Date of the first record

The date of the first documented record of the species occurrence in a country/country region.
Date fields usage example:

Date to be specifiedDate FromDate To
Exact 198519851985
18th century17011800
before 1700 1700
after 20012001 

Environmental position

Environment(s) occupied by a species throughout its life cycle.

OPTIONS:

Biofouling. Assemblage of organisms on wetted artificial substrates.

Commensal. An organism in a symbiotic relationship, in which one benefits while the other is not adversely affected.

Demersal. Synonyms: hyperbenthic, benthopelagic, nektobenthic. An organism living at, in or near the bottom of the sea, but having the ability to swim.

Ectoparasite. A parasite living on the surface of its host.

Endoparasite. A parasite living within the organs or tissues of its host.

Epifaunal. Synonym: epibenthic. An animal inhabiting the surface of the seabed, submerged plants and animals.

Epilithic. An organism living on the surface of rock or other hard inorganic substrata.

Epiphytic. An organism living on the surface of a plant, non-parasitic.

Epizoic. An organism living on the surface of an animal, non-parasitic.

Infaunal. Synonym: endobenthic. An animal living within the seabed sediments.

Interstitial. An organism (< 1 mm) living in the spaces between sediment particles.

Lithotomous. An organism burrowing into rock.

Neustonic. An organism living on (epineuston) or under (hyponeuston) the surface film of water bodies.

Pelagic. An organism inhabiting the water column.

Pleustonic. An organism inhabiting the water surface due to their own buoyancy, normally positioned partly in the water and partly in the air.

Habitat type

Estuary. River mouth, transition zone between riverine and marine environments, subject to influences from both.

Lagoon. Shallow, enclosed water body separated from the sea by barrier islands, narrow spit or reefs.

Offshore. Areas located at least 50 nautical miles from the shore.

Open coast. A coast not sheltered from the sea.

Strait/Sound. Channels between the mainland and an island or between two islands which are open at both ends to the open coast (it does not refer to similar features or narrows within marine inlets).

Sheltered coastal area. Coastal area partly surrounded by land (e.g., bay, inlet, fjord).

Ports. A location on a coast or shore containing one or more harbours where ships can dock and transfer people or cargo to or from land.

Port vicinity. The area near a port where ballast water operations may occur, including areas where vessels may conduct ballast water discharge or uptake operations when approaching a port or leaving it, e.g., port approaches, anchorage areas and designated ballast water exchange areas. The dimension is port specific.

Marina. A specially designed harbour for pleasure craft and small boats.

Aquaculture sites. Areas set out for the purpose of farming aquatic organisms.

Marine Protected Area (MPA). Defined marine area where natural resources are given greater protection than the surrounding waters. Different categories exist depending on the level of protection afforded by legislation.

Migration pattern

Diurnal. Movements between alternative habitats over day and night, e.g. vertical migration.

Life-time. One time migration between different habitats during the life cycle, e.g. anadromus migration.

Not relevant. No evidence of any life history cycle stages to migrate.

Seasonal. Movements between alternative habitats during a specific time of a year (e.g., spawning and feeding migrations).

Pathway / Vector

Pathway

A pathway is the route a NIS takes to enter or spread through a non-native ecosystem e.g. vessels. Each pathway may have a number of vectors.

Vector

A vector is a transfer mechanism and is the physical means by which species are transported from one geographic region to another. More than one vector within a pathway may be involved in a transfer of species.

Pathways and vectors included:
PathwayVector
Aquarium tradeIntentional organism release
Transported water
Waste discharge
Culture activitiesAquaculture equipment
Associated water & packaging material
Intercontinental stock movement
Regional stock movement
Unintentional release & escapees
Leisure activitiesAngling catch
Cultural releases
Live bait
Live souvenirs
Sport equipment
Stocking for angling
Waste discharge
Live food tradeIntentional organism release
Transported water
Waste discharge
ManagementBiological habitat management
Construction equipment
Construction materials
Release for biological control
Natural spread from neighboring countriesOther natural vectors
Water currents
Other canalsCanal de Midi (linking the Bay of Biscay with the Mediterranean Sea)
Kiel Canal (linking the North Sea with the Baltic)
Northern waterway (linking the Baltic with the Ponto-Caspian region through Volga river canal system)
Rhone waterway (linking the North Sea with the Mediterranean)
Southern waterway (linking the North Sea with the Black Sea through Danube river canal system)
Central waterway (linking the Baltic Sea with the Black Sea through the Dnieper river canal system)
Other waterways
Irrigation canals
Research and educationGear movement
Intentional releases
Unintentional release & escapees
Waste discharge
Suez Canal 
VesselsAnchor and anchor chain
Ballast tank sediments
Ballast water
Ship’s hull
Sea chest
Others
Wild fisheriesDiscard of by-catch
Fishing gear
Live bait release
Live packaging material
Processed live material
Stock movements
Transported water

Pathway / Vector – Levels of certainty:
LevelCriteriaExamples
Direct evidenceThe species was actually found associated with the specific vector(s) of a pathway at the time of introduction to a particular locality within a country/country region.Documented evidence of an introduction: release to the wild for stocking or biological control; escape/release of live food; import of cultured species and documented findings of their associate organisms, parasites and diseases on transmission; appearance of organisms by hull fouling, ballast water discharge sampling or other ship vectors documented upon an arrival with appropriate scientific methods.
Very likelyThe species appears for the first time in a locality where a single pathway/vector(s) is known to operate and where there is no other explanation that can be argued for its presence except by this likely pathway/vector(s).A highly localized distribution of a species in an area adjacent to an isolated port or other locality where the only pathway is vessels and its vector(s) (ballast water, hull fouling, etc). This often involves geographically discontinuous distributions. It may be a continuous spread as in case of introduction by canals or by natural means. The conclusion is deduced from the analysis of the invasion event and species distribution patterns.
PossibleThe species cannot be convincingly ascribed to a single pathway, but is known to be introduced by this pathway(s) elsewhere.There may be more than one pathway involved in the introduction within a country/country region. Arrival of a species known to have taken place elsewhere by the same pathway(s) which operates in an area. A conclusion is made by expert judgment based on pathways currently or historically present.
UnknownInvasion of a given alien species cannot be clearly explained.Where no rational explanation for the appearance of a species in a given country/region.

Population status

Population status (the lowest level of certainty):

Unknown. There is no reliable information on population status of a species.
Established. A species is known to form a reproducing population in a wild.
Not established. There is no evidence of a species’ reproducing population in a wild.

Population status (the moderate level of certainty):
Extinct/no recent record. There are old records where a species was recorded but have not been seen in the same region since.
Rare/single record. There are only casual observations or a single record of a species'presence available.
Common. A species with successfully reproducing populations in an open ecosystem, which are unlikely to be eliminated by man or natural causes. Not dominating native communities.
Abundant. A species with successfully reproducing populations in an open ecosystem, which are unlikely to be eliminated by man or natural causes. Locally dominating native communities.
Very abundant. A species with successfully reproducing populations in an open ecosystem, which are unlikely to be eliminated by man or natural causes. Largely dominating native communities.
Outbreak. A species undergoing pulse-like, short-term (days to few months) exponential population growth during which they have an adverse effect on one or more of the following: biological diversity, ecosystem functioning, socio-economic values and human health.

Recipient region

The country/region for which introduction is recorded.

References.



References should follow the standard of Biological invasions:


Journal article
Gamelin FX, Baquet G, Berthoin S, Thevenet D, Nourry C, Nottin S, Bosquet L (2009) Effect of high intensity intermittent training on heart rate variability in prepubescent children. Eur J Appl Physiol 105:731-738. doi: 10.1007/s00421-008-0955-8
Ideally, the names of all authors should be provided, but the usage of “et al” in long author lists will also be accepted:
Smith J, Jones M Jr, Houghton L et al (1999) Future of health insurance. N Engl J Med 965:325–329


Article by DOI


Slifka MK, Whitton JL (2000) Clinical implications of dysregulated cytokine production. J Mol Med. doi:10.1007/s001090000086


Book
South J, Blass B (2001) The future of modern genomics. Blackwell, London


Book chapter
Brown B, Aaron M (2001) The politics of nature. In: Smith J (ed) The rise of modern genomics, 3rd edn. Wiley, New York, pp 230-257


Online document
Cartwright J (2007) Big stars have weather too. IOP Publishing PhysicsWeb. http://physicsweb.org/articles/news/11/6/16/1. Accessed 26 June 2007


Dissertation
Trent JW (1975) Experimental acute renal failure. Dissertation, University of California

Reproductive duration

Long. Breeds in one or more discrete periods, each longer than three months.

Medium. Breeds in one or more discrete periods, each longer than a week and less than three months.

Short. Breeds in one or more discrete periods within a week.

Reproductive seasonality

Months for a species known to reproduce in the invaded site.

Salinity range

The exact salinity range if known (psu), else salinity zone(s) according to the Venice system:
1. Limnetic [<0.5psu]
2. β-Oligohaline [0.5-3psu]
3. α-Oligohaline [3-5psu]
4. β-Mesohaline [5-10psu]
5. α-Mesohaline [10-18psu]
6. Polymixohaline [18-30psu]
7. Euhaline [30-40psu]
8. Hypersaline [>40psu]

Source region

The area the species was introduced from to the recipient country/country region. Depending on the information availability may be ascribed to a particular locality (e.g. port), a country, a LME or a larger Ocean region.
CAUTION: in many cases the source area will be not the same as the area of native origin which is defined in the SPECIES block of the database.

Species status

Non-indigenous species. Non-indigenous species (synonyms: alien, exotic, non-native, allochthonous, introduced) are species, subspecies or lower taxa (such as a variety, form) introduced outside of their natural range (past or present) and outside of their natural dispersal potential. This includes any propagule of a NIS, such as a gamete, seed or resting spore, a gravid female or a pair of individuals of different sexes (in sexual reproduction), or a vegetative reproductive organ and section of tissue (in asexual reproduction), which might survive, reproduce and subsequently form a population. It also includes hybrids between an alien species and an indigenous species, fertile polyploid organisms and artificially hybridized species irrespective of their natural range or dispersal potential.

Cryptogenic. Cryptogenic species are such species which cannot be reliably demonstrated as being either introduced or native. In some cases the true origin of a species remains obscure because of either insufficient taxonomic knowledge or due to a lack of records from the time they became introduced, or for other reasons.

Temperature range

Indicate min. and max. annual temperature range in the area where a species is known to maintain an established (reproducing) population.

Wave exposure

Exposed. Open coastline facing prevailing wind and receiving both wind-driven waves and swell.

Semi exposed. Generally open coasts facing away from prevailing winds or sheltered by offshore reefs/structures.

Sheltered. Coasts with a restricted fetch (<20 km) and lacking persistent swell.

Zonation

Ecological zone(s) occupied by a species throughout its life cycle.

Benthic - Bathyal. Synonym: continental slope. The seafloor between the edge of the continental shelf and abyssal plain (200-4000 m).

Benthic - Littoral. Synonym: intertidal. The shore between the high and low water marks.

Benthic - Sublittoral beyond photic zone. Synonym: lower circalittoral. The lower part of the continental shelf, where photosynthesis cannot take place.

Benthic - Sublittoral within photic zone. Synonyms: subtidal, infralittoral. The shallow part of sublittoral where photosynthesis can occur.

Benthic - Supralittoral. Synonyms: splash zone, spray zone, supratidal zone. The area above the spring high tide line, subject spray or splash.

Pelagic - Littoral. Water mass within littoral zone.

Pelagic - Neritic. Water mass above the continental shelf.

Pelagic - Offshore. Synonym: oceanic. Water mass beyond the continental shelf.

Public domain: Introduction event account

Species Didemnum vexillum  
Date of the first record (?) 2005

References (not structured):
Minchin D and Sides E (2006) Appearance of a cryptogenic tunicate, a Didemnum sp. fouling marina pontoons and leisure craft in Ireland. Aquatic Invasions 1(3): 143-147.

Comments:
The first observation of this species in Ireland was in October 2005. The Irish material published as Didemnum sp. has since been confirmed as Didemnum vexillum following the account by Minchin and Sides (2006). Identification of didemnid tunicates requires careful taxonomic study, in particular the larvae and spicules are used for confirmation of the species. The species was almost certainly present before 2005 in the Malahide Estuary.
Recipient region (?) Country: Ireland
LME: 24. Celtic-Biscay Shelf
LME sub-region: Celtic seas

References (not structured):
Minchin D and Sides E (2006) Appearance of a cryptogenic tunicate, a Didemnum sp. fouling marina pontoons and leisure craft in Ireland. Aquatic Invasions 1(3): 143-147.

Minchin D, Nunn J (2013) Rapid assessment of marinas for invasive alien species in Northern Ireland. A report undertaken for the Northern Ireland Environment Agency, Belfast. 96pp.

Comments:
It was first located in Malahide Marina in an Estuary where there were pendulous growths of over a metre in length suspended from floating pontoons and from the hulls of leisure craft. In the following year it was located at Carlingford Lough Marina. Now known from other sites from the west coast in Galway and Clew bays and Strangford Lough.
Source region (?) Ocean: Pacific
Ocean: Atlantic
--> Ocean region: NE Atlantic

References (not structured):
Gittenberger A (2007) Recent population expansions of non-native ascidians in The Netherlands. Journal of Experimental Marine Biology and Ecology 342: 122-126.

Griffith K, Mowat S, Holt RHF, Ramsay K, Bishop JDD, Lambert G, Jenkins SR (2009) First records in Great Britain of the invasive ascidian Didemnum vexillum Kott, 2002. Aquatic Invasions 4(4): 581-590.

Stefaniak L, Lambert G, Gittenberger A, Zhang H, Lin S, Whitlatch RB (2009) Genetic conspecificity of the worldwide populations of Didemnum vexillum Kott
2002. Aquatic Invasions 4: 29–44.

Comments:
The precise source of the introduction remains unknown. This species is genetically similar to the great majority of populations examined world-wide indicating that what may have been described as different species will be the same as D. vexillum. This species has been established in the southern part of the North Sea. It has been in the The Netherlands since about 1991 but remained present at low population levels until 1996. Following the cold 1995/1996 winter the populations expanded. It was not known from Britain until 2008, where it was found in Holyhead, North Wales.
Pathway / Vector (?) Level of certainty: Highly likely

Pathway: Vessels
Vector: (Highly likely) Ship’s hull

References (not structured):
Minchin D and Sides E (2006) Appearance of a cryptogenic tunicate, a Didemnum sp. fouling marina pontoons and leisure craft in Ireland. Aquatic Invasions 1(3): 143-147.

Hitchin, B. 2012. New outbreak of Didemnum vexillum in North Kent: on stranger shores. Porcupine
Marine Natural History Society Newsletter, 31: 43–48.

McKenzie CH, Reid V, Lambert G, Matheson K, Minchin D, Brown L, Gollasch S, Simard N, Therriault TW, Valentine P, Pederson J (2017) Alien Species Alert: Didemnum vexillum Kott, 2002. Current invasion status, ecosystem impact and mitigation options for an invasive colonial tunicate ICES Co-operative Research Series No. 335 33pp.

Comments:
It's occurrence at a number of marina sites where only small craft are berthed implicate small craft in the transmission of this species. Indeed small craft hulls have been found with extensive colonies. Its occurrence with trestle culture of oysters would indicate that oysters and the equipment that may be transported with them may infest new areas.
Habitat type (?) Aquaculture sites
Estuary
Marina
Sheltered coastal area

Comments:
All sites found in Ireland range from being located close to and associated with Pacific oyster and mussel farming and marinas in sheltered environments.
Wave exposure (?) Sheltered

Comments:
All of the sites in Ireland have to-date been from sheltered environments.
Salinity range (?) Venice system:
6. Polymixohaline [18-30psu]
7. Euhaline [30-40psu]

Comments:
A purge of the D. vexillum took place in Malahide following a deluge of rain draining from a lagoon near the marina. It is unclear at what salinity the loss of colonies took place.
Temperature range (?) Min: -2
Max: 24

References (not structured):
Gittenberger A (2007) Recent population expansions of non-native ascidians in The Netherlands. Journal of Experimental Marine Biology and Ecology 342: 122-126.

McKenzie CH, Reid V, Lambert G, Matheson K, Minchin D, Brown L, Gollasch S, Simard N, Therriault TW, Valentine P, Pederson J (2017) Alien Species Alert: Didemnum vexillum Kott, 2002. Current invasion status, ecosystem impact and mitigation options for an invasive colonial tunicate ICES Co-operative Research Series No. 335 33pp.

Valentine, P. C., Carman, M. R., Blackwood, D. S., and Heffron, E. J. 2007. Ecological observations
on the colonial ascidian Didemnum sp. in a New England tide pool habitat. Journal of
Experimental Marine Biology and Ecology, 342(1): 109–121.

Comments:
According to Gittenberger (2007) once temperatures exceeds 18 C growth declines from the optimum range of 14-18C and colonies decline once temperatures fall to ~5C, and below, (December to April) in The Netherlands. However, its can survive a range from -2 to 24 C.
Zonation / Substratum (?) Benthic:
Bathyal
Littoral (Benthic)
Sublittoral within photic zone
Substratum:
Artificial (manmade)
Biogenic (living or nonliving)
Hard (cobbles to bedrock)
Soft (mud to pebbles)

References (not structured):
Minchin D and Sides E (2006) Appearance of a cryptogenic tunicate, a Didemnum sp. fouling marina pontoons and leisure craft in Ireland. Aquatic Invasions 1(3): 143-147.

Minchin D, Nunn J (2013) Rapid assessment of marinas for invasive alien species in Northern Ireland. A report undertaken for the Northern Ireland Environment Agency, Belfast. 96pp.

Valentine, P. C., Carman, M. R., Blackwood, D. S., and Heffron, E. J. 2007. Ecological observations
on the colonial ascidian Didemnum sp. in a New England tide pool habitat. Journal of
Experimental Marine Biology and Ecology, 342(1): 109–121.

Comments:
Colonies have been found beneath marinas where colonies have collapsed as a result of tidal currents, have overgrown kelps, sedentary worms, mussels and barnacles.
Reproductive duration (?)Medium

References (not structured):
Carmen MR. Morris JA (2012) Fragment reattachment, reproductive status, and health indicators of the invasive colonial tunicate Didemnum vexillum with implications for dispersal. Biological Invasions 14(10):2133-2140.

Valentine, P. C., Carman, M. R., Blackwood, D. S., and Heffron, E. J. 2007. Ecological observations
on the colonial ascidian Didemnum sp. in a New England tide pool habitat. Journal of
Experimental Marine Biology and Ecology, 342(1): 109–121.

Comments:
Generally larvae are released during the late summer and autumn.
Reproductive seasonality (?) Aug.
Sept.
Oct.

References (not structured):
Valentine PC, Carmen MR, Dijkstra J, Blackwood DS (2009) Larval recruitment of the invasive colonial ascidian Didemnum vexillum, seasonal water temperatures in New England coastal and offshore waters, and implications for spread of the species. Aquatic Invasions 4(1): 153-168.

Comments:
Recruitment in New England takes place at 14 to 20C. Asexual development can take place during most of the year.
Migration pattern (?) Unknown

Comments:
Dispersal of fragments torn away by currents can take place. The larval stage in the plankton survives only a few hours.
Population status (?) Abundant (Moderate level of certainty)

References (not structured):
Minchin D and Sides E (2006) Appearance of a cryptogenic tunicate, a Didemnum sp. fouling marina pontoons and leisure craft in Ireland. Aquatic Invasions 1(3): 143-147.

Minchin D, Nunn J (2013) Rapid assessment of marinas for invasive alien species in Northern Ireland. A report undertaken for the Northern Ireland Environment Agency, Belfast. 96pp.

Comments:
Locally abundant. It is probably more widely distributed than is currently known. This species is likely to spread to other localities and perhaps offshore.
Species status (?) Non-indigenous species

References (not structured):
Lambert G (2009) Adventures of a sea squirt sleuth: unraveling the identity of Didemnum vexillum, a global ascidian invader. Aquatic Invasions 4: 5–28.

Stefaniak L, Lambert G, Gittenberger A, Zhang H, Lin S, Whitlatch RB (2009) Genetic conspecificity of the worldwide populations of Didemnum vexillum Kott
2002. Aquatic Invasions 4: 29–44.

Comments:
There is little doubt that this species originates from the north-west Pacific most probably from Japan and has been spread to many regions world-wide as determined according to its mitochondrial and nuclear genes. It continues to spread and may be of great future concern for culture activities and recruitment over cobble and gravel offshore environments.
Created byDan Minchin 
Last update byDan Minchin, 2018-08-29
Contributors
Added by Dan Minchin
Edited by Dan Minchin, 2013-10-13
Edited by Dan Minchin, 2013-10-20
Edited by Dan Minchin, 2013-11-04
Edited by Dan Minchin, 2013-11-06
Edited by Dan Minchin, 2018-08-29

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