Austropotamobius pallipes

Taxobox | name = "Austropotamobius pallipes"

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image_width = 240px
status = VU
status_system = iucn2.3
regnum = Animalia
phylum = Arthropoda
subphylum = Crustacea
classis = Malacostraca
ordo = Decapoda
superfamilia = Astacoidea
familia = Astacidae
genus = "Austropotamobius"
species = "A. pallipes"
binomial = "Austropotamobius pallipes"
binomial_authority = (Lereboullet, 1858)

"Austropotamobius pallipes" is an endangered [IUCN2006|assessors=B. Sket|year=1996|id=2430|title=Austropotamobius pallipes|downloaded=10 May 2006 Listed as Vulnerable (VU B2bce+3bcd v2.3)] European freshwater crayfish, and the only species of crayfish native to the British Isles [cite web |url=http://www.arkive.org/species/ARK/invertebrates_terrestrial_and_freshwater/Austropotamobius_pallipes/ |title=Freshwater white-clawed crayfish ("Austropotamobius pallipes") |publisher=ARKive.org |year=2006] . Its common names include "white-clawed crayfish" and "Atlantic stream crayfish". It is found from the Balkan Peninsula to Spain and reaches its northerly limit in Great Britain and Ireland, where it also has its greatest population density.

"A. pallipes" is an olive-brown colour, with pale-coloured undersides to the claws (whence the specific epithet "pallipes", meaning "pale-footed"). It may grow to 12 cm (5 inches) long, although sizes below 10 cm are more common. It typically lives in rivers and streams about 1 metre deep, where it hides among rocks and submerged logs, emerging to forage for food, and also in lakes.

The distribution of "A. pallipes" is rapidly shrinking and in Great Britain it is now more or less restricted to central and northern England and eastern Wales, though there is a regionally significant population in the River Frome in South Gloucestershire and Bristol [cite book |url=http://www.english-nature.org.uk/lifeinukrivers/publications/crayfish.pdf |title=Ecology of the white-clawed crayfish "Austropotamobius pallipes" |publisher=English Nature |author=David Holdich |year=2003 |id=ISBN 1-85716-702-3] , and a population has been discovered in Essex [cite news |url=http://news.bbc.co.uk/1/hi/england/essex/5359464.stm |title=Endangered crayfish colony found |publisher=BBC News |date=2006-09-19] . There is also a population in Candover Brook, a tributary of the River Itchen in Hampshire [cite book |url=http://www.english-nature.org.uk/lifeinukrivers/publications/crayfish_monitoring.pdf |title=Monitoring the white-clawed crayfish "Austropotamobius pallipes" |publisher=English Nature |author=Stephanie Peay |year=2003 |id=ISBN 1-85716-727-9] . However, it was once found across most of England and Wales.

One of the major reasons for this decline is the introduction of the invasive North American signal crayfish ("Pacifastacus leniusculus"). The signal crayfish is a carrier of crayfish plague, an infectious disease to which it has resistance while the native crayfish have none. The British species is also sensitive to many kinds of pollution, such as insecticides.

"Austropotamobius pallipes" is the only species of crayfish found in Ireland, occurring over limestone areas inhabiting rivers, streams, canals and lakes. They are absent from the more acidic waters of the west. ("Souty-Grosset.C et al p40 2006" [Souty_Grosset.C., Holdich D.M, Noel.P.Y., Reynolds.J.D & Haffner.P. (eds (2006) 'Atlas of Crayfish in Europe. Museum national d'Histoire naturelle. Paris] ). They occur in streams with a moderate flow alongside other freshwater invertebrates such as caddis fly, mayfly and mollusc species. Trout and 3 Spined Stickleback also occur in the same habitat. Tree roots, rocks in the banks provide shelter. Juvenile species shelter in vegetation such as watercress and grass mats growing out of the bank.

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