A turlough (turloch or turlach in Irish), is a seasonal or periodic water body found mostly in

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms w ...

karst Karst is a topography formed from the dissolution of soluble rocks such as limestone, Dolomite (rock), dolomite, and gypsum. It is characterized by underground drainage systems with sinkholes and caves. It has also been documented for more weathe ...

areas of Ireland, west of the

River Shannon The River Shannon ( ga, Abhainn na Sionainne, ', '), at in length, is the longest river in the British Isles. It drains the Shannon River Basin, which has an area of , – approximately one fifth of the area of the island of Ireland. The Sha ...

. The name comes from the Irish ''tur'', meaning "dry", and ''loch'', meaning "lake". The water bodies fill and empty with the changes in the level of the

water table The water table is the upper surface of the zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with water. It can also be simply explained as the depth below which the ground is saturated. T ...

, usually being very low or empty during summer and autumn and full in the winter. As

groundwater Groundwater is the water present beneath Earth's surface in rock and Pore space in soil, soil pore spaces and in the fractures of stratum, rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit ...

levels drop the water drains away underground through cracks in the karstic limestone. Turloughs are almost unique to Ireland, although there is one example in

Wales Wales ( cy, Cymru ) is a country that is part of the United Kingdom. It is bordered by England to the east, the Irish Sea to the north and west, the Celtic Sea to the south west and the Bristol Channel to the south. It had a population in ...

, Pant-y-Llyn at Cernydd Carmel near Llandeilo. They are of great interest to many scientists: geomorphologists are interested in how turloughs were formed,

hydrologists Hydrology () is the scientific study of the movement, distribution, and management of water on Earth and other planets, including the water cycle, water resources, and environmental watershed sustainability. A practitioner of hydrology is call ...

try to explain what makes turloughs flood, botanists study the unusual vegetation which covers the turlough floor, and zoologists study the animals associated with the turloughs.

Locations

Pant y llyn Turlough June 2010 Gareth Farr WIKIPEDIA

Turloughs are mostly found on the central lowlands west of the Shannon, in counties

Galway Galway ( ; ga, Gaillimh, ) is a City status in Ireland, city in the West Region, Ireland, West of Ireland, in the Provinces of Ireland, province of Connacht, which is the county town of County Galway. It lies on the River Corrib between Lo ...

Clare Clare may refer to: Places Antarctica * Clare Range, a mountain range in Victoria Land Australia * Clare, South Australia, a town in the Clare Valley * Clare Valley, South Australia Canada * Clare (electoral district), an electoral district * Cl ...

, Mayo, and

Roscommon Roscommon (; ) is the county town and the largest town in County Roscommon in Ireland. It is roughly in the centre of Ireland, near the meeting of the N60, N61 and N63 roads. The name Roscommon is derived from Coman mac Faelchon who buil ...

, although a few are also found elsewhere, e.g. in

Limerick Limerick ( ; ga, Luimneach ) is a western city in Ireland situated within County Limerick. It is in the province of Munster and is located in the Mid-West which comprises part of the Southern Region. With a population of 94,192 at the 2 ...

Sligo Sligo ( ; ga, Sligeach , meaning 'abounding in shells') is a coastal seaport and the county town of County Sligo, Ireland, within the western province of Connacht. With a population of approximately 20,000 in 2016, it is the largest urban ce ...

Longford Longford () is the county town of County Longford in Ireland. It has a population of 10,008 according to the 2016 census. It is the biggest town in the county and about one third of the county's population lives there. Longford lies at the mee ...

, and

Cork Cork or CORK may refer to: Materials * Cork (material), an impermeable buoyant plant product ** Cork (plug), a cylindrical or conical object used to seal a container ***Wine cork Places Ireland * Cork (city) ** Metropolitan Cork, also known as G ...

. Only three turloughs have been identified in

Northern Ireland Northern Ireland ( ga, Tuaisceart Éireann ; sco, label=Ulster Scots dialect, Ulster-Scots, Norlin Airlann) is a part of the United Kingdom, situated in the north-east of the island of Ireland, that is #Descriptions, variously described as ...

, namely Roosky, Green, and Fardrum Loughs located near Ely Lodge Forest in

County Fermanagh County Fermanagh ( ; ) is one of the thirty-two counties of Ireland, one of the nine counties of Ulster and one of the six counties of Northern Ireland. The county covers an area of 1,691 km2 (653 sq mi) and has a population of 61,805 ...

. These constitute the most northerly turloughs in Ireland and have been collectively designated a

Ramsar site A Ramsar site is a wetland site designated to be of international importance under the Ramsar Convention,8 ha (O) *** Permanent 8 ha (P) *** Seasonal Intermittent < 8 ha(Ts) **

Area of Special Scientific Interest. There is one turlough in

South Wales South Wales ( cy, De Cymru) is a loosely defined region of Wales bordered by England to the east and mid Wales to the north. Generally considered to include the historic counties of Glamorgan and Monmouthshire, south Wales extends westwards ...

, Pant y Llyn.

Rahasane turlough Rahasane turlough is a turlough (an intermittent lake), west of Craughwell in southwest County Galway. It is the largest surviving turlough in Ireland. A turlough is a karst lake, which has no surface outlet and is surrounded on all sides by r ...

in County Galway is the largest surviving turlough in Ireland and is an important location for migrating and overwintering birds. It is noted for its

greater white-fronted geese The greater white-fronted goose (''Anser albifrons'') is a species of goose related to the smaller lesser white-fronted goose (''A. erythropus''). It is named for the patch of white feathers bordering the base of its bill, in fact ''albifrons ...

whooper swan The whooper swan ( /ˈhuːpə(ɹ) swɒn/) (''Cygnus cygnus''), also known as the common swan, pronounced ''hooper swan'', is a large northern hemisphere swan. It is the Eurasian counterpart of the North American trumpeter swan, and the type speci ...

s, wigeon,

teal alt=American teal duck (male), Green-winged teal (male) Teal is a greenish-blue colour. Its name comes from that of a bird — the Eurasian teal (''Anas crecca'') — which presents a similarly coloured stripe on its head. The word is oft ...

, and many waders in winter. 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 Quebec ( ; )According to the Canadian government, ''Québec'' (with the acute accent) is the official name in Canadian French and ''Quebec'' (without the accent) is the province's official name in Canadian English is one of the thirte ...

New Brunswick New Brunswick (french: Nouveau-Brunswick, , locally ) is one of the thirteen provinces and territories of Canada. It is one of the three Maritime provinces and one of the four Atlantic provinces. It is the only province with both English and ...

and

Newfoundland Newfoundland and Labrador (; french: Terre-Neuve-et-Labrador; frequently abbreviated as NL) is the easternmost province of Canada, in the country's Atlantic region. The province comprises the island of Newfoundland and the continental region ...

) temporary waterbodies called ''les lacs mystérieux'' occur. In continental Europe, seasonal waterbodies called ''poljes'' occur in

Slovenia Slovenia ( ; sl, Slovenija ), officially the Republic of Slovenia (Slovene: , abbr.: ''RS''), is a country in Central Europe. It is bordered by Italy to the west, Austria to the north, Hungary to the northeast, Croatia to the southeast, and ...

, and a karstic waterbody has been described at Clot d’Espolla in

Catalonia Catalonia (; ca, Catalunya ; Aranese Occitan: ''Catalonha'' ; es, Cataluña ) is an autonomous community of Spain, designated as a '' nationality'' by its Statute of Autonomy. Most of the territory (except the Val d'Aran) lies on the no ...

. It has recently been proposed that the definition of a turlough, particularly as used in the

European Union The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are located primarily in Europe, Europe. The union has a total area of ...

Habitats Directive, 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.

Geomorphology and hydrology

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. Turloughs will usually have specific place on the floor where water flows in and out, called a

swallow-hole A sinkhole is a depression or hole in the ground caused by some form of collapse of the surface layer. The term is sometimes used to refer to doline, enclosed depressions that are locally also known as ''vrtače'' and shakeholes, and to openi ...

(''slugaire'' in Irish). 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. 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 using

multivariate analysis Multivariate statistics is a subdivision of statistics encompassing the simultaneous observation and analysis of more than one outcome variable. Multivariate statistics concerns understanding the different aims and background of each of the diff ...

of a wide range of variables characterizing the water bodies shows that there are no distinct types, but rather a continuum from wet to dry.

Flora

Turloughs usually have a mixture of aquatic and terrestrial vegetation, 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 as '' Chara'', ''

Ranunculus ''Ranunculus'' is a large genus of about almost 1700 to more than 1800 species of flowering plants in the family Ranunculaceae. Members of the genus are known as buttercups, spearworts and water crowfoots. The genus is distributed in Europe ...

'', ''

Potamogeton ''Potamogeton'' is a genus of aquatic, mostly freshwater, plants of the family Potamogetonaceae. Most are known by the common name pondweed, although many unrelated plants may be called pondweed, such as Canadian pondweed (''Elodea canadensis'' ...

'', ''

Littorella uniflora ''Littorella uniflora'' (vernacular name: (American) shoreweed) is a species of aquatic flowering plant native to the Azores, Morocco, most of Europe excluding the dry southeast, Iceland, and the Faroes. It prefers to live mostly submerged in nu ...

'', '' Polygonum amphibium'' and '' Mentha aquatica''. This gradually gives way to a sward of ''

Potentilla anserina ''Argentina anserina'' (synonym ''Potentilla anserina'') is a perennial plant, perennial flowering plant in the rose family, Rosaceae. It is known by the common names silverweed, common silverweed or silver cinquefoil. It is native throughout the ...

'', sedges such as ''

Carex panicea ''Carex panicea'', commonly known as carnation sedge, is a plant species in the sedge family, Cyperaceae. It is known as grass-like sedge and can be found in Northern and Western Europe, and also in north-eastern North America. The plant produces ...

'', and ''

Viola ; german: Bratsche , alt=Viola shown from the front and the side , image=Bratsche.jpg , caption= , background=string , hornbostel_sachs=321.322-71 , hornbostel_sachs_desc=Composite chordophone sounded by a bow , range= , related= *Violin family ...

'' species. The black turlough moss '' Cinclidotus fontinaloides'' grows on surfaces such as rocks and tree trunks. Further up the sides of the turlough shrubs like '' Frangula alnus'' and ''

Potentilla fruticosa ''Dasiphora fruticosa'' is a species of hardy deciduous flowering shrub in the family Rosaceae, native to the cool temperate and subarctic regions of the northern hemisphere, often growing at high altitudes in mountains. ''Dasiphora fruticosa'' ...

'' occur. Some turloughs will instead transition to fen vegetation including sedges and bogbean ('' Menyanthes trifoliata''). Another characteristic feature is the growth of layers of

filamentous algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular micr ...

during warm and dry weather, which later dry out and form "algal paper".

Fauna

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 turloughs

sticklebacks The sticklebacks are a family of ray-finned fishes, the Gasterosteidae which have a Holarctic distribution in fresh, brackish and marine waters. They were thought to be related to the pipefish and seahorses but are now thought to be more closel ...

can survive by retreating into the swallow-holes), and frogs and

newts A newt is a salamander in the subfamily Pleurodelinae. The terrestrial juvenile phase is called an eft. Unlike other members of the family Salamandridae, newts are semiaquatic, alternating between aquatic and terrestrial habitats. Not all aqua ...

may sometimes spawn in them. The lack of predatory fish allows some usually rare

invertebrates Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordat ...

, such as the

Cladocera The Diplostraca or Cladocera, commonly known as water fleas, are a superorder of small crustaceans that feed on microscopic chunks of organic matter (excluding some predatory forms). Over 1000 species have been recognised so far, with many more ...

'' Eurycercus glacialis'', to thrive. Other Cladocera common in turloughs include ''Alona affinis'', ''

Alonella ''Alonella'' is a genus of Chydoridae. The genus was described in 1862 by Michael Sars. It has cosmopolitan distribution In biogeography, cosmopolitan distribution is the term for the range of a taxon that extends across all or most of the ...

excisa'', '' Chydorus sphaericus'', ''Eurycercus lamellatus'' and ''Simocephalus vetulus''. A number of beetles that are rare or absent elsewhere in Ireland can be found in turloughs, such as '' Hygrotus quinquelineatus'', '' Coelambus impressopunctatus'', '' Graptodytes bilineatus'', '' Agabus labiatus'', and ''A. nebulosus''. Other invertebrates can also occur, such as

fairy shrimp Anostraca is one of the four orders of crustaceans in the class Branchiopoda; its members are referred to as fairy shrimp. They live in vernal pools and hypersaline lakes across the world, and they have even been found in deserts, ice-covered mo ...

, flatworms and snails.

Locations

Geomorphology and hydrology

Flora

Fauna

See also

Turloughs in Ireland

References

Further reading

External links