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Turlough (lake)

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Aturlough(turloch or turlach in Irish[1]) is a seasonal or periodic water body found mostly inlimestonekarstareas of Ireland, west of theRiver Shannon.The name comes from theIrishtur,meaning "dry", andloch,meaning "lake". The water bodies fill and empty with the changes in the level of thewater table,usually being very low or empty during summer and autumn and full in the winter. Asgroundwaterlevels drop the water drains away underground through cracks in the karstic limestone.[2]

Turloughs are almost unique to Ireland, although there is one example inWales,Pant-y-Llyn atCernydd CarmelnearLlandeilo.[3][4]They are of great interest to many scientists:geomorphologistsare interested in how turloughs were formed,hydrologiststry to explain what makes turloughs flood,botanistsstudy the unusual vegetation which covers the turlough floor, andzoologistsstudy the animals associated with the turloughs.

The turlough atCarran,County Clare,Ireland. The water level is high following a spell of wet weather. (Late May, 2005)

Locations[edit]

Pant y Llyn turlough, South Wales

Turloughs are mostly found on the central lowlands west of the Shannon, in countiesGalway,Clare,Mayo,andRoscommon,although a few are also found elsewhere, e.g. inLimerick,Sligo,Longford,andCork.

Only three turloughs have been identified inNorthern Ireland,namely Roosky, Green, and Fardrum Loughs located near Ely Lodge Forest inCounty Fermanagh.[5]These constitute the most northerly turloughs in Ireland and have been collectively designated aRamsar site[6]and anArea of Special Scientific Interest.[7]There is one turlough inSouth Wales,Pant y Llyn.[3]

Rahasane turloughin County Galway is the largest surviving turlough in Ireland and is an important location for migrating and overwintering birds.[8]It is noted for itsgreater white-fronted geese,whooper swans,wigeon,teal,and many waders in winter.[9]

Waterbodies analogous to turloughs can be found elsewhere in the world where similar rainfall patterns, rock type and water table occur. In Eastern Canada (Quebec,New BrunswickandNewfoundland) temporary waterbodies calledles lacs mystérieuxoccur.

In continental Europe, seasonal waterbodies calledpoljesoccur inSlovenia,and a karstic waterbody has been described at Clot d’Espolla inCatalonia.[2]It has recently been proposed that the definition of a turlough, particularly as used in theEuropean UnionHabitats Directive,[10]be modified to include the Slovenian waterbodies as well as others. The proposed definition is based solely on the physical aspects of the waterbodies, rather than flora and fauna, which differ between Ireland and Slovenia.[11]

Geomorphology and hydrology[edit]

When limestone is exposed to rainwater it can dissolve, leading to cracks and joints forming and enlarging. In areas where limestone is at the surface, with very little soil cover, water will drain underground through these cracks rather than running off overground through river and stream systems. The water can then flow underground, emerging later at springs. At times of higher rainfall, the water table will rise, as the underground flow cannot drain all the water, and turloughs will then fill. When the water table drops they will empty again.[12]

Turloughs will usually have specific place on the floor where water flows in and out, called aswallow-hole(slugairein Irish[2]). Sometimes an actual hole can be seen, but more often it is a hollow filled with stones. In some larger turloughs the hole will be permanently wet, allowing fully aquatic plants and animals to survive.[12]

Various attempts have been made to classify turloughs into distinct types, such as highland and lowland, fast fluctuating and seasonally fluctuating, or more complex schemes. However, a recent study usingmultivariate analysisof a wide range of variables characterizing the water bodies shows that there are no distinct types, but rather a continuum from wet to dry.[13]

Flora[edit]

Turloughs usually have a mixture ofaquaticandterrestrialvegetation, occurring in zones depending on the water depth and frequency/duration of filling. In Ireland, the deepest part is characterised by aquatic and semi-aquatic plants such asChara,Ranunculus,Potamogeton,Littorella uniflora,Polygonum amphibiumandMentha aquatica.This gradually gives way to a sward ofPotentilla anserina,sedges such asCarex panicea,andViolaspecies. The black turlough mossCinclidotus fontinaloidesgrows on surfaces such as rocks and tree trunks. Further up the sides of the turlough shrubs likeFrangula alnusandPotentilla fruticosaoccur. Some turloughs will instead transition to fen vegetation includingsedgesand bogbean (Menyanthes trifoliata). Another characteristic feature is the growth of layers offilamentous algaeduring warm and dry weather, which later dry out and form "algal paper".[2]

Fauna[edit]

The intermittent nature of these temporary water bodies provides challenges to aquatic animal life. The organisms commonly found in them have adapted various survival strategies, such as aerial adult forms, production of desiccation-resistant resting stages, and amphibious lifestyles. Fish are usually absent (although in larger turloughssticklebackscan survive by retreating into the swallow-holes), andfrogsandnewtsmay sometimes spawn in them.[12]The lack ofpredatoryfish allows some usually rareinvertebrates,such as theCladoceraEurycercusglacialis,to thrive.[14]Other Cladocera common in turloughs includeAlona affinis,Alonellaexcisa,Chydorussphaericus,Eurycercus lamellatusandSimocephalus vetulus.A number of beetles that are rare or absent elsewhere in Ireland can be found in turloughs, such asHygrotus quinquelineatus,Coelambusimpressopunctatus,Graptodytes bilineatus,Agabuslabiatus,andA. nebulosus.[2]Other invertebrates can also occur, such asfairy shrimp,flatwormsandsnails.[12]

See also[edit]

Turloughs in Ireland[edit]

References[edit]

  1. ^"eDIL 2019: An Electronic Dictionary of the Irish Language, based on the Contributions to a Dictionary of the Irish Language (Dublin: Royal Irish Academy, 1913-1976)".Retrieved8 December2021.
  2. ^abcdeReynolds, Julian D.; Duigan, Catherine; Marnell, Ferdia; O'Connor, A. (1998).Extreme and Ephemeral Water Bodies in Ireland. Chapter 4 in: Studies in Irish Limnology, Editor: P.S. Giller.The Marine Institute (Dublin, Ireland).
  3. ^abBlackstock, T. H.; Duigan, C. A.; Stevens, D. P.; Yeo, M. J. M. (September 1993). "Case studies and reviews. Vegetation zonation and invertebrate fauna in Pant-y-llyn, an unusual seasonal lake in South Wales, UK".Aquatic Conservation: Marine and Freshwater Ecosystems.3(3): 253–268.doi:10.1002/aqc.3270030309.
  4. ^"3180 Turloughs: Freshwater habitats".jncc.gov.uk.Joint Nature Conservation Committee.Retrieved6 December2021.
  5. ^Kelly, J. G.; Enlander, I.; Kelly, A. M.; Fogg, T. (2002)."The geological setting, hydrology and ecology of Roosky Turlough, Ely, Co. Fermanagh, Northern Ireland".Cave and Karst Science.29(3).
  6. ^"Fardrum and Roosky Turloughs".ni-environment.gov.uk.Northern Ireland Environment Agency.Archived fromthe originalon 22 June 2010.Retrieved17 March2010.
  7. ^"Fardrum and Roosky Turloughs ASSI".ni-environment.gov.uk.Northern Ireland Environment Agency.Archived fromthe originalon 5 August 2012.Retrieved17 March2010.
  8. ^"Site Name: Rahasane Turlough SAC"(PDF).SITE SYNOPSIS.Department of Tourism, Culture, Arts, Gaeltacht, Sport and Media.pp. 1-3 [3180] Turloughs*.
  9. ^"Rahasane turlough".datazone.birdlife.org.BirdLife International.Retrieved15 June2015.
  10. ^"Factsheet for Turloughs - EUNIS - European Union".European Environment Agency.Retrieved29 December2021.
  11. ^Sheehy Skeefington, Micheline; Scott, Nick E. (2008)."Do turloughs occur in Slovenia?".Acta Carsologica.37(2–3): 291–306.doi:10.3986/ac.v37i2-3.153.Retrieved29 December2021.
  12. ^abcdCoxon, Catherine; Reynolds, Julian."Turloughs"(PDF).burrengeopark.ie.ENFO – The Environmental Information Service, 17 St. Andrew Street, Dublin 2.Retrieved27 December2021.
  13. ^Visser, Marjolein; Regan, Eugenie C; Moran, James; Gormally, Michael; Sheehy Skeffington, Micheline (September 2006)."The Rise and Fall of Turlough Typologies: A Call for a Continuum Concept".Wetlands.26(3): 745–764.doi:10.1672/0277-5212(2006)26[745:TRAFOT]2.0.CO;2.S2CID19132700.Retrieved27 December2021.
  14. ^Duigan, Catherine; Frey, David G. (1987)."Eurycercus glacialis in Ireland (Cladocera, Chydoridae)".Internationale Revue der gesamten Hydrobiologie und Hydrographie.72(2): 235–249.doi:10.1002/iroh.19870720210.Retrieved27 December2021.

Further reading[edit]

External links[edit]

Look upTurloughin Wiktionary, the free dictionary.
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