Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Datasheet

Botrylloides violaceus
(violet tunicate)

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Datasheet

Botrylloides violaceus (violet tunicate)

Summary

  • Last modified
  • 25 September 2018
  • Datasheet Type(s)
  • Invasive Species
  • Preferred Scientific Name
  • Botrylloides violaceus
  • Preferred Common Name
  • violet tunicate
  • Taxonomic Tree
  • Domain: Eukaryota
  •   Kingdom: Metazoa
  •     Phylum: Chordata
  •       Subphylum: Tunicata
  •         Class: Ascidiacea
  • Summary of Invasiveness
  • B. violaceus is a compound ascidian (tunicate or sea squirt) and belongs to the subfamily Botryllinae. It is made up of individual genetically identical zooids and ampullae that are connected by an internal vascu...

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Pictures

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PictureTitleCaptionCopyright
Botrylloides violaceus colonies occur in many colours and can overgrow large areas. Netherlands coast.
TitleColour morphs
CaptionBotrylloides violaceus colonies occur in many colours and can overgrow large areas. Netherlands coast.
CopyrightAdriaan Gittenberger/GiMaRIS
Botrylloides violaceus colonies occur in many colours and can overgrow large areas. Netherlands coast.
Colour morphsBotrylloides violaceus colonies occur in many colours and can overgrow large areas. Netherlands coast.Adriaan Gittenberger/GiMaRIS
The reddish Botrylloides violaceus colonies overgrow and potentially suffocate the mussels. Massachusetts coast, USA.
TitleInvasive habit
CaptionThe reddish Botrylloides violaceus colonies overgrow and potentially suffocate the mussels. Massachusetts coast, USA.
CopyrightAdriaan Gittenberger/GiMaRIS
The reddish Botrylloides violaceus colonies overgrow and potentially suffocate the mussels. Massachusetts coast, USA.
Invasive habitThe reddish Botrylloides violaceus colonies overgrow and potentially suffocate the mussels. Massachusetts coast, USA.Adriaan Gittenberger/GiMaRIS
The purple and reddish Botrylloides violaceus colonies overgrow and potentially suffocate the mussels. Massachusetts coast, USA.
TitleInvasive habit
CaptionThe purple and reddish Botrylloides violaceus colonies overgrow and potentially suffocate the mussels. Massachusetts coast, USA.
CopyrightAdriaan Gittenberger/GiMaRIS
The purple and reddish Botrylloides violaceus colonies overgrow and potentially suffocate the mussels. Massachusetts coast, USA.
Invasive habitThe purple and reddish Botrylloides violaceus colonies overgrow and potentially suffocate the mussels. Massachusetts coast, USA.Adriaan Gittenberger/GiMaRIS
The reddish colonies have only just settled and consist of one to several individuals. The white Botrylloides colony is a few weeks older. Massachusetts coast, USA.
TitleColonising habit
CaptionThe reddish colonies have only just settled and consist of one to several individuals. The white Botrylloides colony is a few weeks older. Massachusetts coast, USA.
CopyrightAdriaan Gittenberger/GiMaRIS
The reddish colonies have only just settled and consist of one to several individuals. The white Botrylloides colony is a few weeks older. Massachusetts coast, USA.
Colonising habitThe reddish colonies have only just settled and consist of one to several individuals. The white Botrylloides colony is a few weeks older. Massachusetts coast, USA.Adriaan Gittenberger/GiMaRIS
The small red patches are the recently settled Botrylloides violaceus colonies. They are Massachusetts coast, USA.
TitleColonising habit and a natural enemy
CaptionThe small red patches are the recently settled Botrylloides violaceus colonies. They are Massachusetts coast, USA.
CopyrightAdriaan Gittenberger/GiMaRIS
The small red patches are the recently settled Botrylloides violaceus colonies. They are Massachusetts coast, USA.
Colonising habit and a natural enemyThe small red patches are the recently settled Botrylloides violaceus colonies. They are Massachusetts coast, USA.Adriaan Gittenberger/GiMaRIS
The small red patches are the recently settled Botrylloides violaceus colonies. They are threatened by grazers like sea-urchins. Massachusetts coast, USA.
TitleColonising habit and a natural enemy
CaptionThe small red patches are the recently settled Botrylloides violaceus colonies. They are threatened by grazers like sea-urchins. Massachusetts coast, USA.
CopyrightAdriaan Gittenberger/GiMaRIS
The small red patches are the recently settled Botrylloides violaceus colonies. They are threatened by grazers like sea-urchins. Massachusetts coast, USA.
Colonising habit and a natural enemyThe small red patches are the recently settled Botrylloides violaceus colonies. They are threatened by grazers like sea-urchins. Massachusetts coast, USA.Adriaan Gittenberger/GiMaRIS

Identity

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Preferred Scientific Name

  • Botrylloides violaceus Oka, 1927

Preferred Common Name

  • violet tunicate

International Common Names

  • English: orange sheath tunicate

Local Common Names

  • Netherlands: slingerzakpijp

Summary of Invasiveness

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B. violaceus is a compound ascidian (tunicate or sea squirt) and belongs to the subfamily Botryllinae. It is made up of individual genetically identical zooids and ampullae that are connected by an internal vascular system. Like all colonial ascidians, it has two types of reproduction: asexual reproduction, a process known as blastogenesis, and sexual reproduction.

It is native to the west Pacific, and is now found in the Northeast Pacific (Alaska, British Columbia to Ensenada, Baja California; Lambert and Sanamyan, 2001; Cohen et al., 2005), Sydney Harbour, Australia, the Venetian Lagoon, the Netherlands, and the coast of Japan. It can tolerate a wide range of environmental factors including temperature, salinity and nutrients (Carman et al., 2007; Dijkstra et al., 2008).  B. violaceus overgrows shellfish (e.g. mussels) and other sessile invertebrate species. It is a pest to mussel farmers and must be removed either manually or by innovative engineering.

Taxonomic Tree

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  • Domain: Eukaryota
  •     Kingdom: Metazoa
  •         Phylum: Chordata
  •             Subphylum: Tunicata
  •                 Class: Ascidiacea
  •                     Suborder: Stolidobranchia
  •                         Family: Styelidae
  •                             Genus: Botrylloides
  •                                 Species: Botrylloides violaceus

Description

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B. violaceus is a compound ascidian (tunicate or sea squirt) and belongs to the subfamily Botryllinae. It is made up of individual genetically identical zooids (measuring ~2 mm in diameter) and ampullae that are connected by an internal vascular system. Zooids are arranged in loose circles or rows and are embedded in a transparent tunic.

Distribution

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B. violaceus is native to the west Pacific, and is now found in the northeast Pacific (Alaska, British Columbia to Ensenada, Baja California; (Lambert and Sanamyan 2001; Cohen et al., 2005)), Sydney Harbour, Australia, the Venetian Lagoon, the Netherlands, and the coast of Japan. 

 

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.

Continent/Country/RegionDistributionLast ReportedOriginFirst ReportedInvasiveReferenceNotes

Sea Areas

Atlantic, NorthwestWidespreadStachowicz et al., 2002; Pederson et al., 2005; Dijkstra et al., 2007New York (NY) to Eastport (ME), introduced to Gulf of Maine in the 1970s
Mediterranean and Black SeaPresentIntroduced Invasive Zaniolo et al., 1998Venetian Lagoon
Pacific, NortheastWidespread Invasive Lambert and Lambert, 1998; Lambert and Sanamyan, 2001; Cohen et al., 2005Coast off Alaska, from British Columbia to Ensenada, Baja California
Pacific, NorthwestPresentBock et al., 2011

North America

CanadaPresentIntroducedLejeusne et al., 2011
-Newfoundland and LabradorPresentIntroducedCallahan et al., 2010
-Prince Edward IslandPresentGittenberger, 2009
USAPresentIntroducedLejeusne et al., 2011
-CaliforniaPresentIntroducedDavidson et al., 2010

Europe

IrelandPresentMinchin, 2007
ItalyPresentDAISIE, 2011
NetherlandsPresentGittenberger, 2007

Introductions

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Introduced toIntroduced fromYearReasonIntroduced byEstablished in wild throughReferencesNotes
Natural reproductionContinuous restocking
North America Japan   Hitchhiker (pathway cause)Lejeusne et al. (2011) Likely introduced as a hitchhiker in the shellfish aquaculture trade

Habitat

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Once established, B. violaceus occupies a wide variety of habitats, including fouling and benthic surfaces on both vertical and horizontal surfaces. Very few species settle on the tunic of living colonies as it can be acidic. Its rapid growth and acidic tunic reduces the availability of space for settlement and their short larval dispersal allows them to build up local populations. It is a pest to mussel farmers and must be removed either manually or by innovative engineering.

Habitat List

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CategorySub-CategoryHabitatPresenceStatus
Brackish
Inland saline areas Present, no further details Natural
Estuaries Secondary/tolerated habitat Natural
Marine
Inshore marine Present, no further details Natural
Benthic zone Secondary/tolerated habitat Natural

Biology and Ecology

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Genetics

For information on the genetics of this species see Lejeusne et al. (2011).

Reproductive Biology

Like all colonial ascidians, B. violaceus has two types of reproduction: asexual reproduction, a process known as blastogenesis, and sexual reproduction. Asexual reproduction occurs through budding which produces colonies of genetically identical zooids. Studies have shown that small substrates limit asexual reproduction and induce sexual reproduction. B. violaceus is a hermaphrodite that undergoes sexual reproduction between 10 and 12°C. Sexual reproduction begins when the gonads of both sexes develop on either side of the zooid with the ovary situated behind the testis. The egg is ovulated in a brood pouch that forms as an outgrowth of the body wall. Within the brood pouch, the egg is fertilized and develops until the larva escapes. The brooding period depends on several factors including temperature, salinity and number of asexual reproductive cycles (Sabbadin, 1955; Millar, 1971). More on growth and reproductive cycles can be found in Yamaguchi (1975). Brown et al. (2009) report further on whole body regeneration in this species.

Larvae, when release, are relatively large (0.01-0.02 mm) and are brightly coloured. They are lecithotrophic and spend less than 24 hours in the water column before settling on suitable substrate and metamorphosing into adult colonies. During metamorphosis, the larvae sticks to the substrate and begins to form a circle of ampullae. All Botrylliodes of the same generation appear, grow, and die synchronously. Both the zooids bearing embryos and the sterile zooids of the oldest generation begin to disintegrate and are eventually reabsorbed into the common vascular system.

Environmental Requirements

B. violaceus can tolerate a wide range of environmental factors including temperature, salinity and nutrients (Carman et al., 2007; Dijkstra et al., 2008). 

Associations

B. violaceus overgrows shellfish (e.g., mussels) and other sessile invertebrate species.

Water Tolerances

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ParameterMinimum ValueMaximum ValueTypical ValueStatusLife StageNotes
Depth (m b.s.l.) 0 7 Optimum 0-15 tolerated
Salinity (part per thousand) 33 Optimum 15-33 tolerated
Turbidity (JTU turbidity) Optimum B. violaceus is a filter feeder and as such doesn't tolerate a silty environment
Water pH (pH) Optimum 7.0 tolerated
Water temperature (ºC temperature) -1 27 Optimum -1-27 tolerated; optimal temperatures yet to be determined

Notes on Natural Enemies

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B. violaceus has provided a new source of prey for some species including the snails, Mitrella lunata and Anachis lafrashnayi (Osman and Whitlatch, 1995; 2004) and the blood star Henricia sanguinolenta (Dijkstra et al., 2007).

Means of Movement and Dispersal

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At least three potential mechanisms account for the introduction of colonial ascidians to the Gulf of Maine: 1) hull fouling, 2) ballast water, and 3) aquaculture. Because colonial ascidians produce lecithotrophic larvae that have an abbreviated planktonic stage (Lambert, 1968; Olson, 1985; Svane and Young, 1989), the likelihood of larvae surviving in ballast water is very low (Carlton and Geller, 1993). Thus, the most likely vectors for transport are hull fouling, aquaculture or rafting. Rafting on broken leaves and other debris to which they are attached can transport colonies both long and short distances. Some studies show evidence that rafting events occur frequently, and thus may have a substantial effect on population dynamics.Dijkstra et al. (2007) found bivalve aquaculture to the likely mechanism of long-distance (trans-oceanic) spread for this species. Other vectors include sea chests (Coutts and Forrest, 2007). Once transported to a site, further introduction to sites in the region (kms apart) can be from hull fouling of recreational or commercial vessels.

Impact

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B. violaceus overgrows shellfish (e.g. mussels) and other sessile invertebrate species. It is a pest to mussel farmers and must be removed either manually or by innovative engineering.
 
However, ecological knowledge gained from studies on this species and other similar species suggest that B. violaceus may become a permanent member of the community, but is unlikely to replace native species. Thus, management and/or eradication of the species may not be necessary in natural communities.

 

Risk and Impact Factors

Top of page Invasiveness
  • Proved invasive outside its 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
  • Modification of natural benthic communities
  • Modification of successional patterns
  • Monoculture formation
  • Negatively impacts aquaculture/fisheries
Impact mechanisms
  • Competition - monopolizing resources
  • Competition - smothering
  • Filtration
  • Fouling
  • Interaction with other invasive species
  • Rapid growth
Likelihood of entry/control
  • Highly likely to be transported internationally accidentally
  • Difficult to identify/detect as a commodity contaminant
  • Difficult to identify/detect in the field
  • Difficult/costly to control

References

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Bock DG; Zhan A; Lejeusne C; MacIsaac HJ; Cristescu ME, 2011. Looking at both sides of the invasion: patterns of colonization in the violet tunicate Botrylloides violaceus. Molecular Ecology, 20(3):503-516. http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1365-294X

Brown FD; Keeling EL; ADLe; Swalla BJ, 2009. Whole body regeneration in a colonial ascidian, Botrylloides violaceus. Journal of Experimental Zoology, 312B(8):885-900.

Callahan AG; Deibel D; McKenzie CH; Hall JR; Rise ML, 2010. Survey of harbours in Newfoundland for indigenous and non-indigenous ascidians and an analysis of their cytochrome c oxidase I gene sequences. Aquatic Invasions [Proceedings of the 16th International Conference on Aquatic Invasive Species, Montreal, Canada, 19-23 April 2009.], 5(1):31-39. http://www.aquaticinvasions.ru/2010/AI_2010_5_1_Callahan_etal.pdf

Carlton J; Geller J, 1993. Ecological roulette: The global transport of nonindigenous marine organisms. Science, 261:78-82.

Carman MR; Bullard SG; Donnelly JP, 2007. Water quality, nitrogen pollution, and ascidian diversity in coastal waters of southern Massachusetts, USA. Journal of Experimental Marine Biology and Ecology, 342(1):175-178. http://www.sciencedirect.com/science/journal/00220981

Cohen AN; Harris LH; Bingham BL; Carlton JT; Chapman JW; Lambert CC; Lambert G; Ljubenkov JC; Murray SN; Rao LC; Reardon K; Schwindt E, 2005. Rapid Assessment Survey for exotic organisms in southern California bays and harbors, and abundance in port and non-port areas. Biological Invasions, 7(6):995-1002. http://www.springerlink.com/content/l002j203g72wg155/fulltext.pdf

Coutts ADM; Forrest BM, 2007. Development and application of tools for incursion response: lessons learned from the management of the fouling pest Didemnum vexillum. Journal of Experimental Marine Biology and Ecology, 342(1):154-162. http://www.sciencedirect.com/science/journal/00220981

DAISIE, 2011. European Invasive Alien Species Gateway. http://www.europe-aliens.org/

Davidson IC; Zabin CJ; Chang AL; Brown CW; Sytsma MD; Ruiz GM, 2010. Recreational boats as potential vectors of marine organisms at an invasion hotspot. Aquatic Biology, 11(2):179-191. http://www.int-res.com/abstracts/ab/v11/n2/p179-191/

Dijkstra J; Dutton A; Westerman E; Harris L, 2008. Heart rates reflect osmotic stress in two introduced colonial ascidians: Botryllus schlosseri and Botrylloides violaceus. Marine Biology, 154:805-811.

Dijkstra J; Harris LG; Westerman E, 2007. Distribution and long-term temporal patterns of four invasive colonial ascidians in the Gulf of Maine. Journal of Experimental Marine Biology and Ecology, 342(1):61-68. http://www.sciencedirect.com/science/journal/00220981

Faasse M; Blauwe HDe, 2002. [English title not available]. (De exotische samengestelde zakpijp Botrylloides violaceus Oka, 1927 in Nederland (Ascidiacea: Pleurogona: Styelidae)) Het Zeepaard, 62:136-141.

Gittenberger A, 2007. Recent population expansions of non-native ascidians in The Netherlands. Journal of Experimental Marine Biology and Ecology [Proceedings of the 1st International Invasive Sea Squirt Conference, Woods Hole, Massachusetts, USA, April 21-22, 2005.], 342(1):122-126. http://www.sciencedirect.com/science/journal/00220981

Gittenberger A, 2009. Invasive tunicates on Zeeland and Prince Edward Island mussels, and management practices in The Netherlands. Aquatic Invasions [Proceedings of the 2nd International Invasive Sea Squirt Conference, Prince Edward Island, Canada, 2-4 October 2007.], 4(1):279-281. http://www.aquaticinvasions.ru/2009/AI_2009_4_1_Gittenberger.pdf

Lambert CC; Lambert G, 1998. Non-indigenous ascidians in southern California harbors and marinas. Marine Biology, 130:675-688.

Lambert G, 1968. The general ecology and growth of a solitary ascidian, Corella willmeriana. Biological Bulletin Woods Hole, 135:296-307.

Lambert G, 2007. Invasive sea squirts: A growing global problem. Journal of Experimental Marine Biology and Ecology, 342:3-4.

Lambert L; Sanamyan K, 2001. Distaplia alakensis sp. nov. (Ascidiacea, Aplousobranchia) and other new ascidian records from south-central Alaska, with a redescription of Ascidia columbiana (Huntsman, 1912). Can J Zool, 79:1766-1781.

Lejeusne C; Bock DG; Therriault TW; MacIsaac HJ; Cristescu ME, 2011. Comparative phylogeography of two colonial ascidians reveals contrasting invasion histories in North America. Biological Invasions, 13(3):635-650. http://www.springerlink.com/content/q717531836741715/

Millar RH, 1971. The biology of ascidians. In: Advances in marine biology, Vol 9 [ed. by Russell FS, Youge CM] London, : Academic Press, 1-100.

Minchin D, 2007. A checklist of alien and cryptogenic aquatic species in Ireland. Aquatic Invasions, 2(4):341-366. http://www.aquaticinvasions.ru/2007/AI_2007_2_4_Minchin.pdf

Olson RR, 1985. The consequences of short-distance larval dispersal in a sessile marine invertebrate. Ecology, 66:30-39.

Osman RW; Whitlatch RB, 1995. Predation on early ontogenic life stages and its effect on recruitment into a marine epifaunal community. Marine Ecology-Progress Series, 117:111-126.

Osman RW; Whitlatch RB, 2004. The control of the development of a marine benthic community by predation on recruits. Journal Of Experimental Marine Biology and Ecology, 311:117-145.

Pederson J; Bullock R; Carlton JT; Dijkstra J; Dobroski N; Dyrynda P; Fisher R; Harris L; Hobbs N; Lambert G; Lazo-Wasem E; Mathieson AC; Miglietta MP; Smith J; Smith IIIJ; Tyrrell M, 2005. Marine invaders of the Northeast. Massachussetts Institute of Technology.

Ruiz GM; Fofonoff PW; Carlton JT; Wonham MJ; Hines AH, 2000. Invasion of coastal marine communities in North America: apparent patterns, processes and biases. Annual Review of Ecology and Systematics, 31:481-531.

Sabbadin A, 1955. [English title not available]. (Osservazioni sullo sviluppo, l'accrescimento e la riproduzione di Botryllus schlosseri (Pallas) in condizioni di laboratorio) Bollettino di Zoologia, 22:243-263.

Stachowicz JJ; Fried H; Osman RW; Whitlatch RB, 2002. Biodiversity, invasion resistance, and marine ecosystem function: Reconciling pattern and process. Ecology, 83:2575-2590.

Svane I; Young CM, 1989. The ecology and behaviour of ascidian larvae. Oceanography of Marine Biology Annual Review, 27:45-90.

Yamaguchi M, 1975. Growth and reproductive cycles of the marine fouling ascidians Ciona intestinalis, Styela plicata, Botrylloides violaceus and Leptoclinum mitsukurii at Aburatsubo-Moroiso inlet (Central Japan). Marine Biology, 29:253-259.

Zaniolo G; Manni L; Brunetti R; Burighel P, 1998. Brood pouch differentiation in Botrylloides violaceus, a viviparous ascidian (Tunicata). Invertebrate Reproduction and Development, 33:11-23.

Contributors

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23/10/08 Original text by:

Jenn Dijkstra, University of New Hampshire, USA

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