Botrylloides violaceus (violet tunicate)
- Summary of Invasiveness
- Taxonomic Tree
- Distribution Table
- Habitat List
- Biology and Ecology
- Water Tolerances
- Notes on Natural Enemies
- Means of Movement and Dispersal
- Risk and Impact Factors
- Distribution Maps
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PicturesTop of page
IdentityTop of page
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 InvasivenessTop of page
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 TreeTop of page
- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Chordata
- Subphylum: Tunicata
- Class: Ascidiacea
- Suborder: Stolidobranchia
- Family: Styelidae
- Genus: Botrylloides
- Species: Botrylloides violaceus
DescriptionTop of page
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.
DistributionTop of page
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, Northwest||Widespread||Stachowicz et al., 2002; Pederson et al., 2005; Dijkstra et al., 2007||New York (NY) to Eastport (ME), introduced to Gulf of Maine in the 1970s|
|Mediterranean and Black Sea||Present||Introduced||Invasive||Zaniolo et al., 1998||Venetian Lagoon|
|Pacific, Northeast||Widespread||Invasive||Lambert and Lambert, 1998; Lambert and Sanamyan, 2001; Cohen et al., 2005||Coast off Alaska, from British Columbia to Ensenada, Baja California|
|Pacific, Northwest||Present||Bock et al., 2011|
|Canada||Present||Introduced||Lejeusne et al., 2011|
|-Newfoundland and Labrador||Present||Introduced||Callahan et al., 2010|
|-Prince Edward Island||Present||Gittenberger, 2009|
|USA||Present||Introduced||Lejeusne et al., 2011|
|-California||Present||Introduced||Davidson et al., 2010|
IntroductionsTop of page
HabitatTop of page
Habitat ListTop of page
|Inland saline areas||Present, no further details||Natural|
|Inshore marine||Present, no further details||Natural|
|Benthic zone||Secondary/tolerated habitat||Natural|
Biology and EcologyTop of page
For information on the genetics of this species see Lejeusne et al. (2011).
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.
B. violaceus overgrows shellfish (e.g., mussels) and other sessile invertebrate species.
Water TolerancesTop of page
|Parameter||Minimum Value||Maximum Value||Typical Value||Status||Life Stage||Notes|
|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 EnemiesTop of page
Means of Movement and DispersalTop of page
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.
ImpactTop of page
Risk and Impact FactorsTop 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
- Ecosystem change/ habitat alteration
- Modification of natural benthic communities
- Modification of successional patterns
- Monoculture formation
- Negatively impacts aquaculture/fisheries
- Competition - monopolizing resources
- Competition - smothering
- Interaction with other invasive species
- Rapid growth
- 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
ReferencesTop of page
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
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
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 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/
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.
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.
ContributorsTop of page
23/10/08 Original text by:
Jenn Dijkstra, University of New Hampshire, USA
Distribution MapsTop of page
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