Crayfish plague
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Crayfish plague (''Aphanomyces astaci'') is a
water mold Oomycota forms a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms, called oomycetes (). They are filamentous and heterotrophic, and can reproduce both sexually and asexually. Sexual reproduction of an oospore is the result ...
that infects
crayfish Crayfish are freshwater crustaceans belonging to the clade Astacidea, which also contains lobsters. In some locations, they are also known as crawfish, craydids, crawdaddies, crawdads, freshwater lobsters, mountain lobsters, rock lobsters, mu ...
, most notably the European ''
Astacus ''Astacus'' (from the Greek , ', meaning "lobster" or "crayfish") is a genus of crayfish found in Europe and western Asia, comprising three extant (living) species and three extinct fossil species. Due to the crayfish plague, crayfish of thi ...
'' which dies within a few weeks of being infected. When experimentally tested, species from
Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
,
New Guinea New Guinea (; Hiri Motu Hiri Motu, also known as Police Motu, Pidgin Motu, or just Hiri, is a language of Papua New Guinea, which is spoken in surrounding areas of Port Moresby (Capital of Papua New Guinea). It is a simplified version of ...
and
Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...
were also found to be susceptible to the infection.


History

Crayfish plague first arrived in Europe in
Italy Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical re ...
in 1859, either with imported crayfish from North America, or in ballast water discharge. After its original introduction in Italy in 1860, it spread quickly through Europe and was discovered in
Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...
in 1907, in
Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...
in 1972, in
Norway Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and t ...
in 1971, in
Great Britain Great Britain is an island in the North Atlantic Ocean off the northwest coast of continental Europe. With an area of , it is the largest of the British Isles, the largest European island and the ninth-largest island in the world. It is ...
in 1981, in
Turkey Turkey ( tr, Türkiye ), officially the Republic of Türkiye ( tr, Türkiye Cumhuriyeti, links=no ), is a list of transcontinental countries, transcontinental country located mainly on the Anatolia, Anatolian Peninsula in Western Asia, with ...
in 1984 and in
Ireland Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atlantic Ocean, in Northwestern Europe, north-western Europe. It is separated from Great Britain to its east by the North Channel (Grea ...
in 1987. In 1959, to bolster dwindling stocks of native crayfish, the
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 North European ''Astacus astacus'' fisheries, which were being damaged by crayfish plague, but ...
was introduced to
Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...
. The signal crayfish was known to be resistant, and it was not recognised at that time that it was a carrier of the disease. After 150 years of contact, no resistance has been discovered in native European crayfish. This species was studied and named by the German Mycologist Friedrich Schikora (1859–1932), from a type specimen in Germany in 1906.


Transmission

Transport of signal crayfish, red swamp crayfish and infected native European freshwater crayfish between waters is the main cause of contamination, though the disease can also be spread via items that have been in contact with contaminated water, such as a
fishing tackle Fishing tackle is the equipment used by anglers when fishing. Almost any equipment or gear used in fishing can be called fishing tackle, examples being hooks, lines, baits/ lures, rods, reels, floats, sinkers/ feeders, nets, stringers/ k ...
or footwear. The spores are sensitive to high or low temperatures. Most authorities have local rules and regulations to minimize the movement of water between different waterbodies (in for example a boat), and recommend that crayfish used as bait should come from the same water as that being fished, or should be frozen to at least for one day before use, if there is a risk of contamination. The spores of crayfish plague disappear from an infected water system (connected lakes and rivers) within a few weeks once the last infected crayfish is removed. Reintroduction is then possible, as long as no infected waters are in contact with the lake.


Signs

Infection with ''Aphanomyces astaci'' is accompanied by few signs in its early stages, and the first indication of infection may be mortality. In the later stages, the muscles of the tail may appear whitened, or brownish-red where blood cells have encapsulated the hyphae. The effects of the neurotoxins in the
oomycete Oomycota forms a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms, called oomycetes (). They are filamentous and heterotrophic, and can reproduce both sexually and asexually. Sexual reproduction of an oospore is the resul ...
can include appearing in daytime (crayfish are typically nocturnal) and a lack of coordination.


References


External links

*
Global Invasive Species Database
{{Taxonbar, from=Q2858203, from2=Q602370 Saprolegniales Diseases and parasites of crustaceans Crayfish Species described in 1906