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The County Clare Wetlands Survey Patrick Crushell & Peter Foss 2008 ___________________________________________________________ Dystrophic lakes Natural dystrophic lakes are an Annex 1 habitat under the EU Habitats Directive. Natural lakes and ponds that are highly acidic (pH range 3.5-5.5), base-poor and low in nutrients, and where the water is brown in colour owing to inputs of humic and other acids from peat. These lakes are important habitats for insect life. They are usually associated with blanket bogs, mainly the lowland type, raised bogs, cutover bogs and wet heathland areas and are characterised by peaty rather than rocky margins and substrata. The transition from bog to open water is often abrupt. The principal threats to natural dystrophic lakes and ponds are peat cutting, overgrazing and afforestation of peatland habitats. Relatively common in upland blanket bog areas throughout the county such as within the Lough Atorick Bogs NHA. Acid oligotrophic lakes Annex 1 habitat under the EU Habitats Directive. Lakes and ponds that are low in nutrients, base-poor and acidic. Most acid oligotrophic lakes are associated with areas of acidic bedrock and many have rocky margins. The substrate in shallow water is either rock, organic lake sediment, or coarse mineral material (sand and gravel). Water is often brownish in colour as a result of inputs from peaty soils or bogs in the catchments. These lakes support communities of submerged and floating aquatic plants. These lakes are important habitats for insect life. The principal threats to acid oligotrophic lakes include nutrient enrichment arising from agricultural practices such as overgrazing and excessive fertilisation, as well as afforestation, and waste water from housing developments in rural areas. Lakes may also be negatively affected by the introduction of invasive alien species, and their utilization for an increasing number of sport and leisure activities. This habitat type is relatively common in areas with a non-calcareous bedrock. An example is Doo Lough in West Clare. 17
The County Clare Wetlands Survey Patrick Crushell & Peter Foss 2008 ___________________________________________________________ Limestone and marl lakes Hard water lakes and ponds of limestone areas that are base-rich and poor to moderately rich in nutrients (oligotrophic to mesotrophic). The water is typically clear and the lake sediment usually has a high proportion of marl, a white clay precipitate of calcium carbonate. Marl-forming Stoneworts (Chara spp.) are often abundant and may form dense carpets in unpolluted waters. V a r i o u s - l e a v e d P o n d w e e d (Potamogeton gramineus) is also characteristic. These lakes are frequently fringed by rich fen and flush vegetation. These lakes are important habitats for insect and birds. Hard water lakes are often shallow and have a natural high capacity to buffer the effects of enrichment from phosphorus. However, build up of phosphorus in the sediment of these lakes can lead to rapid shifts in ecosystem quality. There is a continued threat from nutrient enrichment in these lowland lakes arising from intensification of agriculture and urban developments. A good example of this habitat type is Lough Bunny located in the Burren region. Mesotrophic lakes Lakes and ponds that are moderately rich in nutrients, and where the water is sometimes discoloured by algae. Characteristic aquatic plants include White Water-lily (Nymphaea alba), Yellow Water-lily (Nuphar lutea), and a large number of Pondweeds, Stoneworts (Chara spp.) may also be present. The fringing and aquatic plant communities are typically more lush than those associated with oligotrophic lakes. These lakes are important habitats for insect and birds. The principal threats to mesotrophic lakes include nutrient enrichment arising from agricultural practices such as overgrazing and excessive fertilisation, as well as afforestation, and waste water from housing developments in rural areas. Lakes may also be negatively affected by the introduction of invasive alien species, and their utilization for an increasing number of sport and leisure activities. Many of the lakes surrounding Ennis such as Ballyallia Lake fit into this category as reported by Tubridy (2006). 18
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Appendix 8. The County Clare Wetlan
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Report Cover Vol I - Clare County Library

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