Third of snail species here threatened with extinction

Poor water quality is contributing to the decline of snails

Poor water quality is contributing to the decline of snails

Wed, Jan 20, 2010, 00:00

ONE THIRD of Ireland’s snail species are threatened with extinction, according to new research compiled by the National Biodiversity Data Centre.

The State body, which monitor’s the country’s biological diversity, has found that declining water quality, the building boom and certain agricultural and forestry practices are contributing to the species’ decline.

Ireland is home to 150 types of snail. Of these, two are now considered to be extinct, five critically endangered, 14 endangered, 26 vulnerable and six “near-threatened”.

Researchers have found that two native species are already extinct. The lapidary snail ( Helicigona lapicida) ,once found only in a gorge of the river Blackwater at Fermoy in east Co Cork, has “not been seen alive since 1968”, while the last recorded evidence of the mud pond snail ( Omphiscola glabra) was in 1979 before it was “lost to habitat destruction”.

One of Ireland’s rarest varieties is the round-mouthed snail ( Pomatias elegans) which is found only in New Quay, Co Clare. The report found it is “critically endangered” by “development pressure and physical disturbance”.

Snails on the “vulnerable list” include the whirlpool ram’s horn ( Anisus vortex), traditionally found in clear, weedy water in larger streams, rivers and lakes. It has suffered a 63 per cent distributional decline since 1980 and “a major factor in its decline is falling water quality”.

The marsh whorl snail ( Vertigo antivertigo) found across Ireland in fens, marshes, lakeshores and riverbanks has declined by more than 30 per cent in the last 30 years.

Among the six species  of snail specifically protected by EU legislation, only one is considered safe in Ireland. The Kerry slug ( Geomalacus maculosus) which is “restricted to sandstone areas of Kerry and west Cork”, has “a strong viable population and may be capable of expanding its range with global warming”.

However, the Kerry slug’s habitat can be endangered by “invasive” plants such as rhododendrons.

The data is contained in a new website,, which has been launched to mark the UN’s International Year of Biodiversity 2010. Its aim is to make “information more readily available for improved decision-making, particularly in relation to climate change, land-use change and biodiversity protection measures”.

The National Biodiversity Data Centre, which was established three years ago, is funded by the Department of the Environment, Heritage and Local Government, and is based in Waterford.