Species name: Anodonta anatina (Linnæus, ). Anodonta-anatina_jpg are better tolerated than by Unio pictorum, but less than by Anodonta cygnea. A more oval shell than A. cygnea, with umbos nearly central. Periostracum glossy , more often green than brown. The shell is thicker in front than behind and. Anodonta anatina (L., ) Family: Unionidae. The duck mussel is a large bivalve mollusc which lives in lakes and slow-flowing rivers where the bottom.
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The duck mussel is a large bivalve mollusc which lives in lakes and slow-flowing rivers where the bottom sediments are coarse. It was formerly common in such places but has been displaced by excess siltation, eutrophication and, recently, by the invasive zebra mussel Dreissena polymorpha. The zebra mussel impacts duck mussels indirectly, by settling on their shells which often provide the only hard substrate in many waterways.
As settlement increases, the filtration activity of the zebra mussels competes with that of the duck mussel which either anstina respiratory failure or starvation. In this way large beds of duck mussel along the Shannon and Erne River systems have perished and enormous numbers of empty shells anodontta ashore.
The story may not end there, however, as the zebra mussel infestation is now waning and there is hope that the duck mussel can regain some of the territory lost to its competitor. Zebra mussels are unable anodontw colonise streams in which water flow is significant and it is thought that these may act as reservoirs of native mussels and assist in abatina of anodonra water-bodies. A large bivalve shell found on sandy or gravelly bottoms of lakes and in slow-moving rivers.
Threatened both in Ireland and Europe by diffuse pollution and the resultant periodic de-oxygenation of waters. A more acute or short-term threat has aondonta delivered by the invasive zebra mussel which competes for dissolved oxygen naodonta food. Species description A large bivalve shell with a flattened profile and broad, somewhat wedge-shaped appearance. The shell is thin and pale, whitish or pearly inside due to a thin layer of nacre, but protected by a periostracum outside which gives it a smooth, glossy green, sometimes brown appearance marked with strong concentric growth lines.
It can reach 80 mm in length and has a nearly straight dorsal upper or hinge margin which is usually at an acute angle to the ventral lower anosonta. The only other large mussel found in still or nearly still waters is the swan mussel Anodonta cygnea. This is larger at up to mm long but with a less distinctly angular shape and more produced posterior end. The dorsal upper margin is usually nearly parallel to the ventral lower margin giving the shell an oblong shape, rather than being angular.
It also has a shallower, more flattened shell with the interior less deeply coated with nacre. Putting a valve of each species up to strong light separates the two.
Reproductive cycle and strategy of Anodonta anatina (L., 1758): notes on hermaphroditism.
Swan mussel shells appear to be of even thickness throughout, whereas duck mussel shells are clearly uneven and much thicker and opaque towards the lower front end.
Life cycle Adults are long lived and there is nearly always a good proportion anldonta mature shells present in colonies. However, this increases where recent breeding and recruitment has been poor.
Breeding depends upon the presence of reasonable water quality and of fish. The parasitic larvae are called glochidia and are produced in spring and carried by the current until they anatiba a bottom-living fish.
After a period of some weeks the glochidia metamorphose and drop off to begin an independent life on the bottom. How to see this species Duck mussels can sometimes be seen from fishing amatina or jetties on lakeshores where the bottom is of clean sand or silt. On a still, sunny day look down at the lake bottom with Polaroid glasses anatinx using a glass-bottomed box. The outlines of shells poking out of the sand can then be seen with the paired pale siphons appearing between the valves.
This mussel is associated with relatively unpolluted slow rivers and lakes with sandy or gravelly bottoms, habitats which are in universal decline. Diffuse pollution has affected most areas and dissolved oxygen levels are reduced in many lakes to dangerously low levels in the summer months. Decline in water quality in lowland lakes and rivers from diffuse pollution with attendant.
Conservation of this species Current action Declaration as a Priority Species.
Support environmental schemes aimed at reducing diffuse pollution whether from agricultural sources, from inadequate sewage treatment in towns or from the malfunctioning or failure of septic tanks in rural areas. Down, BT18 0EU; cedar. An annotated list of the land and freshwater Mollusca of Northern Ireland.
Home Introduction Selection Criteria:: Click on map anovonta open large map in new window. Unionidae The duck mussel is a large bivalve mollusc which lives in lakes and slow-flowing rivers where the bottom sediments are coarse.
Reproductive cycle and strategy of Anodonta anatina (L., ): notes on hermaphroditism.
In brief A large bivalve shell found on sandy or gravelly bottoms of lakes and in slow-moving rivers Threatened both in Ireland and Europe anodinta diffuse pollution and the naodonta periodic de-oxygenation of waters A more acute or short-term threat has been delivered by the invasive anoronta mussel which competes for dissolved oxygen and food Red listed in Ireland as Vulnerable VU and as a Priority Species in Northern Ireland Species description A large bivalve shell with a flattened profile and broad, somewhat wedge-shaped appearance.