''Austropotamobius pallipes'' is an

endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and in ...

European freshwater crayfish, and the only crayfish native to the

British Isles The British Isles are a group of islands in the North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner and Outer Hebrides, the Northern Isles, ...

. Its common names include white-clawed crayfish and Atlantic stream crayfish.

Distribution

It is found from the easterly Balkan Peninsula to Spain and reaches its northerly limit in Great Britain, as well as Ireland (where it is considered introduced), where it is limited to some regions only: its highest densities are in chalk streams. ''A. pallipes'' is the only crayfish found in Ireland, occurring over

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 whe ...

areas in rivers, streams, canals, and lakes. In France, ''A. pallipes'' is found in streams such as the Mornante and Sellon, two small tributaries of the Dorlay in the Loire department. It is protected as a heritage species. It has also been introduced to Corsica,

Liechtenstein Liechtenstein (), officially the Principality of Liechtenstein (german: link=no, Fürstentum Liechtenstein), is a German-speaking microstate located in the Alps between Austria and Switzerland. Liechtenstein is a semi-constitutional monarch ...

, and

Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...

(from where it is now

extirpated Local extinction, also known as extirpation, refers to a species (or other taxon) of plant or animal that ceases to exist in a chosen geographic area of study, though it still exists elsewhere. Local extinctions are contrasted with global extinct ...

). It was once found across most of Great Britain; however its distribution is rapidly shrinking, and it is recorded in

Yorkshire Yorkshire ( ; abbreviated Yorks), formally known as the County of York, is a historic county in northern England and by far the largest in the United Kingdom. Because of its large area in comparison with other English counties, functions have ...

, central and

northern England Northern England, also known as the North of England, the North Country, or simply the North, is the northern area of England. It broadly corresponds to the former borders of Angle Northumbria, the Anglo-Scandinavian Kingdom of Jorvik, and the ...

, east Kent, eastern

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 ...

, the

Candover Brook The Candover Brook is a chalk stream in the English county of Hampshire. It is a tributary of the River Itchen, which it joins near the town of New Alresford. The stream rises from springs just to the south of the village of Preston Candover. ...

that flows into the Itchen in

Hampshire Hampshire (, ; abbreviated to Hants) is a ceremonial and non-metropolitan county in western South East England on the coast of the English Channel. Home to two major English cities on its south coast, Southampton and Portsmouth, Hampshire ...

; parts of

Essex Essex () is a county in the East of England. One of the home counties, it borders Suffolk and Cambridgeshire to the north, the North Sea to the east, Hertfordshire to the west, Kent across the estuary of the River Thames to the south, and Grea ...

, and several long headwaters of the

River Thames The River Thames ( ), known alternatively in parts as the River Isis, is a river that flows through southern England including London. At , it is the longest river entirely in England and the second-longest in the United Kingdom, after the R ...

, where it competes with the introduced noble crayfish, itself also facing competition from the introduced signal crayfish. Dowdeswell Reservoir, Gloucestershire, has the species and during works of 1998,

Severn Trent Severn Trent plc is a water company based in Coventry, England. It supplies 4.6 million households and business across the Midlands and Wales. It is traded on the London Stock Exchange and a constituent of the FTSE 100 Index. Severn Trent, the ...

ensured its protection. Disease from invasive species has wiped it from the naturally alkaline River Frome, Bristol, 2007–08.

Ecology

It is absent from more acidic waters and occurs in streams with a moderate flow alongside other freshwater invertebrates such as caddis fly, mayfly, and mollusc species.

Trout Trout are species of freshwater fish belonging to the genera '' Oncorhynchus'', '' Salmo'' and '' Salvelinus'', all of the subfamily Salmoninae of the family Salmonidae. The word ''trout'' is also used as part of the name of some non-salm ...

and

three-spined stickleback The three-spined stickleback (''Gasterosteus aculeatus'') is a fish native to most inland and coastal waters north of 30°N. It has long been a subject of scientific study for many reasons. It shows great morphological variation throughout its ra ...

also occur in the same habitat. Tree roots and rocks in the banks provide shelter. Juveniles shelter in vegetation such as

watercress Watercress or yellowcress (''Nasturtium officinale'') is a species of aquatic flowering plant in the cabbage family Brassicaceae. Watercress is a rapidly growing perennial plant native to Europe and Asia. It is one of the oldest known leaf v ...

and grass mats growing out of the bank.

Description

''A. pallipes'' is olive-brown, with pale undersides to the

claw A claw is a curved, pointed appendage found at the end of a toe or finger in most amniotes (mammals, reptiles, birds). Some invertebrates such as beetles and spiders have somewhat similar fine, hooked structures at the end of the leg or tarsus ...

s (whence its specific Latin epithet ''pallipes'', "pale feet"). It may grow to long and adult sizes below are more common. It typically lives in rivers and streams about 1 m (3 ft) deep, where it hides among rocks and submerged logs, emerging to forage for food, and in lakes.

Conservation

Two main reasons for decline are: * Introduction of the invasive North American signal crayfish (''Pacifastacus leniusculus'') and red swamp crayfish (''Procambarus clarkii''): The former is a carrier of crayfish plague, an

infectious disease An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable di ...

to which it has resistance, while ''A. pallipes'' has none. *Water

pollution Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the ...

: Many local extinctions are caused by surface runoff of insecticides and of bleached, insufficiently treated, or illegal untreated wastewater.

References

External links