Faxonius rusticus

Invasion History

First Non-native North American Tidal Record: 1996
First Non-native West Coast Tidal Record:
First Non-native East/Gulf Coast Tidal Record: 1996

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General Invasion History:

Faxonius rusticus is native to the Ohio drainage in Ohio, Indiana, and Kentucky, with populations extending into West Virginia, Tennessee, and possibly the western end of the Lake Erie basin. It has been introduced to at least 20 US states, and Ontario and New Brunswick in Canada (Taylor et al. 1996; Taylor and Redmer 1996; USGS Nonindigenous Aquatic Species Program 2017). Introductions are concentrated in the Northeast and Midwest, but populations are known from New Mexico, Colorado, Nevada, and Oregon (Hobbs and Jass 1988; Taylor et al. 1996). Faxonus rusticus has been widely introduced with bait, and probably also from the release of laboratory animals. Its range has rapidly expanded due to a mixture of natural dispersal, aggressive displacement of other species, and human introductions (Hobbs and Jass 1988; Hobbs et al. 1989).

Within the Mississippi-Ohio basin, F. rusticus has drastically expanded its range since it was first introduced in 1932 (Hobbs et al. 1989). It was first recorded from Illinois in 1973, and is now widespread in the Illinois River system in the northern part of the state (Taylor and Redmer 1996). In the Ohio Basin, it expanded into the Kanwaha River and tributaries in southwestern West Virginia by 1978 (Jezerinac et al. 1995). In Wisconsin, it was not recorded in 1932, but it became widespread by the 1960's. Elsewhere in the Mississippi drainage, O. rusticus has invaded streams in Tennessee, Missouri, Indiana, Iowa, and Minnesota (Hobbs and Jass 1988).

In the Great Lakes basin, F. rusticus may have been present in the low country at the western end of Lake Erie in the early 19th century, but did not become widespread around the lake until the 1960's (Perry et al. 2002; USGS Nonindigenous Aquatic Species Program 2017). It is found in many of the streams on the southwest (Wisconsin) shore of Lake Superior (Hobbs and Jass 1988). It was first recorded in Lake-of-the-Woods, Ontario, in 1964, and on the northwest shore of Lake Superior in 1985, and is now widespread (Momot 1992; Momot 1996). By 1988, F. rusticus was established on the Bruce Peninsula between Lakes Erie and Ontario (Corey 1988). The distribution of this crayfish in the Great Lakes region, as mapped by Hobbs and Jass (1988) is spotty and suggests that dispersal to inland lakes and streams by bait and other means has been more important than movement through the open waters of the Great Lakes.

North American Invasion History:

Invasion History on the East Coast:

In Atlantic drainages, the distribution of Faxonius rusticus has also been spotty. It has been introduced to scattered ponds in the Kennebec and Androscoggin River drainages in Maine, and the Connecticut River drainage in Vermont, New Hampshire, and Massachusetts (Crocker 1979; Smith 1997; USGS Nonindigenous Aquatic Species Program 2017). In the Hudson River, it was first collected in an artificial pond in Schenectady County, New York in 1968 (Crocker 1979), and is also present in the Titicus River, New York and Connecticut; and in the freshwater tidal Hudson River near Haverstraw, New York (Mills et al. 1997; USGS Nonindigenous Aquatic Species Program 2017).

In the Chesapeake Bay drainage, Faxonius rusticus was first collected in 1976 in the Susquehanna River, Dauphin County, Pennsylvania (United States National Museum of Natural History collections). According to the collector's notes, F. rusticus was found through much of the river south to the Fall Line (in the vicinity of Conowingo Dam, Maryland). Based on experiences elsewhere, F. rusticus was expected to invade the lower Susquehanna and other Chesapeake tributaries, eventually (Norden 1995, personal communication). In 2007, O. rusticus was found by Maryland Department of Natural Resources (MDNR) personnel in Conowingo Creek, Cecil County, a Susquehanna tributary about 10 km above Conowingo Dam, and about 15 km above tidewater. From 2016 through 2012,

Faxonius. rusticus spread to Upper Bay drainages, including the Gunpowder and Patapsco Rivers (Pelton 2007; Kilian 2010; USGS Nonindigenous Aquatic Species Database 2017). In June 2007, F. rusticus was found in the Monocacy River, Frederick County, Maryland, by MDNR personnel (Kilian 2010). It has spread into the tidal region of the Potomac drainage, reaching Mattawoman Creek, Mallows Bay, and Nanjemoy Creek in Charles County, between 2006 and 2011 (USGS Nonindigenous Aquatic Species Database 2017). Faxonius rusticus has now colonized many drainages on the Eastern Shore of the Bay, including the tidal Little Blackwater River, and branches of the Pocomoke, Nanticoke, Choptank, and Chester Rivers, and freshwater tributaries of Chincoteague Bay (USGS Nonindigenous Aquatic Species Database 2017). The rapid spread of this crayfish among Bay tributaries suggest an ability to disperse through brackish water.

Invasion History Elsewhere in the World:

In 2021, this crayfish was collected in southern France, where it is considered a possible competitor and predator, and a vector for the crayfish plague )Aphanomyces astaci). (Laffitte et al. 2021).

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Description

The Rusty Crayfish (Faxonius rusticus) has a smooth ovoid carapace with a rostrum which is longer than it is wide, with concave margins, and a deep cervical groove. There are no spines in the hepatic (cheek) region, but distinct generally short cervical and branchiostegal spines are present. The antennal scale is 2.3 times as long as it is broad, and tapering distally. The claw (chela) is dotted with small bumps (punctate), and is about 2.3 longer than it is wide, with tubercles along the inner margin of the finger and palm. The carpus of the cheliped is moderately cleft. In first-form (reproductive) males, the first pleopods end in two curved terminal elements. The outer branches of the first pleopods are corneous (hardened) and the 3rd segments (ischia) of the 3rd pair of walking legs bears copulatory hooks. In the female, the annulus ventralis (seminal receptacle) is a rhombus-like structure, which is 1.5 X as wide as long, with a deep depression in the center, located between the 4th and 5th walking legs.

The carapace length can reach 45 mm in males and 44.5 mm in females, but averages to 32.0 and 29.7, respectively. The carapace is mostly rusty-brown, fading to cream-colored on ventral surfaces of the branchiostegal and hepatic regions. The dorsal surface of the thorax is dark reddish-brown or gray. The cheliped (claw-leg) is grayish green, pink, or light reddish brown, often mottled with splotches of dark brown. The tips of the 'fingers' are usually red, with subterminal black bands (Hobbs and Jass 1988; Jezerinac et al. 1995).

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Taxonomy

Ecology

General:

Ecology: Faxonius rusticus inhabits streams, ponds and lakes in a variety of habitats, including rocky, muddy, and vegetated areas. Burrowing has been observed in parts of its range, but in Wisconsin, it made only shallow excavations (Hobbs and Jass 1989). The extent to which this crayfish inhabits tidal fresh or brackish estuaries is unclear, though it does tolerate brackish water up to at least 15 PSU (Bazer et al. 2016). In the lower Potomac River, it has been found in areas which can experience oligohaline to mesohaline salinities (USGS Nonindigenous Aquatic Species Program 2017).

Food:

aquatic plants, worms, snails, bivalves, carrion

Consumers:

fishes, turtles, snakes, birds, raccoons, otters

Competitors:

Other crayfish species

Trophic Status:

Omnivore

Omni

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Habitats

General Habitat	Fresh (nontidal) Marsh	None
General Habitat	Grass Bed	None
General Habitat	Coarse Woody Debris	None
General Habitat	Swamp	None
General Habitat	Nontidal Freshwater	None
General Habitat	Tidal Fresh Marsh	None
General Habitat	Unstructured Bottom	None
General Habitat	Rocky	None
Salinity Range	Limnetic	0-0.5 PSU
Salinity Range	Oligohaline	0.5-5 PSU
Tidal Range	Subtidal	None
Vertical Habitat	Epibenthic	None

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Life History

Life History: Freshwater crayfish of the family Cambaridae, mate by internal fertilization, with the male inserting pleopods into the females seminal (annulus ventralis) which is between the 4th and 5th walking legs. The female curls her abdomen far forward, to create a chamber in which the eggs are driven by the pleopods. The mass of eggs becomes attached under the tail. Larval development takes place inside the egg and the young hatch as miniature adults (Barnes 1983).

Male cambarid crayfish show sharp morphological changes with season. At the start of the breeding season, they molt into a sexually competent stage (Form I), marked by lengthening and stiffening of the modified 1st pleopods, with more pronounced ischial spines (in the basal segments of the 3rd walking leg, and enlarged chelipeds). After breeding, the crayfish molts back into Form II, with the 1st pleopods less differentiated and soft, the ischial spines are reduced, and the chelipeds are less robust (Hobbs 1991).

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Tolerances and Life History Parameters

Minimum Temperature (ºC)	6	1-8.5 C (Westhoff and Rosenberger 2016)
Maximum Temperature (ºC)	38.5	Critical Temperature Maximim, with acclimation (Clauusen 1980; Westhoff and Rosenberger 2016)
Minimum Salinity (‰)	0	This is a freshwater organism
Maximum Salinity (‰)	15	Experimental 80% survival, 17 % survival at 30 PSU (Bazer et al.(2016)
Minimum Length (mm)	14	Carapace Size (Hobbs and Jass 1988)
Maximum Length (mm)	49	49, male carapace size; 44.5 female carapace size;(Hobbs and Jass 1988)
Broad Temperature Range	None	Cold temperate-Warm temperate
Broad Salinity Range	None	Limnetic-Oligohaline

General Impacts

Faxonius rusticus has had ecological impacts in lakes and streams, mostly in the Great Lakes basin, where it has invaded, damaging aquatic vegetation, competing with native crayfishes, and preying on snails (Capelli 1982; Corey 1988; Lodge et al. 1994; Gunderson 1995; Taylor and Redmer 1996; Perry et al. 2002). Impacts of Rusty Crayfish have not yet been studied in Chesapeake Bay tributaries or the Hudson River estuary, but this crayfish is now widespread in the Chesapeake watershed (USGS Nonindigenous Aquatic Species Program 2017).

Economic Impacts

In North America, crayfish of the genus Faxonius have, at present, only minor economic importance. They are harvested for biological supply houses to be sold for research and teaching. Only a small quantity is sold for human consumption, mainly in the state of Wisconsin (Momot 1989). However, they are widely sold and used as bait (Hobbs and Jass 1988; Kilian et al. 2010). In the Great Lakes and upper Mississippi valley, invasions of F, rusticus (Rusty Crayfish) have resulted in replacement of native species with an aggressive invader, which is a more efficient predator and herbivore, and better at avoiding predators than native species (Garvey et al. 1993; Lodge et al. 1994; Lodge et al. 1998). Its ability to destroy macrophytes has negative impacts on fisherman and hunters by removing refuges for fishes and invertebrates, increasing currents and erosion, and removing food for waterfowl (Gunderson 1995). There are some anecdotal observations that F. rusticus invasions might decrease abundances of some fishes, either by removal of submerged vegetation [Esox lucius (Northern Pike); Lepomis macrochirus (Bluegill); Micropterus salmoides (Largemouth Bass)] or perhaps by being less available to predators [M. salmoides (Largemouth Bass)] (Gunderson 1995). Dense populations of Faxonius rusticus in WI lakes have discouraged swimming in some locations by pinching people's toes (Gunderson 1995). Because of the widespread ecological impacts of F. rusticus, Wisconsin and Minnesota have passed legislation prohibiting the sale of live crayfish (Gunderson 1995).

Ecological Impacts

Competition- Invasions of river systems and lakes by Orconectes rusticus (Rusty Crayfish) are often associated with a decline or disappearance of native crayfish species. In Ohio, O. rusticus has replaced O. sanborni in central and west-central Ohio (Butler and Stein 1985). In northern Illinois, northern Wisconsin, the northwest shore of Lake Superior, Ontario, and in eastern Ontario, O. rusticus has largely replaced O. propinquus (introduced in Wisconsin, native in Illinois and Ontario) and O. virilis (native in all regions) (Capelli 1982; Corey 1988; Momot 1996; Taylor and Redmer 1996). Burrowing crayfish of the genera Cambarus and Procambarus are not mentioned as having been displaced by O. rusticus invasions (Capelli 1982; Hobbs et al. 1989).

Species replacements by F. rusticus appear to involve a diversity of mechanisms, including aggressive behavioral competition for resources, earlier recruitment than many competitors, higher fecundity, faster juvenile growth, interference with mating, wider habitat preferences, differential vulnerability to predators, etc. (Butler and Stein 1985; Corey 1988; Hobbs et al. 1989; Hazlett et al. 1992; Mather and Stein 1993; Garvey et al. 1994; Hill and Lodge 1994). In laboratory and field studies, F. rusticus tended to dominate OF propinquus and F. virilis, resulting in reduced movement and foraging by the latter species (Garvey et al. 1994; Hazlett et al. 1992). Faxonius rusticus tended to mate inappropriately with F. sanborni, decreasing reproductive output of both species, but favoring F. rusticus because of its superior reproductive characteristics (Butler and Stein 1985).

Habitat Change -  Faxonius rusticus feeds extensively on macrophytes and periphyton, and can greatly reduce submerged vegetation, but it can also indirectly favor the growth of periphyton by predation on snails and other macroinvertebrates (Charlebois and Lamberti 1996; Lodge et al. 1994). These effects have been demonstrated in experimental ponds, lake enclosure-exclosure experiments, and whole lake experiments (Lodge et al. 1994; Lodge et al. 1998). Other crayfishes are also omnivorous, and can have similar foodweb effects (e.g., F. virilis, Hanson and Chambers 1995). However, replacement of other Faxonius species by F. rusticus may alter foodwebs because F. rusticus, with its larger adult size, more rapid growth, higher mass-specific ingestion rates of snails, and lower vulnerability to fish predation, may have a quantitatively greater impact (Lodge et al. 1994). By controlling types of plant communities, F. rusticus has the potential to affect food supplies and the structural environment for fishes and invertebrates, including refuges, sediment stability, current speed, erosion, etc. (Gunderson 1995).

Predation - Faxonius rusticus is an omnivore, and eats a wide variety of animal prey (Hobbs and Jass 1988). Its predation on snails has been studied in particular detail. In enclosure-exclosure experiments, densities of F. rusticus affected abundance, species composition, and species richness of snails. Of 11 snail species, O. rusticus preferred Physella sp. and Helisoma anceps. Other macroinvertebrates were not significantly effected by F. rusticus density (Lodge et al. 1994). Snail abundance was also related to F. rusticus density in lakes (Lodge et al. 1998). Other crayfish also consume mollusks, but replacement of other species by F. rusticus may result in increased rates of predation due to F. rusticus' higher metabolic rate and competitive life history characteristics (Lodge et al. 1994). In enclosure-exclosure experiments in a stream where snails were rare, F. rusticus abundance resulted in reduced invertebrate (mainly insect larvae), through direct predation, as well as through consumption of periphyton (Charlebois and Lamberti 1996).

Herbivory - Faxonius rusticus has long been known to affect lakes by consumption, and often elimination of beds of submerged vegetation (Hobbs et al. 1989). In enclosure-exclosure experiments, plant biomass was about 9X higher in enclosure treatments, and 12 species were present, compared to 3 species in enclosure treatments. Effects of herbivory did not differ greatly among species (Lodge et al. 1994). In a stream, F. rusticus was found to be a major consumer of periphyton (largely Cladophora), but did not affect periphyton biomass, apparently because of its removal of grazing microinvertebrates, and because foraging crayfish remove debris and detritus from the periphyton, exposing algae to increased light. In enclosures with high densities of F. rusticus, chlorophyll content of periphyton was higher (Charlebois and Lamberti 1996).

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