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Cite
as: Makowka, J. 2000. Monterey Bay National Marine Sanctuary Fact Sheet:
Caulerpa taxifolia. Report to the Monterey Bay National Marine
Sanctuary.
Monterey
Bay National Marine Sanctuary Fact Sheet:
Caulerpa taxifolia
Description:
Green algae with feather-like branches, leaf is 5-65 cm in length,
tropical in origin, found in Caribbean Sea and Indian Ocean, hybrid form
found in Mediterranean Sea is much larger (plants up to 10 ft.), and can
survive out of water for up to 10 days. It can survive in a wide variety
of habitats, including sandy bottoms, rocky outcroppings, mud, and natural
meadows. It can cover up to 100% of the sea bottom from 1 to 35 m and
has been observed in patches up to 100m, although, at greater depths the
patches are less dense. While this is a tropical species, the hybrid prefers
cooler water, 10°C, but has been found thriving in temperatures of
5°C. It has been found in headlands and sheltered bays and the growth
rate appears the same in polluted harbors and areas away from pollution.
The plant
contains a toxin that is not harmful to humans. Most fish and invertebrates
avoid it and some studies have shown it to be lethal to certain species.
There are also studies suggesting that the toxin may interfere with the
eggs of some marine organisms, and kill off many microscopic organisms.
The plant blankets an area, pushing out the invertebrates, fish, and native
algae.
History:
This plant is often used in saltwater aquariums, home and public,
because it is hearty, and has a bright green color that compliments the
colorings of tropical fish. It was used at the Stuttgart Aquarium in Germany
and a heartier hybrid was unknowingly produced and then shared with several
other marine institutions. It is believed to have been leaked into the
environment from the Oceanographic Museum in Monaco (although they deny
this) and has spread at a quick pace.
In the Mediterranean,
what started as 1meter2 has spread to over 2.5 acres in less
than 5 years. It now covers more than 10,000 acres. Dissemination takes
place primarily by fragmentation.
This plant
was only recently banned from sale in the U.S. It is still available over
the Internet and can easily be confused with the less toxic species Caulerpa
sertularioides.
Methods
of Control:
Many methods to control this plant have been tested throughout the
Mediterranean. Some have tried to tear up the patches of algae but one
torn leaf that gets away can generate a whole new outbreak. Divers have
used pumps to pull out the plant but it seems to regenerate in the same
place at a rate quicker than its original growth rate. Other eradication
methods include poison, smothering the algae with a cover that lets in
no light, and using underwater welding devices to boil the plant. Two
species of marine snail, Aplysia depilans and Elysia subornata,
that attack the algae have been found. The Aplysia depilans snail
contains a toxin itself and is avoided by other marine life. Neither has
been tested in open water since its overall affect on the ecosystem has
not been determined.
Recent
Outbreak:
The recent outbreak covering 0.5 acre in a lagoon just north of San
Diego was discovered in late June, 2000 by divers performing habitat monitoring
surveys for a nearby power plant. The most probable cause of this outbreak
is that a home aquarium was emptied into either the lagoon or a storm
drain. The area has been roped off and is under 24-hour watch. Plans are
underway to tarp over the area and poison the plant underneath with chlorine.
Morphology
of Caulerpa taxifolia
Contact
for information about recent outbreak: Bob Hoffman, National Marine
Fisheries Service for Southern California. Phone: (562) 980-4043 E-mail:
bob.hoffman@noaa.gov
*Compiled
by Jennifer Makowka, MBNMS
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