- 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
- Latitude/Altitude Ranges
- Air Temperature
- Water Tolerances
- Means of Movement and Dispersal
- Pathway Causes
- Pathway Vectors
- Impact Summary
- Economic Impact
- Environmental Impact
- Threatened Species
- Risk and Impact Factors
- Similarities to Other Species/Conditions
- Prevention and Control
- Gaps in Knowledge/Research Needs
- Links to Websites
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Tricellaria inopinata d'Hondt & Occhipinti Ambrogi, 1985
Summary of InvasivenessTop of page
T. inopinata forms erect, branched colonies, anchored to the substratum by rhizoids. The overall aspect of the colony is a whitish bush growing on hard substrata, often on mussel shells. Branches are dichotomously divided at internodes (section between branch dichotomies) and are formed by series of alternating autozooids (single feeding bryozoan individuals). Each internode is formed by a variable number of autozooids (5-10). Autozooids vary in shape and size depending on their position within the internode, but all are more elongate and taper in their proximal part, progressively enlarging in the distal part. Lateral avicularia (specialized zooids) are large and prominent and bear a triangular mandible. Generally 3-4 spines are present on the outer margin of the zooid, and 2-3 on the inner one. The scutum (shield-like flattened, or branched spine partially covering the opening of some bryozoans) is highly variable in form and size within an individual colony. Globular ovicelles (brooding chambers) with pores are usually present in some autozooids within a colony.
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Bryozoa
- Class: Gymnolaemata
- Order: Cheilostomatida
- Family: Candidae
- Genus: Tricellaria
- Species: Tricellaria inopinata
Notes on Taxonomy and NomenclatureTop of page
Tricellaria inopinata was described after samples were discovered in 1982 for the first time in the Lagoon of Venice (d’Hondt and Occhipinti-Ambrogi, 1985). The species’ name derives from the Latin term inopinatus, which means unexpected, because this taxonwas unexpectedly found in the Giudecca Canal, in the very centre of the city of Venice, one of the most studied locations in the Adriatic Sea.
DescriptionTop of page
T. inopinata colonies are whitish to cream in colour and arborescent in form, up to 6-8 cm in length. Adult colonies are formed by branches, dividing dichotomously and composed of alternating series of autozooids (5-10 per internode) of 0.40 - 0.65 mm in length, usually tapering at the proximal part and becoming wider at the distal part (0.16-0.20 mm in width).
DistributionTop of page
The native distribution of T. inopinata is difficult to ascertain, as the debate on its taxonomic status has not reached a definite consensus on the nomenclature.
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, Northeast||Widespread||Introduced||1990s||Invasive||Arenas et al., 2006||Growing on hard substrates, algae and other organisms in harbours and marinas|
|Mediterranean and Black Sea||Localised||Introduced||1982||Invasive||d'Hondt and Occhipinti-Ambrogi, 1985||Growing on hard substrates, algae and other organisms everywhere inside the lagoon|
|Belgium||Widespread||Introduced||2000||Invasive||Blauwe and Faasse, 2001||Harbours and marinas|
|France||Widespread||Introduced||2000||Invasive||Blauwe and Faasse, 2001||Harbours and marinas|
|Italy||Widespread||Introduced||1982||Invasive||d'Hondt and Occhipinti-Ambrogi, 1985||On wooden piles and all other hard substrates in the main and secondary canals of the Lagoon of Venice|
|Netherlands||Widespread||Introduced||2000||Invasive||Blauwe and Faasse, 2001||Harbours and marinas|
|Portugal||Widespread||Introduced||2004||Invasive||Marchini et al., 2007||In harbours and touristic marinas on pontoons, wooden piles and hard substrates|
|Spain||Widespread||Introduced||1996||Invasive||Fernández-Pulpeiro et al., 2001||On docks and wharves in recreational and fishery ports at the intertidal level, attached on various organisms and on floating detached algae|
|UK||Widespread||Introduced||1998||Invasive||Arenas et al., 2006||Ports, harbours and marinas|
History of Introduction and SpreadTop of page
T. inopinata was firstly found near the centre of Venice in the Giudecca Canal, but after a few years it colonized all of the lagoon, except the areas with lower salinity (Occhipinti-Ambrogi, 2000b).
IntroductionsTop of page
|Introduced to||Introduced from||Year||Reason||Introduced by||Established in wild through||References||Notes|
|Natural reproduction||Continuous restocking|
|Belgium||2000||Hitchhiker (pathway cause)||Yes||Blauwe and Faasse (2001)||Possibly from UK|
|France||2000||Hitchhiker (pathway cause)||Yes||Blauwe and Faasse (2001)||Possibly from UK|
|Italy||1982||Aquaculture (pathway cause)||Yes||d'Hondt and Occhipinti-Ambrogi (1985)||The genus is known only in the Pacific, but the native location remains unknown due to systematic problems|
|Netherlands||2000||Hitchhiker (pathway cause)||Yes||Blauwe and Faasse (2001)||Possibly from UK|
|Portugal||2004||Hitchhiker (pathway cause)||Yes||Marchini et al. (2007)||Possibly from Spain|
|Spain||Italy||1996||Aquaculture (pathway cause)||Yes||Fernández-Pulpeiro et al. (2001)|
|UK||1998||Aquaculture (pathway cause)
Hitchhiker (pathway cause)
|Yes||Dyrynda et al. (2000)||Possibly from Italy or Spain|
Risk of IntroductionTop of page
Ship traffic can be considered the principal vector facilitating long-distance and regional anthropogenic dispersal of many alien species, but in the case of T. inopinata the most likely form of secondary introduction from Venice to the Atlantic coasts of Spain was the movement of clams (Ruditapes philippinarum) between the two locations, as reported by Fernández-Pulpeiro et al. (2001). From Spain to the other Atlantic localities, both commercial and recreational vessels, as well as natural dispersion due to transport on living organisms (e.g. floating algae), are the most probably ways of expansion, accounting for the rapid colonization of the European Atlantic coasts from Portugal to the Netherlands (Dyrynda et al., 2000; De Blauwe and Faasse, 2001; Marchini et al., 2007).
HabitatTop of page
The species is typical of the intertidal and shallow subtidal zone. It has been described from enclosed or sheltered habitats, like lagoons, estuaries, harbours and marinas. It has been seldom if ever found on the open coast.
Habitat ListTop of page
|Lagoons||Principal habitat||Harmful (pest or invasive)|
|Benthic zone||Principal habitat||Harmful (pest or invasive)|
|Inshore marine||Principal habitat||Harmful (pest or invasive)|
Biology and EcologyTop of page
ClimateTop of page
|C - Temperate/Mesothermal climate||Preferred||Average temp. of coldest month > 0°C and < 18°C, mean warmest month > 10°C|
Latitude/Altitude RangesTop of page
|Latitude North (°N)||Latitude South (°S)||Altitude Lower (m)||Altitude Upper (m)|
Air TemperatureTop of page
|Parameter||Lower limit||Upper limit|
|Absolute minimum temperature (ºC)||3||34|
Water TolerancesTop of page
|Parameter||Minimum Value||Maximum Value||Typical Value||Status||Life Stage||Notes|
|Depth (m b.s.l.)||Optimum||Intertidal|
|Salinity (part per thousand)||28||30||Optimum||20-35 tolerated|
|Water temperature (ºC temperature)||20||25||Optimum||3-34 tolerated|
Means of Movement and DispersalTop of page
The undetermined Pacific origin of the species (belonging to the species complex T. porteri-occidentalis-inopinata) suggests that the first Mediterranean introduction was due to accidental introduction (oyster import). Secondary introductions are likely to have been caused by accidental introductions associated with small vessels (small commercial vessels, yachts, fishing boats in coastal routes), natural dispersion (currents) or vector transport (on floating fragments of Sargassum).
Pathway CausesTop of page
Pathway VectorsTop of page
|Aquaculture stock||Yes||Yes||Occhipinti-Ambrogi, 2000a|
|Floating vegetation and debris||E.g. debris from the 2011 Tohoku tsunami carried individuals from the Japanese coast to Oregon||Yes||Yes||Blauwe and Faasse, 2001|
|Live seafood||Yes||Yes||Occhipinti-Ambrogi, 2000a|
|Ship hull fouling||Yes||Dyrynda et al., 2000|
Impact SummaryTop of page
Economic ImpactTop of page
It is a rapidly growing fouling organism, settling on vessels, pontoons, buoys and ropes and all other kinds of submerged organisms at the intertidal and upper subtidal levels.
Environmental ImpactTop of page
Impacts on Biodiversity
The arrival and spread of T. inopinata in the Venice Lagoon caused a decline in the abundance of some bryozoan species with the same colony form, such as Bugula stolonifera and Bugula neritina. On the other hand, other species as Buskia socialis and Bowerbankia gracillima, previously considered rare species within the Lagoon, gained relative importance (Occhipinti-Ambrogi, 2000a,b).
Threatened SpeciesTop of page
Risk and Impact FactorsTop of page Invasiveness
- Proved invasive outside its native range
- Highly adaptable to different environments
- Is a habitat generalist
- Tolerant of shade
- Highly mobile locally
- 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
- Ecosystem change/ habitat alteration
- Infrastructure damage
- Modification of natural benthic communities
- Modification of successional patterns
- Reduced native biodiversity
- Threat to/ loss of native species
- Competition - monopolizing resources
- Highly likely to be transported internationally accidentally
- Difficult to identify/detect as a commodity contaminant
- Difficult to identify/detect in the field
Similarities to Other Species/ConditionsTop of page
A possible misunderstanding occurred between genus Tricellaria and Bugulopsis due to general colony appearance and branch disposition (d’Hondt and Occhipinti-Ambrogi, 1985). Morphological features such as the scutum, avicularia and vibracularia present in Tricellaria made it distinguishable, under the microscope, from Bugulopsis.
Prevention and ControlTop of page
Aquaculture imports should be strictly quarantined, and only second generation spat should be released; special care should be taken when aquaculture facilities are located in the vicinity of ports and marinas.
Gaps in Knowledge/Research NeedsTop of page
- Genetic information from populations of Tricellaria in different locations could highlight the actual areas of origin and clarify the taxonomic questions.
- Physiological investigations could explain the habitat preferences for sheltered habitats.
- Pathways for introduction could be clarified by examination of likely vectors such as shipment of molluscs or hull fouling.
ReferencesTop of page
Arenas F; Bishop JDD; Carlton JT; Dyrynda PJ; Farnham WF; Gonzalez DJ; Jacobs MW; Lambert C; Lambert G; Nielsen SE; Pederson JA; Porter JS; Ward S; Wood CA, 2006. Alien species and other notable records from a rapid assessment survey of marinas on the south coast of England. Journal of Marine Biological Association, 86:1329-1337.
Blauwe HDe; Faasse M, 2001. Extension of the range of the bryozoans Tricellaria inopinata and Bugula simplex in the north-east Atlantic Ocean (Bryozoa: Cheilostomatida). Nederlandse Faunistiche Mededelingen, 14:103-112.
Breton G; d'Hondt J-L, 2005. [English title not available]. (Tricellaria inopinata d'Hondt et Occhipinti-Ambrogi, 1985 (Bryozoa: Cheilostomatida) dans le Port du Havre (Manche Orientale).) Bulletin de la Société géologique de Normandie Amis Musée du Havre, 91(2):67-72.
Dyrynda PEJ; Fairall VR; Occhipinti-Ambrogi A; d'Hondt JL, 2000. The distribution, origin and taxonomy of Tricellaria inopinata d'Hondt and Occhipinti-Ambrogi, 1985, an invasive bryozoan new to the Atlantic. Journal of Natural History, 34:1993-2006.
Fernández-Pulpeiro E; César-Aldariz J; Reverter-Gil O, 2001. [English title not available]. (Sobre la presencia de Tricellaria inopinata d'Hondt & Occhipinti-Ambrogi, 1985 (Bryozoa, Cheilostomatida) en el litoral gallego (N. España).) Nova Acta Científica Compostelana (Bioloxía), 11:207-213.
Marchini A; Cunha MR; Occhipinti-Ambrogi A, 2007. First observations on bryozoans and enctoprocts in the Ria de Aveiro (NW Portugal) including the first record of the Pacific invasive cheilostome Tricellaria inopinata. Marine Ecology, 28(1):154-160.
Occhipinti-Ambrogi A, 1991. [English title not available]. (The spread of Tricellaria inopinata into the lagoon of Venice: an ecological hypothesis. Bulletin de la Société de Science Naturelles de l'Ouest France Mémoires Hors Série.) In: Bryozoaires actuels et fossiles: Bryozoa living and fossil, 1 [ed. by Bigey, F. P.]. 299-308.
Occhipinti-Ambrogi A, 2000. Recent developments in the history of the bryozoans of the lagoon of Venice: biodiversity and environmental stress. In: Proceedings of the 11th International Bryozoology Association Conference. Allen Press, 305-315.
Occhipinti-Ambrogi A; d'Hondt JL, 1994. The invasion ecology of Tricellaria inopinata into the lagoon of Venice: morphological notes on larva and the ancestrula. In: Biology and Palaeobiology of Bryozoans [ed. by Hayward, P. J. \Ryland, J. S. \Taylor, P. D.]. Fredensborg, Danmark: Olsen & Olsen, 139-144.
Reverter-Gil O; Fernández-Pulpeiro E, 2001. [English title not available]. (Inventario y cartografia de los Briozoos marinos de Galicia (N. de España).) Monografías de Nova Acta Científica Compostelana,Serie Bioloxía, 1. 1-243.
Soule DF; Soule JD; Chaney HW, 1995. The Bryozoa. In: Taxonomic Atlas of the Santa Maria Basin and Western Santa Barbara Channel, Santa Barbara Museum of Natural History, 13 [ed. by Blake, J. A. \Chaney, H. W. \Scott, P. H. \Lissner, A. L.]. 1-134.
ContributorsTop of page
18/10/09 Original text by:
Anna Occhipinti Ambrogi, Director Department "Ecologia del Territorio", Via S.Epifanio4, I-27100 Pavia, Italy
Distribution MapsTop of page
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