Caulerpa taxifolia
Caulerpa taxifolia is a green alga that is invading parts of the Mediterranean Sea and western coasts of the United States. Caulerpa is used in aquariums, as saltwater decorative plants. It is bright green with ern like fronds that connect from a main stem. The fronds extend upward at long lengths. Caulerpa grows in shallow coastal lagoons, and also in deeper ocean waters. The species is native to the tropical oceans and seas, like the Caribbean. Caulerpa is a native alga to Hawai’i, but it has not demonstrated any invasive tendencies there. It has also invaded Australia, Eastern Atlantic, Western Atlantic, Indo-Pacifico, and the Gulf of Mexico. It has begun to spread to spread in California waters as well. It was accidentally introduced in the Mediterranean and California. Natural dispersion of the species occurs near the central invasion zone, however, is also transported by the anchoring systems of boats and fishing nets. It spreads by fragmentation, so even a small broken off fragment can form a new plant.
Caulerpa is above average in size, length, growth rate and temperature tolerance. Another characteristic that allows the species to be successful is its longevity. Caulerpa is protected from being preyed on by sea urchin, fish and other herbivores because of its toxicity. In the Mediterranean, Caulerpa is causing a “major ecological event”. The species is invading and dominating all other seaweeds in the Mediterranean. It is invading the dominant seagrass, Posidonia oceanica, and killed up to 45% of the seagrass in one year. Since the species has become the main food source for herbivores, after killing off other seagrass, it is also causing herbivores to be eliminated because it is toxic to them. A decline in fish biomass in areas where Caulerpa is present is becoming an issue.
There is a lack of natural predators to this species and it is essential to its success. According to the article, in 2000, authorities isolated and poisoned the Caulerpa patches found in the water’s northwest of San Diego, and it appeared successful. The patches of Caulerpa were covered with containment devices that trap adequate volume of water for treatment with chemical herbicides, while still protecting surrounding areas. There was also an infestation in Orange County in 2000 that was treated. Both of these strains of Caulerpa were identical to the aquarium strain of the species. Releases from aquarium into the ocean or indirectly through a storm drain were probably the sources of the Southern California infestations. Other ideas for controlling this invasive species have been to introduce a natural predator into their environment. This could create more problems, however. Caulerpa has been designated as a U.S. Federal Noxious Weed and is prohibited in the U.S. The Assembly Bill 1334 prohibits the possession, sale, and transport of Caulerpa in California. Since early eradication was not attempted from the Caulerpa manifestation in the Mediterranean, it now infests over 30,000 acres of the sea floor, and negatively impact tourism, fishing, and scuba diving. Infestations in Australia are reported to be the aquarium strain, that was also reported in New South Wales, and efforts are being made to control its spread.