INVASIVE DECAPODS LOVE THEM or HATE THEM? David Holdich
The intentional or accidental introduction of invasive species is second only to habitat destruction in causing the global loss of biodiversity. Aquatic systems present few barriers to the spread of invasive species once they become established (Cook & Clark, 2004). However, little emphasis has been put on the considerable impact that decapod crustaceans can have on inland waters.
e.g. Global Strategy on Invasive Alien Species. McNeely et al. (2001). IUCN Gland, Switzerland, and Cambridge, UK, in collaboration with the Global Invasive Species Programme. One brief mention of invasive decapods, i.e. crayfish escaping from a London fish market!
Approximately 10,000 species of decapod crustaceans, which include the prawns, shrimps, lobsters, crabs and crayfish. Many have aquacultural or fisheries potential and have been intentionally moved outside of their home range to new countries, e.g. freshwater crayfish. Others have been moved accidentally outside their home range, e.g. crabs in in ballast water. When established, both intentional and accidental introductions often do better in in new environments than at at home, e.g. North American and Asian species in in Europe.
Whether you love invasive decapods or hate them depends on if if you are interested in in them because of the impact they have on the aquatic environment or from a commercial point of view. Positive features of invasive decapods: e.g. actual or potentially valuable crop or aquarium trade species; additional food source for predators such as fish, birds, otters, and gourmets.
Commercial harvesting and preparation of of the red swamp crayfish Large industry in in Louisiana (native), China (introduced) and Spain (introduced)
New export market, e.g. from Spain to to Scandinavia -- much cheaper than native crayfish species
Australian yabbies for dinner in in Switzerland
Mussels + Turkish crayfish + chips in in the South of of France!
Aquariumornamentals trade, e.g. redclaw and marbled crayfish
Coot eating a signal crayfish new food source
Negative features of invasive decapods Out compete native species for resources Invasive r-selected, natives tend to be K-selected Carry diseases Polytrophic Damage to rice crops Damage to banks by burrowing Ability to escape and move overland
Mortalities of of native crayfish caused by by crayfish plague fungus Damage to to river banks caused by by crayfish and crabs
Signal crayfish circumventing a weir and escaping from a container within seconds of of it it being opened
Invasions by decapods into European inland waters have been on two fronts: 1. 1. Estuarine crabs accidentally introduced via ballast tank water, e.g. a. a. Chinese mitten crab, Eriocheir sinensis, from SE Asia to to Germany in in 1912. b. b. Dwarf mud crab, Rhithropanopeus harrisii, from the USA introduced from North America to to the Netherlands in in 1874. Now widespread in in Northern Europe, including the Baltic. Very small and not yet a problem. c. c. Blue crab, Callinectes sapidus, from the USA to to the Netherlands in in 1932. Similar life history to to the Chinese mitten crab. Not yet a problem.
2. 2. Freshwater crayfish intentionally introduced into Western Europe for stocking and aquacultural purposes: Spiny-cheek crayfish: Orconectes limosus (USA-1890) Narrow-clawed crayfish: Astacus leptodactylus (Eastern Europe-late1800s) Signal crayfish: Pacifastacus leniusculus (USA-1960s) Red swamp crayfish: Procambarus clarkii (USA-1970s) Yabby: Cherax destructor (Australia-1983).
Invasive decapods Future threats from crayfish, e.g. e.g. Cherax spp. spp.,, Procambarus spp.and Orconectes spp. spp.
CRABS Reasons for the success of introduced crabs are that they are euryhaline, eurythermal, polytrophic, and some are able to migrate long distances up rivers and move across land.
Crab development involves the production of of thousands of of free-living larvae very different life cycle to to crayfish. e.g. Chinese mitten crab is is catadromous lives in in freshwater but moves to to estuaries to to breed. Larvae develop in in estuary and then young crabs move back up up river, sometimes very long distances.
The Chinese mitten crab supports a $1.25 billion per annum aquacultural industry in in China. Local and international markets are supplied with live animals. At At present there is is not much call for it it as as food in in Europe except amongst immigrant Chinese peoples. Live specimens are sold in in Chinese supermarkets in in some countries. May fetch 18 18 euro/kg in in London in in season. However, there is is some potential --in in 1936 242 tonnes were caught in in Germany alone (4.4 million individuals)!
Eriocheir sinensis --Chinese mitten crab 6 cm carpace length
The King and Queen Chinese mitten crabs worth 21,000 euros!
Chinese mitten crab crab invasion of of Europe (from Herborg et et al., al., 2003, 2005; Karaman & Machino, 2004) 1912 R. R. Weser, Germany 1914 R. R. Elbe, Germany 1927 Baltic via via Kiel Kiel Canal 1927 Austria via via Germany (R. (R. Danube drainage) 1933 Russia and and Finland 1927 Denmark 1930 Northern France 1931 Netherlands most rivers by by 1936 1932 Czech Rep. via via R. R. Elbe (700 (700 km) km) 1932 R. R. Rhine (512 (512 km) km) 1933 Belgium 1934 Poland via via R. R. Oder (446 (446 km) km) 1954 southern France (Atlantic) 1959 --southern France via via canals (504 (504 km) km) 1973-2000s R. R. Thames (SE (SE England), then N and and SW SW 1973 --Yugoslavia 2000s Black Sea Sea and and Sea Sea of of Azov 2002 & 2003 Serbia 2003 Austria (rediscovered)
* * Spread of of Chinese mitten crab in in Europe from 1912
Rate of movement (from Herborg et et al., 2004, 2005) Baltic coast 1928-1935 416 km/yr Northern Europe 1928-1938 --562 km/yr Southern France 1954-1960 380 km/yr English coast: --1976-1999 78 78 km/yr. 1997-1999 448 km/yr English rivers: 1973-1998 16 16 km/yr. 1995 onwards 48 48 km/yr Upstream migration >50-500+ km/yr Downstream migration 11-18 km/yr
Problems caused by by Chinese mitten crabs 1. 1. During their migration downstream to to breed they occur in in considerable numbers (even on on land) and can cause disruption to to human activities, e.g. recreational and commercial fishing, and even transport. 2. 2. They can carry a lung fluke, Parogonimus westermanii, which can affect humans if if the meat is is not cooked properly. 3. 3. They burrow into banks, particularly in in estuaries. For this reason their import is is banned in in the USA. 4. 4. They eat anything they can find. 5. 5. They compete for resources with other aquatic animals and may be be a threat to to freshwater crayfish.
Control of of Chinese mitten crabs in in Europe 1. 1. Trapping during the migration season has been tried with success in in Germany. 2. 2. Commercial exploitation? Likely to to sell for a high price. But would people eat them if if there is is a threat of of disease from the lung fluke? May well be be free from the parasite as as original stocks probably originate from larval or or juvenile stages. Also the climate may be be too cold for the intermediate snail host.
CRAYFISH Prolonged brood care is is one of the keys to the successful colonisation of freshwater habitats by crayfish. Hatchlings are adapted for hanging on to the mother by morphological and behavioural means.
Crayfish larval development encompassed in in the egg young hatch as as miniature crayfish. First two stages attached to to mother. Only 50-500 eggs produced.
Stage 3 juveniles gradually becoming independent of of the mother.
The marbled crayfish or or Marmorkrebs the first known parthenogenetic crayfish. Sexual maturity at at 4 months. Two weeks incubation of of eggs (50-120). Reproduces continuously in in warm water.
The main reason alien crayfish were brought into Europe was to to compensate for native stocks lost from the mid-1800s onwards by by the rapid spread of of a fungal disease, commonly known as as crayfish plague. Crayfish were a very valuable crop and a popular food item in in the 1800s and early 1900s and their loss, particularly of of the noble crayfish, Astacus astacus, was catastrophic for the industry, e.g. exports from Sweden in in 1908 were 90 90 tonnes (out of of 200), but only 30 30 tonnes by by 1910; in in Finland exports declined from 16 16 million individuals in in 1890 to to 2 million by by 1910.
Catch of of noble crayfish from a crayfish farm in in Bavaria The noble crayfish part of of the cultural history of of Europe
These days they are a bit bit harder to to find! Yoichi Machino searching for noble crayfish in in Austria in in 2004.
The systematic spread of of crayfish plague throughout Europe since the 1860s
Spiny-cheek crayfish 1890 USA-Germany. An invasive plague-carrying species (18 countries).
Current distribution and range in in Europe Corsica England Belarus Croatia Ukraine? Serbia
Native narrow-clawed crayfish, Astacus leptodactylus an an invasive species from the east but susceptible to to crayfish plague.
Generalized distribution of of Astacus leptodactyus in in Europe
Signal crayfish Pacifastacus leniusculus 1960s- Sweden. A large, invasive, plague-carrying species (22 countries)
Giant signals!
Spread by by man from Sweden and by by more US imports to to most of of Western Europe in in 1970s and 80s.
Comparison of of a noble and a signal crayfish ecological and gastronomic homologues?
Comparison of of a native white-clawed and an an alien signal crayfish
Alien takeover in in Britain! One native species in in 1970s, but noble, narrow-clawed, signal, red swamp, and spiny-cheek crayfish now also present.
Density of of signal crayfish burrows in in an an English stream. The highest number are at at the introduction site (after Stanton, 2004). It It has taken the signal 17 17 years to to migrate 12 12 km downstream.
Red swamp crayfish, Procambarus clarkii 1970s- Spain. An invasive, plague carrying species (8 (8 countries)
Spread by by man from Spain and through the aquarium and restaurant trades in in Western Europe.
Yabby, Cherax destructor two sites in in Spain, but also cultured in in Italy. Live specimens used in in Swiss restaurants, one specimens found in in the wild.
The future does not look good for native crayfish in in Europe as as they are being eliminated by by alien crayfish, and perhaps crabs, with superior competitive abilities. Alien crayfish from North America carry the crayfish plague fungus, Aphanomyces astaci, to to which all all European crayfish are susceptible. Alien crayfish continue to to spread in in Europe and with them so so does crayfish plague. New alien crayfish are being introduced despite the current legislation.
As a result of of accidental and deliberate introductions decapod diversity in in Europe s inland waters has more than doubled but at at what cost, particularly to to freshwater crayfish? ICS 2005 NICS 2005
Watch out, we re coming to a river near you!
Me too!
ALIEN CRAYFISH ESTABLISHED IN THE WILD IN WESTERN EUROPE +Astacus leptodactylus Eastern Europe/Near East *Orconectes limosus North America *Pacifastacus leniusculus -North America *Procambarus clarkii -North America Also Orconectes immunis North America Orconectes virilis North America *Marbled crayfish Unknown +Cherax destructor Australia?+Cherax quadricarinatus - Australia?Orconectes rusticus North America?*Procambarus cubensis - Cuba *Proven carrier of crayfish plague +Susceptible to crayfish plague?probably not in the wild yet.
Northern or or virile crayfish, Orconectes virilis presently only in in the Netherlands. Also O. O. immunis in in one region of of Germany.
The rusty crayfish, Orconectes rusticus probably the most invasive crayfish!
One night s catch of of Orconectes rusticus in in a newly invaded Canadian lake.
Redclaw, Cherax quadricarinatus cultured in in Italy and Israel. Can overwinter in in coastal ponds in in the Mediterranean.
Redclaw can grow to to a large size --500 g
Irish Cherax sp. turned up up in in the aquarium trade despite strict bans on on imports.
The marbled crayfish or or Marmorkrebs the first known parthenogenetic crayfish. Wild at at one site in in Germany.