Killer Algae

Killer Algae found in Southern California

Caulerpa taxifolia ("Killer Algae") Found in Southern California

An invasive algae, Caulerpa taxifolia, was discovered in San Diego County's Agua Hedionda Lagoon on June 12, 2000, and subsequently in Huntington Harbor. A green alga native to tropical waters, it has been highly invasive in the Mediterranean Sea. Following its escape from the Oceanographic Museum of Monaco around 1984, the algae rapidly spread from a patch of about one square meter to over a hectare (2.47 acres or 10,000 square meters) by 1989, and today covers many thousands of hectares. Even a tiny piece broken off from an existing stand can regenerate a new plant, resulting in rapid spread of the species and making eradication by mechanical means nearly impossible.

Dubbed the "killer algae", Caulerpa could have devastating ecological and economic consequences for California if it is allowed to become permanently established. It has the ability to form a dense smothering blanket of growth on any surface (rock, sand or mud). It is capable of extremely rapid growth (up to one inch per day). It can grow in shallow coastal lagoons as well as deeper ocean waters. Plant and animal species diversity and abundance has been greatly reduced where Caulerpa has invaded. This algae essentially displaces the natural vegetation in areas where it becomes established and becomes the dominant plant life. Caulerpa secretes a toxin that is avoided by mollusks, herbivorous fish and sea urchins, so it has no known predators outside of its native tropical range. However, there are no human health risks associated with this algae.

The importation of Caulerpa taxifolia into the United States was banned under the federal Noxious Weed Act in 1999. However, its possession and sale remains legal under federal law, and it continues to be sold and transported in the United States by the aquarium trade, where it is popular due to its fast growth and attractive appearance (bright green color). The marine biologist who discovered the algae in San Diego believes that it probably was released into the wild from an aquarium (a practice banned under California law) by someone dumping it into a stormdrain.

The Southern California Caulerpa Action Team (SCCAT) was established to quickly and effectively respond to the discovery of this algae in Southern California. SCCAT includes representatives from several state, federal, local and private entities (including California Department of Fish and Game, National Marine Fisheries Service, San Diego Regional Water Quality Control Board). The goal of SCCAT is to completely eradicate all Caulerpa infestations. All of the patches of Caulerpa in Agua Hedionda Lagoon have been contained and treated with chlorine, apparently successfully killing the plant and its roots.

The California Department of Fish and Game is seeking funds from the legislature to conduct a survey throughout Southern California to look for infestations of this invasive algae. Initially the surveys would focus on areas near the previously discovered infestations, but eventually the entire region should be surveyed for the presence of this algae. If any infestations are discovered, immediate eradication efforts will be implemented, using funds from the State Cleanup and Abatement Account. Los Angeles Regional Board staff has joined SCCAT to assist in these efforts. SCCAT has developed a brochure for distribution to the public which summarizes the threat from this destructive algae. Posters advertising the threat also have been placed in waterfront locations. Divers, fishermen, boaters and other members of the public are being asked to report any observations of this algae in the water or along the shoreline to SCCAT contact persons.

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