Expedition returns with northwestern isles findings

By Rod Ohira
Advertiser Staff Writer

Sixty-five scientists, educators and documentation experts returned this week from a 30-day mission to the Northwestern Hawaiian Islands with new data on coral, species of fish and shipwrecks.

Rapid ecological assessments were made at 189 sites along the 1,200-mile stretch of 10 atolls and islands extending west-northwest of Kaua'i. The most significant discovery was previously unseen extensive coral bleaching on the reefs of the northernmost atolls — Kure, Midway, and Pearl and Hermes.

Bleaching, or the loss of pigmented symbiotic algae cells in coral tissue, is a generic response by corals to environmental stresses such as unusually high water temperatures and exposure to strong solar ultraviolet radiation.

"Two months earlier or two months later and we wouldn't have seen it," Rusty Brainard of National Marine Fisheries Service said at a news conference yesterday at Bishop Museum's Hawai'i Maritime Center.

From mid-July to mid-September, sea surface temperatures at the three atolls averaged 82 degrees, which is 2 to 4 degrees higher than normal. Peak temperatures exceeded 84 degrees.

Some corals older than 100 years turned out to be bleached, Brainard said. "We don't know what percentage will recover."

Coral experts said the bleaching phenomenon is not an immediate cause for alarm.

Other significant findings:

• Fish scientists recorded four species not seen before in the northwestern islands: blue chub or nenue; finescale triggerfish; goldrim surgeonfish; and phoenix damselfish.

"The important distinction is they got here on their own, by a natural process," said Randall Kosaki of the Department of Land & Natural Resources.

• Elizabeth Flint of U.S. Fish & Wildlife, the expedition's terrestrial team leader, reported that 176 nest sites of the threatened Hawaiian green sea turtle were found on Lisianski Island, where the species did not breed before. She also noted that native vegetation on Nihoa is being threatened by grasshoppers; that numbers of a large blue wasp are increasing on Kure Atoll; and that there's a serious weed problem on Kure, Midway, and Pearl and Hermes.