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'Killer Algae' Like Terminator in Thwarting Drive to Kill It Off

Nature: The invasion off Huntington Beach and Carlsbad can be slowed, but eradication so far proves impossible.


Despite spending millions of dollars, state and federal officials have failed to eradicate "killer algae," a noxious emerald-green weed that has taken root off Huntington Beach and Carlsbad.

"We are seeing a reduced number of colonies," said Bob Hoffman of the National Marine Fisheries Service, the lead federal agency in the fight. But "it's just amazing how adaptable and resistant it is to being eradicated."

Caulerpa taxifolia, a Caribbean plant, is popular in saltwater aquariums because of its brilliant green foliage. But released into new environs, it smothers the sea floor and has already caused extensive and costly damage off Europe. The plant is just one of hundreds of exotic species changing marine ecosystems statewide, from the San Francisco Bay to creeks in the Santa Monica Mountains.

About two years ago, the plant was first discovered in this nation--in Huntington Harbour on the Orange County coast and Agua Hedionda Lagoon in Carlsbad, northern San Diego County. Experts believe Caulerpa came from home aquarium owners who emptied tanks into storm drains, and worry that there could be other undiscovered infestations along the California coast.

To imagine what would happen if the weed grew unchecked, one need only look at the Mediterranean. A square-meter patch of it was found below the window of the Oceanographic Museum of Monaco in 1984. Nearly two decades later, the killer now carpets more than 10,000 acres of ocean floor off Spain, France, Italy and Croatia, all offshoots of that original patch. Once-popular scuba diving waters are clogged with thick forests of the stuff. Commercial fishing and boating have been cut off in formerly productive harbors.

Hoffman said a coalition of state and government agencies have spent $4 million trying to quell the two known outbreaks in the U.S. When patches of Caulerpa are found, they are covered with tarps and treated with chlorine.

But two years of effort have not killed all of the algae at either site, a hallmark of why this hardy weed spreads so easily. It can survive 10 days out of the water, and leaving even one speck behind can cause an outbreak. Caulerpa spreads through fragmentation--if a small piece breaks off, it quickly establishes a new colony.

In the Carlsbad lagoon, researchers recently checked 16 treated patches. Fifteen appear to be clean, but the one with surviving Caulerpa had been covered with a tarp the longest, about two years.

"It's sort of dumbfounding us. We don't have a good explanation," Hoffman said. "It's hard to believe a plant can be covered with the tarp where light doesn't get through for two years and be able to survive and--when exposed to favorable conditions--be able to grow again."

In Huntington Harbour, some new sprouts were also found in a spring survey.

Huntington Beach City Councilman Ralph H. Bauer, who lives on the harbor, said, "We're very appreciative of the money being spent to solve the problem. It's a shame someone had to empty their home aquarium and cause all this difficulty. Hopefully, they'll keep at it until it's solved."

The U.S. Department of Agriculture placed Caulerpa on its list of noxious weeds three years ago, which makes it illegal to import into the United States. In 2001, Gov. Gray Davis signed legislation making it illegal to sell, possess, transfer or release the weed in California.

Extensive monitoring and surveys are part of the eradication effort, something officials say is key to containment.

"It is clear that we need to maintain our monitoring efforts at the infested sites in Southern California, probably for years to come," said state Department of Fish and Game Director Robert Hight in a written statement.

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