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 This is an invasive alga
that is causing serious environmental problems in the Mediterranean Sea. This invasive weed was discovered in
southern California and New South Wales, Australia in 2000. Caulerpa
taxifolia was officially eradicated from southern California in
2006. It is native in tropical waters
with populations naturally occurring in the Caribbean, Gulf of Guinea, Red
Sea, East African coast, Maldives, Seychelles, northern Indian Ocean,
southern China Sea, Japan, Hawai‘i, Fiji, New Caledonia and
tropical/sub-tropical Australia. A
cold water strain of this attractive tropical alga, possibly developed from
plants that initially originated from Australia, was selected for by aquarium
managers at the Wilhelma Zoo in Stuttgart, Germany in 1980. By 1984, this
coldwater strain of Caulerpa had been released into the Mediterranean Sea by
the Oceanographic Museum of Monaco where it established. Thousands of hectares of Mediterranean sea
bottom was colonized and it is found from France to Croatia and its range in
the Mediterranean probably will to continue to spread. The invasive strain of Caulerpa tolerates low sea water
temperatures and survival out of water along the shores may exceed 9
days. Colonization is possible on
rock, sand, mud, and seagrass beds in depths of one to 12 meters. A rapid growth and reproduction of the
invasive strain is asexual and dispersal occurs by fragmentation. of pieces
as small as 1 cm. Spread occurs via
ballast water discharge from transoceanic boats and illegal dumping of
aquaria plants and through the movement of plant material on boats, anchors,
or fishing gear, or via algal fragments being dispersed by sea currents.
The
invasive strain in the Mediterranean Sea smothers other algal species,
seagrasses and sessile invertebrate communities. This is done either by competition with other species for food
and light or to the toxic or due to the toxic effects of certain compounds
that are contained in its foliage.
Large meadows of this alga have reduced native species diversity and
fish habitat. Native fish that are able to eat the alga build up toxins in
their bodies making them undesirable for human consumption.
The
alga showed up in southern California in 2000 at Carlsbad by the Pacific
Ocean. In addition to California law
there is a federal law forbidding interstate sale and transport of the
aquarium strain.
When
first detected the size of the southern California populations were small
enough for eradication. Underwater
colonies were covered with tarpaulins
that were fixed with sandbags, and chlorine was underneath to kill the
algae. It required six years to
eradicate the Carlsbad colonies. In
the Mediterranean some fisheries have been devastated when the fish avoided
infested areas.
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