[ OUR OPINION ]
State needs new way
to keep out harmful plants
HAWAII'S fertile environment creates an ideal world in which invasive plants, animals, insects and other organisms thrive. As the current struggle against an aquatic plant in Lake Wilson clearly demonstrates, a vigilant program to review and control non-native species is essential if the state wants to avoid costly and troublesome eradications.
THE ISSUEFast-growing salvinia at Lake Wilson is the most recent of Hawaii's problems with non-native species.
The persistent intrusion of undesirable species -- from miconia to noisy coqui frogs -- calls for reworking of state regulations. The alternative is to continue dealing with these infestations one after the other with no clear strategy.
The state's most recent imported pest is Salvinia molesta, the freshwater weed that has covered almost all of Lake Wilson's surface. While not an immediate danger to humans, the plants are likely to reduce oxygen in the water and smother the more than 20 species of fish there. Tons of dead fish floating in and around the lake would be at best a stinky mess and at worst a health hazard.
An amphibious excavator digs through Lake Wilson's heavy salvinia growth.
The fast-growing salvinia -- listed on the U.S. Noxious Weed List, which bans its movement from state to state -- has flourished because the lake is rich in nutrients. Agricultural and residential runoff as well as about 3 million gallons of wastewater pumped daily from the Wahiawa treatment facility feed the plants so well that one specialist described the lake's growth as the "best-looking salvinia I've ever seen."
Salvinia's presence was noted at least four years ago. At the time, state biologists said there was no danger it would take over the lake as water hyacinths had done in years previous. Now, what they considered a small nuisance has forced officials to close the lake to remove the weed, which will take at least a month and cost about $1 million. Meanwhile, salvinia -- which can spawn from a pin-size specimen and double in two to eight days -- has spread to other Oahu waters, such as Kawainui Marsh, Hoomaluhia and Enchanted Lake and to Waiakea Pond in Hilo.
Officials seldom seem to take seriously the effects invasive and non-native species have on Hawaii's sensitive environment. Miconia, a South American import, has damaged or overtaken tens of thousands of native forest acres, leaving hills and mountains vulnerable to mudslides and impairing watersheds. The state finally banned miconia in 1993, 30 years after it had taken root here. Removal efforts, if at all possible, will cost an estimated $49 million.
It appears that even now, officials haven't quite figured out they must be extremely cautious about introduced species. As another solution to salvinia infestation -- call it the mongoose syndrome -- some are considering bringing in a weevil that feeds on the plant when there have been no studies or tests to determine if this insect eventually will harm the native ecosystem. Until that's done, the weevil should stay out.
Salvinia has not yet made the state's list of banned plants, but no doubt it will. However, the problem is that the state's system for reviewing non-native plants works backwards; if a plant is not on the list, it is allowed in. It should work the other way; no plant should be allowed in until importers show it will not hurt Hawaii's environment.
Far better to nip plant pests in the bud before they bloom into expensive and formidable plagues.
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