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DEPRESSED RIVER MUSSEL
DEPRESSED RIVER MUSSEL (PSEUDANODONTA COMPLANATA)LOCAL BIODIVERSITY ACTION PLAN
Ecology
Appearance
The depressed river mussel is 80mm long, making it smaller than many other unionoid mussels. It has two identical shells, which are hinged on one edge and have a compressed appearance that gives the mussels its name.
Habitat
Found in fine sediment or sand substrates buy avoids silt as this inteferes with respiration and feeding. It is most frequently found at the margins of rivers or canals where sediment accumulates.
Food
The depressed river mussel is a filter feeder and so filters organic matter from the water that passes through it.
Predators
The main predator of the depressed river mussel is otters.
Current Status
This mussel is seriously threatened throughout its European range. In the UK since 1950 it has been recorded from 63 ten km squares in England and Wales - from Somerset through the Welsh borders to south Yorkshire. However, the species is easily overlooked and may be more common than thought. The UK probably has the healthiest populations in Europe, with the possible exception of Finland.
In 1999 Cambridge University found one site in the Cheshire region on the Shropshire Union Canal that has depressed river mussels.
The Environment Agency undertook a survey of the Llangollen Canal and the Shropshire Union Canal in 2009 which found depressed river mussels at 7 sites, 6 of which had not been recorded before. For more information read the report.
The Environment Agency undertook further surveys in 2010, working with colleagues from Welsh and Midlands regions, to extend the known population of depressed river mussels on the Llangollen Canal, and the Prees Branch of the canal (Shropshire and Wales). Unfortunately, no depressed river mussels were found during these additional surveys. For more information read the report.
The species has a national BAP included in the Biodiversity Steering Group Report (1995).
* The threats to this species are not fully known.
* Zebra mussels
* Water pollution (point source and diffuse)
* Physical disturbance of river banks and channels.
* Drought.
* Collection of individuals for garden ponds and aquaria
* Low populations of host fish species (perch and stickleback)
Actions
* Repeat surveying existing positive sites in 2013 - including surveying for juvenile depressed river mussels (to see if the population is breeding or a relic population)
* Research zebra mussel control
* Survey the New Marina at Swanley in 2013 for depressed river mussels
* Arrange volunteers to map the habitat of the canal. Use this information to identify where the habitat is good to survey for depressed river mussels and where to carry out the enhancements
* Look for depressed river mussels in canal dredgings when spread onto land. If found return them to the canal.
How are we helping to conserve the Depressed River Mussel in the Cheshire region?
* Management plan for the Llangollen canal has been produced. For more information click here.
* Designated Llangollen canal, where the depressed river mussel is present as a Local Wildlife Site
* By producing a leaflet/fact sheet for landowners
Objectives, Targets and Actions
The objectives, targets and actions to help conserve the depressed river mussel in the Cheshire region can be found on the Biodiversity Action Reporting System (BARS) along with full details of our progress so far.
How to find out more about the Depressed River Mussel
UK Biodiversity Action Plan - http://www.ukbap.org.uk/UKPlans.aspx?ID=534
Contact details
Environment Agency
Biodiversity Team
Phone: 01925 54 3376
References
http://www.norfolkbiodiversity.org/SAPsHAPs/SAPs/finalversion-14depressed%20river%20mussel-feb2002.pdf
http://www.suffolk.gov.uk/NR/rdonlyres/CE6E9B08-6B7A-4327-A72A-D1D085266154/0/depressedmussel.pdf
http://www.ukbap.org.uk/UKPlans.aspx?ID=534