Your assistance is needed to prevent a grave environmental and economic disaster from occurring along our precious Pacific coastline. A highly invasive strain of the non-native green seaweed Caulerpa taxifolia has been discovered in a coastal lagoon in San Diego County. (August 2000 California Diving News). This finding is the first time the invasive strain of Caulerpa taxifolia, also dubbed “killer algae” in the Mediterranean, has been reported in the Western Hemisphere. However, another infestation has also been identified more recently in an isolated portion of Huntington Harbor. These infestations most likely resulted from the release of aquarium water into a storm drain.

The invasive strain of Caulerpa taxifolia was first discovered in the Mediterranean Sea in 1984. This strain of seaweed most likely originated from an aquarium. Immediate eradication was not attempted, and as a consequence, within a few years government officials determined the infestation to be uncontrollable. Today, marine scientists there are largely resigned to monitoring its continuous expansion.

When introduced in a non-native marine habitat, Caulerpa taxifolia grows as a dense smothering blanket, covering and killing all native aquatic vegetation in its path. The weed is not a health threat to humans. However, fish, invertebrates, marine mammals, and sea birds that are dependent on native vegetation are displaced or die off from the areas where they once thrived.

A team of federal, state, and local agencies, an environmental consulting firm, and other interested parties was immediately formed in response to the recent California infestation. This team promptly developed and is currently implementing a rapid eradication effort. The team is hopeful that Caulerpa taxifolia will be eradicated from Southern California.

California Diving News

As a scuba diver, your help is needed to identify and report the location of any infestations of Caulerpa taxifolia.

If you find the seaweed growing, note the location, but do not disturb it. Any detached fragment has the ability to start a new infestation. Please immediately report any sightings of Caulerpa, made while diving or snorkeling, to the San Diego Regional Water Quality Control Board’s Caulerpa Action Team at (858) 467-2952.

We also want to know who has been looking for the seaweed while scuba diving or snorkeling, and can report an area “free”
of Caulerpa. Please direct these reports to us by e-mail at In the e-mail, please include the location, date, your contact information, and any additional comments that may be helpful.

Early detection is a critical ingredient of California’s effort to prevent the permanent establishment of this destructive seaweed along our coast. For complete information visit the website

Shearwater TERN