Invasion HistoryFirst Non-native North American Tidal Record: 2009
First Non-native West Coast Tidal Record:
First Non-native East/Gulf Coast Tidal Record: 2009
General Invasion History:
The native range of Clavelina lepadiformis extends from southern Norway and the Shetland Islands to the Atlantic coast of Spain and the Mediterranean Sea (Berrill 1950; de Caralt et al. 2002; MarLin 2006). It has been introduced to the Azores (Cardigos et al. 2006), to the east coast of South Africa (Monniot et al. 2001), and the US East Coast (Rheinhardt et al. 2010). These introductions are probably the result of ship fouling.
North American Invasion History:
Invasion History on the East Coast:
In October 2009, Clavelina lepadiformis was discovered in the Thames River, near New London, Connecticut, and in nearby Stonington Harbor. Colonies were found at only these two locations in a survey of 11 sites from Fishers Island Sound, which is part of Long Island Sound (Rheinhardt et al. 2010).
Invasion History Elsewhere in the World:
Clavelina lepadiformis was reported in Madeira and the Canary Islands, but its invasion status is unknown, so we consider it cryptogenic here (Wirtz 1998). Its status as an introduced species is more definite in the Azores, where it first appeared in 1971 on the island of Sao Miguel. It later dispersed to all of the Azores (Cardigos et al. 2006). On the Indian Ocean coast of South Africa, C. lepadiformis was discovered at Port Elizabeth and the Knysna Estuary (Monniot et al. 2001; Robinson et al. 2005). Between 2008 and 2011, it was collected on Chejudo Island, South Korea, in the East China Sea (Pyo and Shin 2011).
In the Mediterranean, the status of Clavelina lepadiformis is complex. A native clade is present in rocky areas on the open coast of Catalonia, Spain, but in harbors, a genetically distinct form, with differing life history and population biology is present. These two clades could represent cryptic species, but have not been formally separated. The harbor form is identical to widespread European Atlantic clades and appears to represent a recent introduction by shipping. However, the date of introduction is not known (Tarjuelo et al. 2001; de Caralt et al. 2002; Turon et al. 2003).
Clavelina lepadiformis is a colonial tunicate made up of groups of transparent zooids joined at the base by short stolons (MarLin 2006). Fully developed zooids are 5-6 cm long and are clear with white, yellow or pink bands around the oral siphon and along the dorsal lamina, giving them a light-bulb appearance (Berrill 1950; Reinhardt et al. 2010). Eggs and larvae vary in color and are visible in the atrial cavity. In the Mediterranean the eggs and embryos are most often yellowish white but can be pink or red in other regions (Fish & Fish 1996; Xavier Turon, pers. comm.). Colonies can be large and may consist of a few or tens to hundreds of zooids. In some areas colonies regress in winter and re-grow in spring, although in the Mediterranean this may not be the case (MarLin 2006).
Clavelina pumillo (Milne-Edwards, 1841)
Clavelina rissoana (Milne-Edwards, 1841)
Clavelina savigniana (Milne-Edwards, 1841)
Potentially Misidentified Species
Colonial (or compound) tunicates consist of many zooids, bearing most or all of the organs of a solitary tunicate, but modified to varying degrees for colonial life. Zooids of the genera Clavelina are elongated, completely or partially embedded in the tunic, and are connected by basal stolons. Each zooid has an oral and atrial siphon, which open on the colony surface, and a body divided into two regions – a thorax and abdomen. The thorax contains the pharynx and below it, the abdomen contains the stomach, intestine, ovaries, testis, and heart. Water is pumped into the oral siphon, through finely meshed ciliated gills on the pharynx, where phytoplankton and detritus is filtered, and passed on mucus strings to the stomach and intestines. Excess waste is then expelled in the outgoing atrial water (Van Name 1945; Barnes 1983).
Colonial tunicates reproduce both asexually, by budding, and sexually, from fertilized eggs developing into larvae. Buds can form from the body wall of the zooid or from the stolons. Colonies vary in size, and can range from small clusters of zooids to huge spreading masses. The zooids are hermaphroditic, with eggs and sperm being relased to the atrial chamber. Eggs may be self-fertilized or fertilized by sperm from nearby animals, but some species have a partial block to self-fertilization. Eggs are brooded in the atrial cavity, and hatch into a tadpole larva, with a muscular tail and a notochord, eyespots, and three adhesive papillae in a triangle formation. The lecithotrophic (non-feeding, yolk-dependent) larva is expelled on hatching, and swims briefly before settlement. Swimming periods are usually less than a day, and some larvae can settle immediately after release, but the larval period can be longer at lower temperatures. On settlement, the tail is absorbed, the gill basket expands, and the tunicate begins to feed by filtering (Van Name 1945; Barnes 1983).
|General Habitat||Marinas & Docks||None|
|General Habitat||Vessel Hull||None|
|Salinity Range||Polyhaline||18-30 PSU|
|Salinity Range||Euhaline||30-40 PSU|
|Tidal Range||Low Intertidal||None|
Tolerances and Life History Parameters
|Minimum Salinity (‰)||14||Field, Dybern 1969; Fish and Fish 1996|
|Maximum Salinity (‰)||40||MacKenzie 2011|
|Maximum Duration||0.1||Larval duration up to 3 hrs, Fish and Fish 1996|
|Broad Temperature Range||None||Cold temperate-Warm temperate|
|Broad Salinity Range||None||Polyhaline-Euhaline|
General ImpactsThere are no known impacts of Clavelina lepadiformis in its introduced range.
Regional Distribution Map
|Bioregion||Region Name||Year||Invasion Status||Population Status|
|NA-ET3||Cape Cod to Cape Hatteras||2009||Def||Estab|
|M040||Long Island Sound||2009||Def||Estab|
|6826||Reinhardt et al. 2010||2009||2009-11-11||New London||Def||41.3512||-72.0946|
|6827||Reinhardt et al. 2010||2009||2009-10-16||Stonington||Def||41.3345||-71.9105|
ReferencesAiroldi, Laura; Turon, Xavier; Perkol-Finkel, Shimrit; Rius, Marc (2015) Corridors for aliens but not for natives: effects of marine urban sprawl at a regional scale, Diversity and Distributions 21: 755-768
Barnes, Robert D. (1983) Invertebrate Zoology, Saunders, Philadelphia. Pp. 883
Canning-Clode, João; Fofonoff, Paul; McCann, Linda; Carlton, James T.; Ruiz, Gregory (2013) Marine invasions on a subtropical island: fouling studies and new records in a recent marina on Madeira Island (Eastern Atlantic Ocean), Aquatic Invasions 8(3): 261-270
Cardigos, F. and 5 authors (2006) Non-indigenous marine species of the Azores., Helgoland Journal of Marine Research 60: 160-169
Chainho, Paula and 20 additional authors (2015) Non-indigenous species in Portuguese coastal areas, lagoons, estuaries, and islands, Estuarine, Coastal and Shelf Science <missing volume>: <missing location>
de Caralt, Sònia López-Legentil, Susanna; Tarjuelo, Isabel; Uriz, María Jesús Turon, Xavier (2002) Contrasting biological traits of Clavelina lepadiformis (Ascidiacea) populations from inside and outside harbours in the western Mediterranean, Marine Ecology Progress Series 244: 125-137
Dybern, Bernt I. (1969) Distribution and ecology of ascidians in Kvirturdvikpollen and Vagsbopollen on the west coast of Norway, Sarsia 37: 21-40
Espla, A. A. Ramos; Buencuerpo, V.; Vazquez, E.; Lafargue, F. (1992) Some biogeographical remarks about the ascidian littoral fauna of the straits of Gibraltar (Iberian sector), Bulletin de l'Institut Océanographique 9 (special): 125-131
Fish, J. D.; Fish, Susan (1996) <missing title>, Cambridge University Press, Cambridge UK. Pp. <missing location>
Holman, Luke E.; Parker-Nance, Shirley; de Bruyn, Mark; Creer, Simon; Carvalho, Gary; Rius, Marc (2021) Managing human-mediated range shifts: understanding spatial, temporal and genetic variation in marine non-native species, Philosophical Transactions of the Royal Society of London B 377: 20210025
Koukouras, Athanasios; Voultisiado-Koukoura, Eleni; Kevrekidis, Theodoros; Vafidis, Dimitri (1995) Ascidian fauna of the Aegean Sea with a checklist of the Mediterranean and Black Sea species, Annales de l Institut Oceanographique, Paris 71(1): 19-34
Locke, Andrea (2009) A screening procedure for potential tunicate invaders of Atlantic Canada., Aquatic Invasions 4(1): 71-79
Lopez-Legentil, Susanna; Legentil, Miquel L.; Erwin, Patrick M.; Turon, Xavier (2015) Harbor networks as introduction gateways: contrasting distribution patterns of native and introduced ascidians, Biological Invasions 17: 1623-1638
Mackenzie, A. B. (2011) Biological synopsis of the light-bulb tunicate (Clavelina lepadiformis), Canadian Manuscript Report of Fisheries and Aquatic Sciences 2967: 1-15
MarLin- Marine Life Information Network 2006-2016 MarLin- Marine Life Information Network. http://www.marlin.ac.uk/aboutMarLIN.php
Mead, A.; Carlton, J. T.; Griffiths, C. L. Rius, M. (2011b) Introduced and cryptogenic marine and estuarine species of South Africa, Journal of Natural History 39-40: 2463-2524
Monniot, Claude; Monniot, Francoise; Griffiths, Charles; Schleyer, Michael (2001) South African Ascidians., Annals of the South African Museum 108(1): 1-141
Moura, Carlos J.; Collins, Allen G.; Santos, Ricardo S.; Lessios, Harilaos (2019) Predominant east to west colonizations across major oceanic barriers: Insights into the phylogeographic history of the hydroid superfamily Plumularioidea, suggested by a mitochondrial DNA barcoding marker, Ecology and Evolution 9: :13001–13016.
Naranjo, S. A.; Carballo, J. C.; Garcia-Gomez, J. C. (1996) Effects of environmental stress on ascidian populations in Algeciras Bay (southern Spain)., Marine Ecology Progress Series 144: 119-131
Pyo, Jooyeon; Lee, Taekjun; Shin, Sook (2012) Two newly recorded invasive alien ascidians (Chordata, Tunicata, Ascidiacea) based on morphological and molecular phylogenetic analysis in Korea, Zootaxa 3368: 211-228
Pyo, Jooyeon; Shin, Sook (2011) A new record of invasive alien colonial tunicate Clavelina lepadiformis (Ascidia: Aplousobranchia: Clavelinidae) in Korea., Korean Journal of Systematic Zoology 27(2): 197-200
Ramalhosa Patrício; Gestoso, Ignacio Rocha Rosana M.; Lambert, Gretchen; Canning-Clode, João (2021) Ascidian biodiversity in the shallow waters of the Madeira Archipelago: Fouling studies on artificial substrates and new records, Regional Studies in Marine Science 43(1901672): Published online
Reinhardt, James F.; Stefaniak, Lauren M.; Hudson, David M.; Mangiafico, Joseph; Gladych, Rebecca; Whitlatch, Robert B. (2010) First record of the non-native light bulb tunicate Clavelina lepadiformis (Müller, 1776) in the northwest Atlantic, Aquatic Invasions 5(2): corrected proof
Rius, M.; Griffths, C. W. (2011) Alien & Invasive Animals: A South African Perspective, Random House Struik, Johannesburg, South Africa. Pp. 71-75
Rius, Marc and 7 authors (2014) Range expansions across ecoregions: interactions of climate change, physiology and genetic diversity, Diversity and Distributions 23: 76-88
Robinson, T. B.; Griffiths, C. L.; McQuaid, C. D.; Rius, M. (2005) Marine alien species of South Africa-- status and impacts, African Journal of Marine Science 27(1): 297-306
Simkanin, Christina; Fofonoff, Paul W.; Larson, Kriste; Lambert, Gretchen; Dijkstra, Jennifer A.; Ruiz, Gregory M. (2016) Spatial and temporal dynamics of ascidian invasions in the continental United States and Alaska, Marine Biology 163: Published online
Tarjuelo, I.; Posado, D.; Crandall, K. A.; Pascual, M.; Turon, X. (2001) Cryptic species of Clavelina in two different habitats: habours and rocky littoral zones in the northwestern Mediterranean, Marine Biology 139: 455-462
Turon, Xavier (1990) Distribution and abundance of ascidians from a locality on the northeast coast of Spain, Marine Ecology 11(4): 391-408
Turon, Xavier; Tarjuelo, Isabel; Duran, Sandra; Pascual, Marta (2003) Characterising invasion processes with genetic data: an Atlantic clade of Clavelina lepadiformis (Ascidiacea) introduced into Mediterranean harbours, Hydrobiologia 503: 29-35
Van Name, Willard G. (1945) The North and South American ascidians, Bulletin of the American Museum of Natural History 84: 1-462
Wirtz, Peter (1998) Twelve invertebrate and eight fish species new to the marine fauna of Madeira, and a discussion of the zoogeography of the area., Helgolander Meeresuntersuchungen 52: 197-207