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Anodonta cygnea

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA MOLLUSCA BIVALVIA UNIONOIDA UNIONIDAE

Scientific Name: Anodonta cygnea
Species Authority: (Linnaeus, 1758)
Common Name(s):
English Swan Mussel
Taxonomic Notes: Fauna Europaea (Bank et al. 2006) considered there to be four different subspecies, concealing cryptic diversity. In addition Falkner (pers. comm., 2009) considered that two subspecies may exist in Lake Constance. However, recent molecular studies indicate that, strains the presence of only one species in Europe with low genetic diversity Lopes-Lima (pers comm., 2013), with the exception of the Italic peninsula where distinct species or sub-species may occur.  Additional molecular studies are needed on the eastern European range, Middle East and North African populations. 

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2014
Date Assessed: 2013-04-04
Assessor(s): Lopes-Lima , M.
Reviewer(s): Kebapçı, U., Numa, C., Seddon, M.B. & Van Damme, D.
Contributor(s): Vinarski, M.
Justification:
Anodonta cygnea has been assessed as Least Concern. This species is geographically widespread throughout Europe, Russia and parts of the Middle East, occurring in a wide variety of different habitats. Whilst it is known that population abundance is currently declining on a local scale, global population trends are unknown. In parts of its European range this species has legal protection and is listed on national Red Lists, but the effectiveness of these measures is not known. Further research into species population trends, abundance and the threats impacting this species on a global scale are required if this species is to be elevated to a threat category in future.
History:
2011 Least Concern

Geographic Range [top]

Range Description:

This species can be found throughout Europe from Portugal in the southwest as far east as Siberia (Zettler et al. 2006). However, there are no data to support species presence within Siberia (Vinarski et al. 2007). Mozley (1936) also described this species from northern Asia but molecular studies should confirm the validity of this claim. It has also been recorded in Northern Iran (Pourang et al. 2009). In Russia, it is found throughout the European part of the state (Kantor et al. 2009). The Iberian populations are restricted to three small lagoons in a 50 km radius in Portugal and it is possibly extinct from Spain after recent construction works in the Valencia albufera (lagoon) by the Mediterranean sea (Araujo pers comm.). A recent record of Anodonta cygnea has been published from Algeria (Khalloufi and Boumaiza 2005) but the validity of the species should also be confirmed with molecular characterization.

Countries:
Native:
Albania; Algeria; Andorra; Armenia (Armenia, Armenia); Austria; Belarus; Belgium; Bosnia and Herzegovina; Bulgaria; Croatia; Czech Republic; Denmark; Estonia; Finland; France (France (mainland)); Germany; Greece (Greece (mainland)); Hungary; Iran, Islamic Republic of; Ireland; Italy (Italy (mainland)); Kazakhstan; Luxembourg; Netherlands; Norway; Poland; Portugal (Portugal (mainland)); Romania; Russian Federation (Central European Russia, East European Russia, North European Russia, Northwest European Russia, South European Russia); Serbia (Kosovo, Serbia, Serbia); Slovakia; Slovenia; Spain (Spain (mainland)); Sweden; Switzerland; Turkey (Turkey-in-Asia, Turkey-in-Europe); Ukraine (Ukraine (main part)); United Kingdom (Great Britain); Yemen (North Yemen, South Yemen)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population:

Although this species is widespread and considered fairly common (Zettler et al. 2006) not many studies have been carried to assess populations’ size and structure. In Poland this species has been declining since the 1950s due to habitat degradation and pollution (Zając 2005). In Britain, river management strategy includes the dredging of rivers which can remove 20% of British subpopulations (Aldridge 2001). At the southeastern edge of its range, the Iberian populations are only restricted to three small lagoons that have been recently invaded by water hyacinth (crassipes spp.) with very negative impacts (Lopes-Lima pers. com.) No detailed population trend data are known. 

Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology:

This species primarily inhabits closed off and small waters such as ponds and peatlands, but can also be found occupying lakes and slow-flowing lowland rivers (Zettler et al. 2006). It is also found in canals, drainage dykes and dam reservoirs (Killeen et al. 2004). The species appears to prefer waterbodies characterized by high concentrations of dissolved oxygen (a likely consequence of the species' fast growth and large size), free from floating vegetation and with fertile bottom sediments (Zając 2002, Rosińska et al. 2008). The species is intolerant of poor environmental conditions, and can be used as a bioindicator of clean water (Rosińska et al. 2008). When present, it is often the only mussel species inhabiting these areas (Zettler et al. 2006). The species is able to use a wide range of host fish (both invasive and native fish) for larvae dispersal and metamorphosis (Giusti et al. 1975, Lopes-Lima pers. comm.) 

Systems: Freshwater

Use and Trade [top]

Use and Trade: This species is known to be poached for supply to artificial basins, garden ponds and aquariums (Rosińska et al. 2008).

Threats [top]

Major Threat(s):

This species has been badly impacted by the zebra mussel Dreissena polymorpha and has suffered localised declines in areas where this species has invaded its habitats (Byrne et al. 2009). In the absence of suitable substrate, Anodonta species are known to be a preferred settlement site for zebra mussels. Heavy infestations can affect the feeding, respiration and reproduction of unionid bivalves, causing mortality and eliminating entire populations (Rosell et al. 1999). The continued range expansion of D. polymorpha into suitable habitat is likely to further impact this species' population numbers (Byrne et al. 2009).

Localized declines have been reported in Poland as a result of habitat degradation, water pollution and eutrophication (Dyduch-Falniowska 1992, cited in Mills and Reynolds 2004). The species is also threatened as a result of poaching for supply in artificial basins and garden ponds (Rosińska et al. 2008). In Britain, poor river management is a significant threat to the species: dredging occurs approximately every ten years and can remove 20% of unioid populations (Aldridge 2001).

The recent invasion of the water hyacinth in the few freshwater lagoons of Iberia is menacing the whole population in this fringe of the distribution (Lopes-Lima pers. com.)

Further research is currently needed into the species' global population to assess the impacts of the documented threat processes.

Conservation Actions [top]

Conservation Actions: In Poland, this species has been strictly protected by law since 2011 and is listed as Endangered on the Polish Red List (Zając 2005). This species has special status in Germany by the BArtSchV (Anlage I) legislation (Federal Species Regulation) (Zettler et al. 2006), and is listed with a status of 2 - 'highly endangered' (Byrne et al. 2009). It is also listed on the local Red List of endangered animals of Brandenburg and of Mecklenburg-Vorpommern in Germany with a status of 3 - 'threatened' (Rosińska et al. 2008). The species is classified as Vulnerable under criterion A4ce on the Irish Red List No. 2 (Non-Marine Molluscs) (Byrne et al. 2009). It is also listed as Vulnerable on the Red List of threatened species of the Czech Republic (Farkač et al. 2005), and as Endangered on the Norwegian Red List (Byrne et al. 2009). It is also listed as Near Threatened on the Austrian Red List of Molluscs (Reischütz and Reischütz 2007).

Citation: Lopes-Lima , M. 2014. Anodonta cygnea. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 24 October 2014.
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