IAA22 Book of Abstracts (PDF)
Meeting Program/Schedule (PDF)
LIST OF MEETING ABSTRACTS
NOTE: You may quickly navigate to a name you are looking for by clicking a letter below (first letter in their lastname).
Day: 2, Session: 1, Talk: 4
HOST COUNTRY LECTURE:
An Overview of U.S. Crayfish Conservation in State Agencies and a Plan to Reverse CRAWnic Neglect
Robert J. DiStefano
Crayfish conservation can be accomplished in the United States (U.S.) by federal government, state governments, universities, non-governmental organizations (i.e., The Nature Conservancy), professional societies (e.g., American Fisheries Society), local governments, and private citizens. State fish and wildlife agencies are charged with protecting and managing each state’s aquatic resources, yet crayfish have historically received little attention from them. This is largely due to state funding formulas that rely heavily on sales of recreational licenses (fishing, hunting, etc.), and perceived responsibility of agencies to be more responsive to that segment of the public who buy licenses. Missouri is unique in having established a state conservation program for crayfish decades ago. The program has produced substantial research data on crayfish species distributions, ecology and threats, especially for imperiled and endemic species. It has yielded several conservation actions (e.g., regulations, education products and activities). I will reference Missouri as one possible model for establishing and maintaining a state government (or regional government elsewhere) crayfish conservation program that involves government staff, but also partners from academia and some stakeholder groups. I will conclude by providing a brief update about states’ involvement in U.S. crayfish conservation.
Day: 2, Session: 2, Talk: 3
Cambarus aff. dubius, a New Species of Crayfish (Decapoda: Cambaridae) Endemic to the Pre-glacial Teays River Valley in West Virginia, USA
DAVID A. FOLTZ II., Nicole M. Sadecky, Greg A. Myers, James W. Fetzner Jr., Stuart Welsh, G. Whitney Stocker, Mael G. Glon and Roger F. Thoma
A new species of crayfish, Cambarus aff. dubius, new species, is described from the preglacial Teays River Valley of Cabell, Kanawha, Lincoln, Mason, and Putnam counties, West Virginia. The species was previously considered to be part of the Cambarus dubius complex (Jezerinac et al. 1995). Loughman et al. 2015 restricted C. dubius to an orange color morph found in central and northern portions of the Allegheny Mountains and Appalachian Plateau in central West Virginia, western Maryland, and southcentral Pennsylvania. The new species described herein can be distinguished from all other members of Cambarus by a double row of cristiform tubercles on the palm, an open areola with two rows of punctations, and a consistent blue coloration.
Day: 2, Session: 3, Talk: 3
Modeling Effects of Crayfish Invasion and Drought on Crayfish Population Dynamics
Leah Bayer, Robert Fournier and DANIEL D. MAGOULICK
Crayfish play a crucial ecological role and are often considered a keystone species within freshwater ecosystems. However, North American crayfish species face several environmental and ecological threats including limited natural ranges, invasive species, and intensified drought. Demographic models can allow examination of population dynamics of a targeted species under a wide variety of disturbance scenarios. Here, we model the population dynamics of crayfish species with varied theoretical life histories and assess their responses to biological invasions and drought. We used RAMAS-Metapop to construct stage-based demographic metapopulation models parameterized using vital rates from established literature sources. Our models explored the population viability of four theoretical species under eleven disturbance scenarios and calculated estimates of terminal extinction risk, median time to quasi-extinction, and metapopulation occupancy. Our models indicate that populations respond differentially to disturbance based on life history. However, both r- and K-selected species appear to be highly susceptible to decline when faced with the additive effects of reduced carrying capacity due to invasion and reduced vital rates due to drought. By constructing models that explore a broad array of life histories and disturbance regimes, we hope to provide managers with tools to develop generalized, widely-applicable conservation strategies.
Day: 2, Session: 3, Talk: 4
Comparison of Traditional Crayfish Trapping and eDNA Monitoring of Noble Crayfish Astacus astacus
DAVID A. STRAND, Stein Ivar Johnsen, Johannes C. Rusch and Trude Vrålstad
During the past decade, the environmental DNA (eDNA) methodology has become an important non-invasive tool to monitor freshwater microorganisms and macroorganisms. From a single water sample, it is possible to detect several species of interest or even whole communities. eDNA studies have been applied to a wide range of aquatic organisms, including freshwater crayfish. eDNA can be used to reveal elusive species, such as alien invasive species at an early stage or rare and endangered species. While eDNA is a great tool for revealing the presence or absence of freshwater organisms, it is not always a clear relationship between eDNA copy numbers and the density of the species of interest. In this study, we have developed a species-specific Taqman MGB assay that targets the COI region of noble crayfish mitochondrial DNA. The eDNA assay is optimised for both quantitative real-time PCR (qPCR) and digital droplet PCR (ddPCR). Further, we have surveyed several lakes with varying crayfish densities using both traditional crayfish trapping (baited traps) and eDNA monitoring. In each lake, several water samples were filtered on site for eDNA capture, followed by trapping (baited traps) along the same shoreline. In one of the lakes, we also surveyed one site with both methods monthly from June to October to monitor seasonal variation of crayfish trapping and eDNA abundance in the water. Relative crayfish density (CPUE – crayfish per trap night) varied from 0.08 to 17.6 in the surveyed lakes. The water samples is in the process of being analysed for eDNA of noble crayfish using both qPCR and ddPCR technology. Using these results, we will compare the traditional cage trapping of noble crayfish (CPUE) with eDNA monitoring to evaluate if eDNA can be used to give an estimate of relative density of freshwater crayfish in a lake. We will also compare the results from qPCR with ddPCR to evaluate the pros and cons of the two approaches. The results will be presented at the IAA22 conference.
Day: 2, Session: 3, Talk: 5
Using Maximum Entropy Modeling to Predict Suitable Habitat Locations for the Cutshin Crayfish (Cambarus taylori)
ERIC TIDMORE and Zachary J. Loughman
The Cutshin Crayfish (Cambarus taylori) is a recently described species endemic to the Middle Fork of the Kentucky River basin that lies within the anthracite coal fields of Eastern Kentucky. As C. taylori has a restricted range in an area heavily impacted by extractive industry, a conservation assessment is warranted. The goal of this study was to predict suitable habitat locations for C. taylori through use of maximum entropy modeling (MaxEnt). The Middle Fork of the Kentucky River’s crayfish fauna was last surveyed during the summer of 2014. The occurrence data from this study coupled with landscape scale environmental variables—such as stream order and land use data—was used to create the model. The mean area under the receiver operating characteristic curve (AUC) value was 0.971, showing the model had high predictive accuracy. Stream order and stream sinuosity had the highest contribution to the model showing that C. taylori prefers 3rd and 4th order streams with low sinuosity. To test the accuracy of the model, ten high probability and ten low probability sites were surveyed. C. taylori was captured in ten of the twenty sites, eight of which were considered high probability for C. taylori presence.
Day: 2, Session: 4, Talk: 3
The Life History of Cambarus veteranus Faxon 1914 (Decapoda: Cambaridae) in the Clear Fork of the Guyandotte River, WV, USA
NICOLE SADECKY and Zachary J. Loughman
Cambarus veteranus Faxon, 1914 (Guyandotte River Crayfish), is an endangered, narrow endemic, residing in just two streams in the southern coalfields of West Virginia. A life history study was initiated for C. veteranus in Clear Fork of the Guyandotte River, Wyoming County, West Virginia to gather basic life history information needed for future conservation efforts. Monthly collections began June 2017 and continued through May 2018. Two 400-meter stream reaches were designated as life history study sites with two different 100-meter sub-reaches sampled each month. Specimens, regardless of species, were collected, sexed, and molt stage determined. Preliminary results suggest an importance of water temperature on crayfish capture with December yielding considerably higher capture rates of C. veteranus in comparison to other species collected. Form I males are ever present and reach their highest density in early winter. Pre-glaired females reached their highest densities in October and December with glaired females present nearly every month. A single ovigerous female was collected, bearing just two stage 4 juveniles, during the November sampling event. Three ovigerous females bearing stage 4 juveniles were subsequently collected during the March sampling event, thus suggesting overwintering with young. Molting events were observed between September and October with pre-molting individuals present in September and freshly molted individuals present in October. Additionally, molting events occurred in March with pre-molting individuals present as well as freshly molted individuals and in May with the majority of the population observed in the soft or fresh molt state. Providing life history information for C. veteranus will assist in conservation efforts and possible repatriation of C. veteranus in the future. Additionally, life history information for C. veteranus can be compared to closely related species that are often used as a surrogate for C. veteranus in captive rearing studies.
Day: 3, Session: 2, Talk: 4
Hunting Crayfish Plague with eDNA – And Making Use of the Results
LENNART EDSMAN, Anna Aspán, Patrik Bohman, Karin Enfjäll, Tomas Jansson, Stein Johnsen, Jenny Monsén, Daniel Nilsson, Johannes Rusch, David Strand, Rune Svensson, Øystein Toverud and Trude Vrålstad
In River Billan that starts in Norway and runs into Sweden, there has been a thriving population of the critically endangered native noble crayfish (Astacus astacus). The population has been good enough to support a sustainable, local, small scale fishery in both countries. Starting in August 2016 dead crayfish were found in the lower part of the river. The dying crayfish were analysed and the cause of death was crayfish plague (Aphanomyces astaci). Illegal introduction of the chronic crayfish plague carrying signal crayfish (Pacifastacus leniusculus) was suspected to be the reason for the plague outbreak, since this has happened numerous times in the neighbourhood. Intensive monitoring with baited traps and by electrofishing was conducted in both countries but no signal crayfish was found. Cages with noble crayfish were put out to monitor survival. The noble crayfish death by crayfish plague progressed upstream the river. On a rainy day in September 2017 we sampled 5 locations in River Billan in search for crayfish plague environmental DNA. The localities stretched from the outlet furthermost downstream up to the furthermost upstream location by the Norwegian border. Duplicate samples of 5 L was filtered on-site onto sterile glass fibre filters at each location. The samples were then analysed and presence/absence of eDNA from crayfish plague was analysed with qPCR. All samples for the four downstream locations were positive for crayfish plague. The furthermost upstream location was however negative for plague. Soon after 88 noble crayfish where caught with electrofishing in the upper part location of the river where no crayfish plague DNA had been found in the samples. They were transferred to a quarantine in a crayfish farm 200 km away, and the crayfish are still alive and healthy in the pond 7 months later, so the salvage action was successful. They can be used in the future for breeding and for restoration of the noble crayfish population in River Billan.
Day: 3, Session: 3, Talk: 2
Comparisons of Enzymatic Thermal Optima Among Narrowly and Broadly Distributed Crayfish Species
HISHAM ABDELRAHMAN, James A. Stoeckel and Jacob T. Westhoff
Previous researchers have shown that extraregional invasive crayfish possess certain biological and ecological traits that facilitate their ability to successfully invade large areas in distant regions, whereas extralimital invaders tend to remain localized and occupy smaller ranges. Physiological optima may provide additional explanatory power for realized and potential range of crayfish species. In this study, we tested for differences in enzymatic thermal optima among multiple crayfish species with narrow (i.e., Faxonius marchandi, ~2,800 km2) to broad (i.e., F. virilis, >11 million km2) native and invasive ranges. We hypothesized that species with broad ranges would be thermal generalists relative to species confined to limited ranges. To test this hypothesis, we generated thermal performance curves of respiratory enzymes in the electron transport system (ETS) for 12 individuals of each species. Optimal thermal range was defined as the temperature range within which ETS enzyme activity was within 10% of the maximum observed value. Preliminary results show that the wide-ranging, invasive F. virilis has a broader thermal optima, and higher individual variation, than a localized invader – F. neglectus – or narrow endemics such as F. eupunctus or F. marchandi. Furthermore neither the thermal optima, nor the optimal range of the localized invader – F. neglectus - was significantly different than that of an endemic (F. eupunctus) within the invaded range. Results thus far suggest that underlying physiology may provide important clues as to which species have the potential to spread broadly and which species may be limited to a relatively narrow range. Additional species are currently being analyzed to better assess the robustness of these conclusions.
Day: 3, Session: 3, Talk: 5
Hunting Missouri’s Rarest Crayfish Using eDNA and Visual Surveys: A First Look at the Natural History of the Caney Mountain Cave Crayfish
ROBERT J. DiSTEFANO, David C. Ashley, Shannon K. Brewer and Joshua B. Mouser
Stygobitic (cave) crayfishes are regarded as the most imperiled crayfishes in the U.S. and Canada. The Caney Mountain Cave Crayfish (Faxonius stygocaneyi), discovered in 1998, is known from only a single population in Mud Cave in the Caney Mountain Conservation Area (CMCA) of southern Missouri. It is listed as “critically imperiled” by the state of Missouri and “threatened” by the American Fisheries Society. We conducted the first study of F. stygocaneyi to gather preliminary data on its natural history and population, and to locate possible additional populations. We visited Mud Cave on 14 occasions (at least once each season) between 2014 and 2018. Visual surveys along a transect of inundated (wet) and non-inundated (mud) habitat were conducted during most visits except late April-May 2017 when the cave was flooded. Supplemental baited trapping was also performed intermittently. Water samples (2 L at two Mud Cave locations) were taken on each of 7 visits in 2017 and 2018. Water and air temperatures were recoded for most of 2014-2016. We captured a total of 23 (carapace length, 15.0-47.0 mm, average: 27.2 mm) and observed an additional 42 F. stygocaneyi, including the first-ever records of juveniles (August 2016 and 2017) and an ovigerous female (August 2016). Multiple visual searches of the known five other caves and three springs at CMCA detected no F. stygocaneyi. In addition to water samples from Mud Cave, we also collected and filtered multiple water samples from Onyx, and Bear Hollow caves, and three springs thought to be in the same drainage in 2017-2018. We developed primers and probes to amplify F. stygocaneyi DNA from those samples. Study results were limited by use of non-invasive sampling methods, high turbidity, flooding on some occasions, and what appears to be a small population. Yet we observed four times more crayfish compared to the previous 17 years since the species’ discovery, and collected the first biological data. Visual and eDNA sampling of adjacent caves and springs suggest the species could be endemic to only Mud Cave.
Day: 3, Session: 3, Talk: 6
Body Size in Freshwater Crayfish: An Intercontinental Comparison
Alaistair M. M. Richardson
The independent evolution of the astacoidean and parastacoidean crayfish in the Northern and Southern Hemispheres provides an opportunity to compare their characteristics. The comparison can be sharpened by comparing the crayfish faunas of Australia and North America, having roughly similar areas and lying at comparable latitudes. Size data were collected from the literature for 230 North American and 125 Australian species, and were compared directly and in terms of the species' burrowing habits. The Australian fauna includes several much larger species, and while the modal body size is very similar in the two faunas, the North American modal size class, and also the entire fauna, is dominated by tertiary burrowers, the Australian by primary ones. Further, Australian primary burrowers are smaller on average. The factors influencing these differences are discussed.
Day: 3, Session: 3, Talk: 7
Burning Down the House: Effects of Prescribed Burning and Mechanical Vegetation Treatments on Primary Burrowing Crayfish Densities
SUSAN B. ADAMS and Scott G. Hereford
Prior to widespread anthropogenic habitat alteration, primary burrowing crayfishes along the Gulf of Mexico Coastal Plain in southern Mississippi and Alabama presumably occupied predominantly open pine savannas, prairies, and bogs. Among other alterations, European settlement brought increasing fire suppression and intensive pine production. The Mississippi Sandhill Crane National Wildlife Refuge was “established in 1975…to protect the critically endangered Mississippi sandhill cranes [Grus canadensis pulla] and their unique, and itself endangered, wet pine savanna habitat.” The cranes require open meadow or pine savanna habitat, now created and maintained via prescribed burning, or when burning is precluded, via mechanical treatment. The US Fish and Wildlife Service (FWS) became interested in how these land management actions affect other at-risk species, including the primary burrowing crayfishes on the refuge: Creaserinus spp. and Procambarus fitzpatricki. In 2016, we initiated a study to survey crayfishes on the refuge and to begin examining how the land management influences burrowing crayfish densities. Crayfishes were surveyed by trapping and dipnetting in perennial and intermittent water bodies and by excavating and trapping from burrows. Burrower density among management classes was addressed by surveying burrow densities in quadrats along six transects on three plot types: regularly burned, regularly mechanically treated, and infrequently managed. We collected six species, including four only from water bodies: Cambarellus diminutus, Procambarus shermani, P. clarkii, and Faxonella clypeata. Procambarus fitzpatricki, considered at-risk by the FWS, was collected from burrows but also from small, isolated, intermittent pools in prairies and savannas. The most abundant burrower was identified as Creaserinus oryktes; however, taxonomic uncertainty creates enormous difficulty in distinguishing C. oryktes (not considered at-risk) from C. danielae (considered at-risk). Preliminary results indicate that burrowers were more abundant in burned or mulched plots than in infrequently managed plots. Confounding factors include interactions between site moisture and burn frequency/intensity and between ease of locating burrows and vegetation density.
Day: 3, Session: 4, Talk: 2
Investigation of the Salinity Tolerance and Life History of the Hammock Island Crayfish, Procambarus lunzi, in South Carolina, USA
ELIZABETH B. UNDERWOOD and Michael R. Kendrick
There are currently 38 confirmed species of freshwater crayfish in South Carolina, with nine of these found in the Sea Island/Coastal Marsh physiographic province (A.K.A. 'near-coastal zone') of the state. This includes Procambarus troglodytes, Procambarus lunzi, and the invasive Procambarus clarkii, among others. Crayfish in the near-coastal zone of South Carolina face numerous threats, including habitat destruction, invasive species, coastal flooding, sea-level rise, and storm surge. Sea level rise and storm surge events will likely lead to the salinization of near-coastal habitats, affecting crayfish that inhabit these wetlands. One crayfish species that will likely be affected by such salinization is the hammock (or hummock) island crayfish, Procambarus lunzi, which is the only crayfish known to inhabit hammock islands of South Carolina. Hammock islands are near-coastal upland features often consisting of maritime forest and depressional freshwater wetlands that are surrounded by salt marsh. Due to the isolated nature of its habitat and proximity of P. lunzi to the coast, potential conservation and management actions will need to consider how this species will respond to the effects of sea-level rise. The objectives of this research were to 1) Determine the salinity tolerance of 3 Procambarus species (P. lunzi, P. troglodytes, and P. clarkii) and 2) Assess life history of P. lunzi on a hammock island in South Carolina. For salinity tolerance trials of Procambarus lunzi, 32 individuals were collected from hammock island wetlands (salinities ranged from 0.3 to 7.0 psu) and exposed to one of two treatment conditions, 0 or 30 psu. Mean percent survival at the end of the first trial was 18.75%. It was hypothesized that the crayfish may have been previously stressed from high-salinity habitat conditions on the island and a second experimental trial was conducted. Crayfish from the first trial's 0 psu treatments (n=16) were kept in freshwater and fed every other day for two weeks. They were then placed in either 0 or 30 psu treatment tanks with each salinity treatment being replicated twice. Mean percent survival at the end of the seven-day trial was 100% at 0 psu, and 87.5% at 30 psu. Similar experiments were conducted with P. troglodytes and P. clarkii, and survival at 30 psu was 63% and 56%, respectively. The life history of P. lunzi is currently being assessed by re-sampling of a population on a hammock island. During each sampling event, post-orbital carapace length, sex, and reproductive state are recorded. Hourly measurements of temperature and salinity are also being recorded at the study location. A total of 50 crayfish have been sampled in December 2017 and February 2018 (30 females, 20 Form II males, and 0 Form I males) and salinities ranged from 3 to 6 psu. Although it is unclear how increased salinity affects fitness of these species, the findings in this study (high survivorship of Procambarus in high-salinity laboratory conditions and the collection of Procambarus lunzi from mesohaline wetlands), suggest that Procambarus is able to survive extended periods of increased salinities.
Day: 5, Session: 2, Talk: 3
Impact of Limb Loss via Autotomy and Regeneration on Crayfish Behavior and the Added Effect of Predation.
LUC ARNAUD DUNOYER, Makayla Dean, Jeremy Van Cleve and Ashley Seifert
Through inter and intra-specific interactions crayfish can lose appendages by autotomizing their chelipeds to escape predation or mortality incurred during competition for mates, shelter, or food (Wood and Wood 1932; Bliss 1960; McVean 1982). While autotomy may provide an immediate advantage, regeneration of the lost limb may temporarily limit access to shelter, food, and the ability to find a mate (Kuris and Mager 1975, Sekkelsten 1988, Davenport et al. 1992, Abelló et al. 1994, Smith 1995). We hypothesized that crayfish (Procambarus clarkii) should avoid open exposure during appendage regeneration to avoid interactions where they would be at a competitive disadvantage. A pilot study we conducted showed us that, in a drought situation when no shelter was provided, all unmanipulated crayfish burrowed whereas autotomized crayfish made a depression at best. However, crayfish preferred to hide in a shelter rather than burrowing up to completely avoiding burrowing when missing a cheliped in presence of a shelter. Finally, crayfish spent more time in a shelter when provided one and this was exacerbated by autotomy. Hence, when exposed to conspecific predation cues, crayfish should hide in their burrow, seek available shelters, or leave the water to avoid predators altogether. In addition, crayfish regenerating one of their chelipeds should avoid predators altogether by leaving the water when exposed to conspecific predation cues because they can neither defend themselves efficiently nor efficiently burrow to avoid predation. To test our hypothesis, we proposed to examine the effect of limb autotomy on crayfish behaviors alone or in the presence of simulated predation using a potent chemical cue (i.e., crunched crayfish in water; Gherardi et al. 2011). We used 15-gallon aquaria with a mud bank on one side and a water pool on the other side. We observed crayfish (unmanipulated or autotomized and regenerating) alone or exposed to predator cues for a week at a time. First, burrowing behaviors was monitored daily (number and type: 0 = no burrow, 1 = depression, 2 = burrow, 3 = partial chimney, 4 = chimney). Second, each night was recorded using infrared cameras. Video recordings are used to determine the time spent outside of the water by crayfish overnight (when crayfish are active) as well as the type of behavior in which they engage (walking, resting, or burrowing). We predict a significant effect of regenerative status on crayfish burrowing behavior as measured by less complex burrow morphologies as well as less time spent outside the water for regenerative compared to unmanipulated crayfish. Similarly, we also predict a significant effect of predation cues on crayfish burrowing behavior as measure by more time spent outside the water in presence of crunched conspecific cues in the water. Finally, we predict a significant interaction between regenerative status and predator cues as measured by a behavioral change from regenerative crayfish in presence of crunched conspecific cues in the water (more time spent outside the water) compared to unmanipulated crayfish unexposed to predator cues. At the time of this abstract submission we just started data recording.
Day: 5, Session: 3, Talk: 1
Geographical Variation in Size and Growth in the Giant Freshwater Crayfish, Astacopsis gouldi. Deductions from a Large Opportunistic Database
ALASTAIR M. M. RICHARDSON and Todd Walsh
A tagging program on the Tasmanian giant freshwater crayfish, Astacopsis gouldi, has been carried out since 1998, using PIT tags since 2007. Almost 600 animals, ranging from 20-215 mm carapace length, have been tagged and around 2500 captures recorded from 123 localities on 62 rivers across the species' range. Comparisons of length-weight relationships and growth are made between the discrete western and eastern ranges of the species, and between populations living in nutrient-poor and nutrient-rich waters. Animals from the eastern range are slightly lighter for a given weight than western animals. Growth is marginally slower in animals from nutrient-poor waters. Individual growth histories are available for 26 animals, some of which have been recaptured up to 6 times, over as long as 10 years. Growth rates vary considerably within river populations, suggesting that there may be fast- and slow-growing animals within the same population. Gompertz growth models showed lower growth rates and asymptotes for the nutrient-poor population, but their usefulness was affected by the limited size at known age data. Models suggested that animals of 220 mm CPL may be 60-70 years old.
Survey Says: U.S. State- and Canadian Provincial-Level Natural Resource Agencies Focus on Crayfish Conservation
Cheyenne E. Stratton and ROBERT J. DISTEFANO
Taylor et al. (1996) issued a "warning shot" about a crayfish imperilment plight, and "neglect" of the fauna by natural resources agencies. In the ensuing decades some highly imperiled aquatic faunal groups, such as unionid mussels and crayfish, have received moderately increased attention by U.S. and Canadian natural resources agencies. Such attention appears to have translated to increased funding for work on crayfish, possibly due to concern for individual species' imperilment, or resource problems caused by them (e.g., invasive crayfishes). We wondered 1) how perceived increased agency attention to crayfish might be reflected in numbers and types of staff assigned to work on crayfish conservation and management?, 2) where (topically) these staff are directing their efforts?, and 3) what are agencies' major constraints/impediments to and needs for crayfish conservation and management? We conducted a two-part telephone survey in 2017 and 2018 to learn about natural resources agencies' level of involvement and direction in crayfish conservation and management. In Part I (2017) we called natural resource agencies in all 50 U.S. states and 13 Canadian provinces/territories (63 "jurisdictions") to determine the number who employed or contracted staff to work on crayfish, where these jurisdictions were located (regionally), and in what topical/subject areas they were working. In Part II (2018) we made follow-up calls to only jurisdictions that had reported doing crayfish work in Part I of the survey. We asked them about their agencies' prioritization of crayfish, impediments to crayfish work, and information they believed most useful to help them conserve/manage crayfish (data needs). Part I results indicated nearly half of jurisdictions are conducting crayfish work, mostly in the Southeastern U.S., and concentrating on determining species' distributions and conservation status, or on threats (i.e., invasive species). Part II suggested that more than half of agencies working on crayfish consider them a priority faunal group, with the largest impediment being insufficient funding. Jurisdictions' most commonly cited information needs were species compositions (native and introduced), distributions, conservation status assessments, ecology, and threats. Our survey results suggest an encouraging but limited increase in U.S. state and Canadian provincial/territorial natural resources agencies working on crayfish since Taylor et al.'s (1996) challenge.
Habitat Associations of Endemic Crayfishes in the Meramec River Drainage: The Freckled Crayfish (Cambarus maculatus) and Belted Crayfish (Faxonius harrisonii).
Joe Chilton, Amanda E. Rosenberger and ROBERT J. DiSTEFANO
Understanding the habitat associations of rare species is important to make informed management and policy decisions. The Freckled Crayfish (Cambarus maculatus) and Belted Crayfish (Faxonius harrisonii) are two of Missouri’s rare and endemic crayfish species. Both species are listed as vulnerable on Missouri’s list of species and communities of conservation concern due to their limited range. Their native range is limited to the Meramec River drainage in eastern Missouri. We sampled 60 sites throughout the two species’ known range for presence and habitat variables. Replication was performed spatially within sites using kick-seines, drag seines, and visual timed-searches. Local- and landscape-scale habitat variables were evaluated for possible associations with the crayfishes through occupancy modeling with the R package “unmarked”. We found boulders and Strahler stream order were positive estimators of occupancy, while percent agriculture was negatively associated with the Freckled Crayfish. Belted Crayfish were associated with larger substrate size, increased embeddedness of substrate, and aquatic vegetation. This information will guide conservation managers in future projects and policy decisions regarding these two species.
Analysis of Species-environmental Relationships with Variance Partitioning and Distance-based Moran Eigenvector Maps: Application for Crayfish Distribution and Community Models
WILLIAM R. BUDNICK, Sophia I. Passy and Michael D. Kaller
Advances in numerical ecology have developed robust modeling techniques that can include spatial information in analyses of species-environmental relationships. We demonstrate how variance partitioning and distance-based Moran eigenvector maps (dbMEM) can determine which spatial scales that environmental factors structure crayfish communities and distributions. We sampled 56 streams from 5 major Louisiana river drainages from 2013-2014. Variance partitioning with redundancy analyses of environmental factors and geographic spatial distances produced a poor model fit and great environmental-spatial covariance, which confounded interpretation. However, including orthogonal spatial variables obtained from dbMEM not only improved model fits, but elucidated which environmental variables constrained community composition across spatial scales, namely among drainages (broad scale), within drainages (intermediate scale) and within stream (small scale). Presence of sand, specific conductance, and stream depth were important community drivers across scales, but presence of clay and grassy banks were more locally important. Temperature, a climatic factor, was important at broad scales. Our methods provided valuable insight into the relevant scales of environmental influence on crayfish and it is our hope that we see wider adoption of these methods for future work.
Gene Expression in the Crayfish Endocuticle
JERONIMO REYES-OLMEDO, Christian Kim, Trevor Dacus and Paul R. Cabe
Few genomic resources exist for any crayfish families and species despite their high species diversity, importance in freshwater ecosystems, and economic importance in aquiculture. The lack of such resources limits many areas of study, including phylogenetic relationships, local adaptation, and gene expression. We report on an exploratory study of transcripts abundantly expressed in the endocuticle tissues of Cambarus crayfish. For this work, mRNA was extracted from endocuticle tissues and copied to cDNA using reverse-transcriptase PCR. This pool of PCR products was fragmented and prepared for Illumina sequencing, yielding more than seven million paired end reads (150 base pairs each end). The sequence reads were assembled into putative transcripts using the Trinity software pipeline, and the transcripts ranked by abundance in the cDNA sample using both Sailfish and Salmon software tools. The most abundant transcripts were identified using DNA and/or protein BLAST searching. The transcripts include both well-known and unidentified gene sequences.
A Night of Devastation: Natural and Life History Observations of an En-masse Single Night Collection of Fallicambarus devastator
ZACHARY W. DILLARD, Katie Scott, Nicole M. Sadecky, Luke K. Sadecky and Zachary J. Loughman
Due to their fossorial tendencies, primary burrowing crayfish are the most difficult behavioral group of crayfish to study in-situ. In this study we elucidated both natural and life history aspects and intraspecific behaviors from a collection of 111 individual Fallicambarus devastator collected in Angelina County, Texas, on the night of May 15th, 2015. We also intend to emphasize the importance of environmental cues on collection success. Significant amounts of precipitation occurred during the days prior to collection efforts, resulting in the majority of burrows to be flooded on the day of collection. All animals were collected either traversing the landscape or captured at the portal of their burrow. Behaviors observed included excavation, respiration, feeding, and interspecific interactions. The majority of animals observed were adults, with juveniles noticeably absent on the surface. Life history observations included evidence of synchronous alteration to reproductive form in males, as well as sexually-dependent chelae morphometric ratios. Fallicambarus devastator meristically displayed sexual dimorphism between form I male and female chelae, with form I chelae having longer propodus length and greater palm widths compared to the squamous and shorter chelae of females. Understanding the significance of studying these animals in favorable conditions is of paramount importance to the quality of future primary burrowing crayfish research.
Soft Serve: The Interactive Biology of the Queen Snake (Regina septemvittata) and Its Specialized Crayfish Prey in Northern West Virginia, USA.
DAN T. MEYER and Zachary J. Loughman
Coevolution of crayfishes and other animals is well documented in the literature. In North America, several species of vertebrates and invertebrates have been documented utilizing the burrows of various crayfish species. Crawfish Frogs (Lithobates areolatus), Hines Emerald Dragonflies (Somatochlora hineana), Kirtland's snakes (Clonophis kirtlandii) and Eastern Massasauga (Sistrurus catenatus) all utilize crayfish burrows during key if not all aspects of their life history and experience declines when burrowing crayfish colonies are destroyed. Several species of animals have also been documented as crayfish dietary specialists. Hellbender salamanders (Cryptobranchus) have long been known to rely heavily on crayfishes as forage. Several sports fish, including but not limited to black basses (Micropterus salmoides), sunfishes (Centrarchidae), catfishes (Siluriformes), and brown trout (Salmo trutta) also feed heavily upon crayfish during all facets of their life history. Arguably one of the most specialized of all North American crayfish dietary obligates could be the Queen Snake (Regina septemvittata). This small natricine snake occurs throughout the Appalachian, Piedmont, Midwest, and Ozarkian region of North America, and feeds exclusively on freshly molted crayfish. Queen Snakes have experienced precipitous declines over much of the western portion of their range, though seem to remain common throughout much of Appalachia. Historically, herpetologists studying Queen Snakes have studied the snake's movement patterns, reproductive biology, and life history, but have not delved deeply into this species feeding biology. Snakes will be captured and any food boluses present in snakes will be collected by palpation of the stomach region. Monthly crayfish life history sampling will be performed in our study streams to determine the molt frequency of Cambarus carinirostris and Faxonius obscurus, which co-occur and serve as forage for queen snakes. Snakes will be captured throughout their activity period and all regurgitated crayfish will be identified to species if possible, measured and weighed, and put into a designated size cohort based on crayfish life history sampling. Our goal is to determine if Queen Snakes rely heavily on a single species of crayfish, or rely on different crayfishes during peak molt periods, as well as determine if anyone size of crayfish experience predation over another. The ultimate outcome of this research will be a better understanding of this predators interaction with it crayfish prey, and provide valuable information for its future conservation.
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