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Killer Alga Not Present in Morro Bay

A survey of Morro Bay in San Luis Obispo County, California has determined that an invasive species of algae - Caulerpa taxifolia - is not present, “clearing the way for dredging to go forward,” according to the Army Corps of Engineers.

The survey for was carried out for the Corps by Everest International Consultants Inc. of Long Beach. The $26,542 project was paid for by a special grant from the American Recovery and Reinvestment Act (ARRA), popularly known as the stimulus bill, said Kirk Brus, environmental coordinator for the Los Angeles Engineer District. Total spending for dredging in Morro Bay this year under ARRA amounted to $5.2 million. An annual c. taxifolia survey in Morro Bay is required before all maintenance dredging.

According to Brus the subcontractors, ABC of Ventura, California, used divers to perform the survey for prime contractor Everest. They were given two days, but completed the survey in one day.

The survey report was received July 30, and annual summer dredging is underway. Dredging is being carried out by AIS Construction of Carpinteria, California. A second round of dredging of inner and back channels, which takes place about every six years, will begin in early fall, said Brus.

Caulerpa taxifolia is a mutated alga which has been called a “killer alga” and “undersea kudzu”. It has been found twice before in California, and removed at a cost of $7 million and six years of effort.

Experts believe c. taxifolia can spread from fish tanks when their contents are dumped into the sewer system.
C. taxifolia has acquired an extensive literature. It was dubbed the “killer alga” by the French press after it escaped into the open ocean from an oceanographic institute directed by Jacques Cousteau.

Man-Made Mutations
C. taxifolia is closely related genetically to a type of algae that is not considered a threat, first discovered long ago in Indonesia’s warm waters. But scientists believe that years of exposure to ultraviolet light and tank chemicals in museum aquaria mutated c. taxifolia into what is now called the Mediterranean variety, by switching on certain genes. These enabled it to survive much colder temperatures than its cousins, to secrete toxins that keep away most undersea predators, and to grow much faster than its tropical relatives.

In the early 1980s, the aquarium curator of the Wilhelmina Zoo in Stuttgart, Germany was taken with the plant¹s hardiness and bright green fronds. As staff bred it in captivity for years, word spread of the plant¹s desirability as an aquarium plant, and requests for cuttings came from aquariums all over Europe.

Role of Monaco Institute
In 1982, a sample was sent to the Oceanographic Museum in Monaco, then headed by famed oceanographer Jacques Cousteau and located right on the seashore. Two years later, marine biologist Alexandre Meinesz discovered the alga in nature under the museum’s windows. He discovered that a worker had dumped a bucketful of the alga into the ocean.

Meinesz’s early warnings that the fast-growing plant should be contained were ignored. He subsequently wrote an entire book, Killer Algae (latest American edition U. Chicago Press, 2001), that detailed what he considered not only negligence by Cousteau¹s institute, but stonewalling, cover-ups, and attacks launched against Meinesz (by Cousteau’s successor) that delayed action during a period when the plant¹s spread might have been stopped.

Oceanographic Museum officials even praised the alga’s virtues, while it spread all over the Mediterranean, displacing native plants and causing declines in fishing and tourism. Meinesz gave the plant an additional scientific name: c. godzilliana.

By 2000, c. taxifolia was observed in 100 locations in eleven Mediterranean countries. According to the web site of the Southern California Caulerpa Action Team, it now covers at least 30,000 acres of Mediterranean seafloor.
In March 1993, France finally banned ownership or sale of the plant, as did Australia in 2000. In the U.S., transportation or sale of the plant is outlawed by the Noxious Weed Act of 1999 and the Plant Protection Act of 2003.

Sightings in California, Australia
C. taxifolia was also confirmed in New South Wales, Australia, and in at least two locations in California: Agua Hedionda Lagoon in Carlsbad, near San Diego, and Huntington Harbor, near Los Angeles.

The two California infestations took six years and $7 million to eradicate, according to the SCCAT Web site. The plants were killed by first covering them with a heavy tarpaulin. Then chlorine was injected into the tarp-covered area, killing all life forms under the tarp.

C. taxifolia can spread asexually, meaning a broken-off piece can quickly generate new plants. This means the likely route of transmission is pieces of plants from saltwater aquaria illegally flushed down the toilet or otherwise dumped into the environment. California has outlawed ownership of c. taxifolia.

At one point, scientists hoped that a Florida sea slug might help in controlling the plant. The slug was able to neutralize the alga¹s toxins as it inserted its proboscis to suck out the juices and kill individual plants.
But experiments showed that the slug never ate enough of the plants to make a difference. In fact, the authors of a study that appeared in 2001 in the Journal of Marine Biology (U.K.) concluded that the slug may even help to spread it by dispersing pieces of it. In addition, the slug cannot tolerate temperatures as cold as those where c. taxifolia can thrive.

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