Over 45 years have passed since the last examination of Maryland's crayfish fauna. We compiled crayfish records from over 1400 sites sampled since 1989 and present an update on the current status and distribution of Maryland's 9 native species. Five non-native species have become established in Maryland waters and represent the greatest threat to Maryland's native species. Orconectes virilis (Virile Crayfish), the most widespread invasive species in the state, has been primarily introduced by anglers as bait and has rapidly expanded its distribution in central Maryland. The spread of this species has been followed by concurrent declines in native species including O. limosus (Spinycheek Crayfish) and O. obscurus (Allegheny Crayfish). Non-native Cambarus thomai (Little Brown Mudbug), O. rusticus (Rusty Crayfish), Procambarus clarkii (Red Swamp Crawfish), and P. zonangulus (Southern White River Crawfish) are now established in Maryland as a result of aquaculture and bait introductions. Recent taxonomic revisions have also added C. carinirostris (Rock Crawfish) to the list of species present in the state.

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.

The diversity of crayfishes in West Virginia represents a transition between the species-rich southern Appalachian faunas and the depauperate crayfish diversity in the northeastern United States. Currently, 22 described species occur in the state, of which 6 are given S1 status, and 3 are introduced species. One species, Orconectes limosus (Spinycheek Crayfish) is considered extirpated within the past decade. Imperiled species include Cambarus veteranus (Big Sandy Crayfish), Cambarus elkensis (Elk River Crayfish), Cambarus longulus (Atlantic Slope Crayfish), and Cambarus nerterius (Greenbrier Cave Crayfish). Three species—O. virilis (Virile Crayfish), Orconectes rusticus (Rusty Crayfish), and Procambarus zonangulus (Southern White River Crawfish)—have introduced populations within the state. Procambarus acutus (White River Crawfish) occurs in bottomland forest along the Ohio River floodplain, and is considered native. Several undescribed taxa have been identified and currently are being described. A statewide survey was initiated in 2007 to document the current distribution and conservation status of crayfishes in West Virginia.

Approximately 390 native North American crayfish species are known, representing nearly two-thirds of the world&s crayfish fauna. The majority of these species occur in the southeastern United States. North Carolina supports a substantial proportion of that diversity with 41 described indigenous crayfish species, 12 of which are endemic, and 3 introduced species, many of which are of significant conservation interest. In the late 1990s, the North Carolina Wildlife Resources Commission (NCWRC) began a focused effort to inventory and establish baselines for monitoring populations of both native stream-dwelling and burrowing crayfishes and invasive non-native species. During 2004–2005, that effort was completed for the Hiwassee, Little Tennessee, Savannah, French Broad, Watauga, New, Catawba, and Broad river basins in western North Carolina. Twenty-four stream-dwelling species and 5 burrowing species were collected from 199 stream sites and 58 burrowing sites. New records for many species, including a new river basin record for Cambarus reduncus (Sickle Crayfish), and new county records for C. howardi (Chattahoochee Crayfish), C. dubius (Upland Burrowing Crayfish), and C. nodosus (Knotty Burrowing Crayfish), were determined during these surveys. Small range expansions were documented for Orconectes virilis (Virile Crayfish; not native to North Carolina) and for Procambarus acutus (White River Crawfish; introduced outside its native range in North Carolina). We failed to detect the non-native O. rusticus (Rusty Crayfish), and P. clarkii (Red Swamp Crawfish) at or near previously reported localities. Observations of life-history traits, such as reproductive condition, fecundity, and habitat use were recorded. Specimens were also provided to crayfish taxonomists to help resolve certain taxonomic problems and to assist in the completion of new species descriptions. Data collected during this and previous NCWRC inventories, as well as data obtained from the North Carolina State Museum of Natural Sciences, North Carolina Division of Water Quality, Ohio State University, and other cooperators, were incorporated into a detailed GIS database. This database was used to identify data gaps to guide sampling efforts and to assess species and population status. In the future, this GIS database should provide a useful tool in monitoring the status of native crayfish populations and the spread of invasive species, and informing conservation and management decision making.

Georgia has historically had one of the best-known crayfish faunas in the United States, mainly due to the work of Dr. Horton H. Hobbs, Jr. In The Crayfishes of Georgia, published in 1981, Hobbs recognized 66 species and subspecies from the state, including 1 species that he hypothesized to be extinct, Procambarus (Ortmannicus) angustatus (Sandhills Crayfish). Herein I document 68 extant native species and subspecies, 1 extinct species, and 3 non-native species. Of the 68 extant native taxa, 17 (25%) are endemic to Georgia. A recent evaluation of the conservation status of United States crayfishes suggests that 6 Georgia species are endangered, 10 threatened, 7 vulnerable, and 1 extinct. The state of Georgia currently lists 7 species as endangered, 10 threatened, and 3 rare and has instituted new rules to protect crayfishes from export for the pet trade, while still permitting collection of some species for bait. Taxonomic studies continue on Georgia crayfishes, with at least 2 forms being examined as probable new species. Of the 3 non-native species now present in Georgia, Orconectes (Buannulifictus) palmeri creolanus (Creole Painted Crayfish) appears to be expanding its range, while the status of Procambarus (Scapulicambarus) clarkii (Red Swamp Crawfish) remains poorly understood. In addition to the presence of non-native taxa, threats to native Georgia crayfishes include persistent drought and land development associated with rapid human population growth.

Alabama has at least 83 species of native crayfish reported, more than any other state in the United States. Information associated with crayfish distribution, life history, and ecological importance in Alabama is extremely limited. The objective of this research is to determine the presence and relative abundance of crayfish species in the southeastern coastal plain of Alabama. Crayfish were collected at 50 sites within the Choctawhatchee River, Pea River, Yellow River, and Patsaliga Creek watersheds by electrofishing and hand excavation. Twelve crayfish taxa were collected, with 10 successfully identified to species. Procambarus suttkusi (Choctawhatchee Crayfish) was found at 40 sites and was the most widespread and abundant of the aquatic species. Procambarus versutus (Sly Crayfish) and Cambarus graysoni (Twospot Crayfish) were also found to be common aquatic species. Cambarus (Tubericambarus) sp. B was the most abundant primary burrower, and C. (Lacunicambarus) sp. B was a common burrower. Species with less than 10 individuals collected were considered rare and were as follows: Procambarus acutus (White River Crawfish), P. okaloosae (Okaloosa Crayfish), C. latimanus (Variable Crayfish), C. ludovicianus (Painted Devil Crayfish), and C. striatus (Ambiguous Crayfish).

Introductions of nonnative crayfish species have resulted in the global decline of native crayfish populations, including those in North America. Historically, the North American range of Orconectes limosus (Spinycheek Crayfish) extended from Maine, southward into northern Virginia, including West Virginia's eastern panhandle. A 1988–1989 survey of the eastern panhandle of West Virginia resulted in the capture of only 14 O. limosus, but an abundance of the nonnative Orconectes virilis (Virile Crayfish). These data along with additional unpublished accounts of declines of O. limosus populations prompted our survey of eastern West Virginia. In 2005 and 2006, crayfishes were collected from streams within the West Virginia range of the O. limosus, including historic capture locations. Our collection of 600 individuals comprised crayfishes from 3 species: O. virilis, Orconectes obscurus (Allegheny Crayfish), and Cambarus bartonii bartonii (Common Crayfish). The nonnative O. virilis was present at 26 of the 30 sites, whereas O. limosus was absent from all collections. Our results may indicate extirpation of some or all populations of O. limosus in eastern West Virginia, but absence data may also reflect a low detection probability of individuals from small populations. Competition between the nonnative O. virilis and O. limosus have been reported elsewhere, and likely explains the extirpation of populations of O. limosus in West Virginia.

Historical collections and records show that Cambarus veteranus (Big Sandy Crayfish) occurred in 3 West Virginia counties (Logan, Mercer, and Wyoming). The last statewide survey (1988–1989) found C. veteranus only in the Bluestone and Guyandotte river drainages in West Virginia. Competitors for C. veteranus niche space include C. sciotensis (Teays River Crayfish) and other cambarids. Using natural history and previous distributional information, a directed survey was conducted searching 15 probable locations, all at elevations greater than 457 m on the Unglaciated Allegheny Plateau province of WV These locations included moderately wide streams (>10 m) with permanent pools and having gravel or sand bottoms with large, flat, overlying rocks. Methods included one-hour timed searches using dip net or hand collection of the 15 sampling areas including historical record sites. At each site, water quality data were recorded, and a rapid bioassessment protocol (RBP) score was produced using several physical characteristics. Sampling for this project occurred between June and December 2001. This field survey failed to produce any individuals of C. veteranus. Possible reasons for this included poor water quality, as indicated by low RBP scores, or inadequate sampling. Large-river surveys in West Virginia may produce C. veteranus. Some of the sampled sites may meet criteria for future re-introduction efforts.

Orconectes williamsi (Williams' Crayfish) is a rare stream-dwelling crayfish that is endemic to the upper White River basin of Arkansas and Missouri. It was described in the 1960s from a type locality in Madison County, AR, and the three localities named in the description comprise the published range of the species in Arkansas. In contrast, 27 locations have been reported in Missouri. This study surveyed a semi-random selection of stream sites in the Arkansas portion of this range in order to characterize the crayfish communities and evaluate the status of O. williamsi in Arkansas. A total of 2372 crayfishes were collected at 68 sites, including 197 Williams' Crayfish from 23 sites. Orconectes meeki meeki (Meek's Crayfish) was the crayfish species most commonly associated with O. williamsi, occurring sympatrically at 87% of sites occupied by O. williamsi. Orconectes williamsi was found in small streams, with coarse substrates and no aquatic vegetation. Orconectes williamsi showed a strong preference for riffle habitats. Due to its limited range and habitat requirements, O. williamsi is moderately imperiled in Arkansas and should be considered rare and vulnerable range-wide.

Orconectes macrus (Neosho Midget Crayfish) and O. nana (Midget Crayfish) are a proposed sister-species pair with a small range on the western edge of the Ozark Highlands Physiographic province. Originally proposed as subspecies, O. macrus was elevated to full species status without explicit reason. This study utilized a single-locus mtDNA region (cytochrome oxidase I) to test: (1) monophyly of the species pair, (2) monophyly of the proposed species, and (3) examine if full species status is warranted for O. macrus. Phylogenetic reconstructions indicate that the two taxa indeed comprise a species pair and that each species is well supported as monophyletic. Additionally, there is significant phylogeographic structuring within each recognized species at fine spatial scales.

We studied the associations of crayfish with reach-scale instream habitat and water quality variables and watershed-scale variables of riparian and watershed land cover, runoff, impervious surfaces, and hydrologic soil type in west-central Indiana. Crayfish assemblage was measured by abundance, species richness, and diversity (Shannon's H) at 180 sites. The western portion of the study area, within the Interior River Lowland ecoregion, has been heavily impacted by agriculture, while the eastern portion, within the Interior Plateau ecoregion, is more heavily wooded and less impacted. The ability of variables at each spatial extent to predict crayfish assemblage was assessed using multiple linear regression analysis. Reach-scale models were better predictors of crayfish assemblage than watershed-scale models. A variety of habitat and water quality characteristics, principally instream cover, appeared as important predictors. Forested riparian and watershed land appeared as significant watershed-scale predictors. Reach-scale models were also better predictors of individual species abundance. Model predictive power was similar when developed separately for the two ecoregions of the study area, indicating that extent of agricultural development had little effect on the ability of variables at a given spatial scale to predict crayfish assemblage. Results indicate that reach-scale variables are more powerful in predicting crayfish assemblage, and important factors to consider in crayfish management are maintaining ample instream cover and intact riparian areas.

The ecology of primary burrowing crayfishes is poorly understood, especially for high-elevation species. An ecological study of Cambarus (Jugicambarus) dubius (Upland Burrowing Crayfish) was conducted at Terra Alta, Preston County, WV (elevation 781 m). The study sought life-history information including size at sexual maturity, age cohort designation, and age estimation. The density and distribution of burrow portals of C. dubius were examined within and near seeps in forested and disturbed habitats. Data were also collected on intraspecific usage of burrows by commensal species. Size at maturity did not differ significantly for males and females. The average age of C. dubius was 1.5 years, and the oldest individuals were estimated at 7 years. Form change of C. dubius occurred synchronously within the population, a phenomenon not previously documented with primary burrowing Cambarus. Burrow portals had highest densities within 5 m of the center of seeps in forested habitats, but reached highest densities between 10 and 25 m from the center of seeps in disturbed habitats. Many commensal species of invertebrates and vertebrates used C. dubius burrows, data that demonstrates a community-level contribution of C. dubius. Information from this study represents most of the available ecological data from the northern range of this species, and is directly relevant for management and conservation of high-elevation populations of C. dubius.

This study observed agonistic interactions and contests between size-matched form I vs. form I, form II vs. form II, and form I vs. form II males to establish baseline dominance orders and behavioral dynamics for Procambarus suttkusi (Choctawhatchee Crayfish). Three types of initiation behaviors, or attacks, were observed during each interaction: ambivalent contact, claw raise, and lunge. Feeding competition studies were also performed to assess the relationship between the winners of the agonistic interactions and feeding contests. Only form I vs. form I contests showed a decline in the number of interactions observed over time, but the duration of each individual agonistic interaction declined for all three types of behaviors during the thirty-minute recording period. Winners and losers did not preferentially use the same initiation behaviors as used in other studies. Previous studies also documented form I dominating form II males, but form I males did not dominate form II males in the present study. Winners of the agonistic contests won significantly more feeding contests. The results of the current study suggested that behavioral dynamics and form dominance may be species specific and that careful consideration of size differences are necessary in order to examine form dominance.

Habitats provide food sources, cover, concealment, and a place to reproduce; thus, habitat selection is an important aspect of an organism's ecology. The objectives of this study were to investigate habitat preferences of crayfish and to determine if there was habitat partitioning among different species of crayfish in wadeable streams. Data were collected while collecting crayfish at 50 sites throughout southeastern Alabama. Data collected along with species and relative abundance were: sex, stream position, type of instream cover, and type of substrate. The 3 dominant aquatic species found in the study area were Procambarus suttkusi (Choctawhatchee Crayfish), P. versutus (Sly Crayfish), and Cambarus graysoni (Twospot Crayfish). These 3 species were most often found in woody debris, on sandy substrate, and in stream runs. In addition, there was a significant difference in abundance in pools where P. suttkusi was found alone and where P. suttkusi was found along with other crayfish species. In contrast to other reported studies, these 3 crayfish species appeared to have no preference among habitat types, but were found in the habitat most available. This result may be due to the limited habitat found in the sandy-bottomed streams of the southeastern coastal plains, and their lack of variety in cover and substrates.

Recent studies have demonstrated the feasibility of using passive integrated transponder (PIT) tags for tracking crayfish spatiotemporally in streams. PIT tags can be inserted internally for long-term tracking, assuming low tagging mortality, or attached externally for shorter-term tracking until the individual molts. To date, the practical use of internal cephalothorax tagging has been limited to individuals >30 mm carapace length (CL). The efficacy of internal tagging for small-bodied crayfish species or juveniles of large-bodied species remains poorly understood. We conducted studies with the small-bodied Orconectes compressus (Slender Crayfish) to assess whether internal placement of small PIT tags (8.5 mm long, 2.12 mm diameter) was a viable methodology for future ecological work. In the field, we tagged 63 crayfish and monitored them with a portable transceiver system for 1.5 weeks. In the laboratory, we tagged 21 crayfish and maintained 21 control crayfish for 12 weeks. Crayfish averaged 18 mm CL (n = 84). In the field, there was high initial (14 of 63) and delayed (16 of 63) mortality. We also observed initial (3 of 21) and delayed (11 of 21) mortality in the laboratory within the first 10 days. Smaller individuals had higher mortality rates in both studies. We constructed logistic regression models with field (P = 0.005) and laboratory data (P = 0.027) to show the likelihood of tagging mortality as a function of carapace length. Our results suggest that internal PIT tagging could induce undesirably high mortality in crayfish <22 mm CL for most ecological study objectives.