Aquatic Invasive Species on the West Coast: Caulerpa Taxifolia
The aquarium strain of Caulerpa taxifolia is an extremely invasive seaweed
Due to its fast-growing hardy nature, and attractive appearance, Caulerpa taxifolia is used as decorative saltwater aquarium plant. The aquarium strain of Caulerpa taxifolia is an extremely invasive seaweed that has infested tens of thousands of acres in the Mediterranean Sea. Since 2000, it had been found in two coastal water bodies in southern California (but has since been eradicated). This "aquarium strain" tolerates colder water and grows more rapidly than the native strain. It forms dense mats and can grow up to three inches per week on any surface at depths up to 100 feet. These mats displace the native aquatic plants and animals that make our waters a rich and productive environment.
It is now illegal to possess, sell, or transport Caulerpa taxifolia in California. Signed into law in 2001, the Assembly Bill 1334 (Harman), prohibits the possession, sale, and transport of Caulerpa taxifolia throughout California. This bill also establishes the same restrictions on several other species of the genus Caulerpa that are similar in appearance and are believed to have the ability to become invasive.
San Diego also has adopted an ordinance banning the possession, sale, and transport of the entire genus of Caulerpa within city limits. The Federal Noxious Weed Act(1999) and the Federal Plant Protection Act (2000) prohibit the import, interstate sale (including Internet sale), and transport of the Mediterranean strain (i.e., aquarium strain) of Caulerpa taxifolia.
NOAA Fisheries is a part of the Southern California Caulerpa Action Team (SCCAT), a committee established to respond quickly and effectively to the discovery of Caulerpa taxifolia in California. SCCAT consists of representatives from local, state, and federal governmental entities, as well as private organizations. The goal of the SCCAT is to help protect California's vital marine habitats by completely eradicating all Caulerpa taxifolia infestations and prevent new infestations. To date, there have been no new infestations in southern California since it was declared eradicated.
Protect our Waters
- Learn to identify Caulerpa taxifolia
- Look for Caulerpa while fishing, boating, or diving
- Do Not use this seaweed in your aquarium
- Before Launching: Check your boat for attached plants and dispose of them in the trash
Aquarium water and other contents should never be emptied into or near any gutter, storm creek, lagoon, bay harbor or the ocean. Aquarium water should be disposed of only in a sink or toilet. Rock and other solid material from an aquarium should be disposed of in a trash can. Caulerpa taxifolia from an aquarium (and anything it is attached to), should be placed in a plastic bag, put in a freezer for at least 24 hours, and then disposed of in a trash can.
If any seaweed suspected to be Caulerpa taxifolia is found on fishing gear, anchoring gear, or vessels, it should be removed, carefully bagged (because even the smallest fragment has the potential to regenerate into a new plant), and reported.
To prevent new infestations and comply with the law, Caulerpa taxifolia should not be purchased sold or distributed.
Description: Caulerpa taxifolia is bright green, with feathery, fern-like fronds that extend upward from a main stem.
Distribution: Caulerpa taxifolia is native to tropical waters, including the Caribbean, Indo-Pacific, and Red Sea. Infestations of the aquarium strain have been found in the Mediterranean Sea, Australia, and California.
Growth: The aquarium strain of Caulerpa taxifolia has the ability to form a dense carpet on any surface including rock,sand,and mud. It is capable of extremely rapid growth, up to one half inch per day (1.27 cm/day).
Depth: Caulerpa taxifolia can grow in shallow coastal lagoons as well as in deeper ocean waters, possibly to depths of greater than 150 feet (nearly 50 meters).
Ecological Risks: Plant and animal diversity and abundance are reduced where Caulerpa taxifolia has invaded. The aquarium strain has been documented to displace native vegetation, particularly seagrass beds, and become the dominant plant life.
Human Health Threat: There are no human health risks associated with Caulerpa taxifolia.
Natural Control: Outside the tropics where Caulerpa occurs naturally, there is no known marine life that eats Caulerpa taxifolia in any significant qualities. Caulerpa taxifolia contains toxins that are distasteful to species that might feed on it
For a visual guide, please see the Guide to 9 Banned Species of Caulerpa in California.
Source and Spread
Source and Spread: Genetic evidence indicates that release from aquaria is the most likely source of Caulerpa taxifolia where it is not native. Once introduced, Caulerpa taxifolia spreads by fragmentation. Even a small, broken off fragment can form a new plant. Distances between colonies can be great due to transport on boat anchors and fishing gear. Caulerpa taxifolia does not float, has never been observed to grow on boat hulls, and is unlikely to be transported in ballast water. Sexual reproduction has not been observed in the aquarium strain of Caulerpa taxifolia.
Mediterranean infestation: The aquarium strain of Caulerpa taxifolia was first found in the Mediterranean Sea off Monaco, adjacent to the Oceanographic Museum of Monaco around 1984. Since then, Caulerpa taxifolia has spread along the Mediterranean coast and dramatically altered and displaced native plant and animal communities. Early eradication was not attempted in the Mediterranean, and the infestation is now considered beyond control. As of 2001, it was estimated that Caulerpa taxifolia has infested over 30,000 acres of seafloor in Spain, France, Italy, Croatia, and Tunisia. Caulerpa taxifolia infestations negatively impacted tourism, commercial and recreational fishing, and recreational activities such as SCUBA diving.
Australia infestation: The invasive aquarium strain of Caulerpa taxifolia has been reported in South Australia and New South Wales and is invading in a pattern similar to the Mediterranean infestation. Efforts are being made to control its spread.
Southern California infestation: The first known outbreak of Caulerpa taxifolia in the Western Hemisphere was in June 2000, when the species was found in Agua Hedionda Lagoon, a coastal marine lagoon located in Carlsbad in San Diego County. Its growth pattern was similar to that observed in the Mediterranean Sea, having spread to many areas and displaced the native seagrass. In July 2000, another infestation was reported in a portion of Huntington Harbor in Orange County. Test results indicate that the Caulerpa taxifolia in both areas was genetically identical to the aquarium strain. Releases from aquaria, either directly into the water body, or indirectly through a storm drain, were the most likely sources of both southern California infestations.
Since the discovery of Caulerpa taxifolia at two locations in southern California in 2000, an all out effort has been undertaken to eradicate the infestations, and to locate and eradicate any other occurrences beyond the known infestation areas.
Immediate action was taken under the direction of the SCCAT. Representatives on the SCCAT included exotic species eradication specialists, researchers, resource managers, regulatory bodies, public communications representatives, the eradication contractor, and private partner stewards who were providing access, equipment, and financial resources to combat the infestation. This program included surveillance, field lab studies, eradication efforts, follow up surveys and spot treatment, support services for out-of-lagoon surveys, and assistance with public outreach.
All identified Caulerpa patches were covered with impermeable 35mil PVC liners. The containment devices trap adequate volume of water for treatment with chemical herbicides, while protecting surrounding areas from collateral damage. This approach also prevents fragmentation of dying plants from spreading viable fragments to adjacent areas.
Chemical Control Treatment
Caulerpa patches covered with impermeable PVC lines were originally treated with injections of 5% liquid chlorine solution. Contained patches were retreated with chlorine until some residual chlorine was detected within the tarped area for a period of 24 hours. That initial methodology was modified to treat contained patches with a solid form of chlorine.
Caulerpa Surveyor Certification
Caulerpa Certification Exam
Caulerpa surveyor certification exams, are scheduled at the NOAA Fisheries office in Long Beach and at the California Department of Fish & Wildlife office in San Diego.
Next Exam is scheduled : TBD
501 W.Ocean Blvd., Suite 4200
Long Beach, CA 90802
CONTACT: Bryant Chesney at Bryant.firstname.lastname@example.org or 562.980.4037
California Department of Fish & Wildlife
4949 Viewridge Ave
San Diego, CA 92123
CONTACT: Loni Adams at Loni.Adams@wildlife.ca.gov or 858-627-3985
- Caulerpa Control Protocol (2008)
- Caulerpa Surveyors Training Information (2003) in support of the Caulerpa Control Protocol
- Certified Caulerpa Surveyors in California