''Caulerpa taxifolia'' is a species of green

seaweed Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of ''Rhodophyta'' (red), '' Phaeophyta'' (brown) and ''Chlorophyta'' (green) macroalgae. Seaweed species such as ...

, an

alga Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular microalgae, suc ...

of the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

Caulerpa ''Caulerpa'' is a genus of seaweeds in the family Caulerpaceae (among the green algae). They are unusual because they consist of only one cell with many cell nucleus, nuclei, making them among the biggest single cells in the world. Referring to ...

'', native to tropical waters of the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or approximately 20% of the water area of Earth#Surface, Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia (continent), ...

, and

Caribbean Sea The Caribbean Sea is a sea of the Atlantic Ocean, North Atlantic Ocean in the tropics of the Western Hemisphere, located south of the Gulf of Mexico and southwest of the Sargasso Sea. It is bounded by the Greater Antilles to the north from Cuba ...

. The species name ''taxifolia'' arises from the resemblance of its leaf-like fronds to those of the yew (''Taxus''). A strain of the species bred for use in aquariums has established non-native populations in waters of the

Mediterranean Sea The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Eur ...

, the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

, and

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

. It is one of two species of algae listed in

100 of the World's Worst Invasive Alien Species 100 of the World's Worst Invasive Alien Species is a list of invasive species compiled in 2000 from the Global Invasive Species Database, a database of invasive species around the world. ISSG booklet giving the original 100 species. The database i ...

compiled by the

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

Invasive Species Specialist Group.

Description

''C. taxifolia'' is light green with

stolon In biology, a stolon ( from Latin ''wikt:stolo, stolō'', genitive ''stolōnis'' – "branch"), also known as a runner, is a horizontal connection between parts of an organism. It may be part of the organism, or of its skeleton. Typically, animal ...

s (stems) on the sea floor, from which sparsely-branched upright fronds of approximately 20–60 cm (8–24 in) in height arise. Algae in the genus ''Caulerpa'' synthesize a mixture of toxins termed caulerpicin, believed to impart a peppery taste to the plants. The effects of the specific toxin synthesized by ''C. taxifolia'', caulerpenyne, have been studied, with extracts from ''C. taxifolia'' being found to negatively affect

P-glycoprotein P-glycoprotein 1 (permeability glycoprotein, abbreviated as P-gp or Pgp) also known as multidrug resistance protein 1 (MDR1) or ATP-binding cassette sub-family B member 1 (ABCB1) or cluster of differentiation 243 (CD243) is an important protein ...

-ATPase in the

sea sponge Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and are o ...

''G. cydonium''. Like all members of the genus ''Caulerpa,'' ''C. taxifolia'' consists of a single cell with many nuclei. The algae has been identified as the largest known single-celled organism. Wild-type ''C. taxifolia'' is

monoecious Monoecy (; adj. monoecious ) is a sexual system in seed plants where separate male and female cones or flowers are present on the same plant. It is a monomorphic sexual system comparable with gynomonoecy, andromonoecy and trimonoecy, and contras ...

Use in aquaria

''Caulerpa'' species are commonly used in aquaria for their aesthetic qualities and ability to control the growth of undesired species. ''C. taxifolia'' has been cultivated for use in aquaria in western

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

since the early 1970s. A clone of the alga that was resistant to cold was observed in the tropical aquarium at the Wilhelma Zoo in

Stuttgart Stuttgart (; ; Swabian German, Swabian: ; Alemannic German, Alemannic: ; Italian language, Italian: ; ) is the capital city, capital and List of cities in Baden-Württemberg by population, largest city of the States of Germany, German state of ...

and further bred by exposure to chemicals and

ultraviolet light Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of th ...

. The zoo distributed the strain to other aquaria, including the Oceanographic Museum of Monaco. The aquarium strain is morphologically identical to native populations of the species. However, a 2008 study found that a population of the aquarium strain near

Caloundra Caloundra ( ) is a coastal town in the Sunshine Coast Region, Queensland, Australia. In the , the town of Caloundra had a population of 96,305 people. Geography Caloundra is north of the Brisbane central business district. Caloundra is acce ...

, Australia exhibited markedly reduced sexual reproduction, with only male plants present during some reproductive episodes. The aquarium strain can survive out of water for up to 10 days in moist conditions, with 1 cm fragments capable of producing viable plants.

Status as invasive species

Outside its native range, ''C. taxifolia'' is listed as an invasive species. It is one of two algae on the

list of the world's 100 worst invasive species 100 of the World's Worst Invasive Alien Species is a list of invasive species compiled in 2000 from the Global Invasive Species Database, a database of invasive species around the world. ISSG booklet giving the original 100 species. The database i ...

compiled by the

Invasive Species Specialist Group (alongside Wakame). The species is able to thrive in heavily polluted waters, possibly contributing to its spread in the Mediterranean.

Presence in the Mediterranean Sea

The presence of ''C. taxifolia'' in the Mediterranean was first reported in 1984 in an area adjacent to the Oceanographic Museum of Monaco. Alexandre Meinesz, a marine biologist, attempted to alert Moroccan and French authorities to the spread of the strain in 1989, but the governments failed to respond to his concerns. The occurrence of the strain is generally believed to be due to an accidental release by the museum, but

Monaco Monaco, officially the Principality of Monaco, is a Sovereign state, sovereign city-state and European microstates, microstate on the French Riviera a few kilometres west of the Regions of Italy, Italian region of Liguria, in Western Europe, ...

rejected the attribution and instead claimed that the observed algae was a mutant strain of ''C. mexicana''. By 1999, scientists agreed that it was no longer possible to eliminate the presence of ''C. taxifolia'' in the Mediterranean. A study published in 2002 found that beds of '' Posidonia oceanica'' in the Bay of

Menton Menton (; in classical norm or in Mistralian norm, , ; ; or depending on the orthography) is a Commune in France, commune in the Alpes-Maritimes department in the Provence-Alpes-Côte d'Azur region on the French Riviera, close to the Italia ...

were not negatively affected eight years after colonization by ''C. taxifolia''. Other published studies have shown that fish diversity and biomass are equal or greater in Caulerpa meadows than in seagrass beds and that Caulerpa had no effect on composition or richness of fish species. Studies in 1998 and 2001 found that the strain observed in the Mediterranean was genetically identical to aquarium strains, with similarities to an additional population in Australia.

Presence in Australia

A 2007 study found that a native

bivalve Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class (biology), class of aquatic animal, aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed b ...

mollusc Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

species was negatively affected by the presence of ''C. taxifolia'', but that the effect was not necessarily different from that of native seagrass species. A 2010 study indicated that the effect of detritus from ''C. taxifolia'' negatively impacted abundance and species richness.

Presence in California

''C. taxifolia'' was found in waters near

San Diego San Diego ( , ) is a city on the Pacific coast of Southern California, adjacent to the Mexico–United States border. With a population of over 1.4 million, it is the List of United States cities by population, eighth-most populous city in t ...

California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

, in 2000, where chlorine bleach was used in efforts to eradicate the strain. The strain was declared eradicated from Agua Hedionda Lagoon in 2006. California passed a law in 2001 forbidding the possession, sale, transport, or release of ''Caulerpa taxifolia'' within the state. The Mediterranean clone of ''C. taxifolia'' was listed as a

noxious weed A noxious weed, harmful weed or injurious weed is a weed that has been designated by an agricultural or other governing authority as a plant that is harmful to agricultural or horticultural crops, natural habitats or ecosystems, or humans or lives ...

in 1999 by the

Animal and Plant Health Inspection Service The Animal and Plant Health Inspection Service (APHIS) is an agency of the United States Department of Agriculture (USDA) based in Riverdale Park, Maryland, Riverdale, Maryland responsible for protecting animal health, animal welfare, and plant h ...

, prohibiting interstate sale and transport of the strain without a permit under the Noxious Weed Act and Plant Protection Act.

Other negative effects

''C. taxifolia'' may become entangled in fishing gear and boat propellers.

Control methods

''C. taxifolia'' may be controlled via mechanical removal, poisoning with

chlorine Chlorine is a chemical element; it has Symbol (chemistry), symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between ...

, or application of

salt In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...

. Researchers at the

University of Nice A university () is an institution of tertiary education and research which awards academic degrees in several academic disciplines. ''University'' is derived from the Latin phrase , which roughly means "community of teachers and scholars". Univ ...

investigated possible use of a species of

sea slug Sea slug is a common name for some Marine biology, marine invertebrates with varying levels of resemblance to terrestrial Slug, slugs. Most creatures known as sea slugs are gastropods, i.e. they are Sea snail, sea snails (marine gastropod moll ...

, '' Elysia subornata'', as a possible natural control method, but found that it was not suitable for use in the Mediterranean due to cold winter water temperatures and insufficient population density.

Gallery

File:Caulerpa taxifolia - National Museum of Nature and Science, Tokyo - DSC07620.JPG, ''C. taxifolia'' on display at the

National Museum of Nature and Science The is in the northeast corner of Ueno Park in Tokyo. The museum has exhibitions on pre-Meiji period, Meiji science in Japan. It is the venue of the taxidermied bodies of the legendary dogs Hachikō and Taro and Jiro. A life-size blue whale mod ...

Tokyo Tokyo, officially the Tokyo Metropolis, is the capital of Japan, capital and List of cities in Japan, most populous city in Japan. With a population of over 14 million in the city proper in 2023, it is List of largest cities, one of the most ...

, Japan File:CaulerpaTaxifolia.jpg, A field of ''C. taxifolia'' amongst

seagrass Seagrasses are the only flowering plants which grow in marine (ocean), marine environments. There are about 60 species of fully marine seagrasses which belong to four Family (biology), families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and ...

File:Lysmata amboinensis on Caulerpa taxifolia.jpg, A Pacific cleaner shrimp (''Lysmata amboinensis'') on top of a ''C. taxifolia'' specimen within a marine aquarium

References

External links

*
Killer Algae
2001 BBC Documentary
In-depth article on invasions of Caulerpa taxifolia, source as escaped aquarium plant, etc.

from ''Killer Algae'' by Alexandre Meinesz *
Caulerpa taxifolia
' at the Center for Invasive Species Research
"Deep Sea Invasion"
'' Nova (TV series)'' broadcast April 1, 2003
Species Profile- Caulerpa, Mediterranean Clone (''Caulerpa taxifolia'')
National Invasive Species Information Center,

United States National Agricultural Library The United States National Agricultural Library (NAL) is one of the world's largest agricultural research libraries, and serves as a national library of the United States and as the library of the United States Department of Agriculture. Locate ...

. Lists general information and resources for Caulerpa, Mediterranean Clone. {{Authority control taxifolia Protists described in 1817 Algae of India Biota of the Mediterranean Sea Flora of the Indian subcontinent Invasive species Invasive species in the Mediterranean Sea Chlorophyta species