Giant reed, invasive algae targets of $2M grants

| Wednesday, December 4, 2002 10:00 PM PST ∞

PHIL DIEHL
Staff Writer

The State Coastal Conservancy approved grants of nearly $2 million Wednesday to aid the fight against a weed called giant reed along the San Luis Rey River in Oceanside and a destructive algae in the water of Carlsbad's Agua Hedionda Lagoon.

The Mission Resource Conservation District will get $600,000 to continue its eradication of giant reed, also known as arrundo donax, along the river's banks. More than $2.3 million has been spent to remove the weed upstream, mostly east of Interstate 15, and the latest grant will bring the work west to College Avenue.

Giant reed is a tall, bamboolike grass that grows in dense stands, crowding out native plants and the animals that live in them along rivers and streams. The giant reed is also a fire hazard, because it is flammable even when green, and a flood hazard, because it constricts water flow.

"During floods it barricades against bridges, culverts and other structures," said Jason Giessow, a biologist who works for the Mission Resource Conservation District. Choked by the giant reed, bridges and culverts turn into dams, which flood surrounding lands until the structures wash away.

"It's a maintenance nightmare for private residents," Giessow said. "Some people spend thousands of dollars every few years to keep it from taking over their property."

Environmental restrictions allow eradication work only between Sept. 15 and March 15, he said. Crews chop down the reed and apply the herbicide Rodeo to it in the fall. They return in January and use mowers and other equipment to mulch it, and a few weeks later they plant native trees such as oaks, sycamores, cottonwoods and willows in the mulch.

"None of the treatments are 100 percent effective in year one," Giessow said. "Ours is very effective compared to most. We get over a 95 percent kill that first year, then we go back for the rest."

The algae, also called Caulerpa taxifolia, was discovered in the east basin of Agua Hedionda Lagoon on June 12, 2000, and in Huntington Harbor about six weeks later.

A product of tropical waters, the algae had never been found before in the Western Hemisphere. It became a popular addition to saltwater aquariums in the 1970s, but is now banned for sale or import into the United States. A clone of the species, which grows larger, deeper and in colder water, was released in 1984 to the Mediterranean Sea, where it now covers thousands of acres.

The rapidly spreading algae is a potential environmental disaster that can eliminate native seaweed and grasses.

"It's like unrolling AstroTurf across the bottom of the sea," said Sam Schuchat, a Coastal Conservancy executive officer.

The conservancy's $1.3 million to the Agua Hedionda Lagoon Foundation is in addition to more than $4 million in federal, state and private money already spent on the eradication effort.

Most of the algae in the lagoon has already been eliminated, said foundation spokesman Bob Richards. For the last two years crews have placed plastic tarps over the algae they've found and killed it by injecting chlorine into the tarps, an effort that costs about $1 million a year and is expected to continue for at least three more years.

"So far it has worked well," Richards said. "Now they are looking for bits and pieces."

Even a tiny fragment of the algae can grow and spread.

About $300,000 of the grant will pay for a scientific review of the process used the last two years to see whether there might be a cheaper and more effective method of killing the algae, he said.

Contact staff writer Phil Diehl at (760) 901-4087 or pdiehl@nctimes.com.

12/5/02