Annex IV protected areas: water dependent habitats and species and high status sites




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3.7. Ground water dependent habitats.





Habitat Code

Habitat Name

Structure and functions (Condition)

Overall Conservation Status

3180

*Turloughs (51)

Inadequate

Inadequate

7220

*Petrifying springs with tufa formation (Cratoneurion) (25)

Bad

Bad

7210


*Calcareous fens with Cladium mariscus and species of the Caricion davallianae (45)

Bad

Bad

7230

Alkaline fens (64)

Bad

Bad

8310

Caves not open to the public (15)

Favourable

Favourable

Note #: The number of SACs in which each habitat occurs as either a qualifying interest, or is present, is given in brackets. * Priority Annex 1 listed habitats are indicated with * and are bold-faced
The groundwater dependent habitats listed above occur as a qualifying interest in 103 SAC sites nationally.

3180: Turloughs.

Turloughs can be defined as topographic depressions in karst limestone, which flood intermittently and mainly from groundwater. Most turloughs occur in areas of thin glacial drift, in gentle relief on well-bedded, pure, grey calcerenite, that has a greater degree of karstification than other limestones as a result of its purity and well-developed bedding. All turloughs are characterised by the fact that they chiefly flood and drain via connections with groundwater, such as springs, swallow-holes and estavelles, they can also be associated with sinking rivers. They occur in a variety of settings, including among limestone pavement (a), and as part of a landscape mosaic of esker ridges, turloughs and raised bogs in parts of Cos. Galway and Roscommon (b), for example (see below).


(a) Turloughs in the East Burren Complex SAC, Co Clare

Includes Ordnance Survey of Ireland data

reproduced under OSI license No.

2003/07CCMA/Galway Co. Council




(b) Coolcam Turlough SAC, Croaghill Turlough SAC, and part of Williamstown Turloughs SAC, set among eskers and remnants of raised bogs in Galway/Roscommon. All are included in the Shannon RBD; however the Williamstown turloughs appear to be hydrologically linked to the WRBD (ECS, 1997)

Includes Ordnance Survey of Ireland data

reproduced under OSI license No. 2003/07CCMA/

Galway Co. Council




The currently known distribution of turloughs in Ireland. The total number of sites (483) in the Turloughs Consolidated Database (16.11.2008), includes 3 duplicate point locations for individual site complexes, and one site which is also listed as a Coastal karst Lagoon. The number of individual confirmed turloughs, and possible/probable turloughs is 477-479.

Turlough typology relates to the type of karst flow at individual turlough sites. Conduit flow turloughs (Type 1) are typically associated with high volume and velocity systems, a large catchment area, and have a relatively high natural trophic status i.e. mesotrophic. Type 2 turloughs are associated with shallow epikarst flow, with low volume and velocity, a relatively small catchment area, and are typically oligotrophic. There are intermediate examples of turloughs which exhibit both types of karst flow. Some turloughs also have surface water inflow and outflow, for example Rahasane in Co. Galway. Some also receive distributed flow from sediments, such as esker ridges. In reality, it is likely to be difficult to assign individual turloughs to any one typology. Turlough ecology varies in relation to hydrology and hydrochemistry, and also in relation to agricultural and other land use practices within the turlough basin, on the adjoining sloping land above flood level, as well as within the groundwater catchment area. A number of studies are currently in progress (see Kilroy and Dunne, 2008, for examples and bibliography)
A consolidated turlough database including previously known and newly identified turlough sites is currently available as a draft database (dated 16.11.2008) from NPWS on request. A consultation version will be available on the GSI website in the near future. It should be noted that the database provides point locations within turlough basins, and that individual turlough basins vary substantially in size. EPA mapped lake water bodies (sometimes more than one) occurring within turlough basins as permanent (though varying in size) and/or as seasonal lakes, are cross-referenced in the turlough database by SEG_CD code. NPWS also holds some mapped polygons for turloughs.
With regard to the Water Framework Directive, a key feature of turloughs is that the turlough basin is in direct contact with groundwater. Activities within and adjoining the basin thus constitute a risk to groundwater.


7220: Petrifying springs with tufa formation.

Petrifying springs are permanently irrigated and kept moist by groundwater that is calcareous and oligotrophic in nature. The water supply is from upwelling groundwater sources, including shallow groundwater seepage sources, or sometimes deep groundwater geo-thermal sources. Petrifying springs may be closely associated with alkaline fens but with less fluctuations in water table (Curtis et al 2006). A key requirement is a steady flow of water, though this may dry up periodically. Petrifying springs can be broadly separated into permanent flow and intermittent flow springs.

Springs are often very small features covering no more than some tens of meters. Petrifying springs occur on shallow peaty or skeletal mineral soils.

On contact with the atmosphere at the spring head, carbon dioxide is lost from the water or is depleted by photosynthetic activities of plants growing in the spring, which results in the precipitation of a calcium carbonate tufa. The vegetation in such areas, and especially mosses may be coated in a thick crust of lime. Larger petrifying springs may form tufa cones that constitute a singular habitat.

Petrifying springs occur in lowland and upland areas and may be associated with a variety of different habitats such as alkaline fen, woodland, heathland, grassland, limestone rich boulder clay or gravel deposits or on exposed rock. Spring vegetation is characterized by an abundant or dominant moss cover and may or may not be peat-forming.

NPWS holds a database of petrifying springs, but it should be noted that there are some difficulties with the accuracy of point locations (see Sections 4 and 7).



7210: Calcareous fens with Cladium mariscus and species of the Caricion davallianae (Cladium fens)

Cladium fens are characteristic of flat ground and not of slopes. This habitat is subject to smaller fluctuations in tater table than alkaline fen. Cladium fen is more calcareous and oligotrophic than alkaline fen (Curtis et al 2006). In Ireland Cladium fens occur in a variety of situations including topogenous fens found in valleys or depressions, floodplains, over-grown-ditches, in flats and depressions, extensive wet meadows, within tall reed beds, on the landward side of lakeshore communities, calcium rich flush areas in blanket bogs, dune slack areas, fens adjacent to raised and blanket bogs, in turlough sites and wet hollows in machair often in association with alkaline fen.



7230: Alkaline fen

Fens are usually peat-forming wetlands that receive minerals (magnesium, iron, and in particular calcium) from sources other than precipitation: usually from upgradient sources through drainage from surrounding mineral soils and from groundwater movement. In general they are poor in nitrogen and phosphorus, the latter of which tends to be the limiting nutrient in fen systems. Although fens can be found as discrete wetland habitats in their own right, they often also occur in association with (or as a mosaic within) a range of other water dependent habitats including blanket bog, raised bog, turlough, dune slack, machair, wet heathland, wet grassland, woodland, karst areas, lacustrine and riverine habitats and systems.

NPWS holds a database of alkaline fens, but it should be noted that there are some difficulties with the accuracy of point locations, and there are few mapped polygons currently (see Sections 4 and 7).

Threats and pressures identified in Conservation Status Assessments for turloughs, petrifying springs, Cladium fens and alkaline fens are shown below. All are highly vulnerable to hydrological pressures, including water abstractions, arterial drainage, local drainage, and infilling. Water quality issues also arise, and individual sites can be expected to vary considerably in their buffering capacity for nutrient loadings. Refer also to groundwater support issues for precipitation dependent habitats in Section 3.8.






7220: Petrifying springs

7210 Cladium fen

7230 Alkaline fen

3180 Turlough

Main current pressures and future threats

140 Overgrazing

150 Restructuring agricultural land holding

310 Peat Extraction

800 Landfill, land reclamation and drying out, general

803 Infilling ditches, dykes, ponds, marshes and pits

810 Drainage

890 Other human induced changes in hydraulic conditions


140 Overgrazing

150 Restructuring agricultural land holding

161 Forestry Planting

310 Peat Extraction

311 Hand-cutting of peat

312 Mechanical removal of peat

701 Water pollution

800 Landfill, land reclamation and drying out, general

803 Infilling ditches, dykes, ponds, marshes and pits

810 Drainage



140 Overgrazing

150 Restructuring agricultural land holding

161 Forestry Planting

310 Peat Extraction

311 Hand-cutting of peat

312 Mechanical removal of peat

701 Water pollution

800 Landfill, land reclamation and drying out, general

803 Infilling ditches, dykes, ponds, marshes and pits

810 Drainage



810 Drainage

148 Overgrazing

709 Eutrophication

311 Peat cutting and marl extraction

301 Quarrying

403 Dispersed habitation




3.7.1 Protected and Annex 2 listed species associated with ground water dependent habitats.





Common name (#)

Scientific name

Main pressures and threats

Geyer’s whorl snail

Vertigo geyeri (15)

Hydrological pressures, land use pressures

Desmoulin’s snail

Vertigo moulinsiana (9)

Drying out of habitat, land use and hydrological pressures

Yellow marsh saxifrage

Saxifraga hirculus (6)

Land use pressures

Slender green feather-moss

Hamatocaulis vernicosus (8)

Land use pressures including eutrophication

Lesser horseshoe bat

Rhinolophus hipposideros (47)

Hydrological pressures on cave hibernation roosts

The number of SACs in which each species occurs as either a qualifying interest, or is present, is given in brackets. Note that lesser horseshoe bats are not formally listed as water dependent, and are listed in the SAC Water Dependency database only in SACs where there are hibernation roosts in caves

Geyer’s whorl snail Vertigo geyeri

Vertigo geyeri occurs as a Qualifying Interest in 14 SACs, and is also known to be present in the River Moy SAC. It occurs in saturated water conditions in calcareous, ground water fed flushes that are often limited in size to a few metres square. These habitats are generally found in mosaics of suitable patches within wider fen macro-habitats, which in Ireland can themselves fall within wider site habitats that can be as diverse as raised bog laggs, transition mires, lake shores, hill or mountain slopes, and wetlands associated with coastal dunes and machair. It lives within the saturated and decaying roots of small sedges (particularly Carex viridula ssp. brachyrrhyncha), and associated fen mosses (particularly Drepanocladus revolvens and Campyllium stellatum).
In Ireland, localised extinctions of Vertigo geyeri have been a direct result of drainage of wetlands in the Midlands. At sites where the species is in low numbers, particular attention needs to be paid to whether hydrological or management changes have taken place, and to pressures on the wider catchment or water body supporting the hydrology of the small patches of suitable habitat where the snails occur. A basic requirement for this species is the maintenance of a favourable hydrological regime, so management practices that alter site hydrology or hydrogeology (whether ground water or surface water are affected) can be very damaging to it. Favourable hydrological conditions include saturated ground, and spring flow with network of dendritic trickles (as opposed to channelled overground flow from a spring).
Nutrient enrichment arising from local land use, whether from agricultural run-off, use of fertilisers (including organic manures) or slurry spreading, or dunging by grazing animals, can also be damaging, as would be pesticide use (including herbicides). Sheep-dip run-off would be especially damaging.
Management prescriptions have been prepared by NPWS for land use issues for all SAC populations, wider issues such as abstractions and other hydrological impacts will require WFD measures under the Habitats Directive. A 3-year monitoring programme for all Vertigo geyeri sites is in progress for NPWS, with annual updates on distribution and a final report due in December 2010. Vertigo geyeri is also monitored on an on-going basis as an indicator species at Pollardstown Fen SAC.

Desmoulin’s whorl snail Vertigo moulinsiana

Vertigo moulinsiana occurs as a qualifying interest in 7 SACs, and is present in a further 2. It mainly inhabits calcareous, lowland wetlands: in swamps, fens and marshes usually bordering rivers, canals, lakes and ponds where very humid conditions prevail, often enhanced by open water evaporation during the spring to autumn. Its habitats include surface and ground water dependent features.
Vertigo moulinsiana lives on both living and dead stems and leaves of tall plants: grasses including reeds (e.g. Glyceria maxima, Phragmites australis), and sedges (e.g. Carex riparia and Cladium mariscus. As well as the tall vegetation structure of the habitats above, V. moulinsiana requires a stable hydrology, where the water-table is at, or slightly above, the ground surface for much of the year, and any seasonal flooding is of very low amplitude. It climbs tall vegetation in the summer and autumn, and in winter it descends to litter level, and in severe conditions aestivates on the lower leaves of plants.
The range of Vertigo moulinsiana has become smaller in recent years than it was in former times, when habitat for the species was widespread along the major river flood plains. It is likely that this habitat began to experience losses when large-scale modification became widespread. With the building of the canals towards the end of the 18th Century, a new set of habitat corridors became available to the species, and most of the modern populations for the snail are within sites that are likely to have been colonised from the canal corridors: fens, ditches and lake margins. Some of its sites are transitional in nature in that they are inclined to dry out progressively, as well as being at risk through direct anthropogenic activity. Monitoring and maintenance of water levels are important to on-going conservation of this species. A 3-year monitoring programme for all Vertigo sites is in progress for NPWS, with annual updates on distribution and a final report due in December 2010.

Yellow marsh saxifrage Saxifraga hirculus.

Saxifraga hirculus occurs as a Qualifying Interest in 5 SACs, and is present in one further SAC, all in Co. Mayo. In Ireland, this plant now appears to be restricted to mineral flushes in what is otherwise ombrotrophic blanket bog, occurring in small areas of ground water dependent poor fen and non-calcareous spring habitats (Fossitt habitat types, 2000), which occur within precipitation dependent habitat. S. hirculus was previously recorded from a number of midland counties in Ireland namely Tipperary, Westmeath, Offaly and Laois, but these raised bog sites have been lost due to drainage and peat removal. S. hirculus is currently found only in County Mayo with eight sites documented (NPWS). A number of additional sites adjacent to an existing documented site were observed in May 2004 and another new site identified in the summer of 2006. All known populations lie within 5 of the Irish national 10km grid squares, these are indicated on the NPWS website public map viewer, and more detailed locational data can be requested from NPWS. All populations lie within SACs, except for one recently discovered population near the Owenpollaphuca River to the east of Glenamoy Bog Complex SAC (000500). All populations are assessed as being at favourable conservation status currently; the main threats to Saxifraga hirculus are from land use pressures, e.g. grazing, drainage and windfarm construction. However, hydrological pressure from ground water abstractions would be damaging.

Slender green feather-moss Hamatocaulis (Drepancladus) vernicosus.

H. vernicosus is present as a Qualifying Interest in 8 SACs. It is characteristic of mires that are mineral-rich but not strongly calcareous. It is strictly confined to relatively base-poor fen, a transitional habitat between acid bog and base-rich fen. This appears to occur in at least two forms in Ireland: upland transitional flushes and wet lowland sedge meadows. Land use pressures including enrichment from agricultural sources are potential threats at lowland sites. Water abstraction and other hydrological change, and groundwater enrichment are potential risks. All populations are assessed as being at favourable conservation status currently.
Information on threatened bryophytes in Ireland, including H. vernicosus, is being compiled by NPWS as part of a project towards a bryophyte Red Data Book for Ireland, which has been running since 1999 and is due for completion in 2010. This has entailed collation of existing data and new fieldwork, and is resulting in a database of threatened bryophytes, from which distribution maps will be produced. Most historical sites for H. vernicosus have been visited, and all will have been visited within the next two years. In addition some new sites have been discovered. All known populations are within the SAC network.

Rhinolophus hipposideros

Lesser horseshoe bats have been included as a water dependent species11 in SACs where there are hibernation roosts in caves, which may be vulnerable to flooding. It occurs as a qualifying interest in 41 SACs, and is present in a further 6 SACs. The only cave roost known to have been adversely affected by flooding in the past is Kiltartan Cave SAC (Site Code 000286), during high flood events in 1994/95. Water status issues arise only for cave roosts. Lesser horseshoe bats are currently listed at favourable conservation status, and are not regarded as water dependent by NPWS; they are included for information only as it currently seems unlikely that WFD management measures arise for this species.




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