Description: C. taxifolia is bright green, with feathery, fern-like
fronds that extend upward from a main stem.
Distribution: C. 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 C. 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 cm/day).
Depth: C. 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 C. taxifolia has invaded. The aquarium strain of C.
taxifolia 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 of the tropics where Caulerpa
occurs naturally, there is no known marine life that eats C. taxifolia in
any significant quantities. C. taxifolia contains toxins that are distasteful to
species that might feed on it.
Source and spread: Genetic evidence indicates
that the most likely source of infestations in areas where C. taxifolia is not
native is through release from aquaria. Once introduced, C. taxifolia spreads by
fragmentation, and 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. C.
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 C. taxifolia.
Mediterranean infestation: The aquarium strain of
C. taxifolia was first found in the Mediterranean Sea off Monaco, adjacent
to the Oceanographic Museum of Monaco, around 1984. Since then, C. 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 C.
taxifolia had infested over 30,000 acres of seafloor in Spain, France, Italy, Croatia
and Tunisia. C. taxifolia infestations have negatively impacted tourism, commercial
and recreational fishing, and recreational activities such as SCUBA diving.
Australian infestation: The invasive aquarium
strain of C. 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 infestations: C. taxifolia
was first identified in June 2000 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 of C. taxifolia was reported in a portion of Huntington
Harbour in Orange County. Test results indicate that the C. taxifolia in both
Huntington Harbour and Agua Hedionda is genetically identical to the aquarium strain.
Releases from aquaria, either directly into the water body, or indirectly through a storm
drain, are the most likely sources of both southern California infestations of C.
taxifolia.
Legislation and regulations: Assembly Bill 1334 (Harman), signed
into law by the Governor in September 2001, prohibits the possession, sale, and transport
of C. taxifolia throughout California. This bill also establishes the same
restrictions on several other species of the genus Caulerpa that are similar in
appearance to C. taxifolia and that are believed to have the ability to become
invasive. Earlier in 2001, the City of San Diego adopted an ordinance banning the
possession, sale, and transport of the entire genus of Caulerpa within city limits.
Furthermore, the importation, interstate sale (including Internet sale), and transport of
the Mediterranean strain (i.e., aquarium strain) of C. taxifolia is prohibited
under the federal Noxious Weed Act (1999) and the federal Plant Protection Act (2000).
Eradication effort: The Southern California Caulerpa
Action Team, SCCAT, is a committee established to respond quickly and effectively to
the discovery of C. taxifolia in southern California. The group consists of
representatives from local, state, and federal governmental entities, as well as private
organizations. The goal of SCCAT is to completely eradicate all C. taxifolia
infestations and to prevent new infestations. As part of the eradication effort,
divers periodically conduct surveys in Agua Hedionda and Huntington Harbour. Wherever C.
taxifolia is found, it is contained and treated with chlorine. Long-term monitoring
will be necessary to assure complete eradication.
Prevention of new infestations: Aquarium water
and other contents should never be emptied into or near any gutter, storm drain, 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. C. 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 C. taxifolia is found on fishing gear,
anchoring gear, or vessels, it should be removed, carefully bagged (since even a small
fragment has the potential to regenerate into a new plant), and reported. In order to
prevent new infestations and comply with the law, Caulerpa taxifolia should not be
purchased, sold, or distributed.
Contact information: Any sightings of Caulerpa taxifolia
should be immediately reported to the California Department of Fish and Game at (858)
467-4218 (wpaznokas@dfg.ca.gov) or National
Marine Fisheries Service at (562) 980-4043 (bob.hoffman@noaa.gov).
For further information, please visit www.caulerpa.cjb.net
and www.sccat.net.
Click to Return to Invasive Species
Page |
