Global invasive species database

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Common name
Asian tunicate (English), rough sea squirt (English), club tunicate (English), leathery sea squirt (English)
Synonym
Styela mammiculata , Carlisle 1954
Bostryorchis clava , Redikorzev, 1916
Styela barnharti , Ritter and Forsyth, 1917
Styela clava , Herdman, 1881
Styela clava clava , Nishikawa, 1991
Similar species
Styela plicata
Summary
Styela clava is a fouling organism native to the Pacific Coast of Asia. Because of its hardy nature and ability to withstand salinity and temperature fluctuations, Styela clava easily establishes wherever it is introduced. It can reach extreme densities and out-compete native organisms for food in the water column. Styela clava also predate on the larvae of native species causing population declines. It is a nuisance to mussel and oyster farmers.
Species Description
Styela clava is a large, club-shaped solitary ascidian with a tough leathery body wall with conspicuous bumps, growing up to 160mm long. It consists of an elongated, cylindrical body on top of a stalk of variable length. It can be brownish-white, yellowish-brown, reddish-brown, or yellowish-grey. There are two short siphons toward the top of the organism pointing upward, each with a 4-lobed opening. The body has conspicuous tubercles and rounded swellings on the upper portion and rounded longitudinal ridges on the lower half. The stalk surface is creased. Internally, the gut is a simple U-shaped loop (Fuller, 2005; and NIMPIS, 2002).
Uses
Styela clava is eaten as seafood in Korea (Fuller, 2005).
Habitat Description
Styela clava is present on coasts in low wave energy environments and sheltered embayments in the upper sublittoral zone to at least 25m depth. As a fouling species, it is common on rocks and pylons and can reach densities of 500-1500 individuals per square metre. It is a hardy species, capable of withstanding salinity changes and temperature fluctuations. It can attach itself to concrete and cement, wood, vessel hulls and reefs. S. clava has also frequently been found on permanently submerged floating surfaces, such as buoys and pontoons. It has also been documented attaching itself to other organisms (Crassostrea gigas, Mytilus edulis, and Sargassum muticum) (Davis and Davis, 2005; and NIMPIS, 2002).
Reproduction
Styela clava is hermaphroditic but male and female gonads mature at different times, hence they are not self-fertile. The gonads are closely applied to the visceral surface of the body wall. It reproduces sexually, is oviparous and larval development is usually of one day duration. Spawning in S. clava is temperature dependant and it is believed to only be able to spawn in waters above 15°C. Fertilisation is external and eggs and larvae planktonic for between one to three days, after which they settle and metamorphose into the sessile adult. Reproduction occurs throughout all but the coldest periods. S. clava can live 2-3 years and reach maturity around 10 months (JNCC, 1997; NIMPIS, 2002; and Parker et al. 1999).
Nutrition
Styela clava is a suspension feeder that consumes matter such as phytoplankton, zooplankton, oyster larvae and other suspended organic materials (NIMPIS, 2002).
Pathway
Possible methods of Styela clava dispersal include being transferred on oysters (JNCC, 1997).Styela clava was possibly transported on the hulls of warships following the end of the Korean War in 1951 (JNCC, 1997).

Principal source: NIMPIS, 2002 Leathery sea squirt : Styela clava
JNCC, 1997 Styela clava

Compiler: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)

Review: Expert review underway: \ Andrew N. Cohen \ San Francisco Estuary Institute Oakland California USA

Publication date: 2006-03-23

Recommended citation: Global Invasive Species Database (2016) Species profile: Styela clava. Downloaded from http://www.iucngisd.org/gisd/species.php?sc=951 on 26-09-2016.

General Impacts
When Styela clava populations explode they often out-compete many native species for food. S. clava can reach densities of 500-1500 individuals per square metre. These extreme densities can have negative impacts on native and aquaculture species through competition for space and food, as well as predation of larvae from the water column. S. clava invasiveness is enhanced through its hardy nature; capable of withstanding salinity changes and temperature fluctuations (JNCC, 1997; NIMPIS, 2002).

It can also occur as fouling on vessels, aquaculture and fishing equipment and other artificial structures. Dense fouling on fishing equipment, moorings, ropes, etc. can be time consuming to remove and can result in tangling of fishing gear. Hull fouling increases drag on vessels, requires an increase in the frequency of hull cleaning, and increases fuel costs. In Japan it has been known to impact human health causing an asthmatic condition in oyster shuckers when hammering open Styela fouled oysters in poorly ventilated areas (NIMPIS, 2002).

Management Info
A two year study was undertaken for the Department of Environment and Heritage (Australia) by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) to identify and rank introduced marine species found within Australian waters and those not found within Australian waters.
All of the non-native potential target species identified in this report are ranked as high, medium and low priority, based on their invasion potential and impact potential. A hazard ranking of potential domestic target species based on invasion potential from infected to uninfected bioregions identifies Styela clava as a 'medium priority species' - these species have a reasonably high impact/or invasion potential.
For more details, please see Hayes et al. 2005.
The rankings determined in Hayes et al. 2005 will be used by the National Introduced Marine Pest Coordinating Group in Australia to assist in the development of national control plans which could include options for control, eradication and/or long term management.

NIMPIS (2002) states that, \"In some power plants, raw water systems, reservoirs, locked marinas and impoundments, water levels can be lowered (drawn-down) to expose fouling infestations to the air. Subsequent freezing or desiccation due to ambient temperatures may kill a large proportion of the exposed population.\" The authors go on to state that this method has been successful in controlling S. clava. Various combinations of salinity, temperature and exposure to air have proved successful in killing S. clava fouled on oysters without harming the oysters (NIMPIS, 2002).

The dipping of dredged oysters, and associated species, in saturated or strong salt solutions is extremely effective in killing ascidians without harming the oysters. Brine dipping of oysters fouled with Sargassum muticum, Codium fragile ssp. tomentosoides and S. clava was found to be an effective control. Brine dipping infested oysters is considered the cheapest, safest and most effective method of control of fouling species, however, this requires collection of all the fouled oysters to place them in a bath as it is not possible to implement in the open environment (NIMPIS, 2002).

Countries (or multi-country features) with distribution records for Styela clava
NATIVE RANGE
  • china
  • japan
  • korea, democratic people's republic of
  • korea, republic of
  • russian federation
  • taiwan
Informations on Styela clava has been recorded for the following locations. Click on the name for additional informations.
Lorem Ipsum
Location Status Invasiveness Occurrence Source
Details of Styela clava in information
Status
Invasiveness
Arrival date
Occurrence
Source
Introduction
Species notes for this location
Location note
Management notes for this location
Impact
Mechanism:
Outcome:
Ecosystem services:
Impact information
When Styela clava populations explode they often out-compete many native species for food. S. clava can reach densities of 500-1500 individuals per square metre. These extreme densities can have negative impacts on native and aquaculture species through competition for space and food, as well as predation of larvae from the water column. S. clava invasiveness is enhanced through its hardy nature; capable of withstanding salinity changes and temperature fluctuations (JNCC, 1997; NIMPIS, 2002).

It can also occur as fouling on vessels, aquaculture and fishing equipment and other artificial structures. Dense fouling on fishing equipment, moorings, ropes, etc. can be time consuming to remove and can result in tangling of fishing gear. Hull fouling increases drag on vessels, requires an increase in the frequency of hull cleaning, and increases fuel costs. In Japan it has been known to impact human health causing an asthmatic condition in oyster shuckers when hammering open Styela fouled oysters in poorly ventilated areas (NIMPIS, 2002).

Red List assessed species 0:
Locations
Mechanism
[2] Competition
[2] Predation
[2] Bio-fouling
Outcomes
[5] Socio-Economic
  • [3] Damage on aquaculture/mariculture/fishery
  • [2] Human nuisance 
Management information
A two year study was undertaken for the Department of Environment and Heritage (Australia) by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) to identify and rank introduced marine species found within Australian waters and those not found within Australian waters.
All of the non-native potential target species identified in this report are ranked as high, medium and low priority, based on their invasion potential and impact potential. A hazard ranking of potential domestic target species based on invasion potential from infected to uninfected bioregions identifies Styela clava as a 'medium priority species' - these species have a reasonably high impact/or invasion potential.
For more details, please see Hayes et al. 2005.
The rankings determined in Hayes et al. 2005 will be used by the National Introduced Marine Pest Coordinating Group in Australia to assist in the development of national control plans which could include options for control, eradication and/or long term management.

NIMPIS (2002) states that, \"In some power plants, raw water systems, reservoirs, locked marinas and impoundments, water levels can be lowered (drawn-down) to expose fouling infestations to the air. Subsequent freezing or desiccation due to ambient temperatures may kill a large proportion of the exposed population.\" The authors go on to state that this method has been successful in controlling S. clava. Various combinations of salinity, temperature and exposure to air have proved successful in killing S. clava fouled on oysters without harming the oysters (NIMPIS, 2002).

The dipping of dredged oysters, and associated species, in saturated or strong salt solutions is extremely effective in killing ascidians without harming the oysters. Brine dipping of oysters fouled with Sargassum muticum, Codium fragile ssp. tomentosoides and S. clava was found to be an effective control. Brine dipping infested oysters is considered the cheapest, safest and most effective method of control of fouling species, however, this requires collection of all the fouled oysters to place them in a bath as it is not possible to implement in the open environment (NIMPIS, 2002).

Bibliography
22 references found for Styela clava

Managment information
Centre for Environment, Fisheries & Aquaculture Science (CEFAS)., 2008. Decision support tools-Identifying potentially invasive non-native marine and freshwater species: fish, invertebrates, amphibians.
Summary: The electronic tool kits made available on the Cefas page for free download are Crown Copyright (2007-2008). As such, these are freeware and may be freely distributed provided this notice is retained. No warranty, expressed or implied, is made and users should satisfy themselves as to the applicability of the results in any given circumstance. Toolkits available include 1) FISK- Freshwater Fish Invasiveness Scoring Kit (English and Spanish language version); 2) MFISK- Marine Fish Invasiveness Scoring Kit; 3) MI-ISK- Marine invertebrate Invasiveness Scoring Kit; 4) FI-ISK- Freshwater Invertebrate Invasiveness Scoring Kit and AmphISK- Amphibian Invasiveness Scoring Kit. These tool kits were developed by Cefas, with new VisualBasic and computational programming by Lorenzo Vilizzi, David Cooper, Andy South and Gordon H. Copp, based on VisualBasic code in the original Weed Risk Assessment (WRA) tool kit of P.C. Pheloung, P.A. Williams & S.R. Halloy (1999).
The decision support tools are available from: http://cefas.defra.gov.uk/our-science/ecosystems-and-biodiversity/non-native-species/decision-support-tools.aspx [Accessed 13 October 2011]
The guidance document is available from http://www.cefas.co.uk/media/118009/fisk_guide_v2.pdf [Accessed 13 January 2009].
General information
Berman, J., L. Harris, W. Lambert, M. Buttrick, and M. Dufresne. 1992. Recent Invasions of the Gulf of Maine: Three Contrasting Ecological Histories. Conservation Biology Volume 6, No. 3, September 1992.
Boyd, M. J., T. J. Miulligan, and F. J. Shaughnessy. 2002. Non-Indigenous marine species of Humboldt Bay, California. A Report to the California Department of Fish and Game: February 28, 2002.
Davis, M. H., and M. E. Davis. 2005. Styela clava (Tunicata: Ascidiacea) - a new addition to the fauna of the Portuguese coast. J. Mar. Biol. Ass. U.K. (2005), 85, 403-404.
Dyrynda, P.E.J. 2001. Distributions and ecological impacts of non-native species within natural estuarine channels (Poole Harbour, UK). In Abstracts: Second International Conference on Marine Bioinvasions, March 9-11, 2001. New Orleans, LA
Summary: Distribution of invasive species in Poole Harbour in England.
Available from: http://massbay.mit.edu/publications/marinebioinvasions/mbi2_abstracts.pdf [Accessed 11 February 2008]
Fuller, P. 2005. Styela clava. USGS-NAS (Nonindigenous Aquatic Species Database, Gainesville, FL.).
Summary: Available from: http://nas.er.usgs.gov/queries/FactSheet.asp?SpeciesID=1292 [Accessed 27 October 2005]
Hewitt, C. L., M. L. Campbell, R. E. Thresher, R. B. Martin, S. Boyd, B. F. Cohen, D. R. Currie, M. F. Gomon, M. J. Keough, J. A. Lewis, M. M. Lockett, N. Mays, M. A. McArthur, T. D. O Hara, G. C. B. Poore, D. J.Ross, M. J. Storey, J. E. Watson, and R. S. Wilson. 1998. Introduced and cryptogenic species in Port Phillip Bay, Victoria, Australia. Marine Biology International Journal on Life in Oceans and Coastal Waters.
ITIS (Integrated Taxonomic Information System), 2005. Online Database Styela clava
Summary: An online database that provides taxonomic information, common names, synonyms and geographical jurisdiction of a species. In addition links are provided to retrieve biological records and collection information from the Global Biodiversity Information Facility (GBIF) Data Portal and bioscience articles from BioOne journals.
Available from: http://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=159337 [Accessed 7 February 2008]
Lambert C. C., and G. Lambert. 1998. Non-indigenous ascidians in southern California harbors and marinas. Marine Biology (1998) 130: 675�688 .
Minchin, D., and S. Gollasch. 2003. Fouling and Ships Hulls: how Changing Circumstances andSpawning Events may Result in the Spread of Exotic Species. Biofouling, 2003 Vol 19 (Supplement), pp 111-122.
NZPA. 2005. Sea squirt alert at Picton. The New Zealand Herald.
Parker, L. E., S. Culloty, R. M. O Riordan, B. Kelleher, S. Steele, and G. Van der Velde. 1999. Preliminary study on the gonad development of the exotic ascidian Styela clava in Cork Harbour, Ireland. Journal of Marine Biol Ass. U.K. 79:1141-1142.
Parry, G. D., and B. F. Cohen. 2001Exotic species established in Western Port, including an assessment of the status of the exotic species Corbula gibba, Alexandrium spp, Gymnodinium spp and Undaria pinnatifida. Marine and Freshwater Resources Institute: Report No. 45.
Pederson, J., R. Bullock, J. Carlton, J. Dijkstra, N. Dobroski, P. Dyrynda, R. Fisher, L. Harris, N. Hobbs, G. Lambert, E. Wasem, A. Mathieson, M. Miglietta, J. Smith, J. Smith, and M. Tyrrell. 2003. Rapid assessment survey of non-native and native marine species of floating dock communities. MARINE INVADERS IN THE NORTHEAST: Massachusetts Institute of Technology Sea Grant College Program, Cambridge, Massachusetts.
The Ocean Biogeographic Information System (OBIS) Dataset Extent Map, Distribution of Styela clava
Summary: The Ocean Biogeographic Information System (OBIS) is the information component of the Census of Marine Life (CoML), a growing network of more than 1000 researchers in 73 nations engaged in a 10-year initiative to assess and explain the diversity, distribution, and abundance of life in the oceans - past, present, and future. OBIS is a web-based provider of global geo-referenced information on marine species. OBIS contains expert species level and habitat level databases and provide a variety of spatial query tools for visualizing relationships among species and their environment.
This page is available from: http://www.iobis.org/OBISWEB/ObisControllerServlet?category=all&names=data&tableName=0&searchName=styela+clava&x=20&y=13 [Accessed 23 August 2006]
Ocean Biogeographic Information System (OBIS) available from: www.iobis.org
Wasson, K., C. J. Zabin, L. Bedinger, M. C. Diaz, and J. S. Pearse. 2001. Biological invasions of estuaries without international shipping: the importance of intraregional transport. Biological Conservation 102 (2001) 143-153.
Whitlatch, R.B. and Osman, R.W. 1999. Geographical distributions and organism-habitat associations of shallow-water introduced marine fauna in New England. In Abstracts: First National Conference on Marine Bioinvasions, January 24 -27, 1999. Massachusetts Institute of Technology, Cambridge, MA
Summary: Report into the distribution of some invasive benthic species in New England, USA
Available from: http://massbay.mit.edu/publications/marinebioinvasions/mbi1_abstracts.pdf [Accessed 8 February 2008]
Whitlatch, R., R. Osman, A. Frese, R. Malatesta, P. Mitchell, and L. Sedgewick. 1995. The ecology of two introduced marine ascidians and their effects on epifaunal organisms in Long Island Sound. Pages 29-48 in Proceedings of the Northeast Conference on Non-Indiginous Aquatic Nuisance Species. Connecticut Sea Grant Publication Number CT-SG-95-04.
Contact
The following 1 contacts offer information an advice on Styela clava
Cohen,
Andrew N.
Organization:
San Francisco Estuary Institute
Address:
7770 Pardee Lane, 2nd Floor Oakland, CA 94621-1424
Phone:
(510) 746-7367
Fax:
(510) 746-7300