Faxonius limosus
(Spiny-cheek crayfish)

Faxonius limosus (formerly Orconectes limosus) is a crayfish native to the Atlantic watershed of North America. It was introduced to Europe in the 1890s for use in aquaculture, and is considered one of the most invasive crayfish there; it is included in the list of species of Union concern attached to the EU Regulation 1143/2014 on invasive alien species. It is an omnivorous species, feeding on aquatic vegetation, fish eggs and invertebrates, and thus affecting biodiversity. It is a carrier of crayfish plague, lethal for the European native crayfish. It can destabilize riverbanks, and modify other habitats, due to its burrowing behaviour. It can live in a variety of habitats, has a high dispersal capability and can spread both unaided and facilitated (deliberately or accidentally) by humans. As well as Europe, it has also been reported in Morocco. It is known or suspected to have been introduced in parts of its North American range, but it is not considered to be particularly invasive there (and is thought to have been extirpated from West Virginia by F. virilis).

Faxonius limosus is native to the Atlantic watershed of North America, specifically the lower catchment of the River Delaware, the area around Chesapeake Bay (Pennsylvania and Maryland), and possibly also other rivers of this region such as the Susquehanna (Filipová et al., 2011; Alekhnovich and Buřič, 2017). It occurs in Québec, New Brunswick, Vermont, Massachusetts, Rhode Island, New Jersey, New York, Connecticut, Delaware, District of Columbia, Maryland, Pennsylvania and Virginia (IUCN, 2019). Its presence in West Virginia is uncertain -- Swecker et al. (2010) reported its possible extirpation by F. virilis. It has been introduced to New Hampshire and Maine (Hamr, 2002), but is probably also introduced in many of the states mentioned above (Hamr, 2002; Alekhnovich and Buřič, 2017). In Canada it is uncertain whether it was introduced, whether it has spread naturally or whether its presence was underestimated in the past; Hamr, 2002). It is the most introduced crayfish in Europe, where it is reported in 24 territories (Kouba et al., 2014; Trichkova et al., 2015; Govedič, 2017), including Corsica (Kouba et al., 2014) and the UK (Holdich and Black, 2007), and is particularly widespread in Germany, Poland and France. It has also been introduced in Morocco (Holdich et al., 2006).

Notwithstanding that Faxonius limosus is widely recognized as invasive and at least in the European Union is banned by the new regulation on invasive alien species, new findings are reported, because it can spread naturally along rivers and canals, as happened for the recent records in eastern Europe.

Hamr (2002) states that “in North America, the species inhabits soft-bottomed, silty, turbid waters such as found in large rivers, wide streams and lakes with abundant vegetation, although in Canada it has been found occupying stony streams with a moderate current”. In Europe, it occupies a wider range of habitats including cool, fast waters, predominantly occurring in larger watercourses, but preferring lentic, warm, deep waters such as ponds and lakes with shallow bottoms having a layer of sediment (Buřič et al., 2009b), in which it digs burrows (Kouba et al., 2016). It can inhabit water bodies that are organically or inorganically polluted (Holdich et al., 2006). Although it is usually found in lowland waters, in Morocco (North Africa), introduced populations have become established at altitudes between 1400 and 2078 m above sea level (Holdich et al., 2006).

Genetics

Similarly to F. rusticus, Faxonius limosus has been reported to form hybrids with F. propinquus in Canada (Hamr, 2002).

Genetic analyses conducted by Filipová et al. (2011) have shown that all the European stocks of F. limosus originate from the first introduction of 90 specimens in 1890.

Reproductive Biology

A detailed description of the reproductive biology of Faxonius limosus is provided by Hamr (2002). As in other cambarid species, males transfer sperm into the annulus ventralis (a seminal receptacle) of females; males show cyclic dimorphism, alternating between the reproductively active form I and the reproductively inactive form II (Buřič et al., 2010) .The species mates in autumn and spring. In both North America and Europe, reproduction can occur once or twice per year, depending on the area. Females mated in autumn store the sperm until spring (late April or May) in the annulus ventralis; eggs are laid as water temperatures begin to increase (Hamr, 2002; Holdich and Black, 2007). Females can lay from 30 to 440 eggs, which are carried under the abdomen (Hamr, 2002), but the usual range is between 50 and 300 (Alekhnovich and Buřič, 2017). On average, eggs hatch after 40 to 50 days (Hamr, 2002; Kozák et al., 2006). Young crayfish are similar to adults and become free-living and actively feeding at the third development stage (after 10 days). Maturity is usually reached during the second year (15-16 months; Hamr, 2002; Alekhnovich and Buřič, 2017), but some juveniles can mature and reproduce within the first year (Kozák et al., 2007). The size at maturity is 25-35 mm cephalothorax length (Hamr, 2002). Under laboratory conditions, females have been shown to reproduce by facultative parthenogenesis and to store sperm (Buřič et al., 2011, 2013).

Physiology and Phenology

Faxonius limosus is generally considered a tertiary burrower, i.e. it builds burrows only for reproduction or to escape extreme conditions (Thoma, 2015). It has been found to burrow extensively in England but not in other European countries or in North America (Holdich and Black, 2007; Aldridge, 2011). Short burrows have been observed in France (Holdich and Black, 2007) and in the laboratory under drought conditions (Kouba et al., 2016). More complex burrows have been reported in the Czech Republic in soft substrata (Holdich and Black, 2007).

Low temperature is not an obstacle to activity or to mating; Faxonius limosus has been observed to mate regularly mate at 15-16°C, but also at 3-5°C (Holdich and Black, 2007), and even in only a few millimetres of water (Aldridge, 2011).

Longevity

The life span of Faxonius limosus is usually 2-3 years, but it can live for up to 4 years (Hamr, 2002; Alekhnovich and Buřič, 2017).

Activity Patterns

Faxonius limosus is most active from spring to autumn (May to October) at temperatures above 3°C, but it is known to be active under ice in France during the winter (Baldry, 2007), and many have been observed in the UK from November to January (water temperature: 6-7°C; Holdich and Black, 2007). Depending on the environment and period of life cycle, it can be active both by day or by night (Musil et al., 2010), or more during the day (during the breeding season; Buřič et al., 2009a).

Faxonius limosus can move across land (Puky, 2014), even in winter (Holdich and Black, 2007). Males can be more nomadic during the reproductive period, when they are searching for mates, while females may move less when they bear eggs and more after hatching (Buřič et al., 2009a).

Population Size and Structure

In the field, Faxonius limosus occurs in densities of up to 70 individuals/m² in Poland (reviewed in Nyström, 1999), or 16 individuals/m² in Italy and Germany (Pilotto et al., 2008; Hirsch, 2009). It spreads rapidly through contiguous water courses and within lakes. The sex-ratio can vary according to season, habitat and area.

Nutrition

Like other crayfish, Faxonius limosus is omnivorous, feeding on a variety of food items: macroinvertebrates, aquatic plants, fish eggs, and detritus (Hamr, 2002; Alekhnovich and Buřič, 2017). It is a voracious feeder, having high consumption rates (Alekhnovich and Buřič, 2017).

Environmental Requirements

In both the native and the introduced range, Faxonius limosus experiences hot and cold temperature extremes (Aldridge, 2011). However, under laboratory conditions simulating climate change, it reduced its agonistic behaviour at the higher temperature, with the red swamp crayfish Procambarus clarkii outcompeting it (Gherardi et al., 2013). It is tolerant to deoxygenated, eutrophic or polluted water (Holdich and Black, 2007; Alekhnovich and Buřič, 2017). In Austria, it has been reported to reach a high density in a waterbody that is oily and muddy, with other aquatic fauna excluded, indicating low water quality (Pöckl, 1999). It can tolerate drying conditions for many weeks (Laurent, 1988; Holdich et al., 2006). It has been showed to reproduce successfully at salinity values up to 7 ‰ (Jaszczolt and Szaniawska, 2011), with individuals having been found also in brackish waters with salinity of up to 10 ‰.

Predators include several fish, such as carp (Cyprinus carpio), pike (Esox lucius), eel (Anguilla anguilla) or burbot (Lota lota); aquatic birds, such as coots (Fulica spp.), herons or cormorants; or mammals, such as otters (Lutra lutra) or mink (Holdich et al., 2006; Holdich and Black, 2007). Large individuals are not much predated as they usually cross the spinous claws and keep them locked, forming a “spinous ball” which is not easy to swallow (Holdich et al., 2006).

Animal feed, fodder, forage

• Bait/attractant

General

• Pet/aquarium trade
• Research model

Human food and beverage

• Meat/fat/offal/blood/bone (whole, cut, fresh, frozen, canned, cured, processed or smoked)

Traps can be used for surveillance and monitoring of Faxonius limosus, even if they are not always effective when it is at low density. Environmental DNA (eDNA) has been used to successfully detect the species in Europe (Mauvisseau et al., 2018). Citizen science could be promoted to monitor its introduction and spread.

There are more than 60 Faxonius species in North America. The spines on both sides of the carapace and the red-brown bands on the abdomen are characteristics of Faxonius limosus.

Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.

Prevention

Like many other aquatic species, Faxonius limosus is difficult to eradicate once established. A ban on live sales would be an effective means of limiting the risk of its introduction. In Europe, it is indeed included in the list of species of Union concern attached to the EU Regulation 1143/2014 on invasive alien species. Inclusion in the list leads to a complete ban on the species in the European Union.

Early warning systems

Traps can be used for surveillance and monitoring of Faxonius limosus, even if they are not always effective when it is at low density. Environmental DNA (eDNA) has been used to successfully detect the species in Europe (Mauvisseau et al., 2018). Citizen science could be promoted to monitor its introduction and spread.

Public awareness

Campaigns to educate and increase awareness on Faxonius limosus can be effective in curbing illegal introductions, especially if targeted at specific sectors.

Control

Physical/mechanical control

The use of baited traps can reduce the density of Faxonius limosus population. However, juveniles and ovigerous females can be trap-shy and thus less trapped; moreover, the species can burrow, making trapping less effective. Long-term trapping programmes are necessary for effectiveness, and usually mechanical removal should be coupled with another technique. Draining invaded ponds has been suggested as a control method but, due to its burrowing behaviour, even drying out for a considerable time might not result in the complete removal of the species (Holdich and Black, 2007).

Movement control

Beaver dams, hydro dams, flood control weirs and waterfalls can block or at least slow movement of crayfish rather effectively (Gherardi et al., 2011).

Biological control

The use of native predators in combination with intensive trapping has been proved to be effective in other invasive congeneric crayfish (e.g. F. rusticus in the USA: Hein et al., 2007), and could presumably be used for control of Faxonius limosus.

Chemical control

In France, various organophosphate insecticides have been tested on Faxonius limosus from Lake Geneva; fenthion (no longer approved for use in the EU – Pesticide Properties DataBase, 2019) was effective at concentrations much lower than those required to kill finfish, but the toxicity of the biocide lasted several weeks. In field trials, fishes, frogs, mammals, many species of Rotifera, and molluscs were not affected, but insects and other crustaceans were killed with the exception of Copepoda (Laurent, 1995).

Synthetic pyrethroids have been suggested but never tested (Holdich and Black, 2007).

IPM

Management practices can be more effective at the early stage of invasion in a closed system (e.g. a pond). An integrated approach is recommended (Gherardi et al., 2011; Stebbing, 2016; Stebbing et al., 2014).

More research is needed to better assess the physiological tolerance threshold of Faxonius limosus and quantify its ecological impacts (there are many more publications on other invasive crayfish such as F. rusticus, Procambarus clarkii and Pacifastacus leniusculus), to test effective management techniques, and to evaluate the relationship with other invasive crayfish.

Czech Republic: University of South Bohemia in České Budějovice, Faculty of Fisheries and Protection of Waters, Laboratory of Ethology of Fish and Crayfish, Zátiší 728/II, 389 25 Vodňany, , České Budějovice, http://www.frov.jcu.cz/en/about-faculty/institutes/research-institute-fish-culture-hydrobiology/lab-ethology-fish-crayfish2

21/07/19 Original text by:

Elena Tricarico, Dip. Biologia, Università degli Studi di Firenze, Via Madonna del Piano 6, 50019 Sesto Fiorentino (FI), Italy