Limu species targeted for eradication
By James Gonser
Advertiser Urban Honolulu Writer
A group of university professors, scientists and the state are joining forces to eradicate an aggressive alien species of seaweed that has taken over a quarter-mile stretch of reef along the coastline fronting the Waikiki Natatorium, though they are not sure how to do it.
Bruce Asato • The Honolulu Advertiser
Gracilaria salicornia, a reddish limu, was planted here by researchers in the 1960s and '70s to foster commercial development of the alga for food products and medical research, but that industry never materialized and the seaweed is now pushing out corals and native algae on which Hawai'i's marine communities depend for food and shelter.
University of Hawai'i student Jennifer Smith shows beachgoer Lyman Higa of Kapahulu some Gracilaria salicornia seaweed. The non-native species of limu is growing aggressively along the coastline near the Waikiki Natatorium.
The seaweed grows into a thick mat, covering the reef and blocking sunlight, which kills the reef. Among the ideas for getting rid of the alien seaweed are removing it and replanting native species such as ogo, or using high-power hoses to wash it off the reefs.
Smith said there are no nurseries growing native seaweed stock to replant on the reefs.
In California, $4 million was spent last year to eliminate a similar seaweed by using bleach as poison.
"Their response was like to an oil spill," Smith said. "Our problem is worse and we can't use the same type of measures."
Bleach would kill everything on the reef, not just the seaweed, Smith said.
Using poison in the Mediterranean Sea has failed to remedy an alga problem there; the alga always comes back. The U.S. Environmental Protection Agency has spent millions of dollars studying a different type of floating alga causing problems along West Maui that has been detrimental to tourism. No solution has been found.
Left unchecked, this alga could come to dominate the entire Waikiki ecosystem on both sides of Diamond Head, threatening the ocean environment, said University of Hawai'i botany professor Celia Smith in announcing the joint effort yesterday in Waikiki.
"There are 500 species of seaweed statewide in competition with this aggressive alien species and it's winning," Smith said. "We need to create a greater level of awareness that we have a substantial problem and start a conservation effort."
UH, the state Department of Land and Natural Resources and the Hawai'i Coral Reef Initiative are looking for a way to rid Waikiki and Kane'ohe Bay of alien limu, including Gracilaria salicornia, and are seeking federal grants to pay for the effort.
Lyman Higa, a retired postal worker, swims at the natatorium several times a week and wants to make sure the water remains safe for swimmers.
"I don't want to see poison in the water," Higa said.
Reach James Gonser at jgonser@honoluluadvertiser.com or 535-2431.
