Primary Burrowers Research Articles

Variation in fine-scale water table depth drives abundance of a unique semi-terrestrial crayfish species.

With anthropogenic changes altering the environment and the subsequent decline of natural habitats, it can be challenging to predict essential habitats for elusive and difficult to study taxa. Primary burrowing crayfish are one such group due to the complexity in sampling their semi-terrestrial, subterranean habitat. Sampling burrows usually requires a labor-intensive, time-consuming excavation or trapping process. However, limited information on burrowing crayfish suggests that fine-scale habitat variation may drive burrowing crayfish habitat choice. This project aimed to evaluate the fine-scale habitat characteristics that influence burrowing crayfish presence and abundance at a large, restored-remnant grassland preserve in north-central Illinois. We documented burrow abundance and quadrat-specific habitat variables such as root biomass, canopy cover, apparent seasonal high-water table (water table) depth and dominant vegetation at sites with and without burrowing crayfish populations. Data was recorded at every quadrat and analyzed using generalized linear mixed models. A total of 21 models were created to determine what habitat variables affected burrow presence and abundance. We found that the water table depth was a significant driver of burrow presence and abundance. Root biomass and vegetation cover were not significant drivers, although they did show up in the final models, explaining the data. These findings demonstrate empirical support for previous observations from other burrowing crayfish research and demonstrate the influence of fine-scale habitat when modeling elusive taxa requirements.

Extension of the geographical range of the primary burrowing crayfish Cambarus strigosus Hobbs, 1981 (Decapoda: Astacidea: Cambaridae) in South Carolina

Abstract Knowledge of the geographical distribution for many primary burrowing crayfishes is often limited to information presented in species descriptions or field notes associated with epigean crayfish surveys. Cambarus strigosusHobbs, 1981, a rare primary burrowing crayfish, was collected as part of a survey of the Sumter National Forest, South Carolina (SC), USA. Prior to this discovery, C. strigosus appeared to be endemic to mid-reaches of the Broad River Drainage in Georgia (GA). We conducted additional field sampling in SC and GA and used mitochondrial DNA (mtDNA) to compare the relative genetic distance between individuals across all populations in an effort to determine the identity of the specimens collected. Genetic data indicated that the crayfish collected in SC was C. strigosus, with one shared haplotype between SC and GA populations. Our genetic results exhibited geographic structuring and indicated that SC populations have a specific haplotype unique to them, providing strong evidence that SC populations are not introduced. Two additional SC records of C. strigosus from 1983 housed in the US National Museum were examined and determined to be C. strigosus. With these records, we hypothesized that like in GA, the distribution of C. strigosus in SC is limited to riparian habitats associated with the Savannah River Drainage. While the range of this species has been extended, it is still limited to small portions of this drainage. Thus, further sampling to determine the true extent of C. strigosus distribution within SC along with conservation efforts are needed to protect this globally rare species.

English

Abstract The southeast United States is the epicenter of global crayfish biodiversity, but these species are among some of the most threatened in the world. Life history and biological trait data deficiencies, particularly of burrowing crayfish species, hampers efforts for accurately assessing imperilment rates and informing conservation efforts. Rising temperatures are a threat to aquatic ectotherms and it is important to evaluate crayfish tolerances to determine if they are at or near their upper thermal limits. We conducted dynamic temperature ramps to evaluate the temperatures at which ecological death (critical thermal maximum; CTM) and physiological death (upper thermal limit; UTL) occurred for the imperiled and narrowly endemic primary burrower Cambarus harti and three common, sympatric species C. latimanus, C. striatus, and Procambarus clarkii. All species differed in CTM with C. latimanus being the most sensitive (35.0°C), C. striatus (37.0°C) and C. harti (37.8°C) having intermediate tolerance, and P. clarkii being the most tolerant (39.0°C). The UTL of all species ranged from 39.4 – 39.8°C. We found no evidence that C. harti, a rare primary burrower, will require more restrictive acute thermal guidelines for protection compared to more common sympatric secondary burrowers.

English

Abstract Understanding species’ habitat and resource requirements is critical for effective conservation. To assess whether a species is imperiled, data are needed on its range and natural history. In this study, we examined the resource use, including diet and habitat associations, of the Slenderwrist Burrowing Crayfish, Fallicambarus petilicarpus, a narrowly endemic primary burrowing crayfish in southcentral Arkansas. We found that F. petilicarpus has an omnivorous diet, feeding on aquatic invertebrates and detritus. We compared habitat characteristics of sites in the Ouachita drainage that contained F. petilicarpus and sites with other primary burrowing crayfish. Fallicambarus petilicarpus inhabits roadside ditches with low elevation and reduced canopy cover, like other primary burrowing species in the region. Comparisons among burrowing crayfish suggest there may be overlap in environmental niches of species in this region and subsequent competition. Field sampling expanded the known range of F. petilicarpus from ~174 km2 to ~1150 km2. Fallicambarus petilicarpus remains a narrowly endemic species with potential to be threatened by habitat loss and food scarcity caused by urban expansion and climate change.

English

Abstract Understanding species’ habitat and resource requirements is critical for effective conservation. To assess whether a species is imperiled, data are needed on its range and natural history. In this study, we examined the resource use, including diet and habitat associations, of the Slenderwrist Burrowing Crayfish, Fallicambarus petilicarpus, a narrowly endemic primary burrowing crayfish in southcentral Arkansas. We found that F. petilicarpus has an omnivorous diet, feeding on aquatic invertebrates and detritus. We compared habitat characteristics of sites in the Ouachita drainage that contained F. petilicarpus and sites with other primary burrowing crayfish. Fallicambarus petilicarpus inhabits roadside ditches with low elevation and reduced canopy cover, like other primary burrowing species in the region. Comparisons among burrowing crayfish suggest there may be overlap in environmental niches of species in this region and subsequent competition. Field sampling expanded the known range of F. petilicarpus from ~174 km2 to ~1150 km2. Fallicambarus petilicarpus remains a narrowly endemic species with potential to be threatened by habitat loss and food scarcity caused by urban expansion and climate change.

Conservation and Taxonomic Assessment of an Undescribed Crayfish in Coastal Virginia

Creaserinus fodiens (Cottle 1863), commonly known as the digger crayfish, is a primary burrower that inhabits complex burrows in wetlands, seasonal pools, wooded floodplains, and roadside ditches. Historically, C. fodiens have been found from Ontario, Canada following the United States down to Texas and across four Atlantic slope states including Virginia, Maryland, North Carolina, and South Carolina. The Atlantic slope clades are geographically isolated from other C. fodiens populations by the continental shelf on the East coast and by the Blue Ridge Mountains. Despite having a wide geographical range, little research has been done on the Atlantic slope clades of Creaserinus spp. Recent genetic and morphological data suggests that the Virginia population of C. fodiens could be described as a different species. Additional morphological and genetic data from gill samples will lead to a better understanding of where the separation in classification lies among the Virginia population. A conservation and taxonomic assessment for Creaserinus fodiens along the Virginia Atlantic slope will be constructed from the results. These assessments will contribute to our understanding of global crayfish biodiversity and provide important biological insight to the management and conservation of these species.

Prey and Predator Behavioral Interactions with a Primary Burrowing Crayfish (Lacunicambarus thomai)

Burrowing crayfish represent a small, specialized group of crayfish that inhabit self-made terrestrial burrows. Primary burrowing crayfish depend upon their burrows for protection, respiration, rearing of young, food storage, and thermoregulation. Burrowing crayfish tend to stay in proximity to or around their burrows causing them to be elusive lifestyle and consequently poorly documented. All crayfish are opportunistic generalists regarding food and have been recorded eating detritus, periphyton, and small invertebrates. Due to their stygobitic lifestyle, food resources are also limited to what is near their burrow, which commonly includes vegetation as well as smaller invertebrates. The predatory behaviors of burrowing crayfish has been studied and observed in abundance in epigean crayfish, however, it has been rare and few studies have been conducted on this behavior in burrowing species. This study utilized 24-h surveillance of a burrowing crayfish species, the Little Brown Mud Bug (Lacunicambarus thomai). A total of 633 H of videos were recorded of 6 different crayfish at varying times for each individual. Predatory behaviors were observed on several organisms including ants, worms, spiders, and dragonfly naiads. Gut analysis was performed on 23 L. thomai from 4 separate populations confirming the findings of the video footage that, in all populations, both animal and vegetation were being consumed. This study suggested that a sit-and-wait predation behavior may be a far more common foraging behavior in burrowing crayfish than previously observed.

Integrating burrowing crayfish and waterfowl conservation management on moist-soil wetlands

SummaryThe North American Waterfowl Management Plan highlights the importance of enhancing waterfowl habitat for productivity and resilience. Many forms of land management are conducted in wetlands to support the diverse communities of waterfowl and other species. Primary burrowing crayfish are also abundant and important in these environments, but little research is available assessing the effects of waterfowl land management on primary burrowers. We examined the response of the digger crayfish,Creaserinus fodiens, to the common vegetation management practices of mowing and disking at waterfowl conservation areas in south-eastern Missouri. Our results demonstrated that at a fine scale, crayfish density was affected by only canopy cover. We also highlighted distributional effects of landscape-level environmental variables and suggested that habitat generalists were tolerant of vegetation management, responding more to vegetation composition and broader landscape effects. We discuss wetlands conservation practices and suggest that burrowing crayfish management would integrate well with some current management strategies for waterfowl.

Evolving in islands of mud: old and structured hidden diversity in an endemic freshwater crayfish from the Chilean hotspot

Parastacus is a genus of South American freshwater crayfishes disjunctively distributed in southern Chile, Northern Argentina, Uruguay and Southeastern Brazil. Parastacus pugnax is a Chilean endemic distributed along 700 km of latitude in central-southern Chile from the Pacific coast to the Andean piedmont, which is intensively captured for consumption for local communities. Considering the habitat (wet meadows) and natural history (primary burrower, non-migrant) of the species, we tested a hypothesis of highly structured genetic diversity using mtDNA of 465 specimens gathered at 56 localities across the species range. The crown age of P. pugnax was estimated at 38 Ma, predating the main Andean uplift. The genetic variation of P. pugnax is large and geographically structured. In some cases, genetic groups do not match basin limits, suggesting a previous to current dynamic of basin evolution. The uncovered intraspecific main lineages have different demographic histories. A latitudinal cline in past effective population size reduction suggests environmental singularities with a glacial effect in the southern populations. We suggest adding morphologic and more genetic data in order to assess species limits. Our results contribute to improve future conservation actions for this taxon, providing basic information to delimit conservation units.

Advancements in the Understanding of Appalachian Primary Burrowing Crayfish Ecology and Habitat Usage with a Focus on Cambarus monongalensis

Primary burrowing crayfish life history and ecology is largely due to their cryptic habitat preferences. Cambarus monongalensis, arguably the most charismatic of all crayfishes, lacks basic life history and habitat data because of the aforementioned obstacles. This study seeks to determine the life history and ecological preferences of populations of C. monongalensis in the northern panhandle of West Virginia and Southwestern Pennsylvania with notes on its natural history. Life history data will include form change and reproductive patterns including juvenile size of departure from the maternal burrow. Habitat data were collected using external burrow morphology and burrow locations within a standardized area collected seasonally to determine the preferences and cyclical patterns of crayfishes. With these data, the conservation of this species, and others that follow a similar life history strategy, is possible

First Record of the Blue Crawfish, Cambarus monongalensis Ortmann, 1905 (Decapoda: Cambaridae), from Ohio, USA

This paper documents the first record of the blue crawfish, Cambarus monongalensis Ortmann, 1905, in the state of Ohio, United States. The blue crawfish is a small- to medium-sized primary burrowing crayfish common in western Pennsylvania and West Virginia. Because of the prevalence of this species on the east side of the Ohio River, numerous researchers have sought the blue crawfish in Ohio—to no avail. On 16 May 2020, turkey hunters in Monroe County, Ohio, located a blue-colored crayfish and sent photos to one of the authors of this study. On 19 May 2020, the authors sampled in the vicinity of where the photo was taken and located 4 sites that yielded a total of 5 blue crawfish specimens, confirming the existence of this species in Ohio. Further research is needed on the blue crawfish to determine its range and abundance in Ohio, and to explore factors relating to its biogeography.

Analysis and description of burrow structure in four species of freshwater crayfishes (Decapoda: Astacoidea: Cambaridae) using photogrammetry to recreate casts as 3D models

AbstractFreshwater crayfishes use burrows for predator avoidance, desiccation prevention, foraging, and brood care. Based on their burrow ecology, crayfishes can be categorized as tertiary, secondary, or primary burrowers, with primary burrowers being semi-terrestrial and highly dependent on burrows for survival; secondary and tertiary burrowers have decreased burrow dependence and complexity. There has been limited investigation into the specifics of burrow structure. We investigated the factors that influence the structure of crayfish burrows including habitat structure and crayfish through the use of burrow casting and photogrammetry to recreate casts as 3D models. Examined species include the primary burrowing Lacunicambarus aff. diogenesGirard, 1852 and Creaserinus fodiens (Cottle, 1863), and the tertiary burrowing Faxonius rusticus (Girard, 1852) and Faxonius propinquus (Girard, 1852). Crayfish burrows (N = 17) were filled with polyester resin and cured burrow casts were excavated, and photogrammetry was used to recreate casts as 3D models. Burrow depth, number and widths of openings, number and widths of chambers, and number of ancillary tunnels were recorded. Differences in burrow features were analyzed by field site/habitat and crayfish species using stepwise linear regression, MANOVAs, and multiple factor analysis (MFA). From stepwise linear regression, “species” was a better predictor than “habitat of burrow structure.” Burrows constructed by L. aff. diogenes were significantly larger and have more chambers than burrows constructed by the other species examined; burrows of C. fodiens were significantly deeper than those of tertiary burrowers. Each species also created a stereotyped burrow shape. The morphometric differences between burrows of primary and tertiary species illustrate the relevance of these informal classifications. Differences between primary and tertiary species may be related to the species social behavior and ecology.

Lacunicambarus dalyae: a new species of burrowing crayfish (Decapoda: Cambaridae) from the southeastern United States.

The Jewel Mudbug, Lacunicambarus dalyae sp. nov., is a large, colorful primary burrowing crayfish found in Alabama, Florida, Georgia, Mississippi and Tennessee. This species is most similar in appearance to the Paintedhand Mudbug, L. polychromatus, a species found across the Midwestern United States. The ranges of the two species overlap minimally, and they can be distinguished from each other based on several characters, the most notable of which is the much longer central projection of the gonopod in Form I and II males of L. dalyae sp. nov. relative to L. polychromatus. Like its congeners, L. dalyae sp. nov. is commonly found in burrows in the banks and floodplains of streams and is resilient to a moderate amount of anthropogenic habitat degradation, being occasionally collected from burrows in roadside ditches and urban lawns.

High air humidity is sufficient for successful egg incubation and early post‐embryonic development in the marbled crayfish (Procambarus virginalis)

Abstract Severe weather events, such as long‐term droughts, are challenging for many freshwater species. To survive drought, freshwater crayfish tend to inhabit shelters or burrows where they can remain in contact with water or high humidity environments. However, it is not known whether embryogenesis or post‐embryonic development can occur without free standing water. To address this question, three experiments were conducted using artificial burrows with high air humidity and using marbled crayfish (Procambarus virginalis Lyko, 2017) as a model species. Marbled crayfish are capable of parthenogenetic reproduction, burrow extensively and are able to travel long distances over land. In the first experiment, ovigerous females were transferred to simulated burrows without free water, but with high air humidity. A control group of females were kept in burrows with free water. Successful hatching was achieved in both groups. In the second experiment, ovigerous females were transferred to simulated burrows with no free water but high air humidity and post‐embryonic development were observed. Following successful hatching, offspring moulted to the second developmental stage (stage 2 juveniles). Stage 2 juveniles remained viable without free water for 20 days, but further development was not observed. However, when some of these stage 2 juveniles were placed back into fully aquatic conditions (experiment 3), they moulted to stage 3 within 4 to 8 days. These results demonstrated the ability of marbled crayfish to undergo terminal phases of embryogenesis, including hatching, as well as early post‐embryonic development under high air humidity conditions only. Post‐embryonic development was suspended in the absence of free water, and successfully resumed when re‐immersed. This similar ability to tolerate drought‐like conditions during post‐embryonic development may also occur in other crayfish species, especially primary burrowers. This unprecedented life history trait may be crucial for inhabiting ecosystems with rapidly changing water regimes. In drying climates, it may confer advantages on some crayfish species (including some invasive species) over others.

Body Size in Freshwater Crayfish: An Intercontinental Comparison

Abstract Body sizes (overall length) of 125 Australian and 230 North American freshwater crayfish were extracted from the literature in order to compare the two major radiations of freshwater crayfish. The size distribution of Australian species is strongly skewed to the right and contains at least 13 species that exceed the maximum size of North American crayfish, however the median size class (74 mm) is the same for both faunas. When the burrowing habits of each species are overlain on the distribution, the Australian fauna is shown to have a higher proportion of primary burrowers, and these are significantly smaller than North American primary burrowers. These differences are discussed in terms of the perceived absence of large predators in Australia, and the long term drying and unpredictability of the Australian climate, but no firm causes can be deduced.

Lacunicambarus chimera: a new species of burrowing crayfish (Decapoda: Cambaridae) from Illinois, Indiana, Kentucky, and Tennessee.

Lacunicambarus diogenes (Girard 1852) was, until recently, considered to be one of the most widely distributed North American crayfish species, occurring in 31 U.S. States and one Canadian province east of the North American Rocky Mountains. Glon et al. (2018) investigated this claim and found that L. diogenes sensu lato was actually a species complex. The authors redescribed L. diogenes and restricted its range to the Atlantic Coastal Plain and Piedmont ecoregions of eastern North America. In doing so, they also revealed the existence of several probable undescribed species of Lacunicambarus that were previously considered to be L. diogenes. Here, we use morphological and molecular techniques to distinguish and describe one of these species: Lacunicambarus chimera sp. nov., a large primary burrowing crayfish found in parts of the Lower Mississippi, Ohio, Tennessee and Upper Mississippi River Basins. Lacunicambarus chimera is morphologically similar to L. diogenes, from which it can be distinguished by the greater number of spines on the ventrolateral margin of its merus, its wider antennal scale terminating in a short spine, and the presence of a single longitudinal stripe on the dorsal side of its abdomen. We also provide an updated key to Lacunicambarus.

Examination of Homing Behaviors in Two Species of Crayfish Following Translational Displacements.

SynopsisCrayfish have been model systems for examining complex behaviors and the underlying neural mechanisms that guide these behaviors. While spatial learning has been examined in a subset of crayfish species, homing behaviors remained largely unexamined. Here we examined homing behavior following translational displacements in a primary burrowing (Creaserinus fodiens) and tertiary burrowing species (Faxonius rusticus). Individuals of both species were placed in an arena with artificial burrows embedded within the arena floor. The arena floor was fitted with a panel, which served as a treadmill belt to allow for translational displacement. Individuals were displaced after they had left the burrows. The movement pathways of displaced crayfish were compared with those in two control groups, one which underwent no displacement and the second in which the treadmill belt was displaced but returned to its original position almost immediately. Homing success for displaced individuals of both species was considerably reduced in comparison to the control groups. Moreover, displaced primary burrowers had significantly lower homing success in comparison to displaced tertiary burrowers. Primary burrowers exhibited greater homing error and significantly impaired homing behaviors compared with tertiary burrowers. Furthermore, heading angles in displaced groups (of both species) were significantly higher than the control group of both species. Species-specific differences in homing success and homing error indicate that primary burrowers were more negatively impacted by translational displacements. These homing differences indicate that these two species of crayfish have differing homing strategies.

Reassessment of the Crayfishes of the Upper Ohio River Basin in Pennsylvania.

Crayfishes are keystone species and ecosystem engineers in freshwater systems and are considered the third most imperiled taxa on the planet. In 1906, Arnold Ortmann published one of the most complete historic crayfish surveys ever conducted, which has allowed Pennsylvania to assess changes to crayfish fauna over the past century. More recently, waterways have been impacted by anthropogenic stressors such as urbanization and extractive industry. Our primary goal is to determine changes in species distributions and relative abundances of crayfishes in western Pennsylvania by visiting historical and new sites. Surveys in 2015-16 focused on collecting primary burrowers by trapping and burrow excavation. In 2017, efforts shifted to epigean species in the Upper Ohio River drainage, using standardized sampling of 10 seine hauls/site to assess 265 sites. Populations of primary burrowing crayfishes were found at 20% of 61 historical sites and 72% of 57 new collection sites. Of epigean crayfishes, 79% were found at 102 historical sites and 97% of 163 new sites. These collections represent approximately 60% of the survey, with remaining collections to occur in 2018. Important findings were three nonnative species: Faxonius rusticus (Rusty Crayfish), Procambarus clarkii (Red Swamp Crayfish), and Procambarus acutus (White River Crayfish). Preliminary data suggests that crayfish fauna in western Pennsylvania has remained moderately stable over the last century, though the presence of nonnative crayfishes indicates the need for continued monitoring. Efforts in Pennsylvania must focus on prevention and management of the spread of nonnative species to preserve the native crayfish populations that remain.

English

Abstract I surveyed the peer-reviewed literature for studies on crayfish population genetics over the last 20 years (1996 to 2015). My objectives were to determine if there is research disparities based on crayfish conservation status, ecological group, geographic location, and genetic methods used. Additionally, I wished to determine overall trends in crayfish genetics related to population variability, systematics, and technique development. An extensive literature search yielded 201 peer-reviewed articles with genetic information published on 335 of the 590 crayfish species found worldwide. The majority of peer-reviewed articles took place in Europe and Australia/Oceania despite the fact that crayfish biodiversity is greatest in North America. Crayfish within each ecological group (primary burrowers, lotic inhabitants, lentic inhabitants, and stygobitic species) are represented in these published papers. I found published articles on ~ 57% of the estimated 590 extant species. Further, of the 173 species listed as critically endangered, endangered, vulnerable, or as near threatened by the International Union for Conservation of Nature, I found published research on ~ 62% of these species in these classifications thus indicating a knowledge gap for many imperiled species. This lack of basic genetic (and ecological) information is significant as species designation is often used to determine where we should focus our conservation actions. Understanding what constitutes a single interbreeding population and identifying taxonomic designations are priorities for defining conservation management plans.

English

Abstract I surveyed the peer-reviewed literature for studies on crayfish population genetics over the last 20 years (1996 to 2015). My objectives were to determine if there is research disparities based on crayfish conservation status, ecological group, geographic location, and genetic methods used. Additionally, I wished to determine overall trends in crayfish genetics related to population variability, systematics, and technique development. An extensive literature search yielded 201 peer-reviewed articles with genetic information published on 335 of the 590 crayfish species found worldwide. The majority of peer-reviewed articles took place in Europe and Australia/Oceania despite the fact that crayfish biodiversity is greatest in North America. Crayfish within each ecological group (primary burrowers, lotic inhabitants, lentic inhabitants, and stygobitic species) are represented in these published papers. I found published articles on ~ 57% of the estimated 590 extant species. Further, of the 173 species listed as critically endangered, endangered, vulnerable, or as near threatened by the International Union for Conservation of Nature, I found published research on ~ 62% of these species in these classifications thus indicating a knowledge gap for many imperiled species. This lack of basic genetic (and ecological) information is significant as species designation is often used to determine where we should focus our conservation actions. Understanding what constitutes a single interbreeding population and identifying taxonomic designations are priorities for defining conservation management plans.