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

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3.4. Coastal transitional habitats.

Habitat Code

Habitat Name (#)

Structure and functions (Condition)

Overall Conservation Status


Salicornia and other annuals colonising mud and sand (24)




Atlantic salt meadows (Glauco-Puccinellietalia maritimae) (56)




Mediterranean salt meadows (Juncetalia maritimi) (44)




Mediterranean and thermo-Atlantic halophilous scrubs (Sarcocornetea fruticosi) (2)




Estuaries (37)




Mudflats and sandflats not covered by sea water at low tide (59)




*Coastal lagoons (36)



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

Coastal transitional habitats occur as Qualifying Interests in 70 SAC sites nationally.

3.4.1. Coastal lagoons.

Coastal lagoons, a priority listed habitat, are included in this group because although salinity varies, all lagoon water bodies are at least brackish water. A key feature of lagoons is restricted tidal exchange, which makes them vulnerable to eutrophication. A total of 87 lagoon sites are recognised currently, including 100 individual lagoons10. The conservation status of each individual lagoon site has been assessed by NPWS (see Figure 2, on the following page).

Five main morphological types of lagoon are recognised:

  • Classic "sedimentary" lagoons found on all parts of the coastline (21 lagoons, 41.4% of habitat area), lagoons separated from the sea by a shingle or cobble ridge.

  • Artificial lagoons found on all parts of the coastline (30 lagoons, 35.2% of habitat area).

  • "Rock/peat" lagoons on the west coast, similar to lagoons in Scotland, but otherwise rare in Europe (18 lagoons, 20% of habitat area).

  • "Karst" lagoons are found in parts of Counties Clare, Limerick, and Galway, and within Europe, are possibly unique to Ireland (11 lagoons, 4.5% of habitat area).

  • "Saltmarsh" lagoons (6 lagoons, 1.5% of habitat area).

Lagoons depend on a range of water source types, including coastal, transitional, surface water and ground water. The main pressures on lagoon habitats are eutrophication arising from agricultural sources, and from urban waste water discharges and on-site waste water systems, resulting in bad conservation status affecting over 60% of the overall lagoon area including sites located within SACs as a qualifying interest. Drainage and modification of hydrography, including the installation of non-return valves resulting in modification of salinity, are also listed as damaging pressures. A database based on the Article 17 conservation status reporting has been prepared by the Western RBD (attached, and with further notes given in Appendix 9 of this guidance). Notes on coastal lagoon sites where unfavourable status requires measures under the Habitats Directive are included in the coastal lagoons database and also in the SAC_Water_Dependency database.

Figure 2. Conservation status of coastal lagoons, 2007.

Colour-coded to represent the 2007 Article 17 Conservation Status assessment: green = favourable, amber = unfavourable-inadequate, red = unfavourable-bad. Grey = unknown.

3.4.2. Intertidal habitats.

Salicornia and other annuals colonising mud and sand (1310), and the three Annex 1 listed salt-meadow habitats (1330, 1410 and 1420), develop in sheltered areas in estuaries and to the lee of islands and other coastal barriers and spits where muddy sediments can accumulate. They occur on the upper shore, and tend to form zones or habitat mosaics of halophytic and salt tolerant plant species in relation to the extent of tidal submergence and salinity. All five habitats are vulnerable to erosion, mobilisation and re-deposition of sediments, and this pressure is likely to increase with climate change impacts including storm surges and rising sea levels. A systematic survey of saltmarsh habitats is in progress for NPWS, and digital mapping will be available on completion of this project (early 2009). Initial indications suggest that most of the adverse impacts to these habitats arise from over-grazing and consequent physical damage to the habitats, with this impact noted more frequently in the west of Ireland. Dumping, land-filling and reclamation have also resulted in loss of saltmarsh habitats. Water quality issues have not been reported to date, however data are not widely available for these habitats.
Estuary (1130) and mudflats and sandflats not covered by sea water at low tide (1140) habitats are located throughout the Irish coastline; Dundalk Bay and the Shannon Estuary are the largest sites nationally which include them. Water quality issues are noted among the adverse pressures on these habitats, and overall conservation status is assessed as inadequate. An NPWS monitoring programme for estuaries is scheduled to commence in 2008.
With regard to water pollution from point and diffuse sources, it is noted that organic particles, nutrients, heavy metals, persistent organic pollutants and dangerous substances tend to deposit with and bind to fine muds in the most sheltered parts of river estuaries and the associated sand and mudflats. Where monitoring of these areas is carried out, it is recommended that a sediment sampling and analysis programme is included, and that sampling sites are chosen to include likely ‘worst case’ scenario pressures.

3.4.3. Water dependent species associated with coastal transitional habitats.

Annex listed mammals associated with coastal transitional habitats are grey seal, common seal (see Section 3.3.1), and otter (see Section

Coastal transitional habitats are used by nationally and internationally important concentrations of wintering waterfowl (divers, grebes, herons, swans, geese, ducks, waders, and gulls). These habitats are also used for feeding by some breeding seabird species, in particular terns, with nesting colonies located on islands and coastal onshore habitats such as shingle banks, and also on man-made structures such as the mooring dolphins in Dublin Port. Most of the important sites are covered by Special Protection Area (SPA) designations under the Birds Directive; the national SPA network is currently under review by NPWS and notifications of updates are on-going.

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