- Summary of Invasiveness
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- 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
- Social Impact
- Risk and Impact Factors
- Prevention and Control
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Polyandrocarpa zorritensis (Van Name, 1931)
Other Scientific Names
- Stolonica zorritensis Van Name, 1931
Summary of InvasivenessTop of page
P. zorritensis is a fast-growing, conspicuous shallow water ascidian.It is a declared invasive species found in different harbours and lagoons of the Pacific Ocean (California, Japan, Hawaii), the Atlantic Ocean (Ruppert in Lambert and Lambert, 1998) and the Mediterranean Sea (Italy, Spain). P. zorritensis is known to be an aggressive invader, tolerant of large fluctuations in temperature (8-30.5°C) and salinity (22.7-38 ppm) (Lambert and Lambert, 1988; Brunetti and Mastrototaro, 2004). The aggressive invasion of this species could be due to its budding which makes possible the rebuilding of the colony even in the absence of adult zooids (Brunetti and Mastrototaro, 2004).
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Chordata
- Subphylum: Tunicata
- Class: Ascidiacea
- Suborder: Stolidobranchia
- Family: Styelidae
- Genus: Polyandrocarpa
- Species: Polyandrocarpa zorritensis
Notes on Taxonomy and NomenclatureTop of page
The genus Polyandrocarpa (family Styelidae) is generally accepted as containing 43 species (Monniot, 2009). Polyandrocarpa zorritensis (Van Name, 1931) was first named as Stolonica zorritensis by Van Name (1931). The genus Polyandrocarpa as the genus Polycarpa is characterized by small hermaphroditic gonads irregularly scattered on the surface of the body wall. Moreover in Polyandrocarpa genus the zooids produce buds and form colonies and each gonad contains several testes (Van Name, 1945).
DescriptionTop of page
P. zorritensis is a colonial Styelidae of the subfamily Polyzoinae. The colony appears as a group of zooids of various sizes closely crowded together, but without the tests merging them. The basal portion of the colony is formed by a tangle of stolons along which there are orange globular bodies (buds) which will be transformed in new zooids. Adult zooids are sub cylindrical, yellow-green in colour, with the oral siphon apical and the cloacal one slightly eccentric. Both siphons are four-lobed with two dark, almost black, bands per lobe. The test is thin and leathery. The well developed zooids, without test, range in height from 9-10 to 12-13 mm. The body wall has a delicate musculature, longitudinal and transversal fibres are of the same size and regularly arranged. According the zooid size there are from 20 to 30 simple tentacles of two lengths. The dorsal tubercle has a transversal wavy split-shaped opening. The dorsal lamina is flat and has a smooth edge. The branchial sac has four few prominent folds per side. The intestinal tube, entirely located to the left of the branchial sac, is formed by a short oesophageal tract followed by a trapezoid stomach with a plicated wall (generally 10-15 folds in addition to typhlosole). From the posterior external ventral corner of the stomach comes out a gastric caecum finger shape with a spherical tip. Its presence is hidden by an endocarp located in the intestinal loop. The gonads are oval polycarps lying in a row on each side of the endostyle, in general 9 on the right and 6 on the left, although up to 10 on the right and 8 on the left. All ovarian apertures are directed towards the dorsal side. The sexually ripe zooids have several embryos in the peribranchial cavity. The larval trunk, at the developmental stage in which the tail completely surrounds it, is about 530 µm in length. The three adhesive organs are included in a sessile frontal process from which at the metamorphosis take the origin of three clusters of ampullae (Brunetti and Mastrototaro, 2004).
DistributionTop of page
P. zorritensis is considered a native of the South Pacific (Zorritos, Perù) (Turon and Perera, 1988). It is present along the coast of Brazil (Millar, 1958), and has also been recorded in California (Lambert and Lambert, 1998), Texas (Lambert et al., 2005), Florida (Vàzquez and Young, 1996), Hawaii (Abbott et al., 1997), Japan (Nishikawa et al. 1993) and in the Mediterranean Sea: in Italy (Brunetti, 1978-1979; Brunetti and Mastrototaro, 2004) and Spain (Turon and Perera, 1988).
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|
|Japan||Present||Introduced||Invasive||Nishikawa et al., 1993|
|USA||Present||Present based on regional distribution.|
|-California||Widespread||Introduced||1994||Invasive||Lambert and Lambert, 1998; Lambert and Lambert, 2003; Cohen et al., 2005||Southern California harbours and marinas (Mission and San Diego Bays)|
|-Florida||Present||Introduced||Invasive||Vázquez and Young, 1996||Jim Island (Ft. Pierce Inlet in the Indian River Lagoon - Florida)|
|-Hawaii||Present||Introduced||Invasive||Abbot et al., 1997||Pearl Harbour, Coconut Island in Kane 'ohe Bay, Kewalo Bay (Oahu)|
|-Texas||Widespread||Introduced||2004||Invasive||Lambert et al., 2005||South Padre Island Texas, Port Isabel deep water docks, Billy Kenan's dock|
|Brazil||Present||Present based on regional distribution.|
|-Sao Paulo||Widespread||Not invasive||Millar, 1958||Sabtos; Itacurussa (Cananeia)|
|Peru||Present||Native||Turon and Perera, 1988|
|Italy||Widespread||Introduced||1974||Not invasive||Brunetti, 1978; Brunetti and Mastrototaro, 2004||Harbour of La Spezia (North Tyrrenean Sea - Mediterranean Sea)|
|Spain||Widespread||Introduced||Invasive||Turon and Perera, 1988||Delta of Ebro River, salt-wedge estuaries in Mediterranean Sea|
History of Introduction and SpreadTop of page
The species is spreading in the Atlantic (Ruppert in Lambert and Lambert, 1998) and also the Pacific Ocean (Japan (Nishikawa et al., 1993; 1994), South California (Lambert and Lambert, 1998) Hawaii (Abbott et al., 1997). At the moment the main cause of this (and that of other species) expansion is considered to be the warming of the ocean waters (Brunetti and Mastrototaro, 2004). According to Lambert and Lambert (2003), the stolidobranch ascidians “both solitary and colonial survive long-range anthropogenic transport better than do other types of ascidians”. Moreover the aggressive invasion of P. zorritensis might also be due to its budding modality. The vascular budding allows the rebuilding of the colony in the absence of adult zooids (Brunetti and Mastrototaro, 2004).
IntroductionsTop of page
|Introduced to||Introduced from||Year||Reason||Introduced by||Established in wild through||References||Notes|
|Natural reproduction||Continuous restocking|
|California||1994||Yes||Lambert and Lambert (1998)||fouling|
|Florida||1994||Aquaculture (pathway cause)||Yes||Vázquez and Young (1996)|
|Hawaii||1997||Yes||Abbot et al. (1997)|
|Spain||1988||Yes||Turon and Perera (1988)||fouling|
|Texas||2004||Yes||Lambert et al. (2005)||fouling|
Risk of IntroductionTop of page
P. zorritensis is accidentally introduced in many countries as an epibiotic species on the shells of oysters and mussels breeding in mussel farms.
HabitatTop of page
P. zorritensis colonizes all hard substrata present in the shallow water down to 2 m depth. In particular, extended colonies may be found under iron buoys, on mussel breeding piles and on the steel wires connecting them. Colonies were also present on detritus of the bottom. The species seems to prefer harbour environments, that is with eutrophic waters, where the colonies develop rapidly by an intense vegetative replication, while the zooids produce an high number of larvae, which showing a positive phototaxis (Vázquez and Young, 1998), and colonize every hard substrata in shallow waters.
Habitat ListTop of page
|Inland saline areas||Principal habitat||Natural|
|Benthic zone||Principal habitat||Natural|
|Inshore marine||Principal habitat||Natural|
Biology and EcologyTop of page
The phylogeny of the Styelidae, inferred from mitochondrial and nuclear DNA sequences, has been studied by Perez-Portela et al. (2009).
Water TolerancesTop of page
|Parameter||Minimum Value||Maximum Value||Typical Value||Status||Life Stage||Notes|
|Depth (m b.s.l.)||0.5||2||Optimum||0.5-5 tolerated|
|Salinity (part per thousand)||Optimum||35-39 tolerated|
|Water temperature (ºC temperature)||Optimum||8-30 tolerated|
Means of Movement and DispersalTop of page
Natural Dispersal (Non-Biotic)
Pathway CausesTop of page
Pathway VectorsTop of page
Impact SummaryTop of page
Economic ImpactTop of page
P. zorritensis may have a negative impact on artificial structures present in the shallow waters. P. zorritensis colonizes all artificial hard substrates includes buoys and iron ropes used in mussel farms.
Environmental ImpactTop of page
Reduction of the availability of hard substrates.
Social ImpactTop of page
See Impact: Economic for impacts on mussel farms.
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
- Tolerates, or benefits from, cultivation, browsing pressure, mutilation, fire etc
- Pioneering in disturbed areas
- Benefits from human association (i.e. it is a human commensal)
- Fast growing
- Has high reproductive potential
- Has propagules that can remain viable for more than one year
- Reproduces asexually
- Damaged ecosystem services
- Ecosystem change/ habitat alteration
- Host damage
- Infrastructure damage
- Modification of natural benthic communities
- Modification of nutrient regime
- Modification of successional patterns
- Monoculture formation
- Negatively impacts aquaculture/fisheries
- Reduced native biodiversity
- Threat to/ loss of native species
- Negatively impacts animal/plant collections
- Damages animal/plant products
- Antagonistic (micro-organisms)
- 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
Prevention and ControlTop of page
To prevent spread it is necessary to check and eliminate epibiotic species on living mollusc shells.
ReferencesTop of page
Brunetti R; Mastrototaro F, 2004. The non-indigenous stolidobrach ascidian Polyandrocarpa zorritensis in the Mediterranean: description, larval morphology and pattern of vascular budding. Zootaxa, 528:1-8.
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
Izquierdo-Muñoz A; Díaz-Valdés M; Ramos-Esplá AA, 2009. Recent non-indigenous ascidians in the Mediterranean Sea. Aquatic Invasions [Proceedings of the 2nd International Invasive Sea Squirt Conference, Prince Edward Island, Canada, 2-4 October 2007.], 4(1):59-64. http://www.aquaticinvasions.ru/index.html
Mastrototaro F; D'Onghia G; Tursi A, 2008. Spatial and sesonal distribution of ascidians in a semi-enclosed basin of the Mediterranean Sea. Journal of the Marine Biological Association of the United Kingdom, 88(5):1053-1061.
Perez-Portela R; Bishop JD; Davis AR; Turon X, 2009. Phylogeny of the families Pyuridae and Styelidae (Stolidobranchiata, Ascidiacea) inferred from mitochondrial and nuclear DNA sequences. Mol. Phylogenet. Evol, 50(3):560-570.
Vázquez E; Young CM, 1998. Ontogenic changes in phototaxis during larval life of ascidians Polyandrocarpa zorritensis (Van Name, 1931). Journal of Experimental Marine Biology and Ecology, 231:267-277.
ContributorsTop of page
03/12/09 Original text by:
Francesco Mastrototaro, University of Bari, Department of Zoology, Via Orabona, 4, 70125, Bari, Italy
Distribution MapsTop of page
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