Conservation, Biology, and Natural History of Crayfishes from the Southern US 2010 Southeastern Naturalist 9(Special Issue 3):33–62 Crayfishes of Western Maryland: Conservation and Natural History Zachary J. Loughman* Abstract - Conservation concerns for imperiled crayfish faunas have recently increased among resource management agencies. In Maryland, major concerns include the introduction of nonnative crayfishes and their impacts on native species. This study documented the species distribution and conservation standing of native and nonnative crayfishes of western Maryland. Native species include Orconectes (Crockerinus) obscurus (Allegheny Crayfish), Cambarus (Jugicambarus) dubius (Upland Burrowing Crayfish), Cambarus (Cambarus) bartonii bartonii (Common Crayfish), and Cambarus (Cambarus) carinirostris (Rock Crawfish). Introduced species are Orconectes (Gremicambarus) virilis (Virile Crayfish), Procambarus (Ortmannicus) acutus (White River Crawfish), and Cambarus (Tubericambarus) thomai (Little Brown Mudbug). Nonnative species were found primarily in areas of high anthropogenic activity, with populations of O. virilis and P. acutus isolated to impoundments. The presence of C. thomai in Maryland was first documented through this study, and represents one of the first situations globally of a primary burrowing crayfish outside of its native range. Major conservation threats to the native crayfish fauna of western Maryland include nonnative crayfishes, land development, and land-use practices. Introduction The diverse crayfish fauna of the Appalachian region is one of the most imperiled animal groups in the United States (Taylor and Schuster 2005; Taylor et al. 1996, 2007). The Appalachian Mountains were the point of radiation for Cambaridae, the largest and most diverse crayfish family (Taylor and Schuster 2005). Within the Appalachians, high levels of endemism resulted in several basal cambarid forms becoming isolated in watersheds throughout the region (Hobbs 1969, Sholtz 2002). High levels of endemism in small watersheds, and an inability to cope with anthropogenic disturbances are two reasons for this high level of imperilment, particularly in the Appalachian region (Taylor et al. 1996). Given the level of imperilment of crayfish faunas within Appalachian watersheds, studies are needed to document species distributions and population status, as well as potential threats to the fauna, such as nonnative species and anthropogenic habitat alterations. Crayfish surveys have occurred within recent years in the southern Appalachian Mountains, with published distribution information available for Kentucky, Georgia, and West Virginia (Hobbs 1981, Jezerinac et al. 1995, Taylor and Schuster 2005), *Department of Natural Sciences and Mathematics, West Liberty University, West Liberty, West Virginia 26704; zloughman@westliberty.edu. 34 Southeastern Naturalist Vol. 9, Special Issue 3 and unpublished studies ongoing in Alabama, Tennessee, and North Carolina. Maryland is also undergoing a surge in astacological research, resulting in updated species distributions and understanding of immediate threats to crayfish conservation (Kilian et al. 2010). The primary goal of this study was to document crayfish distributions in western Maryland (Fig. 1), with an emphasis on introduced crayfish species. A secondary goal was to provide a review of species characters, morphometrics and life history, distribution, natural history and ecology, and conservation concerns of crayfish species in western Maryland. Specific objectives included estimation of species distributions, CPUE, species morphometrics, and life-history parameters. Accounts for species occurring or expected within Garrett and Allegany counties were organized into sections on species characters, morphometrics and life history, distribution, natural history and ecology, and conservation concerns. In some cases, individuals were returned to the laboratory for additional studies of natural history and ecology. Also, this study of western Maryland supplemented data of the Maryland Biological Stream Survey (MBSS; Klauda et al. 1998). This study provides important data for the MBSS surveys of Garrett and Alleghany counties because crayfishes were not a main focus of biotic sampling in the MBSS monitoring program (Millard et al. 2001a, b). Methods Most sites were previously selected by the Maryland Division of Natural Resources as monitoring sites for the Maryland Biological Stream Survey (MBSS; Klauda et al. 1998). The MBSS sites sampled during this study Figure 1. River basins within the Ohio River (grey) and Atlantic Slope drainages of western Maryland. YR = Youghiogheny River, CR = Casselman River, DC = Deep Creek, LY = Little Youghiogheny River, LP = Lower Potomac River direct drains, UP = Upper Potomac River direct drains, SR = Savage River, GC = Georges Creek, WC = Wills Creek, EC = Evitts Creek, TC = Town Creek, FM = Fifteen Mile Creek, and SH = Sideling Hill Creek. 2010 Z.J. Loughman 35 (n = 152) were part of a probability-based sampling program for assessing water quality, physical habitat, and biological conditions (Klauda et al. 1998). Sites for MBSS were on first- through third-order streams stratified by river basin and stream order (Klauda et al. 1998), and were typical of mid-Atlantic stream systems of the Ohio River basin and the Atlantic Slope. An additional 34 sites supplemented the MBSS sites and contributed toward a more comprehensive sampling coverage of western Maryland. All sampling was performed from 15 May–15 Sept 2007. The majority of collections (90%) were performed during June. Seining was the primary collection method for lotic crayfishes (2.43- x 1.54-m minnow seine with 6.35-mm mesh). At each site, 10 seine hauls were performed through a 125-m reach of stream. Values of CPUE were then calculated for stream species for each site from these 10 seine hauls and used to compare and contrast crayfish abundances among and within sites. Catch-per-unit-effort values were analyzed per site and pooled per basin, and ultimately used to determine species conservation standings per basins of 10-digit hydrologic unit codes (HUC 10). All available habitats (riffle, run, glide, pool) were seined. Sites used in data analysis were only sites surveyed through seining. Additional methods used to collect secondary and tertiary burrowers for distributional records included nocturnal searches, hand collecting, dip netting, and snorkeling. Primary burrowing crayfishes were collected using mist-net traps (Welch and Eversole 2006), burrow excavation, and nocturnal searches. Seeps, marshes, and roadside ditches were sampled for burrowers. Mist-net traps were deployed in habitats with large colonies of burrowing crayfish. When mist-net traps were unsuccessful, then burrows were excavated by hand. Burrows with recent activity were excavated, such as those with the presence of chimneys, or fresh mud pellets at burrow portals. Active burrows were excavated with trowels and shovels until an enlarged cul-de-sac, or “resting chamber,” was reached (Hobbs 1981). Once the resting chamber was breached, the burrow was filled with water and plunged with the investigators hand and arm. Crayfishes were usually dislodged with pumping action and then grasped by the investigator from the resting chamber. Crayfishes not dislodged with initial plunges often surfaced after several minutes. Data on burrow morphology were collected on burrows containing crayfish; measurements (cm) included central-shaft depth, resting-chamber width and height, and terminal-burrow depth. Additionally, contents of the burrows were recorded. Captures using the above methods were used to determine which taxa occur in both western Maryland drainages systems. Vouchered crayfish were sexed. Also, the reproductive stage of males (form I or form II) was documented, and in the case of females, the presence and stage of glair were noted. Developmental stage of all ovigerous females, eggs, and instars were recorded. Additional environmental data were collected from each site to aid in elucidating natural history parameters for each 36 Southeastern Naturalist Vol. 9, Special Issue 3 crayfish species. In some cases, it was beneficial to bring individuals into the laboratory for further studies on interactions between native and nonnatives, and for further life-history assessment, such as seasonality of mating and glair glands. Standardized MBSS crayfish data sheets and field jar labels were completed for each study site. One crayfish from each species was vouchered on site in 70% ethanol. Form I males were vouchered when available, followed by females and form II males. In the laboratory, body measurements, including total carapace length (TCL), were recorded with digital calipers (mm) on all preserved crayfishes. The sexual stage of each crayfish was documented as form I male, form II male, or female following Hobbs (1981). Species Accounts Cambarus (Cambarus) bartonii bartonii (Fabricius) (Common Crayfish) (Figs. 2, 3) Species characters. Cambarus b. bartonii were identified by chelae characteristics and coloration. Chelae were nondescript with no ornamentation. Coloration for the majority of animals consists of various shades of brown, ranging from weak beiges to deep chestnuts. In populations near Figure 2. Distributions of Cambarus bartonii bartonii in western Maryland. Black circles indicate presence at a site; white circles indicate absence at a site. Figure 3. Cambarus bartonii bartonii from the Savage River drainage, Allegany County, MD. 2010 Z.J. Loughman 37 Cumberland, Allegany County, the posterior cephalothorax margins were brown grading to slate grey cephalically, and chelae coloration was grey to steel blue. Cambarus b. bartonii is classified as a secondary burrower. Morphometrics and life history. A total of 937 C. b. bartonii were collected in this study, with a male:female ratio of 1.5:1.0. The following morphometric analyses are of vouchered specimens from MBSS sites. Mean TCL for 9 form I males (mean = 31.3 mm, SE = 4.49, range = 12.2–38.9 mm) was higher than that of 56 form II males (mean = 24.4 mm, SE = 4.61, range = 12.1–39.7 mm) and 51 females (mean = 23.8 mm, SE = 7.73, range = 10.6–34.2 mm). The mean TCL of all vouchered specimens was 26.9 mm (n = 116, SE = 7.89, range = 10.6–39.8 mm). Male form was asynchronous and showed no evidence of seasonality. Females showed significant glair development in May and early June. Egg extrusion occurred in mid-July and early August. Ovigerous females were collected in July, and neonate numbers increased dramatically in August and September. Mating was not observed, though previous studies documented no defined breeding season (Hamr and Berrill 1985). Distribution. Cambarus b. bartonii were present in all 10-digit HUC basins of the Atlantic Slope in Garrett and Allegany counties (Tables 1, 2). Although this species occurred in a wide range of lotic environments, it was collected primarily from small streams. Morphological intermediates (possibly hybrids) between C. b. bartonii and C. carinirostris Hay (Rock Crawfish) were observed in the Savage River basin, and may be linked to a stream-capture transfer of C. carinirostris. Ecology and natural history. Cambarus b. bartonii was the only crayfish collected from headwater streams in Atlantic Slope basins of Garrett and Allegany counties. Cambarus b. bartonii were collected from habitats of slab Table 1. Mean CPUE estimates (SD in parentheses) of Cambarus b. bartonii and Orconectes obscurus from Ohio River and Atlantic Slope drainages of western Maryland. Deep Creek basin omitted due to low sample size (1 site). Number C. carinirostris C. b. bartonii O. obscurus Sub-basin of sites mean CPUE mean CPUE mean CPUE Ohio River basins Youghiogheny River 16 1.08 (1.29) 0.00 0.31 (1.18) Little Youghiogheny River 8 0.75 (1.50) 0.00 0.75 (1.54) Casselman River 10 0.50 (0.43) 0.00 0.02 (0.06) Atlantic Slope basins Savage River 18 0.00 0.23 (0.33) 0.45 (0.62) Georges Creek 10 0.00 1.55 (1.83) 0.00 Wills Creek 10 0.00 0.64 (0.80) 0.04 (0.12) Evitts Creek 10 0.00 0.20 (0.26) 1.32 (1.60) Town Creek 20 0.00 0.35 (0.49) 0.42 (0.82) Fifteen Mile Creek 11 0.00 0.77 (1.19) 0.26 (0.50) Sideling Hill Creek 3 0.00 0.35 (0.34) 0.40 (0.12) Lower Potomac River 25 0.00 1.60 (1.38) 0.00 Upper Potomac River 9 0.00 0.60 (4.41) 0.00 38 Southeastern Naturalist Vol. 9, Special Issue 3 boulders, cobble fields, amorphous boulders, and various substrate debris. Plunge pools, eddies, and runs were used over high-velocity microhabitats. Slab rocks and amorphous boulders were commonly used as cover objects and velocity barriers by C. b. bartonii. Crayfish associates collected with C. b. bartonii included Orconectes obscurus (Hagen) (Allegheny Crayfish), O. virilis Hagen (Virile Crayfish), and Procambarus acutus (Girard) (White River Crawfish). Juveniles and adults differed in habitat use. Leaf packs in stream pools produced large numbers of C. b. bartonii juveniles. Five sites in the Georges Creek basin with the highest CPUE values for C. b. bartonii contained leaf packs, and juveniles were the dominant demographic at these sites (Table 1). Periphyton associated with leaf decay likely attracted juveniles (Schofield et al. 2001). Adults were sporadically collected from leaf packs. Adults of C. b. bartonii burrowed in stream banks and benthic stream habitat (Fig. 4). Hardpan and clay banks had high burrow densities, while forested stream sides and gravel banks were rarely used. Burrow architecture of C. b. bartonii consisted of unorganized tunnels, and rarely included resting chambers. Most burrows were positioned in stream banks just above water level at normal flows. Burrows were used during periods of low stream flows. During normal and high flows, no individuals of C. b. bartonii were extracted from burrows. In the latter months of the survey (July–September), several C. b. bartonii were collected from burrows in stream banks, and under exposed slab boulders in stream channels. All occupied burrows contained a single crayfish. Ovigerous females were always associated with burrows under cover objects. Conservation concerns. Cambarus b. bartonii is stable in western Maryland; however, population status varied among drainage basins. Acid mine drainage (AMD), riparian corridor manipulation, and development all appeared to impact C. b. bartonii. Populations were impacted in watersheds Table 2. Presence (X) of crayfish species within sub-basins of western Maryland; Youghiogheny River drainage (YR = Youghiogheny River, LY = Little Youghiogheny River, DC = Deep Creek, and CR = Casselman River), and North Branch Potomac River drainage (SR = Savage River, GC = Georges Creek, WC = Wills Creek, EC = Evitts Creek, TC = Town Creek, FM = Fifteen Mile Creek, SH = Sideling Hill Creek, LP = lower Potomac River direct drains, and UP = Upper Potomac River direct drains). Youghiogheny River North Branch Potomac River Species YR LY DC CR SR GC WC EC TC FM SH LP UP Cambarus b. bartonii X X X X X X X X X Cambarus carinirostris X X X X Cambarus dubius X X X X X Cambarus thomai X Orconectes obscurus X X X X X X X X X X X X X Orconectes virilis X X X Procambarus acutus X X 2010 Z.J. Loughman 39 with AMD, such as the Georges Creek and Wills Creek basins. Within these drainages, crayfishes were absent from large ordered streams with acid mine precipitate. In all situations where AMD effects were present, C. b. bartonii were not collected. Riparian corridor manipulation also represents an important threat to C. b. bartonii. Stream channelization destroys pools and other slack-water environments that are important for juveniles and neonates. Habitat homogenization associated with stream channelization also reduces important C. b. bartonii habitat. Destruction of forests along stream margins reduces forage inputs as well. Large populations of C. b. bartonii were associated with mature mesophytic forest. High-gradient streams in forested environs consistently yielded high CPUE values when compared to areas with deforested headwaters. Cambarus b. bartonii is an adaptable species, capable of persisting in moderately disturbed habitats, and experiences severe declines in association with high pollution levels (Distefano et al. 1991, France and Collins 1993). The preservation of forested streams in Savage River State Forest and Green Ridge State Forest will ensure C. b. bartonii presence in western Maryland. Cambarus (Cambarus) carinirostris Hay (Rock Crawfish) (Figs. 5, 6) Species characters. Coloration and ornamentation of the chelae are traits used to identify C. carinirostris. Chelae are olivaceous brown to forest Figure 4. An unnamed headwater tributary of Town Creek, Allegany County, MD; typical habitat of Cambarus bartonii bartonii. 40 Southeastern Naturalist Vol. 9, Special Issue 3 green. Carapace coloration is always brown, ranging from moderate browns to deep chestnut; walking legs are grey to blue. Abdominal segment margins (terga) are crimson red, with terga bodies olivaceous. Chelae ornamentation includes pronounced dorsal longitudinal ridges, reduced opposable margin widths, and adpressed palmer tubercles. The C. carinirostris in western Maryland are typical of those of other high-elevation areas. Morphometrics and demographics. A total of 334 C. carinirostris were collected with a male:female ratio of 1.6:1.0. Based on vouchered specimens from MBSS sites, form I males averaged 33.5 mm TCL (n = 4, SE = 2.54, range = 31.1–37.9 mm) and were the largest demographic. Measurements of TCL were lower for form II males (n = 51, mean = 25.2 mm, SE = 17.6, range = 15.2–43.9 mm) and females (mean = 28.9 mm, SE = 8.11, range = 13.5–42.2 mm). The mean of pooled TCL measurements for C. carinirostris at MBSS sites was 29.2 mm (SE = 7.89, n = 97, range = 13.5–43.9 mm). Male C. carinirostris undergo an asynchronous seasonal life history, with form I and form II males present year long. Female glair glands become active in April and May. Egg extrusion occurred in late June through July, Figure 5. Distributions of Cambarus carinirostris in western Maryland. Black circles indicate presence at a site; white circles indicate absence at a site. Figure 6. Cambarus carinirostris from the Youghiogheny River drainage, Garrett County, MD. 2010 Z.J. Loughman 41 with an ovigerous female captured on 26 June 2007 in the Casselman River basin. Neonate numbers increased dramatically in late July and early August. Mating may occur all year for this species (Z. Loughman, unpubl. data), but was only observed once during this study—on 24 May 2007 in the Casselman River basin. Amplexus occurred in a burrow (one entrance portal) under an 18- x 30-cm sandstone slab adjacent to the right stream bank, with water temperature of 16.2 °C. Distribution. Cambarus carinirostris occurred in all 10-digit HUC basins of the Youghiogheny River system, and are limited to Garrett County (Table 2). This species was collected in all lotic habitats, but was found most often in headwater systems. Populations with the highest densities, however, were not restricted to headwaters and occurred in Bear Creek, Little Bear Creek, Youghiogheny River, and Mount Nebo Wildlife Management Area. Ecology and natural history. Cambarus carinirostris, a secondary burrower, is an ecological equivalent to C. b. bartonii, and was the only crayfish species collected from headwater streams in Ohio River basins. Unlike C. b. bartonii, C. carinirostris used all available lotic environments, including mainstem habitat of the Youghiogheny River (Fig. 7). Habitats included slab boulders, cobble fields, amorphous boulders, various substrate debris, and slackwater areas. This species did use high-velocity microhabitats more readily than C. b. bartonii. In higher-order streams, C. carinirostris was often associated with O. obscurus. Figure 7. Little Bear Run of the Youghiogheny River, Garrett County, MD. Cambarus carinirostris occurred in all available macrohabitats, while Cambarus dubius colonies were present in seeps adjacent to the stream. 42 Southeastern Naturalist Vol. 9, Special Issue 3 Leaf packs in stream pools were used by juvenile C. carinirostris, similar to findings of C. b. bartonii. Burrowing occurred more often in C. carinirostris than C. b. bartonii. Hardpan and clay banks were environments that maintained high burrow densities, while forested stream sides and gravel banks were rarely excavated. Burrows architecturally were identical to those of C. b. bartonii and occurred along stream margins and in seeps adjacent to streams. Stream seeps were unique habitats used by this species, and harbored a large population within the Mount Nebo Wildlife Management Area. Burrows were used in response to drawdown. During normal and high flows, zero C. carinirostris were extracted from burrows. In the latter months of the survey (July–September), several C. carinirostris were collected from burrows in stream banks, and under exposed slab boulders in stream channels. Multiple occupants per burrow were observed on several occasions in this species, but primarily with juveniles rather than adults. Conservation concerns. Cambarus carinirostris populations are currently stable in western Maryland, though populations have declined in some areas. Future stability however is not certain, given a number of conservation concerns, including habitat destruction, land-use practices, and stream manipulation. Common to all of these threats, and perhaps most pressing of all, is the degradation and destruction of headwater streams in Garrett County (Z. Loughman, unpubl. data). Degradation of habitat includes both manipulation of stream courses and removal of riparian vegetation. Both of these practices are associated with the current flux in development occurring in and around Oakland and Deep Creek, Garrett County. Cambarus carinirostris is capable of surviving developmental perturbations so long as streams are not completely obliterated during construction periods. Unfortunately, many times streams are impacted to the point of local-level extirpation of this species. Several (n = 16) headwater streams were surveyed in areas under current and recently completed development; in all cases, C. carinirostris populations were either depauperate (n = 4) or non-existent (n = 12). Agricultural land-use practices also negatively impact C. carinirostris. Several streams were surveyed (n = 8) running through pasture fields; all of these streams lacked canopies, had nitrogen inputs via cow manure runoff, and did not contain C. carinirostris. These streams not only lacked critical detrital beds, but were subject to above-normal silt loads and high thermal inputs. Complete drawdown in July and August also occurred within most of these sites. While C. carinirostris can survive drawdown conditions, the complete lack of moisture at these sites likely represents a physiological extreme for this species. Direct stream manipulation through channelization, addition of riprap, and dredging also causes species declines. Channelization homogenizes habitat and destroys riffle, run, and pool dynamics and their associated macrohabitats. Loss of habitat diversity toward monotypic habitats likely 2010 Z.J. Loughman 43 leads to intra and interspecific competition for available cover. Riprap along stream banks is less detrimental and, in isolated cases, benefit crayfishes (Z. Loughman, unpubl. data). The problems related to this practice are the destruction of floodplain habitats and the creation of non-erosional stream banks resulting in increased velocities during high flows. Station-holding abilities of crayfish can be maxed by these structures, resulting in downstream displacement and blunt-force trauma (Maude and Williams 1983). Conservation of C. carinirostris in western Maryland should focus on maintaining current protected forests (Glades, Mount Nebo WMA, Garrett State Forest) and increased protection of watersheds within the Ohio River basin. Given the limited range of this species in Maryland, and current landuse trends and development, it is recommended that C. carinirostris receive state-level protection. Cambarus (Jugicambarus) dubius Faxon (Upland Burrowing Crayfish) (Figs. 8, 9) Species characters. Cambarus dubius is a medium-sized crayfish, with most adults ranging from 5–12 cm TL. Carapace coloration is vibrant orange dorsally, grading to pale white or cream along the ventral surface. Walking legs are always cream to white. Chelipeds are blunt with a cristate, ventral propodus margin. Morphometrics and life history. A limited sample size of 6 individuals prevented analysis of demographics and age classes. Sample size was limited given the difficult, time-consuming nature involved in collecting C. dubius. Form I males were not collected, but form II males (n = 3) had an average TCL of 28.2 mm (range = 17.2–34.9 mm). For 3 females, mean TCL was 29.5 mm (range = 19.6–36.9 mm). Many records of C. dubius were procured through the collection of remnants (chelae and carapaces) associated with predation events. The life history of C. dubius in Maryland remains poorly understood, although life-history data of a population at Terra Alta, WV (2.2 air km from Figure 8. Distributions of Cambarus dubius (4) in western Maryland. Black circles indicate presence at a site; white circles indicate absence at a site. 44 Southeastern Naturalist Vol. 9, Special Issue 3 Oakland, MD) likely mirrors that of western Maryland populations (Loughman 2010). No defined breeding season exists for this species, and males, like other cambarids, are seasonally asynchronous in form. Females show increased glair development throughout spring into late June. Egg extrusion occurs in June and July. Unlike other crayfish native to the region, C. dubius egg counts are low, averaging 40 eggs per female in neighboring West Virginia populations. Neonates stay in female burrows after leaving their mothers’ abdomens for several molts, ultimately leaving burrows and creating their own (Z. Loughman, unpubl. data). Distribution. Cambarus dubius is common throughout the Allegheny Mountain province of Garrett County when its habitat is available (see section on ecology and natural history below). Populations become scarce along the junction of the Allegheny Front and Ridge and Valley Province. Disjunct populations occur in extreme western portions of the Ridge and Valley Province, and are limited to mesic forests and forested seeps. Xeric conditions found throughout the Ridge and Valley Province limit the eastern distribution of C. dubius in Allegany County. In the Ridge and Valley Province proper, C. dubius is absent. Ecology and natural history. Forested seeps, roadside ditches, marshes, and bogs were all macrohabitats used by C. dubius, a primary burrower. Large colonies were associated with the following environmental parameters: partial to complete forest canopies, groundwater supplies, and loamy soils. Populations were limited in size within anthropogenically disturbed habitats. The most important variable for C. dubius was forest canopy. Canopies aid in retention of moisture and halt desiccation, provide forage (abscised leaves), and add complexity to ecological systems harboring C. dubius (Colburn 2004). Only one crayfish species, C. carinirostris, occurred sympatrically with C. dubius. Cambarus dubius burrows were complex with the following two distinct morphologies: single or multiple entrance portals. Single portal burrows Figure 9. Cambarus dubius from the North Branch Potomac River drainage in Garrett County, MD. 2010 Z.J. Loughman 45 consisted of central shafts (0.2–0.4 m depth) ending in a resting chamber (Fig. 10). Many central shafts had additional lateral tunnels leading to various bifurcations. The ventral surfaces of resting chambers had as few as one and as many as six tunnels radiating in different directions. Crayfishes in burrows were always extracted from ancillary tunnels. The second morphology had the same architecture as previously mentioned burrows, but consisted of multiple burrow entrances. Entrances either had their own central shafts, or met at bifurcation points to common central shafts. Burrow complexity made extraction of C. dubius via excavation a destructive and time-consuming venture. Most C. dubius (98%) were collected with mistnet traps and through nocturnal searches. Populations of C. dubius in western Maryland appear to require forested seeps, and typically used two distinct seep communities, Golden Sacsophrage/Service Berry and Skunk Cabbage/Red Maple seeps. In these situations, burrow portal densities reached 8 burrows/m2. Loamy soils are easily manipulated by burrowing crayfishes, and associated seep hydrology enables C. dubius to persist in burrows with varying levels of water inundation. Geology associated with seeps also ensures shallow water tables that are easily reached by C. dubius during periods of drawdown and drought. Relict colonies of C. dubius occur in agricultural and developed areas, with several occurring in and around Oakland, Garrett County. Burrow portal densities were limited relative to forest colonies, and occurred primarily in low-lying areas in agricultural fields and residential yards. Possibly, seeps supported these colonies before land development, and the colonies persisted throughout the development process. Roadside ditches were the only anthropogenic habitat that produced large colonies of C. dubius. Given the hydrologic use of roadside ditches, these environments represent conditions similar to those produced by seeps. Like seep populations, larger populations in roadside ditches occurred in association with complete forest canopies and moderately disturbed soils. Cambarus dubius were nocturnal, and activity peaked after rain events. On 17 May and 23 May 2007, C. dubius were observed actively foraging Figure 10. Typical burrow of Cambarus dubius from the North Branch Potomac River drainage, Garrett County, MD. 46 Southeastern Naturalist Vol. 9, Special Issue 3 at burrow portals immediately following a 30-min downpour. One particular site 2.1 km south of Oakland was visited, and C. dubius were observed moving throughout a roadside ditch. Increased movement was coupled with burrow inundation and occurred in temporary pools created by rain. No diurnal activity was observed in this species. Conservation concerns. Forest fragmentation and degradation are the most prominent threats to populations of C. dubius in western Maryland. Given the discrete metapopulation dynamics associated with forested seeps (Colburn 2004), destruction of these macrohabitats leads to destruction of entire C. dubius colonies. Contiguous tracts of protected forest, like Mount Nebo WMA and Garrett State Forest, protect substantial numbers of C. dubius colonies. Preservation of these forests is important for the stability of C. dubius in western Maryland. Development of agricultural and residential lands represent important threats, because alteration of wetland hydrology may lead to dessication of seeps and extirpation of C. dubius colonies. Cambarus (Tubericambarus) thomai Jezerinac (Little Brown Mudbug) (Figs. 11, 12) Species characters. Cambarus thomai were readily identified by the presence of disorganized tubercles on the mesial margins of palms and Figure 11. Distributions of Cambarus thomai in western Maryland. Black circles indicate presence at a site; white circles indicate absence at a site. Figure 12. Cambarus thomai from McHenry, Garrett County, MD. 2010 Z.J. Loughman 47 dorso-laterally compressed cephalothoraxes. Polymorphic C. thomai displayed brown, amber, or green color phases. Cambarus thomai also were the largest burrowing Cambarus observed in Western Maryland, with total body length up to 16 cm. Morphometrics and life history. The sample size of C. thomai was small (n = 18) owing to difficulties with collection (i.e., burrow excavation). The male-to-female ratio was 1.0:1.1. The sample comprised a single form I male (TCL = 38.6 mm), 7 form II males (mean TCL = 31.2 mm, SE = 7.40, range = 19.3–39.1), and 9 females (mean TCL = 33.6 mm, SE = 5.12, range = 22.9–43.9 mm). Pooled TCL measurements averaged 30.6 mm (SE = 6.51, range = 11.4–43.9 mm). Male form was asynchronous and showed no evidence of seasonality. During summer months (June–August), female glair glands were inactive, but collections in September showed beginnings of activity. Glair glands of captive females displayed an increase of activity beginning in November and were 100% active in December. A population of C. thomai on the Ohio River floodplain extruded eggs in February and March, and showed increased levels of surface activity during this time (Z.J. Loughman, pers. observ.). It is highly likely that populations near McHenry also exhibit this pattern. Juveniles use littoral zones and other shallow water microhabitats. On 14 September 2007, a form I male and a female were extracted from the same burrow, but mating was not observed. Distribution. Historic distribution records of C. thomai in western Maryland are likely listed in the literature as Cambarus (Lacunicambarus) diogenes Girard (Devil Crayfish). Faxon (1885) recorded C. diogenes in western Maryland at Deer Park, Garrett County. Ortmann (1906) examined these specimens and declared the records erroneous. In the 1980s, additional distribution records of C. diogenes were reported from western Maryland in the northern reaches of Deep Creek Lake, McHenry (A.W. Norden, Maryland Department of Natural Resources, Annapolis, MD, pers. comm.), but this was before the species description of C. thomai by Jezerinac (1993). Specimens from Maryland were not reviewed in the species description (Jezerinac 1993). Loughman (2007) collected C. thomai from northern reaches of Deep Creek Lake, the first documentation of this species in Maryland. Historic records depict the eastern border of C. thomai’s range as the foothills of the western Allegheny Mountains in West Virginia and Pennsylvania (Jezerinac 1993). In my study, C. thomai were only collected around Deep Creek Lake in areas of heavy anthropogenic use, specifically near the town of McHenry (Figs. 13, 14). In neighboring habitat typical of the region, the only other primary burrower collected was C. dubius, primarily from roadside ditches and forested seepage wetlands. Given that the historic range excludes Maryland and all individuals were collected near Deep Creek Lake, strong evidence exists for an introduced residence standing for C. thomai in Maryland. This report represents the first documented introduction of a 48 Southeastern Naturalist Vol. 9, Special Issue 3 North American primary burrowing crayfish outside of its native distribution range. Conservation impacts are unknown for introduced populations of burrowing crayfish, though competitive interactions with sympatric native species are expected. Ecology and natural history. Cambarus thomai, a primary burrower, occurred in marshes, roadside ditches, and flooded fields. The largest Figure 13. Typical burrow portal of Cambarus thomai near Seng Run Road, McHenry, Oakland County, MD. Figure 14. Site of the largest C. thomai colony adjacent to Seng Run Road, McHenry, Oakland County, MD. Crayfishes burrowed along ditch margins and in yard proper. 2010 Z.J. Loughman 49 population occurred in a residential yard and adjacent drainage ditch. Ditch margins harbored more burrows than the yard proper. Burrows in marshes were linked to areas of high ground and margins between marshes and successional forest. Regions of the marsh that frequently were inundated with water did not possess burrows. In one situation, burrows of C. thomai were observed in hardpan habitat associated with stream margins. Crayfish associates collected with C. thomai included P. acutus and O. virilis. Like C. dubius, C. thomai were collected from colonies. The number of burrows/colony was directly correlated to available habitat. Limiting factors coupled with habitat availability were soil type and weedy vegetation abundance. Burrows of C. thomai were not observed in areas with herbaceous plants and dense root wads; hence, the species may not burrow in this habitat. Burrow complexity was moderate, and burrow depth was directly associated with water table depth. At the Seng Run site, burrow depth ranged from 0.25 m to over 1.25 m. Burrows primarily had single entrance portals (29 of 36, 82%), but some multiple burrow entrances (7 of 36, 18%) occurred as well. Central shafts ranged in size, and composed 60–70% of overall burrow depth. Central shafts of burrows in ditch margins ran laterally with the surface, ending in resting chambers. Resting chambers were large relative to crayfish size and, in many instances, packed with vegetation. Ancillary tunnels originated out of the lateral portions of chambers more frequently than chamber floors. The diameter of entrance portals differed between burrows of C. dubius and C. thomai. The largest entrance portal diameter (74.1 mm) of adult C. thomai exceeded those of C. dubius (54.1 mm) and P. acutus (61.0 mm). Cambarus thomai burrows often had debris “aprons” at entrance portals (32 of 36; 90%) (Fig. 13). Cambarus thomai were nocturnal, with higher surface activities linked to rain events. Rates of CPUE with mist-net traps were highest after rain events (n = 28 traps, 25% capture rate); No individuals of C. thomai were collected by this method during drought conditions. During periods of high (>70%) relative humidity, C. thomai were observed resting and foraging at entrance portals at night (22:00 h–02:00 h). Maryland’s population is tolerant of cold temperatures; on 9 November 2007, C. thomai were observed creating chimneys and resting at burrow portals during air and soil temperatures of 2.7 °C and 5.9 °C, respectively. Burrow activity of a colony on the Ohio River floodplain ceased when air temperatures dropped to 4.1 °C (Z. Loughman, unpubl. data). Conservation concerns. The mechanism for C. thomai introduction is unknown, but bait-bucket introduction seems unlikely, given the intensive collection efforts of burrow excavation. Large numbers of C. thomai, however, can be trapped in late winter through early spring (Loughman 2010). During this time, form I males and ovigerous females increased surface activity and 50 Southeastern Naturalist Vol. 9, Special Issue 3 used river backwaters and ephemeral wetlands (Loughman 2010). Other possible sources of introduction include the transfer of neonates by boat ballast water, and possible transfer of entrapped adults in soil transported to Maryland from C. thomai native range. Cambarus dubius populations in developed areas around Deep Creek Lake are the only populations that likely would be negatively impacted by C. thomai. Cambarus thomai does not commonly use forested seeps, bogs and fens, and high-gradient stream banks, all habitats of C. dubius. Monitoring efforts should be initiated to track any future immigration of C. thomai into suitable habitat adjacent to McHenry, MD. Orconectes (Crockerinus) obscurus (Hagen) (Allegheny Crayfish) (Figs. 15, 16) Species characters. Orconectes obscurus has a shoulder on the cephalic base of the mesial margin of the first form gonopod, the primary key character used to identify this species. Secondary key characters include red highlights on the chelae and setiferous setae along the posterior edge of the propodus. Carapace coloration ranges from beiges to chestnut brown. Figure 15. Distributions of Orconectes obscurus in western Maryland. Black circles indicate presence at a site; white circles indicate absence at a site. Figure 16. Orconectes (C.) obscurus from Evitts Creek drainage, Allegany County, MD. 2010 Z.J. Loughman 51 Populations in the Casselman River are aberrant from the norm, with steel grey carapaces and chelae. Morphometrics and life history. A total of 530 individuals of O. obscurus were collected in this study, and the male-to-female ratio was skewed towards females (0.29:1.0). Morphometric data were analyzed from vouchered specimens from MBSS sites. The mean of 25 form II males (mean = 27.1 mm, SE = 7.58, range = 12.5–39.3 mm) was smaller than that of 41 females (mean = 28.3 mm, SE = 6.61, range = 11.9–42.0 mm). Zero form I males were vouchered. The mean of 166 pooled TCL values averaged 28.2 mm (SE = 8.63, range = 11.9–42.0 mm). The life history of O. obscurus in western Maryland is similar to other mid-Atlantic populations described by Jezerinac et al. (1995) and Fielder (1972). Males overwinter in the form I stage, and breed during spring after winter brumation. After spring mating, males molt into form II by early June, and proceed through most of the summer in this condition. Ovigerous females were collected in May and early June, and were the only demographic to readily use cover objects as refugia. Females carried eggs and instars for 2–3 weeks, followed by separation of the female and neonates. During summer collecting, young-of-the-year first appeared in seine hauls during the first two weeks of July. Beginning in late July and early August, males underwent summer molt into form I condition. An increase in mating efforts was observed from late summer through fall until the start of winter brumation. Mating frequency was higher in the fall than in the spring mating season. Distribution. Orconectes obscurus, the most widespread crayfish in western Maryland, occurs in all major river systems, except those impacted by AMD and extreme siltation (Tables 1, 2). Large populations occur in Casselman River, Little Youghiogheny River, Youghiogheny River, and Evitts Creek watersheds. The CPUE estimates were low at the MBSS site on Evitts Creek (Table 1), but population sizes were higher at alternate sites. Georges Creek and Wills Creek had reduced or limited populations of O. obscurus. Ortmann (1906) questioned the origin of Atlantic slope populations of O. obscurus. During several collection trips throughout the region in the late 1800s, Ortmann (1906) collected O. obscurus in only one Potomac River tributary, i.e., Wills Creek. Stream piracy is documented in upper Wills Creek between the Ohio and Atlantic Slopes; however, piracy is often associated with smaller headwater streams not conducive to O. obscurus. Ortmann (1906) hypothesized that O. obscurus was introduced by fisherman to the Atlantic Slope. Recently, Bouchard et al. (2007) performed a series of surveys in eastern Pennsylvania, and supported Ortmann’s nonnative resident standing for O. obscurus. Jezerinac et al. (1995) treated O. obscurus as a native species in Atlantic Slope systems in West Virginia. Native status of O. obscurus in Atlantic Slope drainages could result from the historic series of stream piracies between the Greenbrier River system 52 Southeastern Naturalist Vol. 9, Special Issue 3 (Ohio) and the South Branch of the Potomac River (Atlantic Slope) along the Appalachian front in West Virginia. Streams in the headwaters of the Greenbrier River watershed harbor O. obscurus populations captured from the Cheat River, part of the greater Monongahela River system of the Ohio River basin. Ortmann (1906) commented on the lack of O. obscurus in the Casselman and Youghiogheny river systems. These watersheds are within the confines of the Ohio River system, and currently have O. obscurus populations. During Ortmann’s collections, both rivers were impacted by AMD and other degradation (J. Kilian, Maryland Division of Natural Resources, Annapolis, MD, pers. comm.); hence, O. obscurus populations were likely reduced at that time, but have since rebounded with water quality improvements. The current study found moderate to high abundances of O. obscurus throughout the Ohio River system when adequate habitats were available. Ecology and natural history. Orconectes obscurus, a tertiary burrower, occurred in mid- to high-ordered streams and reservoirs throughout western Maryland. Individuals used boulders, slabs, and interstitial spaces between substratum objects. Typical of tertiary burrowers, O. obscurus showed preference for large slabs in low-velocity stream reaches. Orconectes obscurus was not often found in high-velocity areas, with the largest populations occurring in runs, glides, and pools. Populations in impoundments were associated with riprap and boulders, and rarely occurred in palustrine habitats of coves. Within stream pools, high densities of O. obscurus were observed in leaf packs. This habitat provides both forage (periphyton) and cover; juveniles and neonates were collected in these situations more often than adults. The burrows of O. obscurus were simple, consisting of weak depressions under boulders. Interstitial spaces between cobbles and boulders represent important microhabitats for O. obscurus, and were used more readily than burrows for cover. In several sites (Casselman River, Little Youghiogheny River, Youghiogheny River), O. obscurus were observed cruising in pools during mid-day, and were the only crayfish that demonstrated diurnal behaviors. Crayfish associates collected with O. obscurus included C. b. bartonii, C. carinirostris, O. virilis, and P. acutus. Conservation concerns. Currently, O. obscurus is stable in western Maryland. Conservation concerns include invasive species, siltation, riparian corridor manipulation, and land-use practices. Orconectes virilis threaten O. obscurus populations in western Maryland. Great Valley and Piedmont populations of O. obscurus in Maryland have already experienced population declines caused by this aggressive invasive crayfish (Jay Kilian, pers. comm.). Orconectes virilis impact O. obscurus through competitive exclusion for refugia. Increased predation rates occur under these situations, resulting in population declines of O. obscurus. The impacts of O. virilis on O. obscurus will likely be lessened if habitat degradation issues are controlled. In neighboring Berkeley County, WV, 2010 Z.J. Loughman 53 homogenized stream habitats possessed only O. virilis (Z. Loughman, unpubl. data). Streams with multiple macrohabitats enabled O. obscurus to occur sympatrically with O. virilis, though population levels were reduced (Z. Loughman, unpubl. data). Populations of O. obscurus in basins of western Maryland’s Atlantic slope will likely experience declines prior to those in basins of the Ohio River drainage. Topographic relief is reduced in the Atlantic Slope region, resulting in lower stream gradients. Previous research on station holding in O. virilis indicated that high-velocity environs select against individuals of O. virilis (Maude and Williams 1983). Faster stream velocities and higher gradients that occur in Ohio River drainage basins represent a physiological filter against the establishment of O. virilis. Habitat manipulation, especially in riparian corridors, increases siltation rates. Siltation impacts crayfish physiologically and behaviorally. Physiological impacts result from silt particles clogging branchial chambers and reducing podobranch function (Taylor et al. 2007). Chemicals and heavy metals in silts are then transferred to the blood, resulting in a diminished physiological state (Taylor et al. 2007). Silt fills interstitial spaces of benthic habitat, reduces available refugia, and increases competition for available cover. Stress associated with territorial bouts leads to decreased immune systems, allowing the previously mentioned physiological impacts to take an even stronger hold (Schuster 1997, Taylor et al. 2007). Acid mine drainage and other impacts associated with coal mining cause declines and extirpation of O. obscurus. Low CPUE values for O. obscurus were recorded from the Wills Creek, Sidling Hill Creek, and Georges Creek drainage basins (both AMD streams), and in many instances O. obscurus were absent at sites on these streams (Table 1). The morphology and gradient of Georges Creek are ideal for O. obscurus; however, low CPUE values or species absence are linked to AMD (Table 1). Orconectids do not display ample station holding abilities (Maude and Williams 1983); this aspect of O. obscurus biology explains its absence from the Savage River system. Stream flows and gradients are elevated compared to other basins harboring O. obscurus, especially during periods of high flow, making Savage River streams inhospitable to most O. obscurus. Orconectes (Gremicambarus) virilis Hagen (Virile Crayfish) (Figs. 17, 18) Species characters. Orconectes virilis possesses long terminal elements on the form I gonopod. Orconectes virilis has a bi-colored cephalothorax with the anterior portion chestnut-brown, and the posterior portion darkerbrown. Chelae coloration is diagnostic in this species. Green is the coloration of the bulk of chelae, with tuberculations highlighted in golden-yellow. Morphometrics and life history. A total of 59 O. virilis were collected in this study, with a male-to-female ratio of 1.1:1.0. Low sample size was attributed to their lentic habitat and the collection method (minnow traps and haphazard search). The mean TCL value of 4 vouchered form I males (41.1 54 Southeastern Naturalist Vol. 9, Special Issue 3 mm, SE = 8.40, range = 34.9–48.8 mm) exceeded that of 16 form II males (32.4 mm, SE = 5.91, range = 23.3–41.6 mm) and 38 females (29.5 mm, SE = 7.61, range = 20.4–46.6 mm). The mean of pooled TCL values was 31.9 mm (SE = 8.50, range = 20.4–48.8 mm). The life history of O. virilis is the least understood of all western Maryland crayfishes. Sampling efforts during spring and summer produced zero ovigerous females, indicating egg extrusion possibly occurs in the fall or winter. This is further supported by the complete absence of glaired females during summer months. Form II males dominate male demographics during the late spring–summer seasons, though terminal molt form I males were collected during the duration of the study. Form I males were collected during fall collecting trips, indicating form shifts occur in late summer and early fall. Future work in the region should elucidate lifehistory specifics of this species. Distribution. In western Maryland, O. virilis is limited to impoundments. Impoundments harboring O. virilis included Deep Creek Lake, Figure 18. Orconectes virilis from Deep Creek Lake, Garrett County, MD. Figure 17. Distributions of Orconectes virilis in western Maryland. Black circles indicate presence at a site; white circles indicate absence at a site. 2010 Z.J. Loughman 55 Youghiogheny River Lake, New Germany State Park Lake, and Lake Habib (Rocky Gap State Park). Orconectes virilis were not collected in Savage River Reservoir, Herrington Manor Lake, and Mountain Lake Park, although non-detection does not necessarily indicate an absence of O. virilis from these waterways, and additional monitoring efforts are warranted for this invasive species. In eastern Maryland, O. virilis is widespread and causing high extirpation rates of native crayfish species (Kilian et al. 2010, Schwartz et al. 1963). Eastern populations are present in lotic systems; however, western Maryland populations are known from only lentic systems. Extensive surveys did not find individuals in lotic waterways in Garrett and Allegany counties. Ecology and natural history. Orconectes virilis, a tertiary burrower, was found solely in impoundments in western Maryland, and natural history data are reported below for a population in Deep Creek Lake. Orconectes virilis were found most often in complex macrohabitats, and individuals were rarely observed in homogenous lake-bottom habitats. An ontogenic habitat shift occurred from juvenile to adult O. virilis. Large numbers of young-of-the-year were observed foraging in palustrine systems. Juveniles and neonates were sampled most often from macrophytes. Juveniles were observed in riprap fields, but at lower abundances than that of adults. Adults had highest CPUE values from riprap areas (CPUE = 3.3/minute search time), including riprap at bridge abutments (CPUE = 2.7/minute search time). During nocturnal snorkeling, O. virilis were observed in large numbers grazing on detritus and periphyton in interstitial spaces and cavities of riprap. Orconectes virilis were not observed on boulder surfaces; all used boulder recesses. Crayfish associates collected with O. virilis included C. thomai, O. obscurus, and P. acutus. Burrow construction was simple, and typical of tertiary burrowers. During active hydroperiods, O. virilis burrows consisted of shallow depressions under boulders. Drawdown resulted in O. virilis exposure on mudflats. Burrows under this condition were more complex, consisting of short (5–15 cm) central shafts leading to resting chambers. Gregarious use of burrows was observed. In 3 instances, form I males and females were extracted from the same burrow. Orconectes virilis are opportunistic omnivores, and were observed feeding on periphyton, detritus, carrion, and smaller conspecifics. In the laboratory, aggressive behaviors toward sympatric crayfishes were observed only in the presence of food sources, and not over retreats. During these interspecific bouts, O. virilis killed their competition (O. obscurus or P. acutus) in 82% of interactions, and then proceeded to feed. Defense of burrows did not result in as many casualties of native species, but did result in increased levels of exposure to extraneous environmental factors. Conservation concerns. Populations of O. virilis in impoundments are possibly controlled, in part, through winter drawdown. The Youghiogheny 56 Southeastern Naturalist Vol. 9, Special Issue 3 and Deep Creek impoundments undergo seasonal drawdown beginning in the fall and ending in the spring. Orconectes virilis often forage in littoral zones of lentic habitats. Following drawdown, littoral zones quickly become exposed, isolating O. virilis to the few microhabitats where water persists. Evidence of this drawdown isolation occurring was observed on 24 September 2007 in Deep Creek Lake at the McHenry Marina. Several coves and palustrine habitats inundated during spring and summer months were 100% desiccated and exposed. In many situations, open water was in excess of 20 m from adequate microhabitats. Orconectes virilis utilized large pieces of riprap for refugia, with the largest stones having the highest numbers of residents underneath. In one instance, 7 O. virilis utilized a riprap boulder (1.1 x 1.3 m). Orconectes obscurus and P. acutus also utilized riprap, but were outnumbered by O. virilis in all situations. Orconectes virilis constructed shallow depressions and vertical shafts and used burrows in response to further drawdown. During winter, western Maryland experiences high freeze rates and extensive snow falls. The ability of O. virilis to survive under these conditions is questionable, and it is likely that large numbers of O. virilis perish under the exposed conditions of winter drawdown periods. Range expansions downstream from impoundments may be controlled by water velocities of high-gradient stream reaches. High-gradient systems limit O. virilis in its native range, and likely explains the disjunct nature of this species in western Maryland. Maude and Williams (1983) documented the inability of O. virilis to maintain station in high-velocity water. The spillways of all known impoundments housing O. virilis empty into highvelocity situations. Blunt-force trauma and predators likely eliminate the majority of animals able to escape impoundments. Orconectes virilis that survive these threats would persist in stream pools and runs; however, highwater events threaten these individuals. Environmental parameters present in western Maryland simply are not conducive to O. virilis, and in essence could work as a natural control mechanism. Moderate- to low-gradients streams in the Ridge and Valley Province, however, are likely susceptible to invasion of O. virilis. Orconectes virilis in lotic systems have caused severe declines and local extirpations of O. obscurus in eastern Maryland and across the mid-Atlantic region (Schwartz et al. 1963). If O. virilis were able to populate streams in Garrett and Allegany counties, then it is likely that O. obscurus populations would undergo declines. Cambarus carinirostris and C. b. bartonii would undergo declines in streams harboring O. virilis, but would persist in headwater streams given the aversion of O. virilis to headwater habitats. Orconectes virilis eliminates native crayfish populations through competitive exclusion (Schwartz et al. 1963). Ideal refugia (amorphous boulders, slab boulders, cobble complexes) occupied by native crayfishes, particularly orconectids, are monopolized by adult O. virilis. Suboptimal habitats (leaf packs, boulder crevices, side-channel pools) then represent the best available 2010 Z.J. Loughman 57 habitats for native crayfishes. These habitats are often occupied by juvenile and sub-adult O. virilis, ultimately limiting their use by native species. Through this complete domination of resources, native crayfishes are left exposed leading to increased predation rates. Stress associated with exposure has also been documented in lowering immune systems leading to high incidence of disease (Lodge et al. 2000). Procambarus (Ortmannicus) acutus (Girard) (White River Crawfish) (Figs. 19, 20) Species characters. Procambarus acutus was the only Procambarus species found in western Maryland. Key characters used to identify P. acutus include narrow elongated chelae, bumps along the branchial region of the cephalothorax, and a maroon wedge running along the abdomen. Procambarus acutus are deep-maroon in coloration. Procambarus (O.) zonangulus Hobbs and Hobbs (Southern White River Crawfish), a close relative of P. acutus, occurs in eastern Maryland. Differentiating between Figure 19. Distribution of Procambarus acutus in western Maryland. Black circles indicate presence at a site; white circles indicate absence at a site. Figure 20. Procambarus acutus from Deep Creek Lake, Garrett County, MD. 58 Southeastern Naturalist Vol. 9, Special Issue 3 these species is difficult, and can only be done with form I males. All animals collected in this study keyed out as P. acutus following characters described by Hobbs and Hobbs (1990). Given P. zonangulus’s high incidence of invasion in eastern Maryland, it is likely that populations of P. zonangulus persist in western Maryland as well. Morphometrics and life history. A large and widespread population of P. acutus occurs in Deep Creek Lake. A total of 23 individuals were collected from Deep Creek Lake with a male-to-female ratio of 1.2:1.0. Form II males were the largest demographic, with a mean TCL (mean = 32.1 mm, SE = 9.24, range = 16.5–45.6 mm, n = 11) lower than that of form I males (mean = 43.2 mm, SE = 4.57, range = 37.3–55.2 mm, n = 3) and females (mean = 24.3 mm, SE = 10.0, range = 18.3–57.5 mm, n = 9). The mean TCL of pooled distances of all P. acutus was 30.3 mm (SE = 11.30, range = 9.3–57.5 mm, n = 23). Male sexual stage is asynchronous with season in this species, with both form I and form II males collected during the spring, summer, and fall seasons. Female glair glands were not active through the spring and summer, but were showing initial activity throughout the fall. Juvenile P. acutus were collected in May and June. Given the activity of glair glands in the fall, and the presence of juveniles in May and June, it is likely that females extrude eggs in late winter and early spring. Mating by captive individuals occurred during all seasons. Distribution. Like O. virilis, P. acutus is an introduced species limited to impoundments in western Maryland. Procambarus acutus were found only at Deep Creek Lake and Youghiogheny River Lake, which supports bait-bucket introduction of this species. Future survey efforts likely will find this species in lentic situations throughout western Maryland. Procambarus acutus is not able to hold station in high-gradient systems; this physiological filter likely inhibits P. acutus expansion via lotic waterways, and will likely limit it to lentic systems in Garrett and Allegany counties. Ecology and natural history. Procambarus acutus is classified as a secondary burrower. Within Deep Creek Lake, P. acutus were associated with coves and palustrine habitats. Macrophyte beds provided microhabitat and forage for this species. Winter drawdown, and the resulting exposure of mudflats is likely an important mechanism of control for this species. Procambarus acutus populations were healthiest in coves that do not experience severe drawdown effects, and depauperate in coves experiencing severe drawdown exposure. Protected coves under these conditions produced the largest individuals, indicating the possible presence of source-sink dynamics for this species in Deep Creek Lake. Within coves, P. acutus were observed nocturnally foraging on macrophytes, periphyton, and carrion. Juveniles foraged on detritus in shallow areas of coves, and were the most abundant crayfish in palustrine settings. Cover objects were used sparingly by this species—one behavioral difference when compared to O. virilis, which used lake cover objects. Whether 2010 Z.J. Loughman 59 this represents competitive exclusion for refugia or a habitat preference remains unknown. Procambarus acutus burrowed readily within habitat. Burrow density was highest in marshes and earthen walls. Architecture of the majority of burrows was simple, with central shafts ranging from 0.25–1.25 m ending in enlarged resting chambers. Very few lateral tunnels were present in P. acutus burrows, and when present, were always lateral extensions of the resting chamber. Several burrows were constructed in exposed mudflats, and were occupied after drawdown. Burrowing behavior likely represents an important survival mechanism for animals trapped in exposed mudflats. Crayfish associates collected with P. acutus included C. thomai, O. obscurus, and O. virilis. Conservation concerns. Given the introduced status of P. acutus in western Maryland, conservation efforts should focus on control and possible reduction of this species. Procambarus acutus often occurs in marshes and shallow areas of lakes; hence, this species may not populate lotic systems in western Maryland. Annual winter drawdown of Deep Creek Lake likely represents an important control mechanism. Exposed crayfishes freeze over the course of winter, and death rates are likely high with those burrowing in mudflats during severe winters. The weak station-holding abilities of P. acutus limits colonization of high-gradient systems. Procambarus acutus may, however, escape Deep Creek Lake and invade high-elevation wetlands (e.g., Cranesville Swamp, the Glades). Given the absence of aquatic fish predators from these wetlands, it is possible that P. acutus would become established. Physiological control mechanisms, however, are in place at these wetlands (extended winter condition into early summer months) that likely would aid in halting their establishment. Future control efforts should focus on educating fishermen on proper elimination of leftover bait, and more importantly, the dangers associated with transferring crayfishes from one water body to another. Cambarus (Jugicambarus) monongalensis Ortmann (Blue Crawfish) Cambarus monongalensis is not documented from Garrett or Allegany counties by this or previous surveys, but a species account is provided given expectations for the presence of this species in western Maryland (Meredith and Schwartz 1960). Considerable effort was undertaken in this survey to locate C. monongalensis populations. While suitable habitat exists in Garrett County, no specimens were captured, and no evidence supports the occurrence of C. monongalensis in western Maryland. Biogeographically, the eastern most populations of C. monongalensis occur in Pennsylvania on the western face of Chestnut Ridge Mountain (Ortmann 1906). This north-central Appalachian ridge represents the southern limit of C. monongalensis, and the northern limit of C. dubius. The only region of range overlap between C. monongalensis and C. dubius 60 Southeastern Naturalist Vol. 9, Special Issue 3 occurs in Pennsylvania (Ortmann 1906). Cambarus dubius is an ecological equivalent to C. monongalensis, and replaces this species between 579 and 915 m elevations in West Virginia. Given that this region of replacement encompasses the highest elevations observed in western Maryland, then C. dubius would likely replace C. monongalensis in similar elevations present in western Maryland. Cambarus monongalensis, if it does exist in western Maryland, possibly could occur in the northwest corner of Garrett County, in the vicinity of Friendsville, west of Chestnut Ridge. This region geographically is closest to the point of sympatric interaction in Pennsylvania, and elevations are similar to that of the transition area between C. dubius and C. monongalensis in West Virginia and Pennsylvania. Acknowledgments I would like to thank Nicole Garrison, Christopher Hearn, Kathleen Loughman, Natalie Mancusso, Cody Rosettii, and Christopher Vopal for assistance in the field. I am also appreciative of Sarah Brammer’s and Melinda Kreisburg’s reviews of earlier drafts of the manuscript, and Stuart Welsh's publication support. Financial support was provided by Maryland Department of Natural Resources, Maryland Biological Stream Survey. Thanks are also expressed to Indiana Biological Survey, Oglebay Institute, and West Liberty University for additional financial support of this project. The publication of this manuscript was supported, in part, by the US Geological Survey Cooperative Research Unit Program, including the West Virginia Cooperative Fish and Wildlife Research Unit. Literature Cited Bouchard, R.W., D.A. Lieb, R.F. Carline, T.R. Nuttall, C.B. Wengert, and J.R. Wallace. 2007. 101 Years of Change (1906–2007). The Distribution of the Crayfishes of Pennsylvania. Part I: Eastern Pennsylvania. Academy of Natural Sciences of Philadelphia, Philadelphia, PA. Report Number 07-11. 39 pp. Colburn, C.A. 2004. Vernal Pools: Natural History and Conservation. 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