|Scientific Name:||Vertigo geyeri|
|Species Authority:||Lindholm, 1925|
Vertigo geyerii Lindholm, 1925 [orth. error]
Vertigo genesii Lindholm, 1925 subspecies geyeri
|Taxonomic Notes:||Vertigo geyeri was considered to be a subspecies of V. genesii or V. parcedentata until 1966 (Walden 1966) and care is needed in interpretation of earlier literature, where references to V. genesii may involve the more frequent V. geyeri.|
|Red List Category & Criteria:||Least Concern ver 3.1|
|Assessor(s):||Killeen, I., Moorkens, E. & Seddon, M.B.|
|Reviewer(s):||Cuttelod, A. & Neubert, E.|
Given the range of protected sites where this species is present, with appropriate site management, the species should reach a stage where it is no longer at risk of extinction. There is, however, in significant parts of the range in Europe, an ongoing deterioration in sites which require active conservation management in order to be sustainable in the long term. Increased development pressure within the catchments supporting V. geyeri can place unsustainable pressure on the finite water resources of this groundwater dependant species. Very remote sites are likely to be more sustainable than sites closer to human habitation. There is still decline in parts of the range however the short generation time means that the species does not qualify for a threatened category across Europe, although it does meet the criteria at a National Level in many countries, due to restricted range. Consequently the species is listed as Least Concern, although if declines continue it may be a candidate for listing as Near Threatened.
The species was previously assessed as Conservation Dependant (LR/cd), as especially in the southern and western part of the range, disturbance and drying out of these water demanding species has meant that hydrological management is needed to maintain the sites in favourable condition. However, a change in the criteria means that this category is no longer available, and hence it has been revised.
This species has also been assessed at the regional level:
European regional assessment: Least Concern (LC)
EU27 regional assessment: Least Concern (LC) at the level of the 27 member States of the European Union
Vertigo geyeri is a boreo-alpine species, probably endemic to Europe (Kerney 1999). It is present in the Boreal, Alpine, Continental and Atlantic zones of the continent from Ireland to Russia (Cameron et al. 2003; Bank et al. 2006). It has a scattered and often localised distribution in many countries and there are documented local extinctions especially where the species occurs in isolated populations, and/or is at the edge of its range.
Bank et al. (2006) list as "Great Britain (UK), Germany, Switzerland, Austria, Czech Republic, Slovakia Italy (Mainland), Romania, Slovenia Norway, Sweden Denmark (Mainland) Finland, Estonia, Latvia, Lithuania, Poland, Republic of Ireland (Eire). In Pokryszko's overview the species (http://www.staff.amu.edu.pl/~polmal/smp/v103.htm) "A Boreo-Alpine species: mostly Scandinavia where its distribution border passes probably between 60° and 62°; north-western part of Russia, British Isles and Czech and Slovak Republic. Recorded from the vicinity of Bialowieza, on the territory belonging at present to the Belarous. Because of its occurrence in adjacent areas the species is likely to be found in Poland."
Native:Austria; Czech Republic; Denmark; Estonia; Finland; Germany; Ireland; Italy (Italy (mainland)); Latvia; Lithuania; Norway; Poland; Romania; Slovakia; Slovenia; Sweden; Switzerland; United Kingdom (Great Britain)
|Range Map:||Click here to open the map viewer and explore range.|
This species is presumed stable. The species range in the UK has increased recently due to species specific survey work targeting likely areas within known regions. The species is not known to have disappeared from any sites in the UK in the last 25 years.
A three year assessment has been carried out in Ireland from 2007-2010 (Moorkens and Killeen 2011). In the past, the number of viable populations surveyed from 1994 to 2006 was chosen as the best proxy in order to estimate population status. Following the wide-ranging survey of 2008-2010, the area of occupancy of the snail was considered to be the best proxy for measuring population condition, as (i) this area had been calculated in the detailed study, and (ii) numbers of individuals are dependent on weather conditions in the months and weeks leading up to a survey. Although it is really equating habitat occupancy with population, it is a better proxy than merely the presence or absence of living V. angustior in a population.
The Favourable Reference Population (FRP) is ‘the population in a given biogeographical region considered the minimum necessary to ensure the long-term viability of the species’ (European Commission 2006).
Expert opinion considers that in order to conserve the long term viability of Vertigo geyeri in the Republic of Ireland, the population Conservation Status should be based upon maintaining the current number of sites in favourable condition and not on number of individuals which is an unreliable measure (see above). Thus sites that were classified as being in unfavourable condition for population (based on assessment of snail presence) were assessed using best expert opinion as to how much more area of occupancy they would have if they were in favourable condition. As the Favourable Reference Population of the species is greater than the Current Population, the population status is currently considered to be unfavourable. This is likely to be the case in other countries, but similar studies have not been undertaken as yet.
|Habitat and Ecology:||Vertigo geyeri is stringent in its requirement of saturated water conditions in calcareous, ground water fed flushes that are often limited in size to a few metres square. Their habitats often occur in mosaics of suitable patches within wider fen macrohabitats, that in Ireland can themselves fall within habitats that be as diverse as raised bog laggs, transition mires, lake shores, hill or mountain slopes, and wetlands associated with coastal dunes and machair (Moorkens 2003). Within these macrohabitats, however, the snail is consistent in where it lives, within the saturated and decaying roots of small calcareous sedges (particularly Carex viridula ssp. brachyrrhyncha), associated fen mosses (particularly Drepanocladus revolvens and Campyllium stellatum). It lives in sedges (e.g. Carex viridula, Schoenus nigricans) and mosses (e.g. Drapanocladus, Palustriella) at the interface between the water table and the base of the herb layer where the surface substrates are at or near field capacity but not subject to seasonal flooding (Cameron et al. 2003). The greatest indicator of optimum V. geyeri habitat is the presence of a tufa-forming spring.These habitats are all restricted in size and vulnerable to disturbance and drainage activities. Vertigo geyeri is a groundwater-dependant species.|
|Use and Trade:||This species is not used.|
|Major Threat(s):||The main threats to this species is the modification of site hydrology, heavy grazing, lack of grazing, supplementary feeding of livestock, species composition change (succession and scrub encroachment), peat extraction, eutrophication, pesticides, modification for wind energy production, fragmentation of habitat, artificial planting on open ground, motorised vehicular damage to habitats, and rise of temperatures and extremes, including flooding.|
|Conservation Actions:||While there now are a range of protected sites where this species is present, these require ongoing appropriate site management, and this should be enough to secure the species albeit in small and fragmented sites. The species will remain conservation dependant in areas that require active management to prevent succession. Conservation is hampered by a lack of information on the wider hydrogeological regimes of the catchments feeding the springs and seepages where the snail resides. Where water abstraction for the catchment aquifer occurs, due consideration should be given to these wetland systems. In the future, the more remote sites are likely to be more sustainable than those with greater urban and agricultural needs for water, if pressure on water resources continues to increase. Species monitoring programmes and grazing management to ensure survival of the species are recommended.|
|Citation:||Killeen, I., Moorkens, E. & Seddon, M.B. 2011. Vertigo geyeri. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 25 November 2014.|
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