Austropotamobius pallipes
Encyclopedia
Austropotamobius pallipes is an endangered
Europe
an freshwater
crayfish
, and the only species of crayfish native to the British Isles
. Its common name
s include white-clawed crayfish and Atlantic stream crayfish.
to Spain
and reaches its northerly limit in Great Britain
and Ireland
, where it also has its greatest population density
.
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. They occur in streams with a moderate flow alongside other freshwater invertebrates such as caddis fly, mayfly
and mollusc species. Trout
and three-spined stickleback
also occur in the same habitat. Tree roots, rocks in the banks provide shelter. Juveniles shelter in vegetation such as watercress
and grass mats growing out of the bank.
s (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.
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
, and a population has been discovered in Essex
. There is also a population in Candover Brook
, a tributary of the River Itchen
in Hampshire
. 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 America
n 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 insecticide
s.
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
an freshwater
Freshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...
crayfish
Crayfish
Crayfish, crawfish, or crawdads – members of the superfamilies Astacoidea and Parastacoidea – are freshwater crustaceans resembling small lobsters, to which they are related...
, and the only species of crayfish native to the British Isles
British Isles
The British Isles are a group of islands off the northwest coast of continental Europe that include the islands of Great Britain and Ireland and over six thousand smaller isles. There are two sovereign states located on the islands: the United Kingdom of Great Britain and Northern Ireland and...
. Its common name
Common name
A common name of a taxon or organism is a name in general use within a community; it is often contrasted with the scientific name for the same organism...
s include white-clawed crayfish and Atlantic stream crayfish.
Distribution and ecology
It is found from the Balkan PeninsulaBalkans
The Balkans is a geopolitical and cultural region of southeastern Europe...
to Spain
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
and reaches its northerly limit in Great Britain
Great Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...
and Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...
, where it also has its greatest population density
Population density
Population density is a measurement of population per unit area or unit volume. It is frequently applied to living organisms, and particularly to humans...
.
Austropotamobius pallipes is the only species of crayfish found in Ireland
Ireland
Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...
, occurring over limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
areas inhabiting rivers, streams, canals and lakes. They are absent from the more acidic waters of the west. They occur in streams with a moderate flow alongside other freshwater invertebrates such as caddis fly, mayfly
Mayfly
Mayflies are insects which belong to the Order Ephemeroptera . They have been placed into an ancient group of insects termed the Palaeoptera, which also contains dragonflies and damselflies...
and mollusc species. Trout
Trout
Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water...
and three-spined stickleback
Three-spined stickleback
The three-spined stickleback, Gasterosteus aculeatus, is a fish native to much of northern Europe, northern Asia and North America. It has been introduced into parts of southern and central Europe.-Distribution and morphological variation:...
also occur in the same habitat. Tree roots, rocks in the banks provide shelter. Juveniles shelter in vegetation such as watercress
Watercress
Watercresses are fast-growing, aquatic or semi-aquatic, perennial plants native from Europe to central Asia, and one of the oldest known leaf vegetables consumed by human beings...
and grass mats growing out of the bank.
Description
A. pallipes is an olive-brown colour, with pale-coloured undersides to the clawClaw
A claw is a curved, pointed appendage, found at the end of a toe or finger in most mammals, birds, and some reptiles. However, the word "claw" is also often used in reference to an invertebrate. Somewhat similar fine hooked structures are found in arthropods such as beetles and spiders, at the end...
s (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
Foraging
- Definitions and significance of foraging behavior :Foraging is the act of searching for and exploiting food resources. It affects an animal's fitness because it plays an important role in an animal's ability to survive and reproduce...
for food, and also in lakes.
Conservation
The distribution of A. pallipes is rapidly shrinking and in Great BritainGreat Britain
Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...
it is now more or less restricted to central
English Midlands
The Midlands, or the English Midlands, is the traditional name for the area comprising central England that broadly corresponds to the early medieval Kingdom of Mercia. It borders Southern England, Northern England, East Anglia and Wales. Its largest city is Birmingham, and it was an important...
and northern England
Northern England
Northern England, also known as the North of England, the North or the North Country, is a cultural region of England. It is not an official government region, but rather an informal amalgamation of counties. The southern extent of the region is roughly the River Trent, while the North is bordered...
and eastern Wales
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...
, though there is a regionally significant population in the River Frome
River Frome, Bristol
The River Frome is a river, approximately long, which rises in Dodington Park, South Gloucestershire, and flows in a south westerly direction through Bristol, joining the former course of the river Avon in Bristol's Floating Harbour. The mean flow at Frenchay is The name Frome is shared with...
in South Gloucestershire
South Gloucestershire
South Gloucestershire is a unitary district in the ceremonial county of Gloucestershire, in South West England.-History:The district was created in 1996, when the county of Avon was abolished, by the merger of former area of the districts of Kingswood and Northavon...
and Bristol
Bristol
Bristol is a city, unitary authority area and ceremonial county in South West England, with an estimated population of 433,100 for the unitary authority in 2009, and a surrounding Larger Urban Zone with an estimated 1,070,000 residents in 2007...
, and a population has been discovered in Essex
Essex
Essex is a ceremonial and non-metropolitan county in the East region of England, and one of the home counties. It is located to the northeast of Greater London. It borders with Cambridgeshire and Suffolk to the north, Hertfordshire to the west, Kent to the South and London to the south west...
. There is also a population in Candover Brook
Candover Brook
The Candover Brook is a 1.2 km 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...
, a tributary of the River Itchen
River Itchen, Hampshire
The River Itchen is a river in Hampshire, England. It flows from mid-Hampshire to join with Southampton Water below the Itchen Bridge in the city of Southampton. The river has a total length of , and is noted as one of England's - if not one of the World's - premier chalk streams for fly fishing,...
in Hampshire
Hampshire
Hampshire is a county on the southern coast of England in the United Kingdom. The county town of Hampshire is Winchester, a historic cathedral city that was once the capital of England. Hampshire is notable for housing the original birthplaces of the Royal Navy, British Army, and Royal Air Force...
. However, it was once found across most of England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
and Wales
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...
.
One of the major reasons for this decline is the introduction
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
of the invasive
Invasive species
"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
n signal crayfish
Signal crayfish
The signal crayfish, Pacifastacus leniusculus, is a North American species of crayfish. It was introduced to Europe in the 1960s to supplement the Scandinavian Astacus astacus fisheries, which were being damaged by crayfish plague, but the imports turned out to be a carrier of that disease...
(Pacifastacus leniusculus). The signal crayfish is a carrier
Asymptomatic carrier
An asymptomatic carrier is a person or other organism that has contracted an infectious disease, but who displays no symptoms. Although unaffected by the disease themselves, carriers can transmit it to others...
of crayfish plague
Crayfish plague
Crayfish plague, Aphanomyces astaci, is a water mould that infects crayfish, most notably the European Astacus which dies within a few weeks of being infected...
, an infectious disease
Infectious disease
Infectious diseases, also known as communicable diseases, contagious diseases or transmissible diseases comprise clinically evident illness resulting from the infection, presence and growth of pathogenic biological agents in an individual host organism...
to which it has resistance
Immunology
Immunology is a broad branch of biomedical science that covers the study of all aspects of the immune system in all organisms. It deals with the physiological functioning of the immune system in states of both health and diseases; malfunctions of the immune system in immunological disorders ; the...
while the native crayfish have none. The British species is also sensitive to many kinds of pollution
Pollution
Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...
, such as insecticide
Insecticide
An insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...
s.