Caulerpa taxifolia (killer algae)
- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Plant Type
- Distribution Table
- History of Introduction and Spread
- Risk of Introduction
- Habitat List
- Biology and Ecology
- Water Tolerances
- Means of Movement and Dispersal
- Pathway Causes
- Pathway Vectors
- Impact Summary
- Economic Impact
- Environmental Impact
- Risk and Impact Factors
- Uses List
- Similarities to Other Species/Conditions
- Prevention and Control
- Links to Websites
- Distribution Maps
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PicturesTop of page
IdentityTop of page
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 InvasivenessTop of page
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 TreeTop of page
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Chlorophyta
- Class: Bryopsidophyceae
- Order: Bryopsidales
- Family: Caulerpaceae
- Genus: Caulerpa
- Species: Caulerpa taxifolia
Notes on Taxonomy and NomenclatureTop of page
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.).
DescriptionTop of page
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.
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 TypeTop of page Aquatic
DistributionTop of page
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 TableTop of page
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.
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|Atlantic, Eastern Central||Present||Native||UNEP, 2004|
|Atlantic, Western Central||Present||Native||UNEP, 2004|
|Indian Ocean, Eastern||Present||Native||UNEP, 2004|
|Indian Ocean, Western||Present||Native||UNEP, 2004|
|Mediterranean and Black Sea||Present||Introduced||1984||UNEP, 2004||accidental|
|Pacific, Eastern Central||Present||Introduced||2000||UNEP, 2004||accidental|
|Pacific, Western Central||Present||Native||UNEP, 2004|
|Bangladesh||Present||Native||Guiry and Guiry, 2008|
|China||Present||Native||UNEP, 2004||Southern China Sea|
|India||Present||Native||UNEP, 2004; Guiry and Guiry, 2008||Northern Indian Ocean coast|
|-Andaman and Nicobar Islands||Present||Native||Guiry and Guiry, 2008|
|Indonesia||Present||Native||Guiry and Guiry, 2008|
|Malaysia||Present||Native||Guiry and Guiry, 2008|
|-Sarawak||Present||Native||Guiry and Guiry, 2008|
|Pakistan||Present||Native||Guiry and Guiry, 2008|
|Philippines||Present||Native||Guiry and Guiry, 2008|
|Saudi Arabia||Present||Native||UNEP, 2004|
|Singapore||Present||Native||Guiry and Guiry, 2008|
|Sri Lanka||Present||Native||Guiry and Guiry, 2008|
|Thailand||Present||Native||Guiry and Guiry, 2008|
|Vietnam||Present||Native||Guiry and Guiry, 2008|
|Yemen||Present||Native||Guiry and Guiry, 2008|
|Cape Verde||Present||Native||Guiry and Guiry, 2008|
|Côte d'Ivoire||Present||Native||Guiry and Guiry, 2008|
|Equatorial Guinea||Present||Native||UNEP, 2004||Gulf of Guinea|
|Gabon||Present||Native||Guiry and Guiry, 2008|
|Gambia||Present||Native||Guiry and Guiry, 2008|
|Ghana||Present||Native||Guiry and Guiry, 2008|
|Kenya||Present||Native||Guiry and Guiry, 2008|
|Madagascar||Present||Native||Guiry and Guiry, 2008|
|Mauritania||Present||Native||Guiry and Guiry, 2008|
|Mauritius||Present||Native||Guiry and Guiry, 2008|
|Sao Tome and Principe||Present||Native||Guiry and Guiry, 2008|
|Senegal||Present||Native||Guiry and Guiry, 2008|
|-Canary Islands||Present||Introduced||Guiry and Guiry, 2008|
|Tanzania||Present||Introduced||Guiry and Guiry, 2008|
|Tunisia||Present||Introduced||2000||Meinesz et al., 2001; FAO-DIAS, 2008||Accidental introduction, introducer unknown|
|Bermuda||Present||Guiry and Guiry, 2008|
|Mexico||Present||Guiry and Guiry, 2008|
|USA||Present||Present based on regional distribution.|
|-Hawaii||Present||Native||UNEP, 2004; Guiry and Guiry, 2008|
Central America and Caribbean
|Barbados||Present||Native||Guiry and Guiry, 2008|
|Belize||Present||Guiry and Guiry, 2008|
|Caribbean||Present||Native||UNEP, 2004; Guiry and Guiry, 2008||Caribbean coasts|
|Cuba||Present||Native||Guiry and Guiry, 2008|
|Jamaica||Present||Guiry and Guiry, 2008|
|Netherlands Antilles||Present||Guiry and Guiry, 2008||and Lesser Antilles|
|Panama||Present||Guiry and Guiry, 2008|
|Puerto Rico||Present||Native||Guiry and Guiry, 2008|
|Trinidad and Tobago||Present||Native||Guiry and Guiry, 2008|
|United States Virgin Islands||Present||Native||Guiry and Guiry, 2008|
|Colombia||Present||Guiry and Guiry, 2008|
|Venezuela||Present||Guiry and Guiry, 2008|
|Croatia||Present||Introduced||1994||Invasive||Meinesz et al., 2001; FAO-DIAS, 2008||Introducer unknown, established in the wild|
|France||Present||Introduced||1989||Invasive||Meinesz et al., 2001; UNEP, 2004; FAO-DIAS, 2008; Guiry and Guiry, 2008||Accidental or natural introduction, established through natural reproduction and spread|
|Italy||Present||Introduced||1990s||Invasive||Meinesz et al., 2001; FAO-DIAS, 2008; Guiry and Guiry, 2008||Accidental introduction, established through natural reproduction|
|Monaco||Present||Introduced||1984||Invasive||Meinesz et al., 2001; UNEP, 2004||Initial site of release in 1980s|
|Spain||Present||Introduced||1990s||Invasive||FAO-DIAS, 2008; Guiry and Guiry, 2008||Accidental introduction, established through natural reproduction|
|-Balearic Islands||Present||Introduced||1992||Invasive||Meinesz et al., 2001; UNEP, 2004||Mallorca - accidental introduction, established through natural reproduction|
|American Samoa||Present||Guiry and Guiry, 2008|
|Australia||Present||Present based on regional distribution.|
|-Australian Northern Territory||Present||Native||Phillips and Price, 2002|
|-Lord Howe Is.||Present||Guiry and Guiry, 2008|
|-New South Wales||Widespread||Introduced||2000||Invasive||Glasby and Creese, 2007; Glasby and Gibson, 2007||Recorded from 13 estuaries or coastal lakes (as of March 2008). Illegal to sell but can be kept in enclosed aquaria.|
|-Queensland||Widespread||Native||Phillips and Price, 2002; Glasby and Gibson, 2007||Evidence that there are invasive and non-invasive|
|-South Australia||Localised||Introduced||2002||Invasive||Theil et al., 2007||West Lakes and Port River|
|-Western Australia||Localised||Native||Phillips and Price, 2002|
|Fiji||Present||Native||UNEP, 2004; Guiry and Guiry, 2008|
|French Polynesia||Present||Native||Guiry and Guiry, 2008|
|Micronesia, Federated states of||Present||Native||Guiry and Guiry, 2008|
|New Caledonia||Present||Native||UNEP, 2004|
|Papua New Guinea||Present||Native||Guiry and Guiry, 2008|
History of Introduction and SpreadTop of page
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 IntroductionTop of page
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).
HabitatTop of page
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 ListTop of page
|Inland saline areas||Secondary/tolerated habitat||Harmful (pest or invasive)|
|Estuaries||Secondary/tolerated habitat||Harmful (pest or invasive)|
|Lagoons||Secondary/tolerated habitat||Harmful (pest or invasive)|
|Inshore marine||Secondary/tolerated habitat||Harmful (pest or invasive)|
|Inshore marine||Secondary/tolerated habitat||Natural|
|Inshore marine||Secondary/tolerated habitat||Productive/non-natural|
|Coral reefs||Principal habitat||Natural|
|Benthic zone||Principal habitat||Harmful (pest or invasive)|
|Benthic zone||Principal habitat||Natural|
|Benthic zone||Principal habitat||Productive/non-natural|
Biology and EcologyTop of page Genetics
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).
ClimateTop of page
|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 TolerancesTop of page
|Parameter||Minimum Value||Maximum Value||Typical Value||Status||Life Stage||Notes|
|Salinity (part per thousand)||15||30||Optimum|
|Water temperature (ºC temperature)||15||30||Optimum|
Means of Movement and DispersalTop of page Natural Dispersal (Non-Biotic)
C. taxifolia is likely to spread locally with the aid of currents.
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 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 CausesTop of page
Impact SummaryTop of page
Economic ImpactTop of page
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 ImpactTop of page
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.
Risk and Impact FactorsTop of page Invasiveness
- 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
- Ecosystem change/ habitat alteration
- Increases vulnerability to invasions
- Modification of natural benthic communities
- Monoculture formation
- Reduced native biodiversity
- Competition - monopolizing resources
- Competition - shading
- Interaction with other invasive species
- Rapid growth
- 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
UsesTop of page
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 ListTop of page
- Laboratory use
- Pet/aquarium trade
Similarities to Other Species/ConditionsTop of page
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 ControlTop of page Prevention
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.
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).
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).
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).
ReferencesTop of page
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. http://www.springerlink.com/content/l666337v906110tr/fulltext.pdf
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.
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. http://www.sciencedirect.com/science/journal/00063207
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. http://www.publish.csiro.au/nid/126.htm
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. http://www.int-res.com/abstracts/meps/v318/p177-185/
Gribben PE; Wright JT, 2006. Sublethal effects on reproduction in native fauna: are females more vulnerable to biological invasion? Oecologia, 149(2):352-361. http://springerlink.metapress.com/content/w726111218626422/?p=2a83b3041d734faaa53f7d80e583fd19&pi=15
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. http://www.sciencedirect.com/science/journal/03043770
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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ContributorsTop of page
03/03/08 Original text by:
Britta Schaffelke, CRC Reef Research Centre, James Cook University, QLD, Australia
Distribution MapsTop of page
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