CARCINUS MAENAS - GREEN CRAB

The green crab is native to the Atlantic coasts of Europe and northern Africa and lives in rocky shores and tidal marshes. It was first detected on the east coast in the late 1800s in Long Island Sound. On the west coast it was first detected in 1989 in San Francisco Bay. The green crab was probably introduced by either ballast water or by discarding seaweed used as packing material for shipping live shellfish. It is now well established on both coasts. Adults are about 2.5 inches long and females can lay up to 200,000 eggs per year. This species prefers a salinity range from 5-30 ppt, and a temperature range from 5-30 ^oC. Given this, the green crab could potentially spread from Baja California to Alaska. It is omnivorous and opportunistic, eating plants insects, clams, oysters, worms, snails chitons, urchins, fish and other crabs. There is much concern that it could impact the important mussel, oyster, and Dungeness crab fisheries in Oregon and Washington. It has been suggested the green crab is to blame for wiping out the soft-shell clam industry on the east coast in the early 1950s. The green crab is also an intermediate host of the acanthocephalan worm, Profilicollis botulus, which causes mortalities in ducks. Controlling the spread has begun on the West Coast by making it illegal to possess or transport any live green crabs in Washington, and, there is a prohibition on the transfer of shellfish from infested waters. Biological controls are being proposed, a egg predator and a parasitic barnacle that inhibits molting and causes sterilization in females.

ERIOCHEIR SINENSIS - CHINESE MITTEN CRAB

Eriocheir sinensis is identifiable by the mass of hairs on the pincers, hence, the name mitten crab. The first reported occurrence was in the Detroit River in 1965 by the city of Windsor. Later, in 1973, commercial fishermen netted several crabs in Lake Erie near Erieau and Port Stanley, Ontario, Canada (Nepszy and Leach, 1973). On the west coast, it was first reported from San Francisco Bay in 1991. Over the past several years, it has spread into the Delta region of California causing problems due the numbers of crabs at water pumping facilities. It is native to temperate climates in Asia from Korea to southeast China, and probably arrived in North America in ballast water. Mitten crabs spend most of their time in fresh water but move to brackish water to reproduce (at least 26 ppt). Their primary food is aquatic vegetation, but will also feed on mollusks, fish, and other crabs. Mature adults are 38-50 mm in carapace width. A female can lay up to 1 million eggs in a one event. One effect of the mitten crab could be the collapse of support structures following successive years of mitten crab burrowing (Ingle, 1986). In the Far East, mitten crabs are an intermediate hosts of lungflukes, Paragonimus ringeri, which occur in humans (Ingle, 1986)

DAPHNIA LUMHOLTZI - LUMHOLTZI

The native range of  Daphnia lumholtzi are freshwater lakes of east Africa, southwest Asia, and east Australia (Havel 1993). It was first reported in Stockton Lake in southwest Missouri in 1991 and can be found in 13 states from Illinois and Ohio down to Texas across to North Carolina and south to Florida. D. lumholtzi has spread much faster than another zooplankton invader, Bythotrephes cederstroemi, for reasons unknown. The method of introduction is uncertain. But, coincidentally, one of its first appearances was a lake in Texas where the Nile perch was first introduced to North America (Havel 1993). It is well established in the U.S. Effects or impacts are yet unknown.

BYTHOTREPHES CEDERSTROEMI - SPINY WATER FLEA

The native range of Bythotrephes cederstroemi is the northern and central Palearctic (northern Europe to Caspian Sea). It may be a ballast water introduction but it is not known for certain since most ocean-going ships do not carry fresh water in ballast. It was first detected in North America in 1984 in Lake Huron (Bur et al.1986). The next year it was found in Lakes Ontario and Erie and then in Lake Michigan in 1986 and finally Lake Superior in 1987. It is established in all Great Lakes. More recently it has been found in several small lakes in Minnesota and in more than a dozen lakes in Ontario, Canada during this decade. Researchers suspect Bythotrephes cederstroemi could be responsible for the decline of 3 daphnia species in Lake Michigan (Lehman 1991).

PROCAMBARUS CLARKII -  RED SWAMP CRAWFISH

The red swamp crawfish is native to fresh waters from northern Mexico to the Florida panhandle and north to southern Illinois and Ohio (Hobbs 1989). This crayfish has been accidentally and deliberately introduced well outside its range in the Americas and in Africa and Asia (Fitzpatrick 1983). In the United States, it has been introduced into at least 15 states (Hobbs 1989). This species and one other, the white river crawfish (P. acutus), are the cultured crawfish in "Cajun" crawfish dishes. Together the two species comprise over 90% of the crawfish produced in the U.S. Both species are very similar.  The way to distinguish the two species is the presence of a blue vein under the tail of the red swamp crawfish; it is absent in the white river crawfish. In California, wild populations of the red swamp crawfish eat rice crops (Pennak 1989). They have also been found to prey on California newts (Taricha torosa) and may be responsible for their decline in some areas (Gamradt and Kats 1996).

ORCONECTES RUSTICUS -  RUSTY CRAYFISH

The rusty crayfish is native to western Ohio, eastern Indiana, and Kentucky. It has become established in 17 states outside of its native range, primarily through bait release by anglers. Contrary to some reports, it is not present in Missouri or central Tennessee (C. Taylor, personal communication). Rusty crayfish often displace native crayfish including O. propinquus, O. virilis, and O. sanborni, reduce the amount and kinds of aquatic plants and invertebrates, and reduce some fish populations (Gunderson 1995).  In Wisconsin, where the rusty crayfish has been introduced, it is hybridizing with the blue crayfish (O. propinquus), another introduced species. The resulting hybrids are outcompeting both parental species for both food and shelter (Roush 1997).  It has been estimated that rusty crayfish may consume twice as much food as the native virile crayfish, O. virilis (Momot 1992). This crayfish may affect fish populations by competing with juvenile fish for food and by preying on fish eggs (Gunderson 1995).

ORCONECTES VIRILIS - VIRILE CRAYFISH

The virile crayfish is native from Saskatchewan to Ontario, Canada, and from Montana and Utah to Arkansas, New York, and possibly southwestern Maine. It has been introduced into 17 states outside its native range. As with most crayfish, the introductions are a result of bait-bucket release. This species is also commonly sold by biological supply houses and could be dispersed this way as well. In California, the virile crayfish may be responsible for the decline of native Shasta crayfish (Pacifastacus fortis). O. virilis was introduced into California in the early 1960s from east of the Continental Divide. It has a higher fecundity and more rapid growth rate than the native Shasta crayfish. The virile crayfish matures at one year and produces up to 443 eggs while the Shasta crayfish matures at 4 years and produces 10-70 eggs. As a result, the virile crayfish is replacing the native species (Light et al. 1995).  Introductions of this species have also displaced native crayfish species in the Patapsco River, Maryland (Schwartz et al. 1963).

PENAEUS MONODON -  ASIAN TIGER SHRIMP

The Asian tiger shrimp is native to southeast Asia, the Philippines, and Australia. These shrimp attain a fairly large size (26.5 cm), making them a popular aquaculture species. In 1988, an unknown number of the 200,000 shrimp being held at an aquaculture facility in Bluffton, South Carolina escaped into a tributary that drains into the Atlantic Ocean. Approximately 1,000 adult shrimp were later captured. Since then, they have been reported in waters off South Carolina south through Georgia, to Cape Canaveral, Florida. An estimation of the population size in the wild is unknown. This species has been experimentally grown for aquaculture in Hawaii and has escaped there as well.