Advertisement

Invasion by Seaweed Species Halted

Share
Times Staff Writer

Two outbreaks of the “killer algae” that once threatened much of the California coast have been quelled in Huntington Harbour in Orange County and the Agua Hedionda Lagoon in Carlsbad.

Federal officials say underwater surveys of both areas in the past year have found no trace of the invasive seaweed, which has also caused extensive damage to fisheries and recreational waters off Europe.

If the emerald-green plant is not found this fall, a state and federal coalition that has been battling the species at the two sites will consider it eradicated, said Bob Hoffman, an environmental coordinator for the National Marine Fisheries Service.

Advertisement

“This will be the first time an invasive marine algae will have been eliminated in the United States,” Hoffman said. “Our efforts are proving to be very successful.”

The plant is called Caulerpa taxifolia, a Caribbean species that has been widely used in saltwater aquariums because of its bright green foliage. It is one of hundreds of exotic species that have been threatening marine ecosystems from San Francisco Bay to creeks in the Santa Monica Mountains.

Released into new environments, the plant, if unchecked, can smother the ocean floor, disrupting kelp beds and habitat for lobster and other bottom-dwelling creatures.

In the Mediterranean Sea, a square-meter patch of the algae was found below the window of the Oceanographic Museum of Monaco in 1984. Almost 20 years later, the plant had infested more than 10,000 acres of sea floor off Spain, France, Italy and Croatia.

Thick patches of Caulerpa clogged popular scuba diving sites and cut off commercial fishing boats from formerly productive waters.

In the United States, the plant was discovered more than three years ago colonizing Huntington Harbour in Huntington Beach and the Agua Hedionda Lagoon in northern San Diego County. Experts believe the outbreak was caused by aquarium owners emptying their tanks into storm drains.

Advertisement

Fearing that the species would spread along the California coast, state and federal authorities organized a multimillion-dollar program to combat the infestation statewide. About $3 million has been spent so far.

Since the discovery, divers have regularly combed the bottoms of the two infested zones. Wherever they found a patch of Caulerpa, it was covered with a tarp and killed with chlorine tablets inserted under the canopy.

Because of the outbreak, the federal government placed Caulerpa on its list of noxious weeds, which makes it illegal to import into the United States or distribute across state lines. In 2001, the state Legislature made it illegal to sell, possess, transfer or release the species in California.

Advertisement