Zoogeography, taxonomy, and conservation of West Virginia’s Ohio River floodplain crayfishes (Decapoda, Cambaridae)

Abstract The crayfish fauna of West Virginia consists of 23 species and several undescribed taxa. Most survey efforts documenting this fauna have been conducted in lotic waterways throughout the Appalachian plateau, Allegheny Mountains, and Ridge and Valley physiographic provinces. Bottomland forests, swamps, and marshes associated with large river floodplain such as the Ohio River floodplain historically have been under-surveyed in the state. These habitats harbor the richest primary burrowing crayfish fauna in West Virginia, and are worthy of survey efforts. In an effort to fill this void, the crayfish fauna of West Virginia’s Ohio River floodplain was surveyed from 2004 through 2009. From this survey, nine species from four genera were documented inhabiting the floodplain. Zoogeography, biology, and conservation status is provided for all nine crayfishes. The dominant genus along the floodplain is Cambarus, which includes Cambarus (Cambarus) carinirostris, Cambarus (Cambarus) bartonii cavatus, Cambarus (Procambarus) robustus and Cambarus (Tubericambarus) thomai. Cambarus (Tubericambarus) thomai is the most prevalent burrowing species occurring along the floodplain. The genus Orconectes consists of two native species, Orconectes (Cambarus) obscurus and Orconectes (Cambarus) sanbornii; and two invasive taxa, Orconectes (Gremicambarus) virilis and Orconectes (Procambarus) rusticus. Orconectes (Cambarus) obscurus has experienced a range extension to the south and occupies streams formerly occupied by Orconectes (Cambarus) sanbornii. Both invasive taxa were allied with anthropogenic habitats and disturbance gradients. The genera Fallicambarus and Procambarus are represented by a single species. Both Fallicambarus (Cambarus) fodiens and Procambarus (Orconectes) acutus are limited to the historic preglacial Marietta River Valley.


Introduction
Crayfi shes are among the most imperiled animal groups in North America (Taylor et al. 1996;Taylor et al. 2007;Taylor 1999;Taylor and Schuster 2004;Schuster 1997). Reasons for this imperilment vary from high levels of endemism and invasive species impacts to habitat destruction (Daniels et al. 2001;Hobbs et al. 1989;Lodge et al. 2000a, b). Invasive species in particular represent an important threat. Species such as Orconectes (Procericambarus) rusticus (Girard, 1852) and Orconectes (Gremicambarus) virilis (Hagen, 1870), can eliminate native species, resulting in lower species diversity and "biotic homogenization" of crayfi sh faunas (Lodge 1993). Documenting native crayfi sh communities prior to invasive species infestation or other impact from environmental stressors is important to crayfi sh conservation (Taylor et al. 2007).
West Virginia crayfi shes have received moderate attention in the past century (Faxon 1914;Newcombe 1929;Jezerinac et al. 1995). Th e fi rst report of West Virginia crayfi shes was that of Faxon (1914), who listed two species in the state. Subsequent studies by Newcombe (1929) increased the number of species to 15; however, Jezerinac et al. (1995) provided the most thorough study of the state's fauna, documenting 21 taxa. Recently West Virginia crayfi shes have received a surge of research. Loughman (2007) increased the known crayfi sh fauna with the addition of Procambarus (Ortmannicus) acutus (Girard, 1852). Swecker et al. (2010) investigated the extirpation of Orconectes (Faxonius) limosus (Rafi nesque, 1817) in the eastern panhandle of the state. Loughman et al (2009) provided natural history information for 11 of 24 species, while Loughman and Welsh (2010) reviewed the state's fauna and reported Procambarus (Ortmannicus) zonangulus Hobbs & Hobbs, 1990, as another introduced species.
Th e focus of this study is on the fl oodplain and stream confl uences with the Ohio River mainstem. Th is area is an ecological system that previous investigators neglected while surveying West Virginia's crayfi sh. In addition, several potential conservation threats have occurred in the state since publication of Jezerinac et al. (1995). In response to these threats, a crayfi sh survey was initiated in the spring of 2004 along the Ohio River fl oodplain of West Virginia. Th e Ohio River's importance as a trade route has attracted increased levels of industrialization and urbanization. Th e crayfi sh fauna inhabiting the Ohio River fl oodplain from Huntington, Cabell County; north to Chester, Hancock County, West Virginia, includes eight native species making it one of the most diverse crayfi sh faunas for a contiguous West Virginia habitat (Jezerinac et al. 1995). Another purpose of this survey was to document shifts in the Ohio River fl oodplain's crayfi sh fauna since Jezerinac et al. (1995) and identify any biotic or abiotic threats to fl oodplain crayfi sh populations.

Ohio River fl oodplain habitats
Th e North American large river fl oodplain is conducive to crayfi sh diversity due to the myriad of lentic and lotic habitats associated with these ecosystems (Trautman 1981;Hardin et al. 1989;Sparks 1995;Benke 2001). West Virginia's portion of the Ohio River fl oodplain houses these systems and supports a diverse crayfi sh fauna. Lentic habitats present on the fl oodplain include swamps, marshes, ephemeral pools, and anthropogenically created habitats (e.g., roadside ditches). Burrowing crayfi shes, especially primary burrowers use lotic habitats and their associated fl oodplains (Hobbs 1981;Taylor and Schuster 2004). Given the lack of fi sh present in ephemeral wetlands, these areas prove to be important nursery habitats for primary burrowers (Hobbs 1981). Tertiary burrowers also occur within the fl oodplain, occupying streams within these environments.

Study Site
Forests occurring along the Ohio River fl oodplain represent the most expansive bottomland forest in West Virginia. Th ese habitats are characterized by nutrient rich, alluvial soils and vegetation adapted for seasonal inundation (Colburn 2004). Forest dominants include silver maples (Acer saccharinum, Marsh), red maples (Acer rubrum, L.) and black willows (Salix nigra, Marsh) (Strausbaugh and Core 1978). Nutrients are provided to soils by seasonal fl ooding events ( Figure 1). Th ese fl oods also inundate ephemeral wetlands present in low-lying sections of fl oodplain forest.
Active hydroperiod seasons typically last from January through early June (Hardin et al. 1989). During this period a multitude of invertebrates and vertebrates, including crayfi sh, utilize these wetlands for various aspects of their life history. A period of drawdown begins during the early summer months and by late June-July much of the fl oodplain's ephemeral wetlands experience complete evaporation. Periodic summer storms occasionally refl ood these wetlands, but the majority of pools remain dormant until the following fall or winter (Z. J. Loughman personal observation).

Collection Methods
Both lentic and lotic habitats were surveyed to determine the crayfi sh diversity on the fl oodplain (Figures 2-4, and Table 1). All marshes, swamps, ephemeral wetland complexes and large roadside ditches from Huntington, Cabell County, to Chester, Hancock County, were assessed through trapping, dip netting, or burrow excavation. All large stream confl uences were surveyed through trapping in deep water or seining. Headwater streams were evaluated through hand collecting and seining.

Burrowing crayfi sh collecting methods -trapping in surface waters
Collapsible minnow traps were the chief collecting method used for this study. Collapsible minnow traps were preferred over classic metal minnow traps because of their ease of storage and manipulation in the fi eld, larger entrance portals, and rate of degradation by natural predators (e.g., turtles, mammals) in the event of trap loss (Z. J. Loughman, personal observation). Entrance portal diameter has been shown to bias capture rates for various crayfi sh, sizes warranting the use of collapsible traps with larger portals (Huner and Espinoza 2004). Traps were placed in all roadside ditches, swamps, marshes, ponds, Ohio River embayments, and ephemeral wetlands along the fl oodplain (n = 31 sites).
Traps were placed in water bodies during mid-to late-January during 2004 and 2005, and checked biweekly January through April. During this sampling period, surface activity of primary and secondary burrowing crayfi shes increase; making crayfi sh community analysis more effi cient than in other seasons for these behavioral groups (Hobbs 1981;Taylor and Anton 1998;Simon 2001). Th is method proved to be effi cient as large numbers of burrowing crayfi shes were obtained in a very short amount of time.

Burrowing crayfi sh collecting methods -excavation
Burrowers were also collected by excavation. Burrow activity was determined by the presence of chimneys or fresh mud pellets at burrow portals. Active burrows were excavated with trowels and shovels until enlarged "resting chambers" were reached (Hobbs 1942;Hobbs 1981). Once the resting chamber was breached, burrows were fi lled with water and plunged with the investigator's hand and arm. Th is pumping action was usually enough to dislodge crayfi sh hiding within the confi nes of the burrow, drawing them into the resting chamber where they were grasped.
If initial plunging eff orts were not successful in dislodging crayfi sh, the burrow was left undisturbed for several minutes. Crayfi sh, curious of this disturbance, often rose to the water/air interface where the waving of their antennae was observed. In this situation crayfi sh were quickly pinned to the sides of the burrow and extracted (Hobbs 1942). Burrow morphology data were collected on burrows containing crayfi sh that were not destroyed during the excavation process; data collected included central shaft depth (earths surface to dorsal surface of resting chamber), resting chamber width and height, terminal burrow depth (earths surface to ventral surface of deepest chamber), and burrow contents. All measurements were in centimeters.  Table 1.

Burrowing crayfi sh collecting methods -nocturnal searches
Nocturnal searches were also employed, specifi cally to collect Procambarus acutus. Th is species is a secondary burrower that is active in ephemeral surface waters prior to drawdown (Page 1985). Random searches were initiated at least two hours after sunset to ensure nocturnal activity had commenced. Headlamps were used to illuminate crayfi sh foraging in thalwegs and littoral regions of ephemeral pools. Crayfi sh were often initially observed by their eyes refl ecting light (Hobbs 1942;Hobbs 1981). Once observed, crayfi sh were collected by hand or with dipnets.
Burrowing species were also collected from burrows at night. Crayfi sh were observed at their burrow entrances with their chelae and antennae resting at the burrow/ atmosphere interface. In the capture attempt, crayfi sh were quickly pinned to the sides of their burrows. Th ey were easily approached if indirect light was used but when direct light made contact with them they quickly retreated to the deepest regions of their burrows. Care was taken not to grasp the crayfi sh by its chelae, which were readily autotomized.

Stream crayfi sh collecting methods
Th e primary collection method used for stream species were seines. Seines were setup at the terminal ends of riffl es, runs, and glides in fi rst through sixth order streams. By  Table 1. disturbing the stream's substrate, crayfi sh were dislodged from their cover and fl owed downstream into the positioned seine. At each stream site (n = 31) a minimum of fi ve seine haul eff orts (a single seine haul = one seining eff ort) and maximum of 10 seine hauls were performed. Eff ort was increased with increasing stream size and habitat complexity.
Leaf packs were surveyed in stream pools using long-handled, sturdy bait well dip nets. Th ese were used to "shovel" leaf packs onto a minnow seine that was spread out on the stream bank. Crayfi sh were then picked from the collected leaf pack on shore. After they were removed from the leaf pack it was returned upstream of its original location so the contents could again be used by the stream's benthos. All crayfi sh life stages utilized leaf packs, making this method extremely important for determining reproductive success and recruitment.

Data collection
Data sheets and fi eld jar labels were completed for each site surveyed (Simon 2004). Vouchered crayfi sh were preserved in 70% ethanol and identifi ed in the laboratory using Hobbs (1989) and Jezerinac et al. (1995). Morphometrics were taken with digital calipers on all preserved crayfi sh following Hobbs (1942Hobbs ( , 1981. Measurements (mm) included carapace length (TCL), palm length (PL), areola width (AW), and areola length (AL). Crayfi sh were sexed, and the reproductive condition of each individual determined, following Hobbs (1981). Ovigerous females and females with pleopodal instars were transported back to the laboratory, where the total number of instars for each female was determined. Maladies (regenerated chelae, missing chelae, chelae scars, etc.) were noted for each crayfi sh. Museum numbers refer to specimen collections maintained at the West Liberty University (WLU) Astacology Collection.

Conservation Ranks
All conservation ranks were determined following Nature Serve's conservation ranking criteria (Masters et al. 2009).

Explanation of Species Accounts
Th e following section provides accounts for each species encountered along the West Virginia Ohio River fl oodplain. Descriptions, morphometrics, natural history and habitat, distribution, and conservation are discussed for each taxon. A description of the information content emphasized for each subheading is explained below.

Diagnosis and Color in life
Th e diagnosis section describes morphological characters for each of the species. Characters and information content that uniquely identify each species are included. Specifi c color patterns and geographic morphs unique to the Ohio River fl oodplain are provided.

Morphometrics
Morphometric data specifi c to animals captured during the survey are discussed. Total carapace lengths (TCL) for the largest male and female of each species are indicated. Morphometric tables are presented for each species and contain mean, range, and standard deviation for carapace length, palm length, areola width, and areola length for all specimens.

Distribution
Distribution of each taxon encountered in the fl oodplain study area is discussed relative to previous survey eff orts. Most of this discussion is a comparison of results observed by Jezerinac et al. (1995) with sites surveyed during this study. Distribution maps for each species are provided and represent sites surveyed during this eff ort only.

Natural History and Habitat
Ecological observations for each species, including burrowing ability and habitat preferences, are described for each taxon. For primary and secondary burrowers, specifi c burrow usage and burrow morphology and architecture, as well as surface water usage, are described. Lentic and lotic habitats used by stream species are noted and specifi c microhabitats utilized are identifi ed. Seasonal shifts in habitat usage and ontogenetic niche shifts are also described in this section. All observed species-specifi c behaviors are identifi ed and discussed.

Conservation Status
Current conservation standing and potential mechanisms of imperilment are identifi ed and discussed following Masters et al. (2009). Recommendations are made for taxa in need of conservation eff orts and future monitoring.
Color in life. Carapace dorsally brown, beige, or pink; rostrum margins red to reddish brown; chelae olivaceous green to brown; dactyl and propodus tubercles cream or yellow; pereiopods white, cream, or yellowish gray, rarely light blue; abdomen terga dorsally brown or beige, bordered in crimson; ventral surfaces cream or white.  Distribution. Cambarus carinirostris ranges from central West Virginia north through the Monongahela River system in West Virginia and Pennsylvania and the Allegheny River system in Pennsylvania and New York (Th oma and Jezerinac 1999). Th e western extent of C. carinirostris is the Flushing escarpment in eastern Ohio (Th oma and Jezerinac 1999). Cambarus carinirostris were collected only from the northern basins along the fl oodplain, including Upper Ohio North, Upper Ohio South, and Middle Ohio North ( Figure 6). Within the Middle Ohio North basin it was collected in the extreme northern regions of the basin. Th e southern limit of this species' range in the fl oodplain is Proctor Creek, Wetzel County. Cambarus (Cambarus) bartonii cavatus  Hay, 1902 replaces this species in Fishing Creek. Th e distribution of C. carinirostris is the same as reported by Jezerinac et al. (1995).
Morphometrics. Cambarus carinirostris is a moderate sized crayfi sh. Mean TCL was 29.1 mm (n = 29, SE = 5.61). Th e largest individual was a form I male with a TCL of 39.4 mm collected from Holbert Run in Hancock County. Th e largest female was also collected from Holbert Run, and had a TCL of 32.1 mm. Morphometric data for C. carinirostris is presented in Table 2.
Habitat and natural history. Cambarus carinirostris (Figure 7) inhabits lotic water bodies, with a preference for headwater streams (Jezerinac et al. 1995;Th oma and Jezerinac 1999). Most specimens collected along the fl oodplain were taken in fi rst and second order streams. Within these environments, C. carinirostris frequented spaces beneath slab boulders, large boulders, and various substrate debris. When the substrate permits, C. carinirostris constructs burrow networks in the stream bank (Jezerinac et al. 1995;Loughman et al. 2009); however, no C. carinirostris were collected from burrows in this study. Loughman et al. (2009) found that Cambarus carinirostris likely created the majority of stream bank burrows in northern West Virginia, given the scarcity of other burrowing species in northern portions of the fl oodplain.
Cambarus carinirostris also was collected from larger streams, where it inhabits side pools, eddies, and stream margins. Th e species appears to be limited to marginal habitats in larger ordered streams through competitive exclusion with larger, more aggressive species such as Orconectes obscurus (Hagen, 1870), and Cambarus robustus Girard, 1852, both of which were collected with C. carinirostris. Seasonal data for C. carinirostris are presented in Table 3.
Diagnosis. Rostrum broad; margins reduced, subparallel, terminating cephalically in a gentle angle to form acumen; anterior region of rostrum excavated; acumen consisting of a single upturned spiniform tubercle; postorbital ridges truncated, cephalic margin with weak tubercle; cephalothorax oval shaped and slightly dorsoventrally fl attened in profi le; 2-3 punctations across narrowest region of areola; branchiostegal region moderately punctate, with small tubercles; chelae broad and robust; mesial surface of palm consisting of two rows of defi ned tubercles; fi rst row with 5-8 rounded tubercles; second with 3-4 tubercles; two prominent subpalmar tubercles present; fi rst form gonopods contiguous at base, with 2 terminal elements bent 90° to the base; central  (Taylor and Schuster 2004). In West Virginia C. b. cavatus is prevalent throughout basins associated with the lower reaches of the Kanawha system west of Kanawha Falls and basins draining into the Big Sandy River system. Cambarus b. cavatus fl oodplain populations inhabit the Middle Ohio North, Middle Ohio South, and Lower Ohio basins, and are the dominant secondary burrowing species inhabiting the fl oodplain ( Figure 6). It is replaced in the Middle Ohio North basin in Proctor Creek with C. carinirostris. A specimen collected from Doolin Run, Wetzel County, a tributary to Fishing Creek, represents the northernmost collection of this species in West Virginia. Th e distribution of this species has not changed since Jezerinac et al.'s (1995) survey in the late 1980's.
Morphometrics. Cambarus b. cavatus is a medium to large crayfi sh. Th e largest individual collected was a female with a 51.6 mm TCL taken from an ephemeral pool complex 3.6 km north of Ravenswood, Jackson County. Th e largest male collected was a form I collected from a roadside ditch 1.9 km north of Glenwood, Mason County, with a TCL of 45.6 mm. Mean C. b. cavatus carapace length was 34.4 mm (n = 25, SE = 12.42) . Morphometric data for Cambarus b. cavatus is presented in Table 4.
Habitat and natural history. Cambarus b. cavatus ( Figure 8) is a secondary burrowing species like C. carinirostris, (Jezerinac et al. 1995). Along the fl oodplain, it utilized fi rst and second order stream habitats, ephemeral wetlands, and roadside ditches ( Figure 9). Th e species demonstrated a preference for roadside ditches, with 42.1% of individuals taken from this habitat. Ditches with an associated fi rst-order stream produced particularly robust populations.   were always present with several branching auxiliary tunnels. One marked diff erence between C. b. cavatus burrows and those of other burrowing species is the width of the central shaft and the dimensions of the central resting chamber.
Th e central shaft and central chamber of other fl oodplain burrowing species (e.g., Cambarus thomai Jezerinac, 1993, Fallicambarus fodiens (Cottle, 1863), were the width of the crayfi sh's carapace at the widest point. Cambarus b. cavatus burrows did not follow this same pattern and, usually, were wide and oblong. Anecdotally, C. b. cavatus burrows were readily identifi ed by the presence of these structural components, but this method of identifi cation was not used to defi nitively verify C. b. cavatus presence at a site.
In late winter females comprised 66% of trap captures. Th ose captured in late winter/early spring all possessed active glair glands. Th is condition has been used in previous studies to indicate future egg extrusion and is likely the explanation for this increase in female activity (Hobbs 1981). No ovigerous females were collected during this study. Jezerinac et al. (1995) reported ovigerous specimens in West Virginia in July. A female retained in captivity collected in a roadside ditch 2.91 km north of Clover extruded eggs on 18 May 2005. Males captured in late winter/early spring did not show any trend toward any single demographic group, with an equal number of form I and form II individuals captured. Crayfi sh associates collected with C. b. cavatus included C. robustus, C. thomai, F. fodiens, O. obscurus, Orconectes sanbornii (Faxon, 1884), O. virilis and P. acutus. Seasonal data for C. b. cavatus are presented in Table 3.
Conservation status within study area. Cambarus b. cavatus populations along the fl oodplain are stable and do not warrant special attention. Diagnosis. Rostrum narrow to slightly broad, margins reduced and parallel, terminating in gentle angle cephalically to form acumen terminating in a single upturned spiniform tubercle; postorbital ridges prominent, cephalic margin with tubercle; cephalothorax dorsoventrally fl attened in profi le, anterior portion weakly vaulted; 2-5 punctations across narrowest region of areola; branchiostegal region moderately punctate, with small tubercles; chelae robust; mesial surface of palm consisting of two rows of defi ned tubercles; fi rst row with 7-9 rounded tubercles; second with 5-7 smaller tubercles; additional tubercles scattered over dorsal region of palm; three prominent subpalmar tubercles present; fi rst form gonopods contiguous at base, with 2 terminal elements bent 90° to base; central projection with distinct subapical notch; total length of central projection equal to mesial process length; mesial process bulbous, truncating distally; second form gonopod non-corneous and and blunt; annulus ventralis rhomboid in shape, embedded shallowly in sternum and movable. Color in life. Carapace dorsally brown; cephalic region reddish brown, branchial region pinkish brown to light brown; cervical groove black; rostrum margins orange or red; chelae olivaceous green to green; tubercles on chelae yellow or orange; dactyl and fi xed fi nger denticles cream or yellow; perieopods green or light blue; abdomen terga bodies dorsally brown or olivaceous brown; bordered in red, ventral surfaces cream or white.

Cambarus (Puncticambarus) robustus
Specimens examined. Cambarus robustus were collected from fi ve counties at seven localities, as listed below. Distribution. Cambarus robustus has an extensive distribution, ranging from southern Ontario and central New York south to North Carolina and Virginia, and west to Illinois (Taylor and Schuster 2004). Given this extensive range, C. robustus likely represents a species complex. Floodplain Cambarus robustus were collected from the Upper Ohio North and Middle Ohio North basins ( Figure 10), but has also been collected in the Middle Ohio South and Lower Ohio drainages outside the fl oodplain (Z. J. Loughman, unpublished data). Jezerinac et al. (1995)  Cambarus robustus was likely under surveyed during this eff ort. Th is species prefers free-fl owing streams more similar to mainstem rivers rather than habitats associated with big river confl uences like those sampled in this survey.
Morphometrics. Th e largest individual collected was a 46.6 mm TCL form II male collected in Kings Creek, Hancock County. Th e largest female was also taken there and was 36.0 mm TCL. Mean C. robustus TCL was 33.0 mm (n = 20, SE = 5.5). Morphometric data are presented in Table 5.
Habitat and natural history. Cambarus robustus ( Figure 11) inhabits 3 rd through 5 th ordered streams that dissect the fl oodplain. Preferred microhabitats included leaf packs, boulder fi elds, and spaces beneath large slab boulders. Cambarus robustus observed in Ben's Run burrowed into hardpan substrates of pools, and readily used available leaf packs. Many individuals eluded capture in this stream, but were observed   Taylor et al. 1996:29. Taylor et al. 2007 Diagnosis. Rostrum slightly broad, margins converging to form acumen terminating in single reduced, upturned tubercle; postorbital ridges reduced, rarely terminating in small tubercle; cephalothorax dorsolaterally compressed in profi le and vaulted; areola obliterated; branchiostegal region devoid of tubercles; chelae robust and diamond shaped; mesial surface of palm with disorganized prominent tubercles, mesialmost tubercles serrate; basiodactyl row consisting of 5-9 reduced rounded tubercles; fi rst form male gonopods contiguous, with 2 terminal elements bent 90° to the shaft; central projection truncated distally and lacking sub-apical notch; total length of central projection equal to mesial process length; mesial process short, truncating distally; second form gonopod non-corneous and blunt; annulus ventralis rhomboid in shape with deep "S" shaped sinus, embedded shallowly in sternum, and movable.
Color in life. Carapace dorsally brown, light green, olive, light blue, or blue grey; rostrum margins orange or red; chelae body light green, light brown, or blue; propodus light blue or light green; dactyl and propodus denticles cream or yellow; pereiopods tan, light green, cream, or gray; abdomen body light green, light blue gray or brown; tubercles covering chelae light yellow, cream, or orange; two light dorsal stripes present on dorsal surface of abdomen; ventral surface cream or white.
Specimens  Morphometrics. Cambarus thomai is the largest burrowing crayfi sh occurring in West Virginia, and the most frequently collected species in this study. Th e largest individual collected was a form I male, 53.6 mm TCL from Bellville, Wood County. Th e largest female measured 38.6 mm TCL and was collected from a fl ooded fi eld 1.1 km north of Ravenswood, Jackson County. Mean C. thomai carapace length was 37.0 mm (n = 148, SE = 5.41). Morphometric data for C. thomai are presented in Table 6.
Distribution. Cambarus thomai distribution includes western Pennsylvania, central and eastern Ohio, central and western West Virginia and eastern Kentucky (Taylor and Schuster 2004). Ortmann (1905aOrtmann ( , 1906 was the fi rst to mention the presence of C. thomai (= Cambarus diogenes Girard, 1852) in Brooke and Hancock counties, stating that populations persisting in both counties were stable. Newcombe (1929) documented the species in Hancock and Brooke counties, and like Ortmann, identifi ed the species as Cambarus diogenes. Jezerinac described C. thomai in 1993 based on material from West Virginia in his description (Jezerinac 1993), but. questioned the validity of Newcombe's records. Jezerinac (1993) found northern C. thomai populations problematic, specifi cally those occurring in Brooke County. Th is study did not collect any specimens from Brooke County, but specimens were collected in Tomlinson Run Backwater, validating previous records for Hancock County. Cambarus thomai was not taken in Brooke County during this study, but has been collected recently from portions of the county not associated with the fl oodplain.
Cambarus thomai was collected from the Upper Ohio North, Middle Ohio North, Middle Ohio South, and Lower Ohio basins ( Figure 12). Specimens from Jackson County, Middle Ohio South basin, represent county records. It is absent from the Upper Ohio South basin and occurs again in the Upper Ohio North basin ( Figure 12). Within the Upper Ohio North, C. thomai was collected, but not in large numbers. Cambarus thomai populations enter the Upper Ohio North basin from the Tuscarawas River in Eastern Ohio. Diff erent soil types are found in the Upper Ohio North and South basins, which could explain the species' distribution. Another possibility controlling C. thomai distribution is the increased agricultural land use practices and declining riparian habitat that has sharply increased in the Upper Ohio South and North basins.
In the Middle Ohio North, Middle Ohio South, and Lower Ohio basins, C. thomai is stable. Mason County contains substantial C. thomai populations, with the species documented at every site (n = 18) sampled in the county. Populations decline north  Ortmann (1906) commented on this population based on surveys in the late 1800's, noting how numerous burrows were in "bottomlands" adjacent to the Ohio River.
Habitat and natural history. Cambarus thomai (Figure 13) was the most frequently collected burrowing crayfi sh along the Ohio River fl oodplain. Marshes, swamps, embayments, wet fi elds, ephemeral pools, ponds, roadside ditches, and bottomland forests are habitats utilized by C. thomai. Population density appears to be directly correlated with mature forest canopies, with a preference for ephemeral pool systems, bottomland forests, and marsh habitats. Population densities decline in exposed agricultural fi elds. Th e species responds negatively to livestock even when adequate habitat is available. Th ese pasture habitats exhibit soil compaction, excess nutrients, and low browse lines. A lack of vegetation possibly expedites drawdown conditions with increased levels of evapotranspiration. Exposed conditions and frequent manipulation of topsoil appear to limit C. thomai density in agricultural settings.
Cambarus thomai uses surface waters during late-winter and early-spring. During all other seasons it was collected from burrows, which are complex, with a 0.3 m to 1.5 m deep central shaft ending in a resting chamber. Central shafts often have multiple ancillary tunnels prior to the resting chamber. Resting chambers also possess additional tunnels, particularly from their fl oors. Vegetation was frequently found in these auxiliary tunnels. In many instances a short 10-20 cm central shaft bifurcates into two complete central shafts, each ending in its own central chamber. Chimneys often were associated with these burrows (Figure 14). Cambarus thomai were nocturnal, and displayed stylized behaviors while resting in their burrow portals. Th ey rest with their antennae held laterally and their chelae barely breaching the burrow's entrance. If pressure pulses are sent through the soil, they orient their antennae toward the pulse without shifting body position. If pulses continued, crayfi sh either retreated into their burrows or left their burrow's to investigate the pulse source. Th e majority of C. thomai observations at burrow portals occurred in June and July. During late winter and early spring, several form I males and ovigerous females were observed nocturnally cruising and feeding on periphyton in ephemeral pools.
As stated previously, February through April, C. thomai uses surface waters extensively. Eighty-six percent of trap captures were form I males. Ovigerous females (n = 12) also used surface waters, with 50% of females captured at this time carrying eggs. Linear regression analysis of ovigerous females indicates there is not a strong relationship between carapace length and the number of pleopodal eggs ( Figure 15). Egg counts ranged from 108-304 eggs per female. Pleopodal egg diameter ranged from 1.51-2.47 mm, with a mean diameter of 2.09 mm.
Given the high percentage of ovigerous females captured in late winter and early spring, mating likely occurs in the fall. Females carry sperm throughout the winter and extrude eggs in early spring when ephemeral pool hydroperiods are at their most active. Instars are carried by females throughout the spring, and released at the beginning of the summer season. Th is life history strategy enables neonates to mature throughout the summer and enter their fi rst winter as juveniles. Jezerinac et al. (1995) collected ovigerous females in March, April, May, and June in West Virginia, and Taylor and Schuster (2004) collected a single ovigerous female in Kentucky in March. Our results validated previous seasonal data for C. thomai as presented in Table 3.
Cambarus thomai neonates used surface waters throughout the summer season (May-September) and were the only demographic observed at this time. Dip netting yielded large numbers of young-of-the-year in July and August; however, whether neonates remain in surface waters may depend on water availablility throughout the fall into winter. During drawdown in several sites in Mason County, juveniles were observed burrowing.
Neonate utilization of surface waters may be a dispersal mechanism to enable colonization and equally distribute individuals throughout wetlands or redistribute individuals into areas of high productivity. Nocturnal searches found C. thomai utilizing surface waters rather than relying on burrows. On several occasions individuals would seek cover under substrate debris in surface waters although burrows were readily available. Diagnosis. Rostrum slightly broad and moderately excavated, defl ected ventrally; margins converging to form acumen cephalically with reduced upturned tubercle; postorbital ridge reduced, not terminating in tubercle; cephalothorax dorsolaterally compressed in profi le and vaulted; areola obliterated; branchiostegal region devoid of tubercles; chelae diamond shaped; mesial surface of palm with 2 distinct rows of tubercles; dorsalmost row consisting of 6-9 serrate tubercles; second row consisting of 3-6 circular tubercles; basiodactyl row consisting of 5-7 punctations; opposable surface of dactyl with distinct basal notch; junction of dactyl and propodus setiferous; fi rst form gonopods basally contiguous, with 2 terminal elements bent 90° to shaft; central projection of populations on the fl oodplain possessing distinct subapical notch; total length of central projection equal to mesial process length; mesial process bulbous, truncating distally; second form gonopod non-corneous and blunt; subapical notch absent in second form gonopod; annulus ventralis rhomboid in shape with deep S-shaped sinus and C-shaped fossa; embedded shallowly in sternum, and movable. Color in life. Carapace dorsally and laterally tan, brown, reddish brown, or gray; cephalic and branchial region mottled with black or deep grey spots; chelae tan, deep gray, or gray brown; tubercles on chelae cream or light gray; distal region of dactyl and propodus increasingly orange; perieopods green or light grey; abdomen grey or olivaceous brown, with 2 distinct dorsal stripes; ventral surfaces cream or white.
Specimens examined. Fallicambarus fodiens were collected from two counties at three locations in the current study, as listed below.  Jezerinac and Stocker (1987) theorized that F. fodiens populations in West Virginia were Marietta River relicts. Currently, the Marietta River Valley is composed of the Kanawha River Valley. Th is hypothesis does help explain the scarcity of this species along the fl oodplain. Future survey eff orts for F. fodiens should focus on wetlands associated with the Kanawha River fl oodplain. Th e Moose Lodge wetland and its associated wetlands include that fl oodplain, which is 0.8 km from the Kanawha River and Ohio River confl uence. Th e Moose Lodge wetland is composed of diverse bottomland forest with multiple ephemeral pools, which possess stable F. fodiens populations.
Habitat specialization may explain low F. fodiens numbers elsewhere since little mature bottomland forests remain along the Ohio River fl oodplain. Apparently this habitat is needed for West Virginia's disjunct population of F. fodiens to persist.
Morphometrics. Several animals were observed, but not disturbed due to the rarity of this species in West Virginia. Th e largest individual was a 40.1 mm TCL form I male collected at the Moose Lodge wetland, Mason County. Th e largest female collected was 37.3 mm TCL from an ephemeral pool complex located inside Krodel Park, Mason County. Mean carapace length for this species was 34.3 mm (n = 26, SE = 8.67). Morphometrics data for F. fodiens is presented in Table 7.
Habitat and natural history. Fallicambarus fodiens (Figure 18) in West Virginia is an ephemeral pool specialist. Within these ecosystems, colonies were associated with Carapace  (Guiasu 2007;Norrocky 1991;Taylor and Schuster, 2004). With the exception of the Greenbottom Swamp population, ephemeral systems are preferred over larger, more permanent water bodies. Fallicambarus fodiens colonies typically consist of 5-10 burrows for every 1 m 2 of substrate.
Within these colonies, the sex ratio of captured individuals was 1:1 male to female. Fallicambarus fodiens burrow morphology is simple, with the majority of excavated burrows consisting of a central shaft ranging in depth from 0.3 m to 1.0 m. One or two short ancillary tunnels often were present radiating from central shafts. Th ese ancillary tunnels often are full of debris. Resting chambers usually were present at the terminus of these shafts, with either few or no ancillary tunnels radiating from them. Several Ovigerous females have been collected February through April in Illinois (Page 1985), Kentucky (Taylor and Schuster 2004), and Michigan (Creaser 1931). All adult males captured during this study were form I. Given that females were ovigerous in early spring and males enter the winter season as form I, mating in this species likely occurs in the fall or winter along the fl oodplain.
Fallicambarus fodiens females carrying instars were observed nocturnally foraging in open water on 18 March 2004 and 4 April 2009 in Greenbottom Wildlife Management Area. Several individuals (n = 8) were resting or grazing at their burrow entrances on periphyton that had colonized submerged canary grass (Phalaris canariensis L.). Within the colony burrows were fl ooded by 15-30 cm of standing water. Instars were observed leaving burrow entrances to graze. Upon provocation, disturbed females stopped moving long enough to allow instars to reattach to their abdomens, then retreated to their burrows. Seasonal data for F. fodiens is presented in Table 3. Crayfi sh associates collected with F. fodiens include C. b. cavatus, C. thomai, O. virilis, and P. a. acutus.
Conservation status within study area. Fallicambarus fodiens warrants conservation attention and is deserving of S1 status. Surveys are needed along the Kanawha River in wetland habitats to determine if this species persists there. Along the fl oodplain threats to this species' survival include land use practices and their associated pollutants, hard surface run off , and destruction of bottomland forests. Distribution. Orconectes obscurus occurs in north-west New York south through western Pennsylvania and north-central West Virginia, east to Maryland's portion of the Youghiogheny River system and west to the Flushing Escarpment of Ohio (Hobbs 1989 Orconectes obscurus has undergone a southern range expansion since Jezerinac's surveys in the 1980's ( Figure 19). Th e southern extent of its range currently is Ben's Run, Tyler County. Orconectes sanbornii's northern limit currently is Middle Island Creek, due north of Saint Mary's, Pleasant County. Orconectes obscurus and O. sanbornii divide the Middle Ohio North basin, with O. obscurus inhabiting northern portions of the basin and O. sanbornii inhabiting southern portions ( Figure 19).

Orconectes
Th e southward expansion of the range of O. obscurus could be natural or an anthropogenic event. Orconectes are used as bait because of their ease of capture and high densities (Distefano et al. 2009b), so bait bucket release may explain the southward range expansion. Orconectes obscurus has a history as an invasive, with such populations present in New York and Ontario, Canada (Crocker and Barr 1968;Taylor et al. 1996). Many of the streams containing O. obscurus populations in the southern region of the Middle Ohio North basin are second or third order streams that do not harbor large game fi sh populations.
Two alternative hypotheses explaining this expansion may include previous misidentifi cation and natural expansion. Orconectes obscurus may have always been present historically where the species was collected in this survey, and misidentifi ed by previous investigators. It is also possible that the species has expanded under natural conditions southward since the 1980's, specifi cally invading the Hannibal Pool of the Ohio River and replacing O. sanbornii in the mainstem. After displacement of O. sanbornii in the Ohio River mainstem, additional streams could be colonized via stream confl uences.
Morphometrics. Th e largest individual was a 39.0 mm TCL form I male collected in Tomlinson Run backwater in Hancock County. Th e largest female was collected from the confl uence of Little Grave Creek and the Ohio River in Marshall County and possessed a 37.4 mm TCL . Mean TCL for the species was 29.2 mm (n = 82, SE = 8.77). Sexual dimorphism is displayed in this species, with form I and form II male chelae signifi cantly larger (t (345) = 6.8201, p = 0.0001) than female chelae. Morphometric data for O. obscurus is presented in Table 8.
Habitat and natural history. Orconectes obscurus (Figure 20) occupy stream habitats throughout the central and northern regions of the fl oodplain. Habitats include fi rst through fi fth ordered streams and Ohio River backwaters. Healthy populations of O. obscurus occur in all 3 rd through 5 th ordered streams from Ben's Run, Tyler County, north to Tomlinson Run, Hancock County. Orconectes obscurus were frequently collected from streams within two specifi c macrohabitats. Slab boulders and leaf packs were utilized by all demographics; form I males were associated primarily with slab boulders. Leaf packs in pool thalwegs were utilized with increased frequency by O. obscurus juveniles. Based on captive observations, leaf packs off er both structural protection and periphyton for foraging (Z. Loughman personal obs.).
Orconectes obscurus is also a tertiary burrower, creating minimal burrows under substrate items. Small gravel and cobble piles usually were present along margins of slab boulders harboring O. obscurus. One signifi cant behavioral diff erence between the genera Orconectes and Cambarus along the fl oodplain is the diff erence in expressed territoriality. Orconectes obscurus and other orconectids displayed limited territorality. In one instance in Cross Creek, Brooke County, 11 individuals were collected from a single slab boulder.
Orconectes obscurus were collected from two ephemeral streams. Th is habitat has not previously been reported for the species, and is rarely reported for any Orconectes species (Distefano et al. 2009a ). In Brooke County, O. obscurus were observed in a fi rst order stream tributary to the Ohio River mainstem, foraging on large mats of Cladophora spp. In another headwater stream in Brooke County, they were collected 1.5 km from the river mainstem and had traversed three 1.0 m waterfalls and their associated plunge pools. It is likely that these crayfi sh inhabit the mainstem of the river and had migrated into the stream, returning to the river during periods of drawdown. Jezerinac et al. (1995) described O. obscurus's and O. sanbornii's life cycle in West Virginia. Form I males are present from fall into winter and mate in the early spring. After spring mating, males molt into second form in late June and proceed throughout most of the summer in this condition (Table 9). Life history data collected during this study validate Jezerinac et al.'s (1995) fi ndings. Beginning in late April and continuing through mid May, females extruded eggs and carried instars. Ovigerous females were collected on 8, 9, and 12 May 2007. Pleopodal egg counts averaged 113 (n = 8 females,  (Table 9). After this molt, mating eff ort increased through late summer and fall until winter hibernation. In addition to the late summer molt, males molted in mass during May at the same time that females became ovigerous. Th is life history mirrors that of Ohio populations as well (Fielder 1972  Diagnosis. Rostrum with slghtly converging margins, not thickened, with marginal spines or tubercles; median carina absent. Cephalothorax ovoid, slightly, dorsoventrally compressed, without setae. Areola 3.4-9.3 times longer than wide, comprising 31-37% of TCL, with 2-3 rows of punctations across narrowest region; cervical groove interrupted just above cervical spine; lacking hepatic spines; suborbital angle obsolete. Antennal scale about 1.5 times as long as wide; basiopodite spine of antenna well developed; ischiopodite of antenna without spine. Chelae smooth, broad and robust, length 85% of TCL; mesial surface of palm with two well developed rows of tubercles; mesialmost row consisting of 7-11 tubercles; dorsolateral row with 7-11; lateral margin of propodus smooth, dorsal surfaces of both dactyl and fi xed fi nger of propodus with weak dorsolateral ridges; some elongate setae at base of fi xed fi nger. First form male gonopods short, comprising 30% of TCL, with two terminal elements about subequal length; corneous central projection comprising 16% of pleopod length, tapering distally to point; mesial process non-corneous, spatulate, partially surrounding central projection; cephalic base of central projection sloping, without right angle shoulder. Form two male gonopod non-corneous, blunt, shoulder not prominent or absent. Female annulus ventralis deeply embedded in sternum, moveable, wider than long, cephalolateral prominences fl attened; fossa and sulcus shallow; sinus straight. Color in life. Carapace, abdomen and dorsal surface of chelae brown; rostral margins, caudal edge of carapace, and central surface of terga dark brown; tips of chelae and tubercles at dactyl base orange; tubercles on mesial and lateral margins of dactyl, Distribution. Orconectes sanbornii occurs throughout the Middle Ohio river drainage in Ohio, West Virginia and Kentucky (Taylor and Schuster 2004). Sites harboring O. sanbornii are shown in Figure 19. Th e most northern historic populations of the species on the fl oodplain occurred in Fishing Creek, Wetzel County were recently replaced by southward expanding O. obscurus populations. Orconectes sanbornii is absent from lower reaches of Fishing Creek associated with the confl uence of the Ohio River, and still is present in mid-and headwater sections of Fishing Creek (Loughman, unpublished data). Currently, Orconectes sanbornii inhabits the Middle Ohio North,  Table 9.
Habitat and natural history. Orconectes sanbornii (Figure 21) habitat requirements were similar to those of O. obscurus. Orconectes sanbornii is typical of tertiary burrowing crayfi sh, and inhabited small-to large-sized streams. Slab boulders, leaf packs, and depositional environments were all habitats used by the species. Based on this study, the life cycle of O. sanbornii mirrors that of O. obscurus (Table 9).
Orconectes sanbornii demonstrated the same gregarious behavior observed in O. obscurus. Behavioral diff erences observed between O. obscurus and O. sanbornii specifi cally diff ered in the use of stream cover. In West Creek, Jackson County, O. sanbornii were observed exposed in the stream channel. Orconectes sanbornii used interstitial spaces between boulder margins, and the majority of individuals were collected from exposed areas. Orconectes sanbornii were exposed mid-channel resting on the stream bottom with their antennae held posteriorly over their cephalothorax, and would not seek cover until prodded. Orconectes were noted for using cover less than cambarids in this study, but the extreme level of behavior observed in O. sanbornii warrants special mention. Crayfi sh associates collected with O. sanbornii include C. b. cavatus and C. thomai.
Diagnosis. Rostrum with straight margins, not thickened or possessing spines or tubercles; median carina absent; postorbital ridges terminating cephalically with spine or tubercle. Branchiostegal spine reduced; hepatic spine absent. Cephalothorax oval shaped and slightly dorsoventrally fl attened in profi le; without setae; suborbital angle obsolete. Areola 7.1-19.0 times longer than wide, comprising 34-39% of TCL, with 1-2 rows of punctations across narrowest region. Chelae smooth, broad and robust; mesial surface of palm with two rows of defi ned tubercles; fi rst row with 6-8 rounded tubercles; second with 5-8 tubercles; lateral margin of propodus smooth; dorsal surfaces of both dactyl and fi xed fi nger of propodus with prominent well developed longitudinal ridges; elongate plumose setae at base of fi xed fi nger of propodus. First form male gonopods long, comprising 42% of TCL, with 2 terminal elements, both bent and curving at about 30° to the base; central projection corneous, comprising 24% of gonopod length, cephalic base without shoulder. Form two male gonopod noncorneus, gently curving caudally; mesial process subequal in length to central projection, blunt. Female annulus ventralis rhomboid, fossa large, sulcus wide, cephalolateral prominences weak, sinus only evident on caudal surface.

Color in life.
Carapace and abdomen dorsally olivaceus or brown; rostral margins darker brown to black; postorbital ridges and caudal margins of cephalic portion of carapace along cervical groove brown; two rows of blotches on dorsal surface of abdomen; dorsal surface of chelae emerald green; tips of propodus and dactyl darker green; all knobs on chelipeds beige or tan; ventral surfaces cream or white.
Specimens examined. Orconectes virilis were collected in Mason and Pleasants counties at three locations in the current study, as listed below. Morphometrics. Th e largest observed individual was a 52.4 mm TCL form I male collected from Krodel Park Lake, Mason County. Th e largest female was 43.3 TCL, also from Krodel Park. Th e mean TCL for O. virilis was 42.8 mm (n = 22, SE = 6.11). Th is species was the largest crayfi sh collected in this study. Morphometrics for O. virilis are presented in Table 11.
Habitat and natural history. Orconectes virilis ( Figure 22) is an invasive fl oodplain species; the closest native populations are endemic to the upper Mississippi River valley (Hobbs and Jass 1988;Page 1985). Two disjunct populations were discovered along the Ohio River fl oodplain, in Krodel Park, Mason County and near Saint Mary's, Pleasant County, in an Ohio River embayment. Krodel Lake population stock undoubtedly came from bait-bucket introductions. Less than fi ve km from Krodel Lake is an aquaculture facility that raises and sells O. virilis for fi sh bait. Discussions with anglers informed the primary author that "soft craws" were purchased from local bait dealers and used in Krodel Park. Orconectes virilis has been collected from six wetlands surrounding Krodel Lake. All of these sites are within one km of the lake proper. Within the lake, O. virilis uses riprap in the littoral zone for cover. Over one hundred adults were observed utilizing this habitat between 20:00-23:00 h on 5 May 2005.
In certain situations O. virilis travels as far as one km from the lake to nearby wetlands. Its presence in a vernal pool system with zero fi shing eff ort shows the propensity of this species to migrate. In one instance, O. virilis had not been captured from an ephemeral pool system in spring and summer of 2004. After severe fl ooding in the fall  Table 9.

Orconectes (Procericambarus) rusticus (Girard, 1852) -Rusty Crayfi sh
Diagnosis. Rostrum with concave margins, not thickened, with spines or tubercles; median carina absent; mandible with smooth cutting edge. Cephalothorax oval, slightly dorsoventrally compressed in profi le. Areola 4.6-19.4 times longer than wide, comprising 36-39% of TCL, with 2-3 rows of punctations across narrowest region; branchiostegal spine poorly developed; suborbital angle obsolete or poorly developed. Chelae robust; mesial surface of palm with two rows of defi ned tubercles, fi rst row with 5-9 tubercles; second row with 4-9 tubercles of smaller diameter. First form male gonopods long, comprising 26% of TCL, with 2 straight terminal elements; central projection comprising 56% of gonopod length; well developed shoulder at cephalic base of central projection. Second form male gonopod non-corneous, straight, mesial process slightly subequal in length to central projection, blunt, shoulder not evident. Annulus ventralis rhomboid in shape, fossa moderately large, cephlolateral prominences well developed, trough narrow, sinus evident on caudal surface. Distribution. Orconectes rusticus (Figure 23) is native to lower and central portions of the Ohio River system in Kentucky, Ohio, and Indiana north to western portions of Lake Erie in southeastern Michigan and north western Ohio (Taylor 2000.), and is one of two invasive crayfi sh species in West Virginia. Prior to this survey, it appeared to be limited to Four Pole Creek in Huntington, and isolated sections of the Kanawha and Little Kanawha River systems. Both fl oodplain populations are allied with the upper Ohio River South basin in the northern panhandle ( Figure 10) and are associated with Ohio River embayments adjacent to industrial sites. Additional investigators discovered O. rusticus populations throughout the Kanawha River system in recent years (Casey Swecker, Marshall University, personal communication).
Th e Upper Ohio South basin is the only basin within the fl oodplain that currently harbors O. rusticus populations. Bayer Chemical Plant and Pittsburgh Paint and Glass (PPG) Chemical Plant both possess embayments connected to the Ohio River mainstem that contain O. rusticus populations. Th e PPG population is present in a "pond" with a connection to the Ohio River mainstem. Th e Bayer population is present in a series of backwaters with mainstem connections. Trapping results show that the Bayer population has higher densities than the PPG population.
Why O. rusticus is limited to these two backwaters despite its presence in the Ohio River mainstem needs furthur investigation. Populations present in the mainstem could operate as sources for future invasions into new watersheds. Th e extent of the range of O. rusticus within the mainstem is also in need of future work. Given the Ohio River's manipulation into a series of non-contiguous pools, investigations into those pools that harbor O. rusticus populations and those pools that do not is a proactive move to understand basins at risk of future invasions.
Morphometrics. Forty-four O. rusticus were collected from two sites. Th e largest individual was an ovigerous female 44.1 mm TCL. Th e largest male was a 38.4 mm TCL form I male from PPG Wildlife Management Lake. Mean O. rusticus TCL was 31.0 mm (n = 41, SE = 6.12). Nine females were ovigerous and had a mean carapace length of 30.1 mm. Morphometrics data for O. rusticus is presented in Table 12.
Habitat and natural history. In West Virginia's Ohio River fl oodplain, Orconectes rusticus inhabits two Ohio River back-waters ( Figure 10). Both embayments are nutrient rich, shallow, lentic systems with an abundance of detritus and algae. Nutrient-rich environments are preferred habitats of O. rusticus and Ohio River backwaters provide ideal conditions for the species Lodge, 2000a). All O. rusticus collected in this study were trapped in late winter and early spring. Very little natural behavior was observed. Life history parameters of the Bayer population were determined from specimens and a review of the literature. All males captured in traps in March and April were form I and possessed heavily encrusted carapaces. Th e level of encrustation is directly proportional to the length of time between molts (Hobbs 1981). Given the conditions of collected males, which in many instances were black and encrusted, individuals likely molted into form I the previous fall. Other O. rusticus populations undergo a late summer/fall mating season, and it is likely that this population may mate during the fall as well (Jezerinac et al. 1995, Taylor andSchuster 2004).
Ovigerous females were collected on 2, 14, and 18 April 2006 (Table 9). Seventy percent of females were ovigerous at this time. Egg counts increased with female size and ranged from 75 ova for 26.5 mm TCL to 356 for a 35.9 mm TCL female. Mean egg diameter was 1.8 mm. Th ere was not a correlation between egg number and TCL (r 2 = 0.18, n = 7); however, this could possibly be an artifact from small sample size. Date of egg extrusion and counts are similar to native Kentucky populations at similar latitudes (Prins 1968). Females likely mate in the fall, hold active sperm inside spermatheca throughout the winter, and extrude eggs in late-March. Orconectes rusticus in previous life history studies were noted to undergo the typical Orconectes life history cycle, which has been explained in the O. obscurus natural history section (Prins 1968;Capelli 1982;Jezerinac 1982).
Orconectes rusticus expansion into new territory was observed at the Bayer site. A headwater stream that was not connected to the Bayer series of backwaters became connected to this system in the spring of 2004. At this time extensive survey eff orts were undertaken to determine if O. rusticus was present within the stream; none were found. Ten months after initial surveys of this stream, O. rusticus had migrated 2 km upstream.  Conservation status within study area. Given the aggressive nature of this invasive species, annual monitoring eff orts are warranted. Th e impact of this species on native crayfi sh communities in northern West Virginia is unknown and should be determined as soon as possible. (Girard, 1852)  Diagnosis. Rostrum slightly broad and triangular; width of rostrum margins reduced; margins converging terminating in 2 marginal spines; acumen with distal rostral spine; postorbital ridges prominent, cephalic margin with tubercle; cephalothorax dorsolaterally compressed in profi le, anterior portion vaulted; areola obliterated at narrowest point; branchiostegal region moderately punctate, with small tubercles; small cervical spine present; chelae elongate and lance shaped; mesial surface of palm with single dorsal row of 7-9 pronounced tubercles; additional tubercles scattered over dorsal surface of palm. Bases of fi rst form male gonopods contiguous; gonopod with 4 terminal elements, covered by dense setae; central projection pointed and corneous; caudal process short; mesial process pointed and straight in profi le; cephalic process elongated and pointed; second form gonopod annulus ventralis circular in shape, embedded deeply in sternum, and movable. Color in life. Carapace, chelae, and pereiopods dorsally and laterally red-gray, gray-purple, burgundy, or red; branchial region of smaller individuals mottled with black spots; tubercles on chelae cream, red-brown, red, or black; dorsal surface of abdomen with a distinct black wedge. Distribution. Procambarus acutus is a wide-ranging species associated with wetlands present throughout the central and eastern United State excluding the majority of the Appalachian Mountains (Taylor and Schuster 2004). Several introduced populations occur through North America (Taylor et al. 2007). In West Virginia, Procambarus acutus occurs in the Middle Ohio South and Lower Kanawha basins (Figure 16), and was fi rst reported occurring in West Virginia by Loughman (2007). Given its history of introductions elsewhere, P. acutus was initially thought to be an introduced species in West Virginia. It's use in aquaculture and as bait for fi shing has led to non-indigenous populations occurring throughout North America, with confi rmed non-indigenous populations documented in California (Gander 1927), Maine (Crocker 1979), and Kentucky (Taylor and Schuster 2004). As discussed below, current evidence suggests that P. acutus is a native species in West Virginia.

Procambarus (Ortmannicus) acutus
Several species, including the oak, Quercus bicolor Willd., the salamander, Ambystoma texanum (Mathes, 1885), and F. fodiens, are found in the Lower Ohio and Lower Kanawha drainages in West Virginia. Th ey are theorized to be pre-glacial Marietta River relicts (Green and Pauley 1987;Jezerinac and Stocker 1987;Strausbaugh and Core 1978). Th e Marietta River was a major tributary of the pre-glacial Teays River, and the area of the Ohio River and Kanawha River confl uence is considered to be the Marietta River Valley (Stout et al. 1943). Several species that are found in no other part of the state inhabit this biotic region. Jezerinac and Stocker (1987) used the Marietta River Valley to explain the disjunction of the West Virginia F. fodiens population from the core of its range across the midwest. Th is species occurs sympatrically with P. acutus at two of three sites along the fl oodplain.
Ambystoma texanum (Green and Pauley 1987) occurred at two sites harboring P. acutus populations. Both A. texanum and F. fodiens have limited, disjunct ranges in West Virginia. In Ohio, P. acutus has been collected from sites in the pre-glacial Teays River drainage, as well as in the area theorized to be the Teays River, Marietta River confl uence (Th oma and Jezerinac 2000). Th e presence of these two species at three of the four P. acutus collection sites, along with P. acutus only being collected in the Marietta River Valley and nowhere else along the Ohio River fl oodplain of West Virginia, appears to validate the hypothesis that P. acutus is native to West Virginia Morphometrics. Th e largest P. acutus collected in this study was a 43.1 mm TCL female collected from the Moose Lodge wetland, Mason County. Th e largest male was a 40.6 mm TCL form I also collected from the same locality. Mean P. acutus carapace length was 28.7 mm (n = 68, SD = 7.79). Morphometrics data for P. acutus are presented in Table 13.
Habitat and natural history. Procambarus acutus (Figure 24) had not been collected from West Virginia prior to this survey. Loughman (2007)  Form I males were collected in all months between February and May, while form II males were also collected from February through April (Table 9)  populations appear to have six distinct size cohorts although these data need to be interpreted with caution due to low sample size (Jezerinac et al. 1995). Amplexus was observed in the fi eld on 5 May 2005 at 22:00 h. Two amplexing pairs were observed resting on pond substrate adjacent to fallen logs. No amplexing pairs were observed away from cover objects. Several specimens also amplexed in collecting buckets within minutes of being introduced on this same day. An interspecies amplexus was observed on 5 May 2005, when a large form I male P. acutus was coupled with a female O. virilis for 30 minutes. In the laboratory P. acutus displayed reproductive behaviors (amplexes) from early May 2005 through mid-July 2005. Crayfi sh associates collected with P. acutus included C. thomai, C. b. cavatus, F. fodiens and O. virilis. Conservation status within study area. Based on the Marietta River Valley theory, we believe that P. acutus is a native species and should be given protection. Future investigations need to focus on the Kanawha River Floodplain between Point Pleasant and St. Albans. Th e Moose Lodge wetland is located on the Kanawha River and is the most diverse site surveyed in this study. All major habitats along the Ohio River fl oodplain that have been surveyed extensively in Mason County did not yield any additional P. acutus populations. When present at a site, P. acutus was the dominant surface water crayfi sh. Conservation eff orts for this species should focus on preserving habitat. Th e Moose Lodge wetland should be conserved for protection and monitoring, not only for P. acutus populations, but also for the myriad of Marietta River relicts occurring in the wetland.

Potential West Virginia Ohio River fl oodplain species
Cambarus (Jugicambarus) monongalensis Ortmann, 1905 Allegheny Blue Mudbug Cambarus monongalensis Ortmann, 1905 (Figure 25) inhabits the Upper Ohio North, Upper Ohio South, and Middle Ohio North basins (Jezerinac et al., 1995). Within these basins, C. monongalensis occur in seeps, springs, roadside ditches, and creek banks in mesophytic habitats away from the fl oodplain. Jezerinac et al. (1995) noted that C. monongalensis inhabits the Ohio River fl oodplain. A review of historic records indicated that specimens have been collected on hillsides adjacent to the fl oodplain, but not from the fl oodplain proper. Riparian corridors are used by this species; however, more terrestrial situations are preferred. Along the fl oodplain, insular C. monongalensis populations likely exist, though no populations were discovered in this study. Th e species prefers terrestrial mesophytic situations, and microhabitats associated with fl oodplain systems appear to be disadvantageous for this species.
Several C. monongalensis colonies have been discovered in anthropogenic habitats close to the fl oodplain by the primary author. Th ree populations in Hancock County are within 2 km of the Ohio River in exposed environments without canopy cover. Within the Upper Ohio North and Upper Ohio South basins, C. monongalensis populations are present on hillsides bordering the Ohio River mainstem, but not on the  (Jezerinac et al. 1995); however, Cambarus thomai was the only crayfi sh collected at these sites in this study. Th is species constructs intricate burrows in rocky soils with multitudes of ancillary tunnels that follow crevices, making collecting extremely diffi cult (Dewees 1972, Jezerinac et al. 1995. Although this species was not collected during this study, populations may persist along the fl oodplain and warrant future survey eff orts. Middle Ohio South and Lower Ohio. Basins are referred to as 8-digit watersheds as designated by government agencies. Th e following is a synopsis of each basin's fl oodplain crayfi sh fauna.

Upper Ohio North
Four crayfi sh species inhabit the Upper Ohio North basin's fl oodplain (Table 14). Cambarus carinirostris is a secondary burrower that occurs throughout the basin and is present in most streams along the fl oodplain. It uses headwater systems, but was observed in larger streams with reduced relative abundance. Interspecifi c competition with O. obscurus and C. robustus, may limit its expansion into these environments.
Orconectes obscurus and C. robustus are dominant in larger streams. Orconectes obscurus outnumbers C. robustus in all streams; but C. robustus specializes in colonization of slab boulders and is dominant in this microhabitat (Hamr and Berrill 1985). Orconectes obscurus and C. carinirostris comprise the typical basins stream crayfi sh assemblage. Kings Creek, Holbert Run, and Hardin Run are stream examples with this fauna.
Cambarus thomai is the only primary burrower found in lentic habitats along the fl oodplain. Cambarus monongalensis can replace this species in terrestrial systems, and although it was not captured during this survey, insular populations likely inhabit the fl oodplain. Unlike in southern basins, C. thomai is not abundant throughout the Upper Ohio North, indicating that possible limiting factors exist for this species in northern West Virginia.

Upper Ohio South
Four crayfi sh species, including an invasive species, comprise the Upper Ohio South basin fauna (Table 14). Cambarus carinirostris occupies the same niche there as in the Upper Ohio North; however, increased population densities exist in larger No burrowing crayfi shes were collected along the Upper Ohio South basin fl oodplain, but Cambarus monongalensis is present in terrestrial mesophytic habitats. Insular populations likely inhabit portions of the fl oodplain. A decrease in riparian bottomland habitat occurs within the basin. Hillsides with steep relief directly abut the Ohio River for large reaches, eliminating the potential for bottomland hardwood habitat occurrence. Th e lack of physical relief needed for bottomland forest may explain the lack of fl oodplain burrowing crayfi sh populations within the Upper Ohio South drainage. Historic bottomland forests present within this basin have been either altered or destroyed, and currently no contiguous tracts exist.
Orconectes rusticus, an invasive species, has populations within this basin. Populations are limited to the southern portion of the basin along the Marshall /Wetzel county lines. Th ese populations represent potential sources for future invasions, and could spread into the Upper and Middle Ohio North basins. Monitoring is needed to see if such an invasion occurs.

Middle Ohio North
Th e Middle Ohio North basin crayfi sh fauna is composed of six native and one invasive species (Table 14). Northern and southern faunas merge within this basin, with several crayfi sh community shifts occurring. Th ese shifts include O. obscurus and O. sanbornii, and C. carinirostris and C. b. cavatus, which change from a northern (O. obscurus and C. carinirostris) to a southern fauna (O. sanbornii and C. b. cavatus).
Th is is the only basin where two secondary burrowing stream forms occur but not syntopically. Cambarus carinirostris occupies Proctor Creek in extreme northern areas, while Cambarus b. cavatus dominates in the remaining stream systems. Both species occur in headwater streams. Cambarus carinirostris occupies larger streams within the northern regions of the basin than does C. b. cavatus, with the latter limited to fi rst through third order streams.
Orconectes obscurus and O. sanbornii are both tertiary burrowers, which occupy the Middle Ohio North basin. Orconectes obscurus populations are shifting south and occupy stream systems where O. sanbornii historically occurred. Cambarus robustus, another tertiary burrower, is also found but in reduced numbers relative to the orconec-tids. Within the Middle Ohio North basin, C. robustus inhabits smaller streams than occupied by populations in the Upper Ohio North and Upper Ohio South basins. Orconectes virilis, an invasive species, occurs in one river embayment. Th is population could be a potential source for future invasions.
Cambarus thomai is the sole primary burrowing crayfi sh species inhabiting the Middle Ohio North fl oodplain. Populations in New Martinsville, Wetzel County, are the most abundant and there are healthy northern populations along the fl oodplain. Large populations of the species are present at the Ben's Run/Ohio River confl uence (Figure 27), New Martinsville maple swamp, and ephemeral wetlands in Friendly. Relief in this part of the basin allows for well-developed bottomland habitats.

Middle Ohio South
Six native and one invasive species comprise the Middle Ohio South crayfi sh fauna (Table 14). Invasive Orconectes virilis populations reside in a critical location at the border of the Upper Ohio, Lower Kanawha, and Middle Ohio South basins. Based on their close proximity, it is highly probable that O. virilis populations are present within these neighboring basins.
Th e crayfi sh fauna of this basin is similar to that of "southwestern West Virginia". Cambarus b. cavatus colonizes headwater streams and O. sanbornii larger streams in Figure 27. Ben's Run, Tyler County, West Virginia at confl uence with the Ohio River. Cambarus thomai and Orconectes obscurus were collected at this site. the basin. Cambarus thomai is the dominant primary burrower. Th ese three species are sympatric throughout the basin, with each specializing in its own microhabitats. Th is assemblage is contiguous throughout the remainder of the state's watersheds along the fl oodplain.
Cambarus robustus was not collected from Ohio River stream confl uences, but occupies stream mainstems. Th e lack of confl uence collections is most likely an artifact of sampling bias, since many of the reaches exhibit adequate habitat but sampling is diffi cult. Cambarus b. cavatus occurs in several lentic habitats including road rut pools and marshes fed by headwater streams. Th ese habitats are utilized particularly by C. b. cavatus and C. thomai. For most of the watersheds these species are sympatric.
Primary and secondary burrowers occupy large sections of this basin, with the exception of Jackson County. Th e county's fl oodplain is mostly used for agriculture, and both C. thomai and C. b. cavatus appear to respond negatively to such practices. Th us, both species within Jackson County are limited. Th e remaining portions of the basin have restricted amounts of agriculture, and consequently thriving C. b. cavatus and C. thomai populations.
Procambarus acutus and F. fodiens populations occur in the southern portion of the Middle Ohio South and Lower Kanawha border. Th ey are limited to the historic Marietta River Valley, and their absence from the central portions of the basin could be due to lack of immigration corridors. Krodel Park in Point Pleasant needs immediate conservation action; Orconectes virilis populations within Krodel Lake need to be eliminated. Given the small, isolated nature of the lake this action could be performed in an effi cient manner so that future invasions via this source do not occur. In addition, laws regulating invasive species culture in West Virginia are needed to limit aquaculture production of such species.
Native crayfi sh populations are plentiful in ephemeral wetlands in southern portions of the basin; Th e Moose Lodge wetland has the most diverse native fauna along the fl oodplain (Figures 28 and 29). Four species, including P. acutus and F. fodiens, attain high population densities there, where P. acutus populations reach their highest densities for its entire known range in West Virginia. In addition, both C. b. cavatus and C. thomai populations occupy the Moose Lodge wetland complex. Th is represents a rare situation, since no other known location within the state has such a diverse burrowing crayfi sh fauna.

Lower Ohio Basin
Six native crayfi shes comprise the Lower Ohio basin fauna (Table 14). No invasive species are presently in the fl oodplain, but they do reside within the basin. Orconectes rusticus and O. virilis are located sporadically throughout the basin and most likely will appear in the future along the fl oodplain (Jezerinac et al. 1995;Loughman et al. 2009). Th e need to maintain the current native composition of this fauna is of primary conservation importance.
Topographic relief along the fl oodplain reaches its lowest gradient within this basin, producing numerous lentic and lotic habitats conducive to fl oodplain crayfi shes. Th e  Burrowing species reach their highest densities within this basin, particularly C. thomai. Roadside ditches, maple swamps, bottomland forests, and embayments are all utilized by this species. Within lentic habitats Cambarus b. cavatus populations are reduced compared to Middle Ohio South populations. One potential cause for this reduction is the lack of headwater streams within the fl oodplain, with the majority of aquatic habitats being ephemeral lentic pools.
Procambarus acutus was collected only from northern portions of the basin. Historical range limits within the central and southern portions remain unknown and require future investigation. Fallicambarus fodiens populations are disjunct from counterparts in the Middle Ohio South basin, with one population present in the northern reaches and another in the southern portion. Th e northern population is the population reported by Jezerinac and Stocker (1987).
Th e largest F. fodiens fl oodplain population occurs in Greenbottom Swamp, Greenbottom Wildlife Management Area. Greenbottom populations reach their highest densities at Hoeft Marsh. Within the marsh these populations coexist with C. thomai and C. b. cavatus. No invasive crayfi sh were collected from Greenbottom Wildlife Management Area, which is surprising in light of this location's use by anglers. Concentrated sampling eff ort was performed within Greenbottom to locate P. a acutus populations, but none were collected. Crayfi sh diversity in Greenbottom Wildlife Management Area is second only to that of the Moose Lodge wetland, and conservation eff orts should focus on preserving this diversity.

Conservation concerns for West Virginia Ohio River Floodplain crayfi sh populations
Several potential areas of imperilment exist along the fl oodplain, results of destruction and alteration of fl oodplain habitat and invasion of nonindigenous species. Th e following discussion is an assessment of the most relevant conservation concerns confronting Ohio River fl oodplain crayfi shes in West Virginia. Th e connections between crayfi sh conservation concerns suggest that none of the issues is more signifi cant than another, but each of the following requires future research.

Habitat degradation, fragmentation, and destruction
Th e current thinking in conservation biology is to change emphasis of protection of individual species to protection of ecosystems (Groom et al. 2006). Crayfi sh conservation along the Ohio River fl oodplain would benefi t from an integrated management plan. Th e most detrimental impact to fl oodplain crayfi sh populations is anthropogenic manipulation of habitat (Z. J. Loughman, personal observation). Along the fl oodplain, diverse crayfi sh faunas seem to be correlated with contiguous bottomland forest tracts or mature wetlands with buff er zones composed of heterogeneous microhabitats that refl ect limited anthropogenic pressures. Positive habitat attributes are exemplifi ed by the Moose Lodge wetland in Point Pleasant, Mason County, West Virginia, a mature bottomland forest (Figures 28 and 29).
Ephemeral wetlands provided by the Moose Lodge property comprise the most diverse crayfi sh assemblages present on the Ohio River fl oodplain. Four native species, including C. b. cavatus, C. thomai, F. fodiens, and P. acutus and the invasive O. virilis, occur within the wetland. Satellite imagery analysis (Wadsworth and Treweek 1999) indicates riverine bottomland forest comprises 95% of the site with mixed stands of pin oak (Quercus palustris Müenchhausen), silver maple (Acer saccharinum L.), and black gum (Nyssa sylvatica Marsh). Bottomland forest sites, such as Moose Lodge wetland, represent an ecological dynamic unique to ephemeral wetlands. Forest canopies and the allochthonous energy contained within them are important forage for crayfi shes and provide cover in ephemeral pools (Colburn 2004). Th ese stands provide adequate nutrient cycling and shading during active hydroperiods. Forest canopies prolong hydroperiods by reducing evaporation. Hydroperiod length can be extended through late spring and early summer, enabling neonate and juvenile crayfi sh longer forage duration in open water prior to the construction of their initial burrows (Taylor and Anton 1998).
Periphyton growing on abscised leaves and other woody debris in pools has been shown to be a preferred forage of several crayfi shes, producing larger, stronger individuals compared to animal protein or vegetative matter (Charlebois and Lamberti 1996;Chambers et al. 1990). During drawdown the duration and availability of this forage is reduced. When crayfi shes leave open water environments and begin life in the burrow, there is a switch in forage type from periphyton to roots in the burrow proper and various plants and animals that wander near the entrances to burrows (Z. J. Loughman, personal observation). Forage associated with burrow existence is not as readily available as pool periphyton, which results in decreased growth and possible loss of juvenile fi tness. Wetlands lacking forest canopies have shorter hydroperiods. Juvenile crayfi sh in these habitats enter burrows earlier than individuals occupying mature bottomland forests; thus valuable time to forage on periphyton is lost.
Th e importance of hydroperiod in ephemeral wetlands is refl ected in the life history adaptations of burrowing crayfi sh. Primary burrowing crayfi sh generally deposit 4 th stage instars into surface waters in late spring to forage and mature (Hobbs 1942(Hobbs , 1981. As neonates and juveniles disperse they distribute themselves throughout a wetland. Mature bottomland forest pools include a variety of diverse microhabitats, providing sympatric crayfi shes multiple niches to exploit. Heavily impacted ephemeral pools tend to have homogenized microhabitats, which may promote competitive exclusions among crayfi sh populations. Th e Moose Lodge bottomland wetland possesses an array of microhabitats that likely reduce competitive exclusion, allowing for the diverse fauna observed at the site. Buff ers mediate between direct contact with anthropogenic impacts (i.e., roads, industrial sites, houses) and improve site condition, providing more stable, diverse, and increased numbers of crayfi sh populations than those without buff ers (Figure 1). Th ese buff ers range from riparian areas with herbaceous vegetation to small stands of trees with moderately impacted soil. In this study, sites with mature bottomland forests and buff er zones had the highest C. thomai catch-per-unit-eff ort (CPUE), while sites without buff er zones that lacked canopies comprised less stable populations with reduced numbers of individuals ( Figure 30). Sites without buff er zones usually had direct contact with hard surfaces that were impaired by road runoff . Increased water quantity and increased soil conductivity from hard surface runoff s (i.e., road salt and brine) have been linked to disruption during molt cycles with crustaceans (Th orp and Covich 2001). Similar issues could be impacting fl oodplain crayfi sh populations.
Agricultural impacts caused the most extreme anthropogenic stressors, including the clearing of forests and riparian buff er zones, increased usage of chemicals (i.e., pesticides and herbicides), and compacted soils. Cambarus thomai, which was the most prevalent burrowing species along the least-disturbed portions of the fl oodplain, were particularly impacted and reduced at sites associated with agricultural activities (Figure 30). At agricultural habitats crayfi sh burrowing activity ceased, with 97% of agricultural sites lacking any burrowing crayfi sh. Anthropogenic pressures associated with agricultural land use likely work synergistically toward the extirpation of burrowers, but specifi c factors may be more important than others (Z. J. Loughman, personal observation). For example, livestock foot traffi c compacts regoliths and destroys burrow entrances. Grow and Merchant (1980) investigated Cambarus diogenes burrow physiochemical attributes and determined that multiple entrances to a burrow not only off er crayfi sh an extra exit portal but also functioned in replenishing fresh oxygen to the burrow network. As these entrance portals are destroyed by free-ranging livestock, aeration function is lost. Other direct eff ects include crushing of crayfi sh by livestock. Likewise, large amounts of nitrogenous waste are deposited within confi ned animal feedlots (Z. J. Loughman, personal observation) With the conservation goal of preserving diverse fl oodplain crayfi sh populations, protection of remaining bottomland forest habitat in the Ohio River riparian corridor must occur. Less than 10 tracts of bottomland forest remain that are 100 hectares or larger in size. Sites such as Boaz Swamp, Greenbottom Swamp, McClintock Wildlife Management Area, and the Moose Lodge wetland are critical areas in need of protection. Th is action will preserve both crayfi sh diversity and multiple fl oral and faunal communities unique to this habitat.

Invasive crayfi sh populations
Two invasive crayfi shes, O. rusticus and O. virilis, were discovered along the Ohio River fl oodplain. Both species occur throughout the mid-Atlantic region and are responsible for native crayfi sh declines and extirpation (Loughman et al. 2009;Kilian et al. 2010;Loughman and Welsh 2010;Swecker et al. 2010). Th e impact these invasive populations have on primary burrowing species is largely unknown. Invasive populations carry the possibility of new pathogen and parasite introductions into a system. Th is situation has previously been exhibited by the decline of astacid crayfi shes by cambarid introductions into European waterways (Hobbs III et al. 1989;Lodge et al. 2000a). North American primary burrowing crayfi sh likely have evolved alongside possible pathogens. Exposure risk to introduced Orconectes species may be minimized by habitat diff erences. Th ese two groups possess decreased exposure possibilities between primary and tertiary burrowing crayfi shes, which could result in juvenile primary burrowers being exposed to pathogens unique to tertiary burrowers while in river backwaters and ephemeral pools impacted by river pulses. Exposure could result in possible increase in pathnicity should a primary burrower be exposed to unique Orconectes pathogens.
Invasive orconectids impact stream dwellers more extensively than other groups Distefano et al. 2009b;Taylor et al. 1997;Taylor et al. 2007). Species under direct threat along the Ohio River fl oodplain include O. obscurus, O. sanbornii, and C. robustus. Th ese species occupy lotic systems and share resource areas overlapping invasives. Lodge et al. (2000a, b) have shown that invasion by orconectids is two-tiered. Habitat domination causes increased native species physiological stress, as well as increased rates of predation to exposed natives (Lodge et al. 2000a, b).
Impact among Orconectes species results in the production of hybrid swarms (Butler 1988; Lodge et al. 2000a, b). Interspecies mating between native and invasive Orconectes species occurs at increased levels resulting in infertile hybrids. Butler (1988) observed this interaction between O. rusticus and O. sanbornii in Ohio and it is likely this interaction occurs within West Virginia populations.
Orconectes rusticus populations were collected in Ohio River backwaters in Marshall county. All O. rusticus sites were heavily impacted by land use (i.e., nutrient rich agriculture and channelization) and had direct connections to the Ohio River; however, stream confl uences within 1 km north and south of these sites did not harbor O. rusticus populations. Orconectes rusticus reached high densities in these backwater habitats, feeding on the abundance of macrophytes and periphyton. Backwater microhabitats utilized by O. rusticus include shallow, littoral regions. Th is microhabitat provides abundant forage and refugia along large river backwaters. Th e invasion dispersal occurs through smaller stream confl uences with the Ohio River. Understanding the dispersal relationship between invasive crayfi sh and large river system corridors and smaller stream confl uence connections is an important research need.

Natural and Life History Study Needs
Successful conservation of imperiled species is directly correlated with a fundamental understanding of life history parameters and species ecological needs (Groom et al. 2006). Crayfi sh life history diversity is poorly understood. Elucidating diff erent ecological patterns utilized by crayfi shes as life history parameters is an action needed to better understand the biology of these animals (Taylor et al. 1996;Schuster 1997;Taylor et al. 2007). Based on a pool of research, crayfi sh do not have a single life history strategy (Simon et al. 2005;Loughman et al. 2009). Th is is evident in the diversity of speciation events that have occurred within the cambaridae in North America (Hobbs 1942;Hobbs et al. 1969;Hobbs 1981). Many of these events are proving to be cryptic in nature, and only now are being described via genetic analysis (Taylor et al. 2007). One causal agent of speciation is niche occupation and specialization; an act that has occurred repeatedly with crayfi sh in eastern North America (Hobbs 1969). Speciation is directly associated with a change in ecological needs in response to environmental stressors acting on gene fl ow such as geographic barriers, which leads to diversity of natural histories among closely related taxa (Groom et al. 2006).
Organisms respond diff erentially to environmental stressors, and in the case of genetic lineages, diff erent approaches to ecological adaptation can result in the creation of unique forms. Life history models (i.e., primary, secondary, and tertiary burrowers as proposed by Hobbs (1981) have proven reliable and enable niche groupings among species utilizing similar life histories. However, many crayfi shes remain understudied and in many instances unknown. An understanding of diff erent life histories can only increase our knowledge of ecological needs of crayfi shes and allow more effi cient conservation management.
Future Ohio River fl oodplain conservation eff orts should focus on elucidating specifi c aspects of crayfi sh natural histories. Forage preference, macro-and micro-habitat usage, inter-and intra-specifi c interactions, behavioral ecology, and fecundity are just a few natural history parameters in need of determination for many crayfi sh species. Most Ohio River fl oodplain crayfi sh basic life history information such as life span, total possible fecundity, recruitment rates, and foraging preference is unknown. Th e only species within the fl oodplain that have received considerable ecological research include O. rusticus and O. virilis (Capelli 1982;Chambers et al. 1990). Th e focus of these eff orts was to better understand their destructive nature.
Most species, especially non-invasive taxa, have received minimal consideration. One reason for these diff erences in attention is that one or two landmark studies have been performed on species whose life histories are then broadly applied to crayfi sh behavioral groups (i.e., primary or secondary burrowers). For instance, Grow and Merchant (1980) investigated the abiotic realm of C. diogenes, a primary burrower, on the coastal plain of Maryland. Th e ecological theater for C. diogenes on the coastal plain is quite diff erent than that of C. thomai on the Ohio River fl oodplain. Automatically assuming that the needs of these closely related species are the same may mislead an investigator. Studies on a variety of primary burrowing species should be conducted prior to generalizing the ecological requirements of this behavioral group.
Details of Ohio River fl oodplain crayfi sh natural history may provide linkages to the specifi c mechanisms causing species decline. Once specifi c mechanisms are identifi ed, conservation actions can be formulated. Information can be shared among astacologists and government agencies responsible for protecting non-game wildlife. Th ese data can assist in the creation of management plans and their implementation; thus ensuring a rich fl oodplain crayfi sh fauna for future generations.