The Mud Snail - Omphiscola glabra / Lymnaea glabra

Survey and habitats in North West England

The Mud Snail or Mud Pond Snail (Lymnaea glabra or Omphiscola glabra) is a rare and endangered wetland mollusc. It is much more uncommon than a quick look at the NBN Database might suggest for some of those records are a century old. Lymnaea glabra needs "late succession ponds" or more properly stable old ponds and ditches with a fluctuating water level and a tendency towards acidity. They are associated with ponds which have floating mats or floating rafts of vegetation, usually containing Sphagnum Bog-moss species. These ponds usually contain few other mollusc species. The animals can be found by netting the pond and examining submerged vegetation or rubbish, or, where a pond or marsh has dried up, by searching in the leaf-litter of the pond vegetation. The Mud Snail is becoming rare due to a failure to recognise the importance of marshy ponds - the species can be removed by "cleaning out" a pond or ditch or by hydrological impacts which damage the fragile hydrology, making it more permanent, making it dry up sooner in the year, or deepening to remove the "drawdown" marshy zone. The species cannot be translocated to new ponds as it cannot survive in new pond habitats where the habitat is wrong and competition from ecologically fitter new pond colonisers is strong. Some local planning authorities require surveys for this species and their presence is usually a material planning consideration so it is best to survey for them as part of a general Pond Biodiversity Survey.

mudsnailhyRR
              Breeding pond

Juvenile Mud Snails bear a striking resemblance to juveniles of both the much more common Dwarf Pond Snail (Galba truncatula) and the Marsh Snail, which also inhabit marshy ponds. Additionally there are certain monstrous forms of the Dwarf Pond Snail which are more elongated than normal, looking, to the untrained eye, very like the Mud Snail. To avoid either overlooking the presence of the Mud Snail, or indeed protecting by error a much more common species your surveyor needs the necessary field skills.

Single visit surveys are generally carried out by Dave Bentley Ecology Services as part of a general Pond Biodiversity Survey.

Mud Snail against Alisma leaf                 Mud Snail                                   Mud Snail                                    Dwarf Pond Snail (left) & Mud Snail

MsalismaMSfrontMSsideMud_Snail_Omphiscola_Lymnaea_glabra_with_Dwarf_Pond_Snail





 


 






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