IAA22 Book of Abstracts (PDF)

Meeting Program/Schedule (PDF)






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Oral | Posters

Oral Presentations



Day: 2, Session: 1, Talk: 3

Welcome Address

James W. Fetzner Jr. and Eric Dorfman

Welcome Address



Day: 2, Session: 1, Talk: 4

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: 2

Female Form Alternation in American Cambarid Species

Tadashi Kawai

American Cambarid species are the most diverse group in the Infraorder Astacidea The group shares a unique key character state, Form Alternation (or Cyclic Dimorphism) of adult males. Form Alternation of isometric and allometric character growth is related to seasonal breeding. In summer Form I males capable of breeding have larger chelae, larger hooks on the ischia of their pereiopods, and cornified terminal elements of their 1st pleopods. They consequently molt to a non-breeding stage (Form II), which has smaller chelae, smaller hooks on the ischia of their pereiopods, and un-cornified terminal elements of their 1st pleopods. Adult Form II males molt back to Form I males for the next breeding season which normally runs in a yearly cycle. Recently it has been reported that Form Alternation also occurs in female members of Cambarus and Faxonius. Form I females display wider abdomens than same-size Form II females, and their annulus ventrali have un-cornified and a more convoluted crest along the longitudinal sinus, with a median sinus that reaches the caudal margin. The author visited the Department of Invertebrate Zoology, Smithsonian National Museum of Natural History to access Hobbs' collections. Museum specimens of adult females of four Procambarus and three Cambarellus species were examined to compare abdomen width and morphology of the annulus ventralus between breeding and non-breeding season specimens. Female Form Alternation (as listed above) was observed in all four Procambarus species; Procambarus allenii, P. clarkii, P. fallax, and P. pallidus. However, Form I females do not show wider abdomens than same-size Form II females. Cambarellus montezumae, Cambarellus patzcurensis, and Cambarellus zempoalensis did not show form alteration, and it is concluded that Cambarellus species do not undergo Form Alternation as member of Cambarus, Faxonius, and Procambarus do.



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: 1

Assessing Crayfish Habitat Requirements: A Proposed Method for Determining Habitat Breadth in Lotic Ecosystems

CHRISTOPHER A. TAYLOR and Christopher J. Rice

Lotic ecosystems in the central and eastern United States can be highly variable in habitat structure, ranging from shallow riffles to deep pools. These same ecosystems harbor a highly endemic and threatened crayfish fauna. Understanding habitat requirements for rare species is fundamental for effective conservation, yet habitat descriptions for many of these species rely solely on data from easily accessed sampling locations. We tested a new sampling method for collecting the narrowly endemic Coldwater Crayfish (Faxonius eupunctus) in the southern Missouri Ozarks by utilizing SCUBA in deep, largely non-wadeable pools. Our methods allowed for unbiased and repeatable sampling within and across sites and for the collection of rigorous data on crayfish density and habitat associations. By combining our proposed pool sampling method with wadable riffle sampling, we expanded the known habitat requirements for the Coldwater Crayfish. Data from pool sampling increased known suitable ranges for temperature and substrate size for the species. Our work also found agreement between both habitat types for physcial habitat variables exhibiting significant relationships with Coldwater Crayfish density. Using mulitple sampling methods has long been known to increase the accuracy of community inventory sampling given differences in microhabitat use by community members. Our work demonstrates that employing multiple sampling methods can increase the accuracy of habitat requirements for rare crayfish species.



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: 3, Talk: 6

Crayfish Conservation in Southern England

JEN NIGHTINGALE, Grainne McCabe, Gareth Jones and Paul Stebbing

The white-clawed crayfish, Austropotamobius pallipes has suffered severe declines within the south west of England, where the first signal crayfish, Pascifastcus leniusculus farms were established in the 1970s. In response to this decline, The South West Crayfish Partnership (SWCP) was formed in 2008; comprising Bristol Zoological Society, Buglife, Cefas, the Environment Agency, Wildlife Trusts and Associates. The SWCP implements landscape scale, strategic conservation for A. pallipes, in an attempt to safeguard the future of this species in South West England. The conservation effort has four strands: 1. Ark sites: established throughout the south west England, for translocation of the most highly threatened white-clawed crayfish populations and captive-bred reintroductions. 2. Crayfish captive breeding facility: established at Bristol Zoo, which provides plague-free A. pallipes brood stock for ark site release, wild supplementations, research and outreach. 3. Communication strategy: running in tandem with the other three elements, targeting key audiences such as anglers, restaurants, students, school children and zoo visitors. 4. Invasive crayfish control – trialing different control techniques specifically targeting the signal crayfish. The presentation will cover the key elements of this conservation programme, evaluating its success to date and discuss the research elements that run in tandem with all of these conservation strands.



Day: 2, Session: 4, Talk: 2

Invasive Rusty Crayfish (Orconectes rusticus) Populations in North America are Infected with the Crayfish Plague Disease Agent (Aphanomyces astaci)

LAURA MARTÍN-TORRIJOS, David Buckley, Ignacio Doadrio, Annie Machordom and Javier Diéguez-Uribeondo

European freshwater crayfish are currently included in the IUCN Red list as threatened. In the Iberian Peninsula, the native species (i.e., the white–clawed crayfish, Austropotamobius pallipes) has experienced a drastic decline since 1973. Currently, the implemented management strategies of these species require a better understanding of the patterns of genetic diversity. In this study, we assessed the levels and patterns of the genetic variation by analyzing the largest number of populations of the whole distributional range of the WCC in the Iberian Peninsula. The two ribosomal mitochondrial markers applied (Cytochrome Oxidase subunit I and rDNA 16S genes) indicated high levels of genetic variability, which are significantly geographically structured in three main genetic groups, i.e., two corresponding to Northern and one to Central-Eastern Iberian Peninsula). The diversity found includes new private haplotypes, and reveals WCC populations (i.e., Southern and Central European WCC populations), may be result of the ancient palaeogeographic events, such as geographic barriers, and the Last Maximum Glacial scenario (LMG) (i.e., isolation in glacial refugia). Current conservation and management programs for the WCC in the Iberian Peninsula should take into account these three phylogeographic areas as essential management units in order to preserve the maximum genetic diversity.



Day: 2, Session: 4, Talk: 6

100+ Years Since Ortmann: Conservation and Distribution of Crayfishes of the Upper Ohio River Basin in Pennsylvania

TANYA N. KHAN, David A. Lieb and Zachary J. Loughman

Crayfishes in North America face numerous anthropogenic stressors such as urbanization, extractive industries, and introduction of non-native crayfish species. In 1906, Arnold Ortmann published his survey of crayfishes of Pennsylvania, where he found only native populations. Comparing Ortmann’s work to more recent investigations of southeastern Pennsylvania crayfishes has revealed the presence of five non-native species which have destabilized historic populations. Given these findings, there are reasons to be concerned about the status of crayfish populations in the Upper Ohio River Basin in Pennsylvania, where three native species historically occur: Cambarus carinirostris (Rock Crawfish), Cambarus robustus (Big Water Crayfish), and Faxonius obscurus (Allegheny Crayfish). The goal of this study was to assess changes in crayfish fauna of western Pennsylvania since the 1906 survey. In addition, we set out to determine if abiotic factors influence presence of the three native species. Using standardized sampling of 10 seine hauls/site, we conducted surveys of 256 sites in the Upper Ohio River drainage, with a focus on collection of epigean species. Site covariates including physiochemical and physical habitat data (utilizing the Qualitative Habitat Evaluation Index, QHEI) were obtained at 175 sampled sites. Presence and absence data of each species were analyzed using logistic regression modeling to fit single covariate or additive-effects models of stream habitat, water quality, or presence/absence of other crayfish species. Crayfishes were found at 79% of 102 historical sites and 97% of 163 new sites. To date, only one non-native population of Faxonius rusticus (Rusty Crayfish) has been discovered in the North Branch of Slippery Rock Creek. These collections represent approximately 60% of the survey, with remaining collections to occur in 2018. Model results show correlations of: Faxonius obscurus presence to a global model (containing 8 covariates), temperature + conductivity, and temperature + pH; Cambarus carinirostris presence to temperature + substrate; and Cambarus robustus presence to pool quality + substrate and temperature + substrate. Preliminary data suggests that crayfish fauna in western Pennsylvania has remained moderately stable over the last century, though the presence of a non-native crayfish population indicates the need for continued monitoring. Efforts in Pennsylvania must focus on prevention and management of the spread of non-native species to preserve the native crayfish populations that remain.



Day: 3, Session: 1, Talk: 3

STURE ABRAHAMSSON MEMORIAL LECTURE: Crayfish Color Patterns: Their Overlooked Significance

Guenter A. Schuster

Crayfish colors and color patterns have not been well studied. Horton H. Hobbs, Jr. and others, in descriptions of new species, mostly relied on verbal color pattern descriptions. This began to change with the publication of Raymond Bouchard's late 1980s color poster entitled "America's Crayfish." Since then, crayfish books and color posters representing crayfishes from several states and countries have been published. Now, color photographs are usually included in new species descriptions. State and federal agencies, as well as NGOs, are commonly using color photographs of crayfishes for conservation purposes. This talk addresses the North American cambarid crayfish fauna research on vision, and how color patterns might be useful to crayfishes. It will also address how these color patterns could provide important insight into the biology, behavior, taxonomy and systematics of crayfishes.



Day: 3, Session: 3, Talk: 3

Multi-method Inference of Temperature Tolerance and Preference for a Native and an Invasive Crayfish

JACOB T. WESTHOFF, Chris Rice, Hisham Abdelrahman and James A. Stoeckel

Conservation and management of crayfishes can be informed through a greater understanding of crayfish thermal ecology, especially as it relates to the suitability of thermal habitats for native and invasive crayfish. We used a combination of behavioral and enzymatic endpoints to estimate temperature preference, optimal respiratory enzyme tolerance (ORET), and critical thermal maximum (CTM) for the imperiled native Coldwater Crayfish (Faxonius eupunctus) and the invasive Ringed Crayfish (Faxonius neglectus). Significant differences in these parameters would allow for thermal partitioning of space and thus enhance the probability of coexistence. Crayfish used in CTM and preference tests were acclimated at one of four temperatures (10, 15, 20, 25°C) for two weeks prior to testing, whereas ETS assays used crayfish acclimated at 21°C. Estimates of CTM were 33.9°C for F. eupunctus and 33.2°C for F. neglectus. Mixed linear model analysis of CTM data showed no difference between species or genders, but a strong effect of acclimation temperature (p-value < 0.01). Mixed linear model analysis using likelihood ratio tests indicated F. eupunctus preferred slightly colder water (19.6°C) than did F. neglectus (21.3°C; p-value = 0.03). That analysis also identified a significant difference (p-value = 0.01) between males (20.3°C) and females (21.0°C), but acclimation temperature and the interaction between gender and species were not significant. Mean ORET did not differ between F. eupunctus (28.4°C) and F. neglectus (28.5°C), but did differ from a third congener, Faxonius marchandi (29.7°C), based on two-way ANOVA results. For all species, ORET was higher than organismal thermal preference estimates, but lower than CTM, suggesting it may provide a useful breakpoint for managers. Management strategies should target temperature regimes that approach but do not exceed OET to increase the frequency of optimal temperature occurrences while minimizing the risk of exposing crayfish to their thermal maxima. Across all estimated metrics, F. eupunctus and F. neglectus differed by less than 2°C, indicating that significant biological difference is unlikely. Thus, habitats suitable for the native F. eupunctus will also be thermally available to the invasive F. neglectus, thereby increasing the opportunity for interaction and negative population effects.



Day: 3, Session: 3, Talk: 4

Normal Biochemistry of the Murray Crayfish Euastacus armatus (Parastacidae)

Martin Asmus, Shane Raidal and MAGGIE J. WATSON

Haemolymph samples were collected from wild and captive held adult male and female Murray Crayfish Euastacus armatus. Haematological analyses were performed in order to determine reference values for this species including protein, albumin, globulin, creatine kinase, aspartate transaminase, glutamate dehydrogenase, glucose, gamma-glutamyltransferase, potassium, sodium, calcium, phosphate, chloride, uric acid, cholesterol, amylase and bile acids. Additionally, protocols for measurements of phenoloxidase and prophenoloxidase (part of the non-specific immune system in crayfish which leads to the melanisation and sclerotisation in stressed animals) are being trialled. Alterations from these reference values can be used to determine stress and disease state of the crayfish. These tests are being used to monitor the health and stress levels of Murray Crayfish intended for use in a large-scale translocation of crayfish from healthy populations to areas of the Murray River that no longer support crayfish. Murray crayfish populations in affected parts of the river dropped by 81% in 2010–11 due to hypoxic water events.



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: 4, Talk: 1

Chemical Control Trials for Invasive Crayfish Infestations

ANN L. ALLERT, Kim T. Fredricks and James A. Stoeckel

Few chemical control tools are available for management of invasive crayfish infestations. Cypermethrin, pyrethrin, and carbon dioxide (CO2) are being investigated as potential chemical controls for invasive crayfish integrated pest management programs. Adult Red Swamp Crawfish (RSC; Procambarus clarkii) were exposed in the laboratory to CO2, cypermethrin, and pyrethrin; adult Virile Crayfish (VC; Faxonius virilis) were exposed to cypermethrin and pyrethrin. Test temperatures for CO2 trials and chemical toxicity tests were 10 and 24°C. A shuttle box was used to determine if crayfish avoided inhabiting an area with CO2-enriched water. Preliminary results of the CO2 trials suggest that RSC were more active in the 24°C trials (n = 150 crossings) compared to the 10°C (n = 75 crossings), but crayfish showed no preference for left or right sides of the shuttle box during the 30-min baseline portion of the trials. Crayfish response to the infusion of CO2 were similar for both temperatures; crayfish moved away from the CO2 side and remained on the non-CO2 side for the remainder of the 30-min trial. Crayfish avoided chambers with a CO2 concentration of about 114 mg/L. Static 24-hr toxicity tests will be conducted to determine lethal concentrations of cypermethrin and pyrethrin to RSC and VC, with and without the effect of turbidity. Pilot field trials will be conducted in <0.4 hectare research ponds (CO2), artificial burrows (cypermethrin and pyrethrin) and retention basins (cypermethrin or pyrethrin) in Michigan and Alabama, during summer and fall 2018. Results will provide resources managers with best practices for the application of CO2 to enhance mechanical and biological control methods and for the application of chemicals based on chemical sensitivity of crayfish.



Day: 3, Session: 4, Talk: 3

Epigenetic Regulation in the Marbled Crayfish

VITOR COUTINHO CARNEIRO, Anny Gatzmann, Cassandra Falckenhayn and Frank Lyko

The all-female marbled crayfish (Procambarus virginalis) attracted the attention of the scientific community due to its 'self-cloning' capacity. The obligatory parthenogenetic reproduction provided interesting research opportunities and also established a potent ecological threat. Despite its identical DNA, this model has an extraordinary variety in appearance and behaviour between isogenic batchmates reared in the same environment. This suggests that epigenetic mechanisms play a key role in marbled crayfish phenotypic variation. Our group has recently annotated the draft genome of the marbled crayfish, which revealed a conserved, functional and versatile DNA methylation system for epigenetic regulation. We have also used whole-genome bisulfite sequencing, RNA-seq and ATAC-seq for a comprehensive analysis of multiple individuals and tissues. Our results provide a novel concept for how methylation-dependent regulation of gene expression may facilitate the phenotypic adaptation and invasive spread of this animal.



Day: 5, Session: 2, Talk: 1

Crayfish Chimney Function: Airflow, Oxygen, and Pheromones

JAMES A. STOECKEL, Hisham Abdelrahman, Mary Szoka, David Blersch and Jeremiah Davis

Most burrowing crayfish build chimneys. However, chimneys are often present only seasonally, located only over a single burrow opening, or completely absent, suggesting that they are periodically constructed for specific function and purpose(s). In this study we use a combination of field and wind-tunnel experiments to investigate function and purpose of Cambarus c.f. polychromatus chimneys. Field trials with smoke bombs and natural burrows showed that air flow is a major outcome of chimney construction. In a typical burrow complex, smoke was drawn in through three non-chimney openings, traveled ~0.5 m underground to the groundwater level, and then back up to the surface and exited through the chimney. Smoke was not drawn through the burrow when the chimney was removed. Chimneys appear to drive airflow through burrows by creating temperature differentials with non-chimney openings, and/or pressure differentials related to wind blowing across chimney and non-chimney entrances (Bernouli’s Principle). Wind tunnel trials with model burrows showed that air velocity through burrows was highest when chimneys were upwind of chimneyless openings. Air velocity through burrows also increased with increasing chimney height and increasing wind speed. Ongoing field studies suggest that need for increased oxygen is not likely the primary purpose driving crayfish to build chimneys to draw air through burrows. Individuals that were freshly molted or brooding, representing two life-history stages that require the most oxygen, were only found in plugged and chimneyless burrows, respectively. Alternatively, based on results of this and previous studies, we hypothesize that an important outcome of increased airflow through and out the burrows is dispersal of pheromones to facilitate intraspecific communication between adults during the reproductive season, and subsequent recruitment of young to conspecific burrow colonies.



Day: 5, Session: 2, Talk: 5

Invasive Rusty Crayfish (Orconectes rusticus) Populations in North America are Infected with the Crayfish Plague Disease Agent (Aphanomyces astaci)

JÖRN PANTELEIT, Thomas Horvath, Japo Jussila, Jenny Makkonen, William Perry, Ralf Schulz, Kathrin Theissinger and Anne Schrimpf

The American rusty crayfish, Orconectes rusticus, is an invasive species in various parts of North America, where it displaces resident crayfish species. While the influence of the crayfish plague disease agent, Aphanomyces astaci, has been studied extensively in Europe, the impact of A. astaci on the invasion success of crayfish within North America has so far received no attention. As a first approach to the question, whether A. astaci might play a role in the invasion success of O. rusticus within North America, we tested 84 O. rusticus samples for infection with A. astaci from 10 different locations in the Midwest, which are outside of the O. rusticus native distribution range. We used quantitative real-time PCR (qPCR) to assess the infection prevalence and determined the mitochondrial haplotypes and multilocus microsatellite genotypes where this was possible. With qPCR, we detected A. astaci DNA in 4 out of 10 locations. The results were confirmed by isolation of A. astaci. Analyses of the pure culture isolates and the crayfish tissue samples by haplotyping and genotyping revealed a novel microsatellite genotype. Our results clearly identify O. rusticus as a vector of A. astaci in North America for the first time. The threat caused by these novel strains to endangered crayfish species in North America still remains unknown, but conservation efforts should consider A. astaci infections when developing and implementing invasive species management plans.



Day: 5, Session: 3, Talk: 4

The Development and Application of a Commercially Viable and User Friendly Environmental DNA (eDNA) Methodology for the Conservation of the Endangered White-Clawed Crayfish

CHRISTOPHER TROTH and Michael J. Sweet

Over the last thirty years, in the UK and Europe the endangered indigenous white-clawed crayfish (Austropotamobius pallipes) has suffered extensive population decline due to the introduction of competitive and disease carrying non-native species. Detection of these now isolated populations is becoming more difficult using established and often destructive or invasive traditional ecological survey techniques. The recent emergence of molecular species detection, defined by the term ‘environmental DNA – eDNA’ has proven to be a valid additional cost-effective method to traditional surveys for many aquatic species worldwide. Here we develop an eDNA based method for the non-invasive detection of A. pallipes; inferring fast species presence or absence data within freshwater habitats. Working alongside stakeholders, commercial organisations, ecologists and end-user groups in the UK we have validated this method for use as a commercially available tool, through careful design and assessment of all variables and limitations that are known to effect eDNA. This has enabled the validation of the technique in ‘real world’ conservation and commercial based settings. Primary trials into the potential quantification of white-clawed crayfish biomass using eDNA have had success with high and medium densities of crayfish in controlled environments. However, at lower natural densities quantification attempts were more varied. We also present the analysis of two different, commonly used sample collection methods to identify the most suitable and commercially applicable technique for effective detection of A. pallipes which may depend on the goal of each individual study. In this paper we report our findings on A. pallipes distribution and abundance in both lotic and lentic habitats using eDNA, incorporating two different approaches to sample collection. We also explore the variation of eDNA detection rates through the seasons, to determine if eDNA could be used for the detection of A. pallipes all year round, or during the more active summer season of crayfish activity. Coupled with further research into the rate of eDNA decay over time, and sample collection methodology choice we can we can now apply these methods in the field successfully taking all major limitations into account to get the most out of A. pallipes detection using non-invasive eDNA techniques. Using feedback from end-users we can now provide a basis for the commercial development and use of eDNA for crayfish, providing a more accessible detection method which will allow for more citizen science within this field to contribute to a greater conservation effort of the white-clawed crayfish.



Day: 5, Session: 4, Talk: 4

Detectable Effects of Impoundments on the Genetic Structure of Crayfish (Faxonius spp.) in Alabama 43-Years After Dam Closure

ZANETHIA C. BARNETT, Ryan C. Garrick, Clifford A. Ochs and Susan B. Adams

Numerous freshwater species have highly fragmented populations due to barriers created by impoundments. Dams and impoundments can prevent or reduce dispersal by physically blocking movement of individuals, reducing floodplain-river connectivity, and creating a lentic zone and tail waters unfavorable to stream organisms. The loss of longitudinal and lateral connectivity can lead to population isolation, failed recruitment, and local extinction. Using population genetic analyses, we assessed fragmentation of crayfish populations caused by impoundments in the southern Appalachians, a global center of crayfish diversity and a region with numerous impoundments. We sampled one unimpounded and two impounded streams. Six to 10 sites were sampled along each stream between 2015 and 2017, with at least four sites sampled up- and downstream of impoundments. Faxonius erichsonianus and F. validus, two of the most abundant and widespread species in the streams, were collected for genetic analyses. For all individuals, a portion of the mitochondrial cytochrome oxidase subunit I (COI) gene was amplified via polymerase chain reaction, and sequenced. Analyses of F. erichsonianus are in progress. Faxonius validus genetic diversity was lower in unimpounded than impounded streams. Local populations of F. validus up- versus downstream of impoundments differed genetically from one another, but up- and downstream populations in the unimpounded stream did not differ. Directionality of gene flow analyses indicated that in the unimpounded stream, F. validus individuals moved both up and downstream. However, as expected, this connectivity was asymmetric, with greater gene flow originating from upstream sources. Notably, whereas downstream gene flow occurred in both impounded streams, upstream gene flow occurred in only one of these streams. Overall, the magnitude of genetic connectivity among local populations was higher in unimpounded than impounded streams.


Poster Presentations




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.




Influence of Climate Warming on the Ecological Impacts of Invasive Crayfishes

VICTORIA CHICATUN and Anthony Ricciardi

Aquatic systems in temperate regions are particularly sensitive to temperature change, which can cause seasonal stress for cold-water adapted species and hospitable conditions for warm-water invaders. Altered thermal regimes may mediate the ecological impacts of non-native species by affecting their abundance and per capita effects, causing shifts in predator-prey dynamics and competitive dominance over native species. High-impact invaders tend to exhibit higher functional responses (maximum feeding rates) than functionally-similar native taxa. It has also been shown that individuals' maximum feeding rates are inversely proportional to the deviation from their environmental optima and could potentially be used a performance metric for invasive species across a thermal gradient. My research investigates the effects of water temperature and population latitude on prey consumption and competitive dominance by invasive (Faxonius rusticus) and native (F. virilis) crayfishes in the Great Lakes basin. For this, I have planned a series of lab experiments comparing functional responses and outcomes of competitive interactions across temperatures (based on projected warming scenarios for the lower Great Lakes) to test the prediction that native species will exhibit lower maximum feeding rates than invaders and that increasing temperatures will result in competitive dominance of southern species over northern species.




Another Cautionary Tale of Numts: Multiple Different Copies of the COI Gene in the Camp Shelby Burrowing Crayfish (Fallicambarus gordoni)


During a preliminary phylogeographic study conducted several years ago involving the Camp Shelby Burrowing Crayfish (Fallicambarus gordoni) it was noted that most of the generated COI barcode sequences were “messy” (i.e., contained multiple peaks at many sites along the length of the sequence), suggesting some sort of contamination was being co-amplified. This messy data was so prevalent (almost every specimen) that it ultimately eroded confidence in the base calls for the region sequenced and led to the termination of the project due to a very limited sequencing budget that had already been expended. In order to investigate the source of this contamination, COI PCR products from eight F. gordoni individuals (one from each sampled site), plus one specimen of another Fallicambarus species, were subsequently cloned. Eight individual colonies per individual were picked, amplified, and sequenced to see if the source of the contamination could be identified (i.e., as bacterial, human, pseudogene, or other). Checking the sequences using Genbank BLAST searches revealed that the sequences were most closely related to COI genes from the genus Fallicambarus, suggesting they are additional copies present within the genome, rather than contaminant DNA from an external source (i.e., bacterial). The results suggested that multiple different copies of the COI gene appear to be present within the genome of F. gordoni individuals, often containing multiple point mutations and/or length differences (=indels), which directly resulted in the messy sequences seen during the original project. In some cases, the sequences appeared to be pseudogenes because they often contained multiple stop codons. This study provides another cautionary tale about numts (nuclear copies of mitochondrial genes) and making sure they are accounted for when analyzing mitochondrial datasets in phylogeographic and systematic studies of freshwater crayfish.




Historical and Current Distribution of Western Pennsylvania’s Appalachian Primary Burrowing Crayfishes: A Century of Change or Stasis?

KATIE SCOTT, Zachary W. Dillard, Nicole M. Sadecky, Zachary J. Loughman and David A. Lieb

Astacological efforts in Pennsylvania have increased over the past decade. However, the distribution and conservation standing of Western Pennsylvania (WPA) burrowing crayfish represents the greatest void in knowledge regarding the state’s crayfish fauna. To rectify this situation, burrowing crayfish surveys were initiated across WPA in 2014-2016 using Ortmann’s (1906) historical records as a guide. 61 historic sites were resampled, and 19.6% maintained burrowing crayfish populations. 57 new sites were sampled, of which 71.9% supported burrowing crayfish populations. Overall, burrowing crayfish were detected at 44.9% of the 118 sites sampled. Ortmann documented Cambarus dubius, Cambarus monongalensis, and Cambarus thomai in WPA. All three species were found during this survey, with each taxa allied to a physiographic region. Urbanization has negatively impacted burrowing crayfish over the past century, and greenspaces proved to be important islands of habitation in the presence of urbanization. Comprehensively, our survey results indicate that WPA burrowing crayfish taxa are currently stable.




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.




A New Species of Faxonius Crayfish from the Red River System of Kentucky and Tennessee

ERIN T. BLOOM, Brittany McCall, Guenter A. Schuster and Rebecca E. Blanton

Faxonius barrenensis is a crayfish endemic to the Green River system of Kentucky and Tennessee and is closely related to F. mirus, which is restricted to Tennessee River tributaries in Tennessee and Alabama. A morphologically similar but undescribed crayfish, Faxonius sp., occurs in the Red River system (Cumberland River) of Kentucky and Tennessee. Whether the latter represents a disjunct population of F. barrenensis or F. mirus, or alternatively, a distinct, species is unknown. Furthermore, whether the shared morphological traits reflected shared ancestry or convergence has not been tested. We used molecular and morphological data, including two mitochondrial (COI and 16s) and two nuclear (28s and GAPDH) genes and a standard suite of phenotypic measurements and meristics to examine phylogenetic relationships and the taxonomic status of Faxonius sp. relative to F. barrenensis, F. mirus and other Faxonius. Results from the concatenated and individual gene datasets supported a close relationship among the three focal taxa, implying their gross morphological similarities likely reflect recent shared ancestry. In all mitochondrial and combined gene trees, Faxonius sp. was recovered as a genetically divergent clade from F. barrenensis and F. mirus. Additionally, Faxonius sp. is phenotypically distinguished from F. barrenensis and F. mirus based on several characteristics. Given these findings, we propose Faxonius sp. represents a distinct species of crayfish that is closely related to F. mirus and F. barrenensis. However, our data does not resolve which of the latter is its sister species; additional molecular markers are needed to resolve this question. The new species has only been collected at four different localities within the Red River system (Cumberland), three of those located on the Ft. Campbell Army Base along the Tennessee/Kentucky state line. Several other streams have been searched, but no other populations have been identified, suggesting it has a small range and warrants conservation concern.




The Crayfish Morphology Database: Developing an Online Platform for Maintaining and Sharing Specimen Data and Images Used in the Descriptions of New Crayfish Species


A new online database, and associated website, are under development with the goal of capturing, maintaining and sharing a standard suite of morphological measurement data and specimen images used in the description of new freshwater crayfish species. The website is password protected, allowing authors to secure their project data under a user account that only they can access. Once published, their data could become available to the community. The site consists of eight tabbed web forms that capture information on field collections, geographic locality, and specimen-level morphological measurements broken out by major feature (e.g., Carapace, Rostrum, Chela, Gonopod, and ‘Miscellaneous’). A tab is also provided to upload specimen images captured from a variety of views. The database currently is set up for capturing data on North American taxa, but if there is interest from the community, this could be expanded to include other crayfish groups from around the globe. Measurement data can be entered automatically into the web form via a digital caliper connected to a computer, or entered manually. A standard set of photographic images can also be captured and annotated, and then uploaded to the project, making them available for side-by-side viewing, allowing for multiple specimen comparisons of various morphological features. Features such as simple statistical analyses of the data (counts, frequencies, etc.) still need to be implemented, but could be generated and output as a summary report. The full project data can also be output to Excel format to allow for more detailed statistical analyses. Most of the data presented in new species descriptions are just estimates of the mean and/or the range of values measured. Thus, all of the underlying data captured for each individual specimen in a study are often lost to science, unless the specimens have been designated as types. Having a repository for these types of data will help to make comparisons among species a lot easier in the future and will reduce the duplication of effort when making comparisons among multiple species.




Assessing Metals-Mining Impacts to Stream Ecosystems Using Crayfish

ANN L ALLERT, Danielle Cleveland, Christopher Schmitt, Robert J. DiStefano, John Weber, David Mosby and Eric Gramlich

Quantifying injury to aquatic natural resources caused by the release of contaminants is essential for pursuing damage claims from responsible parties within the context of the U.S. Natural Resource Damage Assessment framework. Natural resource trustees, including U.S Fish and Wildlife Service and state conservation agencies, assess physical, chemical and biological metric and endpoints when pursuing claims. Studies conducted in Missouri’s lead mining districts have evaluated the direct effects of metals mining on native crayfish species as well as indirect effects related to their structural and functional roles in Ozark Mountain ecosystems. Crayfish were found to be indicator or sentinel species due to their site fidelity, abundance, and sensitivity to metals. Crayfish densities were significantly lower at sites downstream from mining areas compared to sites upstream for mining-impacted sites. Crayfish are important food items for predatory fishes and riparian wildlife, which may be at risk from dietary exposure to metals in crayfish. Results from our study have contributed to recovery of funds for stream habitat restoration and for status assessments for potentially threatened or endangered crayfish species residing in mining-impacted watersheds.

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