, the Waikíkí Aquarium has the largest coral collection in the western hemisphere.

The ark program also aims to reintroduce corals into the wild. But they will not thrive if environmental threats persist.

In Hawaii, tainted sedimentation does the most damage to indigenous coral.

"There's no buffer between the watershed and the reef," Rossiter said. Shoreline construction and beach development have eliminated most natural marsh and mangrove areas. "So, if somebody upstream washes his car next to a storm drain, it goes straight into the drain, into the stream and onto the reef" in shallow waters.

"Rain that lands on a mountain here ends up on the reef. On its journey, it picks up pollutants. It picks up shampoo from you washing your car. It picks up pesticides from you treating your gardens." He added, "You might be miles away from the reef, but you're still affecting it."

Keeping the mauka-makai connection pollution-free will improve the reef's health, Rossiter said.

NO 'DEAD ZONES'

Compared to other coral reef systems, Hawaii's is in fairly good shape — thanks to the mid-Pacific's strong currents and deep waters, Rossiter said. Elsewhere: gradually warming waters, El Nino conditions, overfishing, invasive algae and choking agricultural runoff are among the top environmental threats.

In Hawaii there are no underwater "dead zones," devoid of all marine life. But bleachings, during which corals are stressed by changes in water salinity, temperature and other factors, continue to be a concern, Klobuchar said.

Bleaching occurs when the symbiotic relationship between coral and noninvasive algae falls apart. Without the algae helping to providing food energy, coral turns bone white and is left vulnerable to disease.

The mass bleachings of M. dilatata in Käneohe Bay during the late 1990s prompted efforts to protect the reef, which has rebounded to now include about 12 coral colonies.

According to the Center for Biological Diversity, M. dilatata is among the first corals to bleach during increased water temperatures. "It has experienced significant climate-related population fluctuations over the last 20 years, and its small distribution makes it extremely vulnerable to extinction," the petition for protection under the Endangered Species Act states.

In 2006, the elkhorn and staghorn corals, which occur in Florida and the Caribbean, became the first — and to date only — coral species protected under the Endangered Species Act. The listings, petitioned by the center, marked the first time the U.S. government acknowledged global warming as a primary threat to the survival of a species.

At the Waikiki Aquarium, Rossiter said, the coral ark's behind-the-scenes rescue and reviving efforts are helping researchers better understand the biological workings of M. dilatata and other rare coral as well as imperiled environments.

"A modern-day aquarium should be, in my mind, a lot more than a glass zoo for fishes," he said. "It has to focus on conservation, education and research."