Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide


Caulerpa taxifolia
(killer algae)



Caulerpa taxifolia (killer algae)


  • Last modified
  • 20 November 2019
  • Datasheet Type(s)
  • Invasive Species
  • Preferred Scientific Name
  • Caulerpa taxifolia
  • Preferred Common Name
  • killer algae
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Plantae
  •     Phylum: Chlorophyta
  •       Class: Bryopsidophyceae
  •         Order: Bryopsidales
  • Summary of Invasiveness
  • C. taxifolia is a green marine macro-algae native to tropical waters of the Indian, Pacific and Atlantic oceans. In the 1980s, a specifically bred cold-resistant clone of C.taxifolia was introduced by accident into the Mediter...

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Mediterranean clone of Caulerpa taxifolia.
CaptionMediterranean clone of Caulerpa taxifolia.
Copyright©Rachel Woodfield/Merkel & Associates, Inc./ - CC BY-NC 3.0 US
Mediterranean clone of Caulerpa taxifolia.
HabitMediterranean clone of Caulerpa taxifolia.©Rachel Woodfield/Merkel & Associates, Inc./ - CC BY-NC 3.0 US
Mediterranean clone of Caulerpa taxifolia with Caulerpa racemosa in background.
CaptionMediterranean clone of Caulerpa taxifolia with Caulerpa racemosa in background.
Copyright©Rachel Woodfield/Merkel & Associates, Inc./ - CC BY-NC 3.0 US
Mediterranean clone of Caulerpa taxifolia with Caulerpa racemosa in background.
HabitMediterranean clone of Caulerpa taxifolia with Caulerpa racemosa in background.©Rachel Woodfield/Merkel & Associates, Inc./ - CC BY-NC 3.0 US


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Preferred Scientific Name

  • Caulerpa taxifolia (M. Vahl) C. Agardth

Preferred Common Name

  • killer algae

Other Scientific Names

  • Fucus taxifolius Vahl

International Common Names

  • English: green sea palm; killer alga

Local Common Names

  • Germany: Schlauchalge
  • Philippines: lukay-lukay

Summary of Invasiveness

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C. taxifolia is a green marine macro-algae native to tropical waters of the Indian, Pacific and Atlantic oceans. In the 1980s, a specifically bred cold-resistant clone of C.taxifolia was introduced by accident into the Mediterranean Sea from a public aquarium in Monaco, from where it has spread around the Mediterranean and also been found in California and southern Australia. Now commonly known as the ‘aquarium strain’, it grows rapidly and smothers seagrass and other benthos in coastal locations, especially where affected by wastewater or other forms of environmental disturbance. Once well established, it is impossible to eradicate.

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Plantae
  •         Phylum: Chlorophyta
  •             Class: Bryopsidophyceae
  •                 Order: Bryopsidales
  •                     Family: Caulerpaceae
  •                         Genus: Caulerpa
  •                             Species: Caulerpa taxifolia

Notes on Taxonomy and Nomenclature

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The genus Caulerpa is thought to contain nearly 100 variable taxa (Meinesz, 2002). C. taxifolia is named after the resemblance of its fronds to the leaves of yew trees (Taxus spp.).


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C. taxifolia is a siphonalean alga, a green macro-alga with a siphonous (coenocytic) morphology, i.e. algal thalli have no cell walls but are composed of a single or few large multinucleated cells. The gross morphology resembles that of higher plant. The thallus consists of a creeping ‘stolon’ that is often above the sediment, anchored by colourless ‘rhizoids’. The photosynthetic, upright parts of the thallus are ‘fronds’, resembling leaves with midrib and feather-like ‘pinnules’. The following description is modified from Boudouresque et al. (1995) and Meinesz et al. (1995).

The ‘aquarium strain’ of C. taxifolia is somewhat different, chiefly in size, length, growth rate and temperature tolerance from samples collected in tropical areas. Fronds are feather-like ‘leaf blades’ each of which has a relatively wide central axis (rachis), from which grow many pinnules. Primary fronds grow directly on the stolons at regularly intervals, and may be quite short or even absent in shallower water, leaving only the stolons, becoming longer in deeper water in low light conditions. Primary fronds of the native tropical strains are 2-15 cm long, whereas in the ‘aquarium strain’, primary fronds range from 5 cm in shallower water to 40 cm at depths of 15 m, and up to 60-80 cm long at greater depths. Branching fronds grow from the primary fronds. Pinnules are up to 1 cm long, with 4-7 per cm along each side of the frond axis, usually upcurved, tapering at the ends, with some pinnules bifurcating at the ends, pinnule spacing and length depend on light availability Primary frond cover density may range from 5,100 (September) to 14,000 (April) fronds per m2. Stolons (stems) bear fronds and rhizoids, stolon length 1.0-1.5 m in autumn; new stolons arising from old stolons that have survived the winter. Unlike vascular plants there are no ‘roots’ on algae, however in C. taxifolia, regularly spaced ‘rhizoid pillars’ descend from the stolons, tapering at the ends with many extremely thin filamentous ‘rhizoids’, mimicking roots by attaching to rocks and other substrata and taking up and translocating inorganic and organic nutrients from the substrate, and may form a fine mat completely covering the substrate.

Plant Type

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C. taxifolia is a green marine macro-algae native to tropical waters of the Indian, Pacific and Atlantic oceans. It was first discovered around the Virgin Islands, and is native to both sides of the mid-Atlantic from the Caribbean Sea to Brazil and along the western African coast, in the Indian Ocean from Pakistan to Indonesia, and in the Pacific Ocean from Japan to Australia to Polynesia (Meinesz, 2002). UNEP (2004) note a broader native range with most tropical coasts of the Indian Ocean including East Africa and the Red Sea. Thus, C. taxifolia is likely to be native to coastal waters of many more countries than listed in the Distribution table.

Distribution Table

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The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.

Last updated: 10 Jan 2020
Continent/Country/Region Distribution Last Reported Origin First Reported Invasive Reference Notes


Cabo VerdePresentNative
Côte d'IvoirePresentNative
Equatorial GuineaPresentNativeGulf of Guinea
São Tomé and PríncipePresentNative
TunisiaPresentIntroduced2000Accidental introduction, introducer unknown


ChinaPresentNativeSouthern China Sea
IndiaPresentNativeNorthern Indian Ocean coast
-Andaman and Nicobar IslandsPresentNative
Saudi ArabiaPresentNative
Sri LankaPresentNative


CroatiaPresentIntroduced1994InvasiveIntroducer unknown, established in the wild
FrancePresentIntroduced1989InvasiveAccidental or natural introduction, established through natural reproduction and spread
ItalyPresentIntroducedInvasiveAccidental introduction, established through natural reproduction; First reported: 1990s
MonacoPresentIntroduced1984InvasiveInitial site of release in 1980s
SpainPresentIntroducedInvasiveAccidental introduction, established through natural reproduction; First reported: 1990s
-Balearic IslandsPresentIntroduced1992InvasiveMallorca - accidental introduction, established through natural reproduction
-Canary IslandsPresentIntroduced

North America

Netherlands AntillesPresentand Lesser Antilles
Puerto RicoPresentNative
Trinidad and TobagoPresentNative
U.S. Virgin IslandsPresentNative
United StatesPresentPresent based on regional distribution.


American SamoaPresent
AustraliaPresentPresent based on regional distribution.
-Lord Howe IslandPresent
-New South WalesPresent, WidespreadIntroduced2000InvasiveRecorded from 13 estuaries or coastal lakes (as of March 2008). Illegal to sell but can be kept in enclosed aquaria.
-Northern TerritoryPresentNative
-QueenslandPresent, WidespreadNativeEvidence that there are invasive and non-invasive
-South AustraliaPresent, LocalizedIntroduced2002InvasiveWest Lakes and Port River
-Western AustraliaPresent, LocalizedNative
Federated States of MicronesiaPresentNative
French PolynesiaPresentNative
New CaledoniaPresentNative
Papua New GuineaPresentNative

Sea Areas

Atlantic - Eastern CentralPresentNative
Atlantic - Western CentralPresentNative
Indian Ocean - EasternPresentNative
Indian Ocean - WesternPresentNative
Mediterranean and Black SeaPresentIntroduced1984accidental
Pacific - Eastern CentralPresentIntroduced2000accidental
Pacific - Western CentralPresentNative

South America


History of Introduction and Spread

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A cold-resistant strain of C. taxifolia was discovered in the tropical aquarium in Stuttgart, Germany in 1980, and distributed to aquaria and institutes in Nancy, Paris and Monaco. Four years later, in 1984, a single square metre of C. taxifolia was found below the Oceanagraphic Museum in Monaco, expanding to a 10,000 m2 in five years, by 1989, and a year later, in 1990, it was also found 5 km east of Monaco at Cap Martin (Meinesz, 2002). C.taxifolia was thus introduced into the Mediterranean Sea by an accidental release from this public aquarium in Monaco.

In 2000, the ‘aquarium strain’, was discovered at two coastal locations in southern California, USA.

In Australia, C. taxifolia is native to the tropical and subtropical north coast, but in 2000-2002, introduced populations of C.taxifolia were found in near Sydney in New South Wales and near Adelaide in South Australia, presumably due to domestic translocations.

Risk of Introduction

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Due to a 15-year history of spread in the Mediterranean Sea, the ‘aquarium strain’ of C. taxifolia was placed on the US Federal Noxious Weed list in 1999. Specifically, it is a Class A Noxious weed in Alabama, North Carolina and Vermont, and otherwise regulated in Massachusetts, Oregon and South Carolina (USDA-NRCS, 2008). The possession or sale of C. taxifolia in California is banned.

Twelve species have distributions extending into temperate seas, indicating that, if introduced, several other taxa of aquarium-traded Caulerpa besides C. taxifolia might be capable of establishing populations in southern Californian or other temperate waters (Zaleski and Murray, 2006).


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C. taxifolia grows naturally in tropical oceans (Meinesz, 2002), but the cold-tolerant ‘aquarium strain’ is well-adapted to more temperate, Mediterranean climates. Where invasive in the south of France, it is found between 3 and 30 m deep, but it has also been found in water to 100 m deep (Boudouresque et al., 1995).

Habitat List

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BrackishInland saline areas Secondary/tolerated habitat Harmful (pest or invasive)
BrackishEstuaries Secondary/tolerated habitat Harmful (pest or invasive)
BrackishEstuaries Secondary/tolerated habitat Natural
BrackishLagoons Secondary/tolerated habitat Harmful (pest or invasive)
BrackishLagoons Secondary/tolerated habitat Productive/non-natural
MarineInshore marine Secondary/tolerated habitat Harmful (pest or invasive)
MarineInshore marine Secondary/tolerated habitat Natural
MarineInshore marine Secondary/tolerated habitat Productive/non-natural
MarineCoral reefs Principal habitat Natural
MarineBenthic zone Principal habitat Harmful (pest or invasive)
MarineBenthic zone Principal habitat Natural
MarineBenthic zone Principal habitat Productive/non-natural

Biology and Ecology

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Meusnier et al. (2001) present two sets of evidence that support an Australian origin for the Mediterranean populations of C. taxifolia. Complementing previous biogeographical studies based on nuclear ribosomal DNA (rDNA) internal transcribed spacer (ITS), a new chloroplast marker was developed, and comparison of intrapopulation genetic diversity between invasive Mediterranean and 'native' Australian populations revealed the occurrence of two divergent and widespread clades. The first clade grouped nontropical invasive populations with inshore-mainland populations from Australia, while the second clustered all offshore-island populations studied so far. Despite finding nine distinct nuclear and five distinct chloroplast profiles, a single nucleocytoplasmic combination was characteristic of the invasive populations and sexual reproduction was found to be very rare, thus C. taxifolia is clearly a complex of genetically and ecologically differentiated sibling species or subspecies (Meusnier et al., 2002).

Reproductive Biology

The rapid expansion and high abundance of invasive C. taxifolia are underpinned by post-recruitment vegetative growth and, during expansion, by a feedback between vegetative growth and asexual fragmentation (Wright and Davis, 2006). C. taxifolia can reproduce both sexually and asexually but the reproduction and life cycle of this species is poorly understood. In most introduced populations only vegetative reproduction via rhizoid extension or thallus fragmentation has been observed, which may be a temperature effect as sexual reproduction has only been observed at temperatures above 25°C. In the introduced Mediterranean population, only male gametes have been observed. Other Caulerpa species have episodically release of gametes, and are monoecious with moderate anisogamy (Clifton and Clifton, 1999).

Physiology and Phenology

C. taxifolia in its native range is normally found as isolated, spindly plants, whereas where introduced, it often appears in dense mats. This may, however, be an adaptation of the cold-resistant strain.

Against the prediction of a large size for invasive C. taxifolia, native populations from Moreton Bay, Queensland, Australia had larger stolons and fronds than invasive populations (Wright, 2002). However, invasive populations consistently had much higher densities of stolons, fronds and fragmented fronds, and a greater biomass compared to native populations. Average densities at invasive sites exceeded 4700 stolons and 9000 fronds/m2 and were as high as 27,000 stolons and 95,000 fronds/m2, which are the highest reported for C. taxifolia anywhere, with average densities of fragmented fronds at invasive sites were as high as 6000/m2 (Wright, 2002).

The most northerly recorded infestation of C. taxifolia is in Croatia, where vegetative growth showed consistent seasonal patterns (Ivesa et al., 2006). In Malinska, the alga nearly disappeared in April-May while regenerating from over-wintering parts of the thalli in summer. Maximum development occurred in autumn and winter, but biomass and frond production generally lower than that in the north-western Mediterranean, though biomass was closely correlated to frond number and length. During the study period, the total colonized area which was several thousand square metres spontaneously declined. No major changes in winter seawater temperatures (9.5-10.5°C) were observed in the area, thus, other unknown processes played a role on specific vegetation patterns of C. taxifolia (Ivesa et al., 2006).

Environmental Requirements

C. taxifolia has successfully displaced several native, benthic communities and can establish on a variety of substrates from sand to rocky shores. Fronds, stolons and thalli of the alga all displayed similar responses under a range of salinities (15-30 ppt) and water temperatures (15-30°C). Many of the algal fragments doubled in size in one week with a maximum growth rate of 17.4 cm/week was recorded (West and West, 2007), with optimal growth of over 20 mm/week at salinities above 20 ppt and temperatures above 20°C.

C. taxifolia recorded at Malinska, Croatia represents the highest northern latitude (45° 7' 30" N) at which this species has been found in the wild (Ivesa et al., 2006).


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A - Tropical/Megathermal climate Preferred Average temp. of coolest month > 18°C, > 1500mm precipitation annually
C - Temperate/Mesothermal climate Tolerated Average temp. of coldest month > 0°C and < 18°C, mean warmest month > 10°C

Water Tolerances

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ParameterMinimum ValueMaximum ValueTypical ValueStatusLife StageNotes
Salinity (part per thousand) 15 30 Optimum
Water temperature (ºC temperature) 15 30 Optimum

Means of Movement and Dispersal

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Natural Dispersal (Non-Biotic)

C. taxifolia
is likely to spread locally with the aid of currents.

Accidental Introduction

The release of aquarium plants into the natural environment is considered to be the cause for the initial introductions of C. taxifolia into at least the Mediterranean Sea and coastal Californian waters.


The anchoring of vessels removes fragments of C. taxifolia from estuaries, and conditions inside anchor lockers may enhance fragment survival. Thus, boats may be an important vector for dispersal of C. taxifolia within and between estuaries (West et al., 2007). Boat traffic across and around the Mediterranean is thought to be the means of spread of this alga from Monaco to Spain, Italy, Croatia and Tunisia. Sport fishing is also considered to aid local movement of C. taxifolia in the Ligurian Sea, Italy, being attached to fishing equipment (Relini et al., 2000). For these reasons, new infestations tend to occur in ports, harbours and marinas.

Intentional Introduction

The sale of aquarium plants by mail order and via the internet, including the ‘aquarium strain’ of C. taxifolia continues, making further long distance introductions likely.


Pathway Causes

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CauseNotesLong DistanceLocalReferences
Fisheries Yes Yes Relini et al. (2000)
Intentional releaseHome aquarium contents Yes Yes Meinesz (2002)
Internet salesUnproven but suspected Yes
Pet trade Yes Yes Meinesz (2002)

Pathway Vectors

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VectorNotesLong DistanceLocalReferences
Pets and aquarium species Yes

Impact Summary

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Cultural/amenity Positive
Environment (generally) Negative

Economic Impact

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Economic and social impacts are due to the reduction in catches of fish by commercial fishermen due to the reduction of fish habitat by C. taxifolia, and the weed becoming entangled in boat propellers and fishing nets also affect efficiency (NIMPIS, 2008). The few fish which are able to eat C. taxifolia, such as the Mediterranean bream (Sarpa salpa), accumulate toxins in their bodies making them unsuitable for human consumption (Meinesz and Hesse, 1991).

Economic impacts resulting from the cost of eradication included approx US $6 million spent in southern California in 2000-04 (Anderson, 2004), and estimated AUS $6-8 million in southern Australia.

Environmental Impact

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The Mediterranean strain of the species known as the ‘aquarium strain’ grows rapidly and smothers seagrass beds and other benthos in coastal locations, especially where affected by wastewater or other forms of environmental disturbance. Mat-forming invasive species such as C. taxifolia change the habitats where they invade, and as benthic invertebrates are sensitive to environmental disturbance, important sublethal effects on native species may occur (Gribben and Wright, 2006a). Large monospecific meadows have vastly reduced native species diversity and fish habitat. The mechanisms whereby it does this are either by out-competing other species for food and light, or due to toxic effects of caulerpenyne compounds present in the foliage. However, despite the threat posed by C. taxifolia, virtually nothing is known of its effects on native estuarine fauna (Gribben and Wright, 2006b).

Montefalcone et al. (2007) found substitution of Posidonia oceanica seagrass meadows in the north-west Mediterranean Sea by invading C. taxifolia.


A decline in the abundance and condition of a native bivalve Anadara trapezia was associated with C. taxifolia invasion in New South Wales, Australia (Wright et al., 2007); however, C. taxifolia invasion appears complex, and in some places, its effects may not differ from those in native seagrass. Gribben and Wright (2006a) showed that C. taxifolia has strong negative effects on the reproductive traits of A. trapezia, affecting the timing of reproductive development and spawning, and follicle and gamete production, even though C. taxifolia had positive effects on recruitment. Also, gender specific responses occurred indicating that females were more susceptible to invasion than males (Gribben and Wright, 2006a). However, C. taxifolia may also provide a refuge from predation thus enhancing recruitment of A. trapezia compared to uninvaded sediment, but the long-term consequences of this enhanced recruitment are unknown, and contrary to commonly held views the effects of C. taxifolia are not always negative (Gribben and Wright, 2006b).


Based on the grazing of four native fishes in Australia, Gollan and Wright (2006) concluded that the low diversity and abundance of native herbivores, their weak grazing pressure on C. taxifolia and its low attractiveness as habitat, could facilitate further local spread. Comparing fish populations in two flat marine areas 4-8 m deep in the Ligurian Sea, Italy, one colonized by C. taxifolia, and a control area without C. taxifolia but colonized by the phanerogam Cymodocea nodosa, there were 9 species mostly those found on soft bottoms exclusive to the control site, and 14 species, 6 of which were wrasses, exclusive to the C. taxifolia site (Relini et al., 1998). The high specific richness and the structural complexity in C. taxifolia invaded sites rated this environment above other flat environments.

Risk and Impact Factors

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  • Invasive in its native range
  • Proved invasive outside its native range
  • Has a broad native range
  • Abundant in its native range
  • Highly adaptable to different environments
  • Is a habitat generalist
  • Pioneering in disturbed areas
  • Tolerant of shade
  • Fast growing
  • Has high reproductive potential
  • Reproduces asexually
Impact outcomes
  • Ecosystem change/ habitat alteration
  • Increases vulnerability to invasions
  • Modification of natural benthic communities
  • Monoculture formation
  • Reduced native biodiversity
Impact mechanisms
  • Competition - monopolizing resources
  • Competition - shading
  • Fouling
  • Interaction with other invasive species
  • Rapid growth
Likelihood of entry/control
  • Highly likely to be transported internationally accidentally
  • Highly likely to be transported internationally deliberately
  • Difficult to identify/detect as a commodity contaminant
  • Difficult to identify/detect in the field
  • Difficult/costly to control


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C. taxifolia contains 3.7% dry matter, comprising 5.8% protein, 65.8% carbohydrate, 14.8% ash, fat, and 6.5 mg/100 g vitamin C, 138 mg/100 g sodium, and 116 mg/100 g potassium (Hasni et al., 1986). Some natural products of Caulerpa have been identified (Aliya and Mustafa, 2003), but no commercial exploitation is known.

Uses List

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  • Laboratory use
  • Pet/aquarium trade

Similarities to Other Species/Conditions

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Exotic C. taxifolia may be mistaken with native Caulerpa spp. where introduced, such as in the Mediterranean, southern Australia, California and the northern Caribbean. However, large frond size and formation of dense populations tend to easily separate the ‘aquarium strain’ from other species.

Prevention and Control

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Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.


SPS measures

C. taxifolia is on a number of regulated noxious weed lists (see Risk of Introduction).

Rapid response

Due to reports of the spread of C. taxifolia in the Mediterranean Sea, it was placed on the US Federal Noxious Weed list in 1999, and awareness of this threat greatly facilitated consensus building and setting clear eradication goals among a large number of state, federal and local agencies as well as private groups and non-governmental organizations that became the ‘Southern California Caulerpa Action Team’ (SCCAT) (Anderson, 2005). Field containment and treatments began 17 days after the initial discovery on 12 June 2000, due to: (1) timely identification and notification of the infestation; (2) the proactive staff of the San Diego Regional Water Quality Control Board who deemed this invasion tantamount to an 'oil spill', thus freeing up emergency funding; and (3) the mobilization of diver crews already working at the site.


Three well-integrated components of this rapid response have resulted in an effective eradication program: (a) expertise and knowledge on the biology of C. taxifolia; (b) knowledge on the uses, 'ownership' and characteristics of the infested site; and (c) knowledge and experience in the implementation of aquatic plant eradication. Together, with the requisite resources (approximately US $1.2 million per year), this approach has resulted in containment, treatment and excellent progress toward eradication of C. taxifolia. Successful rapid response to other aquatic invasive species will require similar readiness to act, and immediate access to adequate funding (Anderson, 2005).

Public awareness

It is important to prevent further accidental releases of C. taxifolia by aquarium owners into natural waters, which requires education and extension, informing the public about the risks to the environmental from disposing of aquarium contents, plants as well as fish or other animals, into local rivers, lakes or the sea.


The best example of control of C. taxifolia is from California, USA, starting 17 days after its initial discovery in June 2000 (see also Rapid Response) (Withgott et al., 2002; Anderson, 2005). The Southern California Caulerpa Action Team used liquid chlorine as a control method, the production of an educational brochure and collecting data on the commercial availability of Caulerpa spp., which contributed to state legislators banning nine Caulerpa spp. Over 99% of the original biomass has been treated, surveys are finding fewer new plants, and the need for research into Caulerpa biology, to assist in future control is discussed (Withgott et al., 2002).

Cultural control and sanitary measures

There is no evidence that C. taxifolia is capable of acclimation to gradual reductions in salinity, and consequently, hyposalinity is an effective means of killing C. taxifolia and may prove highly effective for populations in relatively small, contained water bodies (Theil et al., 2007). Looking at means of controlling C. taxifolia in Lake Conjola, California, West and West (2007) observed that almost total mortality occurred at salinities lower than 20 ppt and temperatures less than 20°C, and noting from historical records that prior to entrance manipulation in 2001, salinities had often dropped to below 17 ppt for periods up to 2 years, suggesting that management of C. taxifolia may be improved if the lake was allowed to undergo its normal cycles of opening and closing to the ocean, and entrance manipulation may be one factor that has influenced the success of this invasive species.

Physical/mechanical control

The most effective times for control (i.e. the greatest reduction in rate of increase) were removal of established patches before summer and removal of fragments after summer, corresponding to just before maximum growth and just after maximum reproduction, respectively (Ruesink and Collado-Vides, 2006). Only a combined strategy, incorporating 99% removal of all fragments and annual removal of 99% of established patches, was predicted to eliminate C. taxifolia entirely, but this level of effort is only likely to be possible during the first few years of an invasion, thus arguing strongly for careful monitoring and rapid response to potential high-impact invaders (Ruesink and Collado-Vides, 2006).


In Croatia, suction pumps were used to control C. taxifolia at four sites where it was widespread, but it immediately and intensively recolonized all but one site (Ivesa et al., 2006). Also in Croatia, covering C. taxifolia colonies with black plastic was found to be reasonably successful on an area of around 500 m², with little regrowth occurring after treatment (McEnnulty et al., 2001). In France, manual removal by scuba divers was successful in eradicating C. taxifolia in small patches of a few square metres at rates of approximately 1-3 m² per diver/hour (McEnnulty et al., 2001).

Biological control

At present, there is no proven, effective biological control agent for C. taxifolia. However, four species of herbivorous gastropods (molluscs) have been examined in Europe for potential reduction of the extensive Mediterranean C. taxifolia populations; Elysia suboranata, Lobiger serradifalci, Oxynoe azuropunctata and Oxynoe olivacea (Anderson, 2002). The tropical Elysia suboranata appears to be the best candidate, although it is unable to survive below 15°C, feeds well above 20°C, and has direct, benthic development and no pelagic larvae. However, being not native, further host specificity testing is required. Lobiger serradifalci, native to the Mediterranean, feeds on C. taxifolia, but also tends to produce fragments which can spread the alga further (Anderson, 2002).


Thibaut and Meinesz (2000) report that the Mediterranean ascoglossan Oxynoe olivacea and Lobiger serradifalci, scarce in meadows of their usual food the native Caulerpa prolifera, have become adapted to feeding on the invasive C. taxifolia. Grazing rates are low, O. olivacea destroys only a 5 cm C. taxifolia frond in 3-7 days, being a function of temperature. Despite a high spawning frequency and a large number of eggs released per spawning event, the recruitment on Caulerpa meadows is usually low due to the hazardous pelagic development of the larvae. The possible use of these molluscs as agents of biological control against C. taxifolia appears to be possible only through an artificial enhancement of their populations after cultivation of the veligers and release of juveniles during the winter season (Thibaut and Meinesz, 2000).

Chemical control

Eradication of the invasive seaweed C. taxifolia is possible with chlorine bleach and despite presumably being from a single clone, C. taxifolia still exhibited a highly variable response to treatments (Williams and Schroeder, 2003). At temperatures favourable to growth, no stolon fragments survived at chlorine concentrations of 125 ppm, though 70% survived at below 50 ppm with many regenerating after two weeks. After 4 months of cold treatments, even C. taxifolia not receiving chlorine treatments failed to regrow, despite unusual chloroplast migration into belowground tissues, and re-establishment of a favourable temperature regime did not result in regrowth over 3 months, and acclimation of C. taxifolia to cold waters did not improve its survival. Thus, chlorine concentrations in eradication treatments should be maintained at 125 ppm for at least 30 min in both the water column and in the sediments to reach stolons and rhizoids, and fragments of C. taxifolia are unlikely to survive or grow at ambient temperatures (8-10°C) off the open coast of northern California (Williams and Schroeder, 2003).


In New South Wales, Australia, the New South Wales Department of Primary Industries (Fisheries) has attempted various control methods, including covering the alga with granulated sea salt to induce osmotic shock and cell lysis (Uchiura et al., 2000). In Lake Macquarie, C. taxifolia often occurs in patches within beds of the native seagrass Zostera capricorni, although effects of salt treatment on this native seagrass and infauna are minimal and there was no evidence of a consistent effect of salting on diversity or abundance of other epifauna (O’Neill et al., 2007). The action of copper, potassium and sodium ions on C. taxifolia survival rates and photosynthetic parameters showed that the utilization of copper cations is possible following technical approaches such as ion exchange textile covers, allowing a controlled release of cupric ions without dissemination in the marine environment.


Also in Australia, the application of coarse sea salt at a concentration of 50 kg/m2 was found to be the most effective method, rapidly killing C. taxifolia, with relatively minor effects on native biota (seagrass and infauna), and was relatively inexpensive (Glasby et al., 2005). In trials, frond density of C. taxifolia decreased by 70-95% one week after salting and no fronds were present after 1 or 6 months. Seagrass and infauna were also affected by salt, but abundances had generally recovered after 6 months. The effectiveness of salting at larger scales depended on the method of application and salting appeared to be most successful in the cooler months when C. taxifolia dies back naturally. In was concluded that eradication of C. taxifolia from New South Wales is unlikely, but local control measures, extensive monitoring and experimentation are continuing in an attempt to limit the impacts (Glasby et al., 2005). 


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Aliya R; Mustafa Shameel, 2003. Marine natural products of Caulerpa (Siphonocladophyceae). Pakistan Journal of Botany, 35(5):659-669.

Anderson LWJ, 2002. Biological control of killer algae, Caulerpa taxifolia. In: California Conference on Biological Control III, University of California at Davis, USA, 15-16 August, 2002 [ed. by Hoddle MS] Berkeley, USA: Center for Biological Control, College of Natural Resources, University of California, 79-85.

Anderson LWJ, 2004. Eradication of Caulerpa taxifolia in the US five years after discovery: are we there yet? In: 13th International Conference on Aquatic Invasive Species. 20-24 September 2004, Ennis, County Clare, Ireland.

Anderson LWJ, 2005. California's reaction to Caulerpa taxifolia: a model for invasive species rapid response. Biological Invasions, 7(6):1003-1016.

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Boudouresque CF; Meinesz A; Ribera MA; Ballesteros E, 1995. Spread of the green alga Caulerpa taxifolia (Caulerpales, Chlorophyta) in the Mediterranean: Possible consequences of a majro ecological event. Scientia Marina, 59((Suppl. 1)):21-29.

Clifton KE; Clifton LM, 1999. The phenology of sexual reproduction by green algae (Bryopsidales) on Caribbean coral reefs. Journal of Phycology, 35:24-34.

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Glasby TM; Creese RG; Gibson PT, 2005. Experimental use of salt to control the invasive marine alga Caulerpa taxifolia in New South Wales, Australia. Biological Conservation, 122(4):573-580.

Glasby TM; Gibson PT, 2007. Limited evidence for increased cold-tolerance of invasive versus native Caulerpa taxifolia. Marine Biology, 152:255-263.

Gollan JR; Wright JT, 2006. Limited grazing pressure by native herbivores on the invasive seaweed Caulerpa taxifolia in a temperate Australian estuary. Marine and Freshwater Research, 57(7):685-694.

Gribben PE; Wright JT, 2006. Invasive seaweed enhances recruitment of a native bivalve: roles of refuge from predation and the habitat choice of recruits. Marine Ecology, Progress Series, 318:177-185.

Gribben PE; Wright JT, 2006. Sublethal effects on reproduction in native fauna: are females more vulnerable to biological invasion? Oecologia, 149(2):352-361.

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Iveša L; Jaklin A; Devescovi M, 2006. Vegetation patterns and spontaneous regression of Caulerpa taxifolia (Vahl) C. Agardh in Malinska (Northern Adriatic, Croatia). Aquatic Botany, 85(4):324-330.

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Meinesz A; Belsher T; Thibaut T; Antolic B; Ben Mustapha K; Boudouresque CF; Chiaverini D; Cinelli F; Cottalorda JM; Djellouli A; Abed AEl; Orestano C; Grau AM; Ivesa L; Jaklin A; Langar H; Massuti-Pascual E; Peirano A; Tunesi L; Vaugelas Jde; Zavodnik N; Zuliejevic A, 2001. The introduced green alga Caulerpa taxifolia continues to spread in the Mediterranean. Biological Invasions, 3:201-210.

Meinesz A; Benichou L; Blachier J; Komatsu T; Lemeé R; Molenaar H; Mari X, 1995. Variations in the structure, morphology and biomass of Caulerpa taxifolia in the Mediterranean Sea. Botanica Marina, 38:499-508.

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Meusnier I; Olsen JL; Stam WT; Destombe C; Valero M, 2001. Phylogenetic analyses of Caulerpa taxifolia (Chlorophyta) and of its associated bacterial microflora provide clues to the origin of the Mediterranean introduction. Molecular Ecology, 10(4):931-946.

Meusnier I; Valero M; Destombe C; Godé C; Desmarais E; Bonhomme F; Stam WT; Olsen JL, 2002. Polymerase chain reaction-single strand conformation polymorphism analyses of nuclear and chloroplast DNA provide evidence for recombination, multiple introductions and nascent speciation in the Caulerpa taxifolia complex. Molecular Ecology, 11(11):2317-2325.

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Phillips JA; Price IR, 2002. How different is Mediterranean Caulerpa taxifolia (Caulerpales: Chlorophyta) to other populations of the species? Marine Ecology, Progress Series, 238:61-71.

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Distribution References

CABI, Undated. Compendium record. Wallingford, UK: CABI

CABI, Undated a. CABI Compendium: Status inferred from regional distribution. Wallingford, UK: CABI

CABI, Undated b. CABI Compendium: Status as determined by CABI editor. Wallingford, UK: CABI

FAO-DIAS, 2008. Database on introductions of aquatic species. FAO Fisheries Global Information System. In: Database on introductions of aquatic species. FAO Fisheries Global Information System, Fisheries and Aquaculture Department, FAO.

Guiry M D, Guiry G M, 2008. AlgaeBase. In: AlgaeBase, Galway, Ireland: National University of Ireland.

Meinesz A, Belsher T, Thibaut T, Antolic B, Ben Mustapha K, Boudouresque C F, Chiaverini D, Cinelli F, Cottalorda J M, Djellouli A, Abed A El, Orestano C, Grau A M, Ivesa L, Jaklin A, Langar H, Massuti, 2001. The introduced green alga Caulerpa taxifolia continues to spread in the Mediterranean. Biological Invasions. 201-210.

Phillips J A, Price I R, 2002. How different is Mediterranean Caulerpa taxifolia (Caulerpales: Chlorophyta) to other populations of the species? Marine Ecology, Progress Series. 61-71. DOI:10.3354/meps238061

Theil M, Westphalen G, Collings G, Cheshire A, 2007. Caulerpa taxifolia responses to hyposalinity stress. Aquatic Botany. 87 (3), 221-228. DOI:10.1016/j.aquabot.2007.06.001

UNEP, 2004. Environment Alert Bulletin, 1, 1-4.

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03/03/08 Original text by:

Britta Schaffelke, CRC Reef Research Centre, James Cook University, QLD, Australia

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