Posted on: Thursday, March 14, 2002

Non-native limu a growing threat

By Jan TenBruggencate
Advertiser Science Writer

An aggressive reddish seaweed is causing problems for native reef species, particularly off Waikiki and Kane'ohe, where it's changing the biology of the reefs.

This fast-growing limu breaks up in waves, and small pieces can settle on reefs, where it quickly can begin growing. A large patch is right off the Waikiki Natatorium.

Known as Gracilaria salicornia, the seaweed can crowd out corals and native algae on which Hawai'i's complex marine communities depend for food and shelter.

And it's tough to control.

"We have to approach it with nonstandard methods," said University of Hawai'i botany professor Celia Smith. "We have to think out of the box. Nothing keeps it in check naturally, apparently,"

The limu has been in Hilo Bay for many years. It may have been brought there on ballast rocks by early whaling ships or other vessels, Smith said. It was brought to O'ahu in the 1970s in hopes it would form the basis for an agar industry — making from the seaweed the gel laboratories use in petri dishes.

"It was a series of biological/business experiments where the biology worked and the business didn't," Smith said.

A team of experts is working to develop techniques for gaining control of the weed. Its members include Smith, William Devick, head of the state Division of Aquatic Resources, and Cynthia Hunter, curator at Waikiki Aquarium.

Smith said it's edible, and she has seen it blanched and placed under sashimi like cabbage, or used in poke.

One solution, she said only half-jokingly, might be to get more people to eat it.