If compared with the congeneric Procambarus clarkii, P. acutus acutus’ biology and ecology is understudied, notwithstanding its relatively wide range of distribution across the USA. It is excluded from the available alert lists but,...
If compared with the congeneric Procambarus clarkii, P. acutus acutus’ biology and ecology is understudied, notwithstanding its relatively wide range of distribution across the USA. It is excluded from the available alert lists but, using the FI-ISK tool (http://www.cefas.co.uk/4200.aspx), it has been classified as a high-risk species (Tricarico et al., 2009). Published studies have mostly focused on cultivated populations and have been conducted in the laboratory or in artificial ponds. No information is available about the ecology of natural populations. As a consequence, the environmental impacts of the introduced populations in California, Kentucky, and New England are unknown and may be only inferred from its biological similarity with P. clarkii. P. acutus acutus, being an r-selected species and a generalist/opportunistic feeder, is expected to exercise a strong impact on communities and ecosystems. Its ability to reduce native crayfish diversity might be high. In fact, it is a vector of parasites and diseases, and is likely dominant over other species in the competition for the access of vital resources, such as shelter and food.
The taxonomic status of the so-called “white river crayfish” is confusing. According to Dr Horton H. Hobbs Jr., Procambarus acutus is a species complex (Hobbs, 1989). The species previously identified as P. acutus acutus in the coastal plains of Texas, Louisiana, Mississippi and Alabama in the 1970s and 1980s (as reported by Huner, 1988) was classified by Hobbs and Hobbs (1990) as a new species, Procambarus zonangulus (southern white river crayfish). The name of P. acutus acutus continues to apply to the “eastern white river crayfish” occurring naturally and being cultured eastwards from Louisiana to the Atlantic coast northward to Maine. The Mexican Procambarus (Ortmannicus) a. cuevachicae (synonym: Procambarus blandingii cuevachicae) has been designated as another subspecies of P.acutus (Hobbs, 1967). The extensive translocation of P. acutus acutus for aquaculture purposes and live fish bait makes the native distribution of the “white river crayfish” confusing. To make the matter worse, there are other species, all very similar in physical appearance, that are referred to as “white river crayfish” in the south-central USA, such as Procambarus neuches (Huner, 2002).
If not otherwise specified, the present datasheet will deal with the eastern white river crayfish, P. acutus acutus. The original description of the species was provided by Girard (1852) under the scientific name of Cambarus acutus. The type locality is a tributary to Tombigbee River of Mobile River, Kemper County, Mississippi. However, the type was lost in a Chicago fire, in 1871. In 1967, Hobbs designated the species as Procambarus acutus acutus.
General description: Rostrum acuminate; cervical spine present; areola narrow with about 2-3 punctations in narrowest part; chela elongate, punctate, with row of prominent tubercles along mesial margin of palm; male first pleopod terminating in 4 elements, all directed caudodistally, distal part not tapered, bearing tuft of subapical setae on distinct, cephalodistally situated knob near base of cephalic process; hooks on ischia of male 3rd and 4th pereiopods. [Total length to 110 mm; width to 20 mm; weight to 80 g].
Diagnostic characteristics: Male with hooks on ischia of 3rd and 4th pereopods; first pleopod with tuft of subapical setae borne on distinct knob situated laterodistally near base of cephalic process.
Form I (i.e. reproductive) adult males have a colour pattern that is off-white to tan laterally becoming brownish with age, or dark to black dorsally becoming purplish with age. Juveniles and Form II males are off-white to tan, with true juveniles often exhibiting many black specks on the body surface.
In culture ponds in South Carolina, P. acutus acutus can grow to significant size, with Form I males reaching higher weight than either females or Form II males of the same length, probably due to the accelerated development of the chelae in males with sexual maturity, whereas chelae of females remain isometric throughout life (Mazlum et al., 2007). Under aquaculture conditions, growth is fastest in autumn and spring (mean water temperature: 17.5°C), and lowest in winter (mean water temperature: 7.3°C).
Complete and accurate range of distribution is lacking because of the still existing taxonomic confusion between the eastern and the southern white river crayfish. P. acutus acutus’ natural range encompasses more than half of the US, being widely distributed and tolerant of a great range of habitats although not found locally in abundance. In the Cumberland Plateau it occurs in tributaries of the Tennessee River eastward to Sequatchie Valley in Alabama and lower tributaries of the Black Warrior and probably Sipsey (Tombigbee basin) River systems (Bouchard, 1974). Hobbs et al. (1976) documented it in the Savannah River Plant Park (on the Savannah River) in southwest South Carolina. In Alabama, it is known from all river systems in the state with the exception of the Cahaba, Tallapoosa, Perdido, and Chattahootchee River systems (Mirarchi et al., 2004; Schuster and Taylor, 2004; Schuster et al., 2008). In Kentucky, it occurs commonly in most aquatic habitats west of the lower Cumberland River and sporadically in the middle and lower Green River drainage; and is also known from several probably introduced populations, including the Pond Creek drainage in Jefferson County, from ponds in the Bluegrass Army Depot and Central Kentucky Wildlife Management Area in Madison County, and Minor Clark Fish State Hatchery in Rowan County (Taylor and Schuster, 2004). In Missouri, it occurs throughout the Lowland Faunal Region, penetrating a short distance into the adjacent Ozarks, and northward along the Mississippi River flood plain to Clark County; with isolated populations along the Chariton River in Schuyler County and the Grand River in Livingston County (Pflieger, 1996). In Kansas, it occurs in one locality in Cherokee County (Ghedotti, 1998). In Ohio it is believed to have entered in the northwest corner postglacially by migrating across swampy glacial plains and it is now well documented in the northwest portion of the state and is likely throughout the Maumee, Portage and Sandusky basins as well as the Grand River (Thoma and Jezerinac, 2000). In Indiana, it is limited to lowland streams in the Patoka River drainage in Pike and Dubois counties (Simon et al., 2005). This species was recently added to the fauna of West Virginia based on six specimens collected east of Point Pleasant, Mason County in vernal pools (Loughman, 2007). Recently it was found at several sites in the Catawba River and tributaries in North Carolina and extending into South Carolina to the Wateree drainage (Alderman, 2005). In South Carolina, it occurs throughout much of the coastal plain and piedmont (Eversole and Jones, 2004). It has been introduced into southern New England but it is restricted to an area extending from the Blackstone River drainage system eastward through all the southeastern coastal drainage systems, including Cape Cod but not north of the Charles River basin; with populations outside this range in the Spicket River in Methuen (Merrimack River drainage), a few tributaries in the Northampton and Amherst vicinity (Connecticut River drainage), and the Millers River in Ashburnham (Connecticut River drainage); all in Massachusetts (Smith, 2000).
Outside the USA, it is known from the River Nile in Egypt, where it co-occurs with P. clarkii (Ibrahim et al., 1997), and from the Netherlands, where it has been present since 2005 (Soes and van Eekelen, 2006). However, whether these latter populations belong to P. acutus or P. zonangulus is unknown.
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
There is no reason to suspect that it could not become successfully established outside the USA. This may occur as bulk shipments of Procambarus spp. are made to areas where attempts are being made to develop crayfish aquaculture. We only know about the attempt to introduce the white river crayfish (possibly, P. zonangulus) into the rice fields of Lower Gauadalquivir in the province of Seville (Spain), together with P. clarkii. For unknown reasons, the white river crayfish did not prosper whereas P. clarkii did so (Gutiérrez-Yurrita et al., 1999). On the contrary, the introduction of P. acutus (or P. zonangulus) in Egypt and in the Netherlands was successful.
P. acutus acutus is widely tolerant in most lentic situations and in sluggish streams. In Missouri, it is most often found in sloughs, marshes, and natural lakes along the flood plains of streams (70% from standing water, 19% from ditches, 11% from small to medium sized streams, 0% from open channels of rivers) (Pflieger, 1996). In West Virginia, it is found in ephemeral wetland habitats whereas in Illinois it was collected primarily from sluggish streams (Loughman, 2007).
The species constructs simple shallow burrows, to which crayfish of all sizes, whether mature or immature, male or female, retreat to reproduce and survive temporary dry periods, occupying them for 3-4 months or more (Huner and Barr, 1991). Crayfish may use atmospheric oxygen to breathe, provided gills remain moist. Burrows consist of simple vertical shafts 30–40 cm deep ending in an enlarged cul-de-sac. Five 15 cm-high chimneys may be present at the entrances of burrows.
P. acutus acutus is relatively short-lived (2 years or less), have relatively high juvenile survival rates, and, at least the males, can alternate between sexually active (Form I) and inactive forms (Form II).
As all the arthropods, crayfish moult to increase in size, growth rate being affected by many factors, including water temperature, population density, dissolved oxygen levels, food quality and quantity, and genetic influences; however, environmental factors have the most influence on growth rate. After growing and attaining sexual maturity, both males and females stop growing.
Contrary to P. clarkii that mates more than once during the year when environmental conditions are favourable, P. acutus acutus is a seasonal spawner. It has one reproductive period, restricted to the dry-phase, that produces a single annual cohort. Fastest year-on-year growth for P. acutus acutus occurs in autumn (November–December) and spring (April–May) and the slowest growth occurs in winter (December–January) and during the harvest season (May–June).
Mature animals mate in open water in autumn and early winter; the sperm, packaged into spermatophores, are stored in a seminal receptacle (annulus ventralis) on the underside of the female. The female may mate with more than one male and eventually retreats to the burrow to spawn with a peak in autumn. The burrow provides protection while the eggs and offspring are attached to the abdomen. Although crayfish can survive in a very humid environment within the burrow, they must have free-standing water for spawning. Spawning consists of expelling large, dark eggs through the oviducts; eggs are fertilized externally with the sperm released from the spermatophores stored in the seminal receptacle, and then remain attached to the pleopods under the abdomen with an adhesive substance called glair. The incubation period is temperature dependent and it takes about 3 weeks for eggs to hatch at 23°C. Hatchling crayfish remain attached to the female’s pleopods through two moults, after which they closely resemble adults in appearance. Hatchlings quickly become separated from the female and disperse as she moves about in open water.
In a laboratory study by Mazlum and Eversole (2004), P. acutus acutus extruded and attached over 95% of the ovarian eggs. Pleopodal egg number per female increases linearly with the female total length but also with her nutritional status (Mazlum, 2005). The number of pleopodal eggs varies from 106 to 556 for 81 and 127 mm total length of the females in simulated burrows and from 32 to 330 eggs for 65 mm and 125 mm total length females in excavated pond burrows, respectively (Mazlum, 2005).
Nutrition
Little is known about P. acutus acutus’ natural diet, except that it is an opportunistic and generalistic feeder, immature forms being more so. Whole body lipid content of females sampled from culture ponds found to be significantly greater than males with the proportion of lipids in adults varying through the culture cycle with the lowest lipid levels occurring in crayfish sampled after pond reflooding (Eversole et al., 1999).
Environmental Requirements
Based on their distribution in North America, the eastern white river crayfish is classified as a temperate species; however, aquaculturists generally regard it as having traits normally associated with a warm-water species, similarly to P. clarkii. Nothing is known about its environmental requirements in natural conditions. In cultivation ponds of South Carolina, it was shown that the mortality of P. acutus acutus at warmer water temperatures of spring and autumn is 10 times that experienced at colder temperatures in the winter but that its growth rate is faster in the warmer water temperatures than in the colder water temperatures.
Natural enemies may be parasites/diseases, predators, and competitors. P. acutus acutus is known to be infected by the parasitic worm Alloglossidium dolandi (Turner, 2007, 2009) and Alloglossoides caridicola (Trematode, Digenea) (Turner, 2000). However, the effects of these parasites are unlikely to impact P. a. acutus’ populations. Other diseases and parasites are identical to those known to affect P. clarkii, including the White Spot Syndrome Virus, the fungus-like Aphanomyces astaci, and Microsporida. No information is available about predators. P. clarkii is a potential competitor of P. acutus acutus since they sometimes coexist and share the same limiting resources, such as food and shelter. P. clarkii can also prey on P. acutus acutus (and vice versa). However, the factors that govern the relative abundance of the two species are not fully understood. On one hand, the eastern white river crayfish produces larger (but fewer) eggs than P. clarkii (and thus larger juveniles) (Mazlum and Eversole, 2005), has a faster growth rate (Mazlum and Eversole, 2005), possesses larger chelae, and can attain larger sizes than P. clarkii (Huner, 1988), particularly at cooler temperatures. It is a highly aggressive species (Gherardi and Daniels, 2003). Size differences may be providing a competitive advantage in aggressive interactions. On the other hand, a laboratory experiment showed that P. clarkii dominates over P. acutus acutus of similar size in competition experiments (Gherardi and Daniels, 2004). Additionally, the frequently spawning P. clarkii generates more recruits than does P. acutus acutus.
P. acutus acutus has been introduced intentionally into California and New England for aquaculture purposes and/or as a live bait. The possibility remains that it has been moved unintentionally as a contaminant of P. clarkii’s stocks. Nothing is known about the time of introduction. Natural dispersal may occur within the same basin but nothing is known about its migration ability.
There are no experimental studies analyzing the impacts of P. acutus acutus. We can infer the impacts on the basis of its biology and the similarities between this species and P. clarkii.
P. acutus acutus is cultivated in some states of the USA, e.g. in South Carolina. Particularly in the southeastern United States, the yield potential for this species with a single recruitment wave is less than for P. clarkii with multiple recruitment waves. However, experimentation is underway in both South Carolina and Delaware to make its production competitive. A study that used a two-stage dynamic-stochastic simulation modeling framework suggested that farming of eastern white river crayfish in the mid-Atlantic region year-round is economically feasible (Hasegawa et al., 1999).
No studies have focused on the environmental impact exerted by P. acutus acutus. We may infer that environmental impacts may be high both when it is the only crayfish species in the ecosystem of introduction and also when other crayfish species are present (see Gherardi, 2007 for a general discussion on the impacts of alien crayfish). These effects are due to the high fecundity, fast growth rate, competitive ability, and feeding habits of the species. Biodiversity may decrease due to the potential of hybridization with congeneric species (to be proven), to compete for food or space (e.g. with P. clarkii), to prey on macroinvertebrates including snails, as well as on fishes and amphibians (to be proven), to consume macrophytes (to be proven), and to be vector of parasites.
No social impact is known. The possibility exists that this species might be a vector of parasites and diseases that might affect commercial species, as occurred in Europe with the transmission, by the North American crayfish species (e.g. Pacifastacus leniusculus and P. clarkii), of the crayfish plague to the native species, and in particular, to the commercial species Astacus astacus (Gherardi, 2007).
P. acutus acutus is used in aquaculture (see the section Economic Impact) and occasionally as a live bait. The potential for making its cultivation more feasible from an economic point of view, thus increasing its economic value, might inevitably lead to its (legal or illegal) human-aided movement outside its native range, unless efficient preventative and control measures are implemented (see the European Commission Council Regulation No 708/2007, June 11, 2007, concerning aquaculture practices in relation to alien and locally absent species).
The white river crayfish is similar in appearance to P. clarkii, especially at a young age. As the common names suggest, adults of the white river crayfish are off-white to tan, whereas the adult P. clarkii is red. However, colour alone is not a definitive distinguishing characteristic, particularly in immature individuals. The chelae of adult white river crayfish are more elongated and narrow than those of adult P. clarkii. The areola, or space on the dorsal surface where the two halves of the carapace meet is wider on white river crayfish. The white river crayfish lacks the dark stripe on the underside of the tail or abdomen that is a distinguishing characteristic of P. clarkii.
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.
No attempts have ever been made to manage introduced populations of P. acutus acutus. Most efforts should be directed to developing detection and inspection methods, diagnosis, and prevention (including SPS measures, early warning system, rapid response, and public awareness). Risk assessment protocols should be developed to quantify the magnitude of the impact of this potential invaders on the recipient ecosystems (Tricarico et al., 2009). However, this exercise requires a deeper knowledge of the biology of the species than is available today. Meanwhile, since scientific certainty about the alien species’ impacts is lacking, a “precautionary approach” should be applied to avoid potentially serious or irreversible harms to the environment. The story of the several attempts to control P. leniusculus and P. clarkii in Europe tells us that, once an alien crayfish has been introduced into natural water bodies, the probability of eradicating or controlling their invasive populations is low. Once the species has formed established populations in the wild, mechanical methods, biological control with indigenous predators, and the use of the sterile male release technique (Aquiloni et al., 2009a, b) might be adopted. The likelihood of unintentional introductions through merchandise imports could be reduced through more strict control procedures.
There are very few publications about the biology and ecology of P. acutus acutus. Studies have mostly focused on problems associated with the species’ cultivation and were conducted in the laboratory or in artificial ponds. Our knowledge about the environmental and social impacts of the species is practically absent.
Taylor CA; Hardman M, 2002. Phylogenetics of the crayfish subgenus Crockerinus, genus Orconectes (Decapoda: Cambaridae), based on cytochrome oxidase I. J. Crust. Biol, 22(4):874-881.
