A Hawai‘i Undersea Research Laboratory ocean probe into the spread of an introduced coral species that threatens Hawai‘i’s $30-million-a-year black coral industry bodes well for Kaua‘i and areas by Ni‘ihau, but not for Maui. The HURL probe that involved the
A Hawai‘i Undersea Research Laboratory ocean probe into the spread of an introduced coral species that threatens Hawai‘i’s $30-million-a-year black coral industry bodes well for Kaua‘i and areas by Ni‘ihau, but not for Maui.
The HURL probe that involved the use of a launch ship, a small submarine and mobile submersible equipment last month showed snowflake coral (Carijoa riisei) has not spread beyond the shallow waters off Port Allen Harbor and Makahuena Point in Po‘ipu, said Sam Kahng, a University of Hawai‘i chief researcher.
The probe also found the introduced coral, which smothers black coral prized by divers, had not yet colonized areas of Kaula Rock, which is located west of Ni‘ihau.
At the same time, the probe found the introduced coral had overrun the Au‘au Channel between Maui and Lana‘i, home to great amounts of black coral, Kahng said.
The snowflake coral is found in deep waters off O‘ahu, the Big Island, Moloka‘i and Maui.
With the exception of Port Allen and Makahuena Point, the coral has not been found anywhere else off Kaua‘i waters, Kahng has said.
Stopping the coral at the doorstep of Kaua‘i would help preserve black-coral kingdoms here and in Northwestern Hawaiian Islands, and would be unprecedented, Kahng said.
Earlier this year, Kahng and others attempted to halt the spread of the invading coral by removing them from two sites on Kaua‘i.
Even though the job is doable, the task proved daunting for the team because it was undermanned, he said. Only five or so researchers participated in that project, and Kahng, who led them, has vowed to return to Kaua‘i to continue the work.
The introduced coral has laid waste to black coral kingdoms found in the deep waters of Hawai‘i, threatening the state’s multi-million-dollar black-coral industry.
The coral provides the material that is used to fashion jewelry that is sold in Hawai‘i and throughout the world.
As part of ongoing efforts to stop the spread of the snowflake coral to more islands in the Hawaiian archipelago, HURL officials conducted the Kaua‘i and Ni‘ihau expedition last month.
HURL was created by officials in the federal National Oceanic and Atmospheric Administration and the University of Hawai‘i. HURL has been tasked to study ocean processes as a way to protect ocean resources.
The HURL expedition involved six dives on the Pisces V submersible, and four “remotely operated vehicle deployments” of the RCV-125.
The mobile craft and equipment were brought out to sea by the R/V Ka‘imikai-o-Kanaloa. Ocean dives ranged between 50 to 2,000 meters in depth.
The Kaua‘i surveys focused on two strategic sites where the invading coral has been discovered previously — Port Allen Harbor and Makahuena Point.
Large colonies of snowflake coral were discovered around the main pier at the Port Allen Harbor in November 2002, triggering the first efforts to map out the location of the bad coral and its removal by hand earlier this year.
For that job, Kahng led a small team that tried to remove as much of the coral by hand. The effort was considered unprecedented because no effort of its kind has been mounted before.
The team members included Anthony Montgomery and Paul Murakawa, both aquatic biologists with the state Department of Land and Natural Resources Division of Aquatic Resources, Jason Leonard, a fisheries specialist with the same division, and Decy Devere, a UH diver.
“Because we knew there is a shallow-water population on the pier, we wanted to see if it had spread outside of the harbor into deeper water,” Kahng said. “We found no traces of the coral in the deep reef, the deep waters off Port Allen or Makahuena Point. And that is good news.”
The need to keep the coral from moving seaward of Makahuena Point is somewhat critical, he said.
The area is known for its black-coral beds, which have been harvested in the past, Kahng said.
The investigation outside Port Allen Harbor revealed a small outcropping of Scleractinian corals and rocks at 50 meters and an “exposed island shelf” between 105 and 120 meters, Kahng reported in a summary report of the Kaua‘i probes.
This shelf apparently circles the island and is sparsely populated with black coral, Kahng said.
But the area of concern might be prime for a visit by the snowflake coral, he cautioned. “It is hard rock, which is the stuff the snowflake coral likes to establish itself on,” Kahng said. “It (the shelf) gets a good current flow. There is zooplankton, which the Carijoa needs, (and is) a good, productive area.”
The low light found in the area also is to the liking of the snowflake coral, Kahng said.
The deep-reef habitat investigated off Makahuena Point revealed a similar “shelf at 105 to 120 meters” that was studded with large, exposed boulders with black coral and wire corals, but was absent of the invading coral, Kahng said.
The black coral grows unfettered in spots there, Kahng said. “An extensive black-coral bed was observed 65 to 75 m (meters) on an exposed series of underwater cliffs,” Kahng wrote. “Healthy black-coral colonies carpeted the rocks in high abundance with no signs of C (Carijoa riisei) despite the plentiful shaded and well-ventilated habitat.”
The researchers also found the snowflake coral had not yet colonized Kaula Rock, and that favorable “habitat” for the snowflake coral may be limited, Kahng said.
Lester Chang, staff writer, may be reached at 245-3681 (ext. 225) or lchang@pulitzer.net.
