Unio tumidus 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Mollusca Bivalvia Unionoida Unionidae

Scientific Name: Unio tumidus Retzius, 1788
Regional Assessments:
Common Name(s):
English Swollen River Mussel
Tumidiana conus ssp. borysthenensis (Kobelt, 1880)
Tumidiana muelleri (Rossmässler, 1838)
Tumidiana tumida ssp. falcatulus (Drouët, 1881)
Tumidiana conus ssp. conus (Spengler, 1793)
Unio tumidus ssp. depressus (Donovan, 1802)
Unio tumidus ssp. godetianus Clessin, 1890
Unio tumidus ssp. zelebori Zelebor, 1851
Taxonomic Notes: This synonymy is the one given by Graf & Cummings (2010). It should be noted that in the Russian Federation Unio tumidus is placed in another genus, namely Tumidiana Servain, 1882, which consists of Tumidiana tumida tumida (Philipsson in Retzius, 1788), Tumidiana tumida falcatulus (Drouët, 1881), T. conus (Spengler, 1793) and T. muelleri (Rossmässler, 1838) (Kantor et al. 2010). According to Graf (2007) all of these belong to U. tumidus. This assessment follows Graf's view of the species taxonomy.

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2011
Date Assessed: 2011-07-22
Assessor(s): Van Damme, D.
Reviewer(s): Böhm, M. & Collen, B.
Unio tumidus, though rapidly declining in the western part of its range, is still common and widespread in eastern Europe. It is hence considered as Least Concern. However, population declines are occurring, so that further information is required on these declines and their causes in order to prevent the species from slipping towards Near Threatened or even a threatened category in the future.

Geographic Range [top]

Range Description:This species is widely distributed throughout Europe. It is found from northern France to western Switzerland, south and central Enland, eastern Wales, Germany to central Sweden, southern Finland and the western Ural region (Welter-Schultes 2010).
Countries occurrence:
Albania; Andorra; Austria; Belgium; Bosnia and Herzegovina; Bulgaria; Croatia; Czech Republic; Denmark; Estonia; Finland; France (France (mainland)); Germany; Greece; Hungary; Italy; Jersey; Latvia; Lithuania; Luxembourg; Macedonia, the former Yugoslav Republic of; Moldova; Monaco; Montenegro; Netherlands; Norway; Poland; Portugal; Romania; Russian Federation (Kaliningrad, North European Russia); Serbia (Serbia); Slovakia; Slovenia; Spain; Sweden; Switzerland; Turkey; Ukraine (Ukraine (main part)); United Kingdom (Great Britain)
Additional data:
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:There are no population data available for this species.
Current Population Trend:Unknown
Additional data:
Population severely fragmented:No

Habitat and Ecology [top]

Habitat and Ecology:This species is found in freshwater rivers, generally concentrated in marginal zones where substrate is firm and muddy. It is also found in canals, drainage channels, river oxbows, fish ponds and flooded gravel pits and are less common on sand, fine gravel and soft mud substrates (Aldridge 1999). It is also found in some lakes, artificial lakes and old river arms, and is mostly restricted to lowlands. It seems to require cleaner and better oxygenated waters than other Unio species (Welter-Schultes, 2010).

Use and Trade [top]

Use and Trade: In Germany the species has been harvested for animal feed and fertilizers, and numbers have rapidly declined (Welter-Schultes 2010).

Threats [top]

Major Threat(s): The main threat to this species is habitat loss and disturbance through habitat modification for river and canal management, industrial development, dredging and pressures from invasive species (Weber 2005). Some populations have shown tolerance to water pollution while others have appeared sensitive to changes in water quality (Mouthon 1996). In Germany, this mussel was collected in large numbers from small running waters near the villages and boiled as food for pigs and chicken, the shells were crushed and dispersed on crops as fertilizers (Welter-Schultes 2010). Affected by increasing water pollution and habitat destruction, the species is rapidly declining in many countries. In Belgium, it was common but know has become virtulally extict in lower and central Belgium (D. Van Damme pers. comm. 2011)

Conservation Actions [top]

Conservation Actions: There are no species-specific conservation strategies in place for this species. It is listed as Critically Endangered in Austria, Endangered in Germany and as Vulnerable in Switzerland (Welter-Schultes 2010). The predominant threat to this species is poor river management, so that management of marginal river zones would greatly reduce threats of habitat loss. Further information gathered on population trends would help elucidate the true status of the species in order to assess the species more accurately in future.

Citation: Van Damme, D. 2011. Unio tumidus. The IUCN Red List of Threatened Species 2011: e.T156111A4898810. . Downloaded on 18 October 2017.
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