IAA22 Book of Abstracts (PDF)
Meeting Program/Schedule (PDF)
LIST OF MEETING ABSTRACTS
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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: 1
Molecular Phylogenetic Analysis of the Devil Crayfish Group, with Elevation of Lacunicambarus to Generic Rank and a Re-description of the Devil Crayfish, Lacunicambarus diogenes comb. nov.
MAEL G. GLON, Roger F. Thoma, Chris A. Taylor, Marymegan Daly and John V. Freudenstein
As North American crayfish biodiversity becomes increasingly imperiled, the lack of a well-resolved, underlying taxonomic framework impedes conservation efforts. The taxonomy of the family Cambaridae has historically been based on morphology, but recent studies using molecular phylogenetic techniques have revealed taxonomic inconsistencies including a polyphyletic genus Cambarus. Here, we take a step towards increasing the taxonomic resolution of Cambaridae by investigating a group of primary burrowing crayfishes which were historically part of the Cambarus subgenera Lacunicambarus and Tubericambarus. This group, which we provisionally call the Devil Crayfish Group (DCG) because it contains the Devil Crayfish (Cambarus diogenes), has a complicated taxonomic history and is in need of revisionary work to inform conservation assessments. In this study, we test the hypothesis that the DCG forms a monophyletic clade through phylogenetic analyses of mitochondrial DNA sequence data from multiple specimens of the eight DCG species and from a broad sample of taxa representing approximately 70% of the species in what is currently recognized as Cambarus. We find that seven of the eight species from the DCG form a well-supported, monophyletic clade that is distinct from the remainder of what has traditionally been recognized as Cambarus. Although we were not successful in resolving the backbone of our phylogeny with high confidence, our analyses place the DCG as sister to a clade consisting of taxa from the genera Creaserinus, Faxonius, and Barbicambarus. Based on our results and on unique morphological and ecological characteristics of the DCG, we split seven of the eight DCG species from Cambarus and place them in Lacunicambarus, which we elevate to generic rank. We also redescribe the devil crayfish sensu stricto (Lacunicambarus diogenes comb. nov.) and designate a neotype for the species to facilitate subsequent revisionary work.
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: 2, Talk: 4
Examination of Morphological Variation in Faxonius jeffersoni Populations Indicates the Presence of a Species Complex
Zachary L. Couch
Faxonius jeffersoni Rhoades is a poorly known member of the crayfish family Cambaridae currently found in six small stream systems in Jefferson, Oldham, and Bullitt counties in Kentucky, USA. Fitzpatrick (1967) was the first to report morphological variation in gonopod sculpturing, rostrum width, and areola width between populations of F. jeffersoni found in the Beargrass and Pond Creek drainages in Jefferson and Bullitt counties. During qualitative and quantitative surveys conducted as a part of this study from 2007–2010 throughout Kentucky, examination of several morphological characteristics indicate that F. jeffersoni may represent multiple species. Examined specimens of F. jeffersoni from the Beargrass (n=48) and Goose Creek (n=15) drainages possess a gonopod with terminal elements (equal in length) that are 26.51% (0.026) and 26.62% (0.019) of the total length of the gonopod, respectively, lack a shoulder below the central projection, and typically exhibit a smooth mandibular margin. Specimens of F. jeffersoni examined from the Pond Creek (n=21) and Abrams Run (n=6) drainages are typically characterized by having a gonopod with terminal elements (the central projection being longer than the mesial process) that are 31.93% (0.019) and 31.54% (0.026) of the total length of the gonopod, respectively, possess a shoulder on the gonopod below the central projection, and typically exhibit a dentate mandibular margin. A median carina is often observed in larger specimens from the Pond Creek and Abrams Run drainages but was always found to be lacking from examined specimens from the Beargrass and Goose Creek drainages. This study reports the findings of preliminary morphometric analyses collected to clarify the taxonomic status of F. jeffersoni. Additional data collection and analysis is ongoing. However, results of morphometric analyses conducted to date suggests that the population of F. jeffersoni found in the Pond Creek and Abrams Run drainages represents a new species. As the current range of the species resides in a largely urban watershed, these initial findings are encouraged for use by resource managers to begin to reassess the conservation status of the F. jeffersoni species complex and consider its need for legal protection at the state and federal levels.
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: 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: 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: 7
Introduced and Then Almost Forgotten: Invasive Crayfish (Procambarus clarkii and Cherax quadricarinatus) in Costa Rica, Central America - Preliminary Results
JUAN CARLOS AZOFEIFA SOLANO, Ingo S. Wehrtmann, Fresia Villalobos-Rojas, Raquel Romero-Chaves and Adrián García-Rodríguez
Costa Rica harbors a remarkable diversity of freshwater native decapods, including 15 crab species (Pseudothelphusidae) and more than 21 species of caridean shrimps (Atyidae and Palaemonidae). Crayfish (Astacoidea) are not part of the native freshwater decapod fauna of the country. However, during the last century, two crayfish species were introduced: Procambarus clarkii in the Reventazón basin (Caribbean slope) in the 1970's, and Cherax quadricarinatus in the Tempisque basin (Pacific slope) in the 1980's. Both species have been recognized as invasive species in many other countries, and there is broad evidence suggesting its negative impact on native species, ecosystem functioning, and even human activities. Despite the potential threat of these crayfish species for the Costa Rican freshwater environments, very limited information is available about their occurrence in the country. Therefore, it is imperative to document the current distribution of both species and to assess their possible effects on the freshwater ecosystems in Costa Rica. We initiated a study aimed to explore the presence of these invasive crayfish species in Costa Rican streams and lakes and to provide information about their feeding ecology. So far, we have collected P. clarkii in two locations, outside the Reventazón basin were it was initially introduced, and belonging to the Pacific slope. More than 160 specimens have been analyzed, ranging in size from 6.5 to 78.1 mm total length. The predominant food item found at the stomachs was unidentified plant detritus, followed by filamentous plants, fragments of chironomid and Ephemeroptera larvae, and plastic. Our collections revealed two new locations for C. quadricarinatus in Costa Rica: one of them a stream in the Caribbean slope, and the other in the Arenal Lake, the largest reservoir in Costa Rica. The size of the collected specimens (n=7) ranged from 45.1 to 92.2 mm total length. Currently, both crayfish species inhabit both Caribbean and Pacific slopes in Costa Rica. It remains to be studied whether these species dispersed naturally or if they were locally introduced by humans. Since both species have been introduced in Costa Rica and the Central American region, the results of the study aim to raise awareness about the possible impacts of these crayfish species on the native flora and fauna of the local freshwater ecosystems, and to develop recommendations for the implementation of management programs.
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: 4
An Update on the Distribution and Conservation Status of the Crayfishes of Alabama
STUART W. McGREGOR, Guenter A. Schuster, Christopher A. Taylor, Rebecca A. Bearden and E. Anne Wynn
Each state is required to have a State Wildlife Action Plan (SWAP) to be eligible for federal funds through the Wildlife Conservation Restoration Program (WCRP) or the State Wildlife Grants Program (SWG). For Alabama to move forward in conserving its aquatic species, a first step is understanding biodiversity patterns: What species do we have and where are they found? Second, it is important to know which species need conservation action. These fundamental levels of understanding did not exist for crayfishes in Alabama before our project. Starting in 2005 Drs. Guenter Schuster and Chris Taylor performed an exhaustive literature search and visited numerous museum collections and compiled a database with over 4,600 records documenting 85 crayfish species from Alabama. Subsequently, with funding supplied on two occasions by the SWG program and independently by the U.S. Fish and Wildlife Service, Geological Survey of Alabama staff, Drs. Schuster and Taylor, and associates sampled crayfish in areas of the state that showed a dearth of records based on maps generated from the Schuster and Taylor database and surveyed for species petitioned for listing by the U.S. Fish and Wildlife Service. The first SWG project (2008-10) added over 760 collection records, documented 64 of 85 species recognized from the state at that time, tightened collection coverage gaps, and recommended a preliminary conservation priority status for each species. In 2012, a group of subject matter experts convened in Auburn, Alabama, for the Third Nongame Wildlife Symposium and provided information on each species known from Alabama at the time. The result was an updated SWAP with conservation priority status designated for each species. Crayfish were included for the first time and 12 species were found to be of Highest Conservation Priority, 30 of High Conservation Priority, 15 of Moderate Conservation Priority, 14 of Low Conservation Priority, and 12 of Lowest Conservation Priority. Another important result of the first SWG project was the need to further close coverage gaps, further address undersampled habitats, and refine species-specific distributional information. The second SWG grant was secured to address those needs (2014-17). Final results of these studies yield about 9,300 records documenting 97 species of crayfishes (94 natives), with 15 state endemics, a few species whose taxonomic status remains unclear, a few undescribed taxa awaiting formal descriptions, and 5 hypothetical species. Another result was the opportunity to make preliminary conservation priority recommendations for species added to the state list or systematically reassigned during the latter phase of the project. We recommended 1 species status be changed to Highest Conservation Priority, 6 others added to Highest Conservation Priority, 4 to High Conservation Priority, 2 to Low Conservation Priority, and 1 to Lowest Conservation Priority. The state list will very likely surpass 100 species upon further research. During our studies 94 of the 97 species known from the state were encountered, with only 3 rare troglobites unobserved (but likely extant).
Day: 3, Session: 2, Talk: 1
Development of Mass Production Hatchery Technology for Cherax quadricarinatus
CLIVE JONES and Colin Valverde
Aquaculture production of redclaw (Cherax quadricarinatus) in Australia, has never reached the high level projections made in the 1990’s. This can be attributed to a range of factors, but the most significant is the supply of seedstock. One of the most positive aquaculture characteristics of redclaw is its bearing of offspring in adult form, obviating the requirement for larval rearing, as is necessary for most successfully commercialised aquaculture species. Among other positive characteristics, this was seen as the most significant and methods for pond-based, mass production of juvenile redclaw were devised and implemented by industry. This relied on natural reproduction, and natural productivity in the pond to support the survival and growth of the juveniles. Mean productivity was reported as 63.2 juveniles produced per berried female, and a harvest density of 24.6 juveniles per m2. Under suitable, summer photoperiod and temperature conditions, three consecutive crops of juveniles could be produced per year. Such managed pond production of seed stock for redclaw production was applied by industry with some success, but it soon became evident that productivity was too low and the practice occupied valuable pond space that would be more profitably applied to growout. An alternative production method for the supply of lobster juvenile redclaw was conceived by an innovative redclaw farmer, Colin Valverde, utilising artificial egg incubators, that had been successfully applied to freshwater crayfish species in Europe. The putative advantages of artificial egg incubation include savings of space, water and energy, minimising egg loss, control over the period of embryogenesis, known parentage for genetic selection and prevention of transmission of disease from parent to offspring. The primary advantages were initially for its application to genetic selection and for generating specific pathogen free stock. However, an even greater benefit became apparent, that this approach could support mass production of seedstock. The system that formed the basis of the that developed in Australia for redclaw was based primarily on the Hemputin™ incubator from Finland used for Pacifastacus leniusculus and Astacus astacus. Its design was modified to suit the specific requirements of redclaw and greater production volumes. The procedures and equipment have evolved, providing a foundation for more consistent and greater production of seed. The juvenile crayfish produced by the hatchery have generally moulted twice since hatching and are referred to as stage 3 juveniles or craylings. A hatchery supply of craylings provides the opportunity for farmers to stock an exact quantity of uniform size crayfish into growout ponds, which in turn enables calculation of likely survival, growth and biomass at the end of the production cycle. The Valverde hatchery system can generate tens of thousands of craylings per batch and is scalable. However there are production issues to be resolved including year round supply of eggs to the hatchery and management of egg health. This paper will detail the development of the Valverde hatchery system, and the challenges to see it develop into fully commercial production that can support expansion of the redclaw farming industry.
Day: 3, Session: 2, Talk: 3
Crayfish, Conservation, and the Coalfields: A Case Study in the Initiation of a Crayfish Conservation Effort in North America
Zachary J. Loughman
Crayfishes have been recognized as one of the most imperiled animal groups on the planet internationally now for more than a decade. Conservation efforts in Europe and Australia have been many, and respective governments on both continents and their associated conservation agencies have been quick to recognize and protect pockets of diversity and specific highly imperiled species. In North America, most recent efforts have occurred via state level conservation agencies, which when said agencies have effective, forceful legal power, garner extensive protection for crayfish. Not all state level agencies are created equal, and when agencies lack enforcement power, crayfishes and other imperiled species can be eliminated in the names of progress. In these situations, listing as a federally imperiled species becomes paramount for protection of said taxa and their associated current and potential habitat. Cambarus callainus (Big Sandy Crayfish) and Cambarus veteranus (Guyandotte River Crayfish) are two Central Appalachian endemic species of tertiary burrowing crayfish whose populations have experienced drastic declines due to excess sedimentation and other stressors allied with extractive industries and development of riparian corridors. In 2014, a status assessment was written by the United State Fish and Wildlife Service (USFWS) based on work completed by astacological workers prior to that time, which indicated that water quality threats associated with coal mining, development, and off-road vehicle tourism were likely pressures to both species ability to persist in the coal fields of Kentucky, Virginia, and West Virginia, and in the case of C. veteranus, West Virginia only. In 2015, a range-wide assessment was completed for both species that involved visiting every historical location as well as over 100 new sample locations. Resultant of this work, current data was acquired that identified the principal current threats to both taxa had not changed, and possibly had gotten worse, which ultimately was used in addition to previous workers data to justify listing both species federally. On April 7th, 2016 C. callainus was listed as threatened and C. veteranus was listed as endangered. Beginning in the spring of 2017, an aggressive conservation campaign was initiated involving federal, nonprofit, and state level conservation agencies to gather data that ultimately will be used to conserve and protect both species. Captive rearing protocols, life history studies of C. callainus and C. veteranus as well as their crayfish associates, telemetry studies, and crayfish community analysis in addition to the creation of a response team for spills associated with extractive industry was created. In addition to research efforts, development of educational workshops for biologists working in the coalfields was also undertaken and initiated in the spring of 2016. Here in a review and case study will be provided detailing this process and the hope for its ultimate utilization in the preservation and future conservation of these highly imperiled central Appalachian endemics.
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: 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: 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: 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: 3, Session: 4, Talk: 4
Effect of an Analgesic at Environmental Concentration on Crayfish Locomotion and Cardiac Physiology
FILIP LOŽEK, Iryna Kuklina, Tomáš Randák, Pavel Kozák, Petr Císař and Miloš Buřič
There is an increasing evidence on ecological and biological impacts of pharmaceutical pollution (e.g., antidepressants, anxiolytics, psycholeptics and analgesics) on aquatic organisms. Tramadol is an example of opioid analgesic frequently used treating chronic and acute pain. In order to investigate long-time effects of tramadol at environmentally relevant of 1 ?g L-1 on signal crayfish Pacifastacus leniusculus as an important participent of the predator-prey relationships, cardiac activity (heart rate, HR) and behavior (locomotion) were evaluated under repeated stimuli of a natural stressor (i.e., hemolymph) as an odor of injured conspecific 4 times within 3 weeks of tramadol exposure and 4 times within following 2 weeks of depuration period. For evaluation of crayfish primary physiological and ethological reactions to the stressor, the data within half an hour prior to and half an hour post stressor addition were used. A significant increase of the HR after stressor application was found, as well as there was a significant difference between tramadol free (control) and tramadol exposed groups. However there was no statistical difference in the locomotion of both control and exposed crayfish recorded before and after stressor application. According to the discovered shifts in crayfish cardiac physiology under long-term exposure to tramadol at non-lethal concentration, the significance of these shifts will need further detailed investigations.
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: 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: 2, Talk: 4
Using Crayfish as a Bio-indicator – Practical Experience from a Brewery Factory
PAVEL KOZÁK, Viktoria Shchennikova, Filip Ložek, Iryna Kuklina, Michal Vold?ich, Roman Dedic and Petr Císa?
We operated our patented non-invasive monitoring system using crayfish as a bio-indicators to control the water quality at the brewery factory. The system is based on monitoring of etho-physiological status of crayfish combining analysis of the heart rate and detection of movement as basic parameters. Monitoring of cardiac activity is done with the aid of a non-invasive sensor connecting crayfish by a flexible wire to the measuring unit and the locomotion is registered by cameras that enable complex analysis of the data by a software developed particularly for this purpose. The system was established in the water treatment facility of the factory in spring 2016. The period from February to August 2017 was precisely analyzed with the focus on the effect of water hygienic treatment with chlorine dioxide (ClO2) on crayfish heart rate and their subsequent mortality. Adult individuals of signal crayfish, Pacifastacus leniusculus, were kept separately in flow through aquariums, placed following the water treatment device producing ClO2 in concentration from 0.01 to 0.29 mg·L-1. Observed crayfish response to disinfectant varied among specimens that could be explained by different physiological conditions and individual reaction. Diurnal rhythm of some crayfish was disturbed even at lowest concentrations of chlorine dioxide (0.01-0.2 mg·L-1), that resulted in interruption of circadian cardiac and locomotor activity, while higher concentrations (? 0.2 mg·L-1) affected all animals and in addition to that, mortality significantly increased. The highest concentrations (0.2-0.29 mg·L-1) were observed 28 times in total during 202 days of monitoring, which resulted in 25 mortality cases occurred several days after exposure. In average, mortalities of crayfish occurred 3-4 weeks after stocking to the experimental system. Possible lethal concentration of ClO2, which caused animal mortality, exceeded 0.2 mg·L-1. Results suggested that crayfish exposure to ClO2, obviously, negatively affect their physiological processes; however, further studies are needed to examine specific effects of chlorine dioxide on internal organs of crayfish. Also, the results can serve the background data for an efficient crayfish application as biological indicators of appropriate disinfection at the water treatment and supply facilities.
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.
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: 3, Talk: 5
A New Technique for Determining Crayfish Population Demographics
JOSHUA MOUSER, Jason Glover and Shannon K. Brewer
Aging organisms provides crucial population demographic information such as growth, recruitment, and mortality. Crustaceans are typically aged via indirect techniques, such as length-frequency histograms and mark recapture. Indirect techniques are limited to the populations and specific study period, do not provide an actual age, and histograms are inaccurate for older age classes with fewer individuals. In contrast, direct techniques rely on calcified structures, but often the individual must be sacrificed. Recent work has demonstrated that the gastric mill, located in the stomach of crustaceans, may be useful for obtaining direct age estimates. Therefore, our objective was to determine if a common North American crayfish species could be reliably aged using gastric mill ossicles. We collected approximately 100 adult and 300 age-0 (<13 mm carapace length) ringed crayfish Faxonius neglectus from streams in the Ozark Highlands ecoregion. Gastric mills were extracted from the crayfish, separated, cleaned, sectioned, and mounted on a microscope slide. Each crayfish was aged independently by three different readers and a consensus age was reached if there were discrepancies. For a subset of individuals, two readers aged each ossicle independently to determine which ossicle provided the most consistent age estimates. We compared length-frequency histograms from field collections to our direct age estimates. All three ossicles showed consistent growth bands, but the zygocardiac and mesocardiac ossicles had superior readability. Crayfish age estimates ranged from zero to ten years, whereas the length-frequency histograms suggested eight year classes. Our age estimates did not match length-frequency histograms well, especially after year 4. Independent age estimates from each of the paired zygocardiac ossicles were similar. Our results suggest that ringed crayfish may live to be much older than five years as generally accepted, and aging crayfish directly may improve the age bias reflected in histograms. Future work will focus on validating that bands correspond to one year of growth, environmental effects on band deposition, and if daily bands are deposited in age-0 crayfish.
Day: 5, Session: 4, Talk: 1
Origin and Speciation of the Marbled Crayfish
Marbled crayfish are a globally expanding population of parthenogenetically reproducing freshwater crayfish. They are closely related to the sexually reproducing slough crayfish, Procambarus fallax, which is native to the southeastern United States. However, reproductive incompatibility and substantial genetic differences suggest that the marbled crayfish should be considered an independent species (Procambarus virginalis). We have recently established a draft assembly of the marbled crayfish genome. We are now using comparative whole-genome sequencing to clarify the origin and speciation of marbled crayfish and I will discuss our available data.
Fishery-dependent Stock Assessment of Crayfish in the Eastern Atchafalaya River Basin
GABRIELLE A. SISSON and Christopher P. Bonvillain
Stock assessments are vital in fisheries management to monitor past and current status on population size and structure, and the potential responses of the fishery to future management decisions. However, there have not been extensive stock assessments for crayfish in the Atchafalaya River Basin (ARB), the largest wild crayfish fishery in Louisiana. Conducting crayfish stock assessments in the ARB have been difficult due lack of population data and reporting from harvesters, and the enormous spatial scale of the ARB. The purpose of this research is to obtain an extensive stock assessment for crayfish in the eastern ARB (east of the Atchafalaya River) by partnering with a local crayfish processor that purchases crayfish from harvesters throughout the eastern ARB. Harvest data collected from individual crayfish harvesters includes the total number of traps used, total weight of crayfish collected, and ARB spatial zone where crayfish were harvested (upper, middle, lower). Crayfish population characteristics (species, sex, carapace length, and male reproductive form) were examined weekly from three sub-samples of at least 400 individuals from different harvesters in each ARB zone (1,200 crayfish per week in each zone). Additionally, a minimum 100 female Procambarus clarkii were collected monthly from three different harvesters in each ARB zone (a total of 900 females per month, 300 from each zone) to determine the monthly percent ovigerous females. When eggs were present the gonad development was classified into five maturation stages based on egg color. The results from this research will provide novel, high-quality fisheries-dependent data for the stock assessment of the eastern ARB crayfish fishery.
Development of a Captive Rearing Protocol for Threatened & Endangered Appalachian Crayfish
CHRISTOPHER VOPAL, Emmy Delekta and Zachary J. Loughman
In 2016, two Appalachian endemic species were federally listed by the United States Fish & Wildlife Service: Cambarus callainus (Big Sandy Crayfish) and Cambarus veteranus (Guyandotte River Crayfish), which are listed as threatened and endangered respectively. Both species were listed due to limited and declining ranges caused by various anthropogenic activities, especially those causing stream sedimentation. Captive propagation can be used as a tool for crayfish conservation by helping to restore the native range of a species or improving their fecundity within their current range. Over a ten week period, 120 young-of-the-year (YOY) Cambarus chasmodactylus (New River Crayfish), a surrogate species for C. callainus and C. veteranus, were raised in individual cells to compare (1) growth and (2) survival on two different diets. They were fed every other day, with half (60) raised on trout diet pellets (TD) and the other half raised on blood worms (BW). Results showed more YOY growth with BW (17.3% growth) than with TD (13.6% growth). Increased survival was also observed with BW (84.5% survival) when compared to the TD (70.5% survival). Our results may be influenced by the ease and ability for the crayfish to forage on the blood worms and may also have a higher nutritional value in comparison to the TD. Our findings suggests a BW diet may be more effective in the captive rearing of Camabrus crayfish. Using information gathered from this study, a modified protocol will be used for a new study beginning July 2018 for C. callainus and Cambarus smilax (Greenbrier Crayfish). This modified protocol will compare three diets (bloodworm, detritus, and bloodworm/detritus) in the growth and survival of YOY C. callainus and C. smilax in a six month period.
Assessing Rarity Patterns in Crayfish at Multiple Spatial Scales Using Scale-area Curves
JOHN W. JOHANSEN, Hayden T. Mattingly, Christopher A. Taylor and Guenter A. Schuster
Identification of at-risk species often relies mostly on range size, particularly for poorly studied species. Although this provides a relatively efficient method for identifying species of conservation concern, it may lead to an inaccurate assignment of conservation status. For example, many species occupy small native ranges but are locally abundant and temporally stable. Additionally, extinction processes operate at different spatial-scales. Scale-area curves provide a framework that examines rarity at multiple spatial scales, and thus, can lead to development of more impactful conservation strategies. Using a well-vetted database of Alabama crayfish collections, we used measures of area of occupancy to construct scale-area curves and assess rarity patterns for lotic crayfishes at two spatial scales: 1 km2 and 100 km2. Area of occupancy (AOO) is a measure of range size that varies depending on the spatial-scale of interest. For each species, AOO was estimated by counting the number of occupied cells in nested grids at increasing user-defined areas. In addition to AOO, the degree of range fragmentation was determined for each species from the slope of the scale-area curve at each spatial scale. Principle components analysis was used to identify scale-specific patterns of rarity. For example, at the 1 km2 spatial scale, we identified 5 groups of species based on AOO and degree of range fragmentation while at the 100 km2 scale six groups were identified. At the 1 km2 scale, several state imperiled species (S2) had higher levels of fragmentation than many critically imperiled species (S1). This indicates the lower ranked (S2) species may actually be more susceptible to loss of local populations due to increased range fragmentation. Accordingly, understanding metapopulation dynamics and maintaining habitat connectivity should be a priority for this subset of state imperiled (S2) species. This demonstrates the need to examine multiple variables and spatial scales in prioritizing species of conservation concern, particularly for those species that lack basic biological and ecological data beyond range size.
Water Quality Analysis and Habitat Threats Concerning Cambarus cracens on Sand Mountain in Northeast Alabama
Rebecca A. Bearden, E. Anne Wynn, Patrick E. O’Neil, STUART W. McGREGOR, Guenter A. Schuster and Christopher A. Taylor
Understanding habitat threats for species of concern is paramount for establishing effective conservation strategies. Although the Slenderclaw Crayfish, Cambarus cracens, was found in the 1970s at five sites in Scarham, Short, and Town creeks on Sand Mountain in northeast Alabama, surveys in 2011 found the species at only a single site in Scarham Creek. Our goals were to determine the current range of this species and identify any water quality issues or habitat threats that may be causing its decline. We conducted status surveys for C. cracens at 71 sites in northeastern Alabama and northwestern Georgia from 2015 to 2017 and collected the species in low abundance at five sites in Scarham and Town creeks. We also collected the invasive Virile Crayfish, Faxonius virilis, in Short Creek, revealing a possible recent threat to the status of C. cracens. Our water quality surveys in Scarham, Short, and Town creeks in 2015 and 2016 revealed elevated levels of ammonia, nitrate and phosphorus, concentrations of lead and zinc that exceeded aquatic life criteria, the presence of pesticides, and concentrations of bacteria that exceeded established limits. Our land use analysis confirmed intense poultry production and high levels of human disturbance in Scarham, Short, and Town creeks. In order to conserve remaining populations of C. cracens, we recommend continued efforts at establishing watershed projects to reduce pollutant loads, promoting best management practices for agriculture, and monitoring future water-quality trends to help assure the integrity of water quality in these tributaries and assist in improving habitat quality throughout the Scarham, Short, and Town Creek watersheds.
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.
Identification of Pathogens Causing Porcelain Disease in North America: Call for Samples
Porcelain disease refers to the appearance of certain symptoms in crayfish, primarily a white opacity of the musculature. The disease is usually slow-progressing but believed to be fatal in all cases. In crayfish it is typically caused by microsporidians of the Thelohania genus. However, the symptoms may also be caused by members of other genera. Species identifications are currently made by morphology and more importantly through genetic techniques. Porcelain disease is well documented in European and Australian crayfish populations, but has not been well-studied in North America where anecdotal evidence suggests it occurs at a low rate in wild crayfish populations. I hope to acquire samples of infected crayfish from field researchers in North America to identify the species of microsporidians causing the disease on this continent. I am looking for assistance with this project from any researchers in North America who encounter visibly-infected crayfish and are willing to provide a tissue sample for investigation. Sampling kits will be made available for any willing participants.
Are Soil Properties Good Predictors in Distribution Modelling for Three European Crayfish?
CONSTAN?A MIHAELA ION, Andrei Dornik and Lucian Pârvulescu
Niche-based species distribution models (SDMs) using different algorithms (like generalized linear model, MaxEnt, random forest) are largely used in various applications for many species of plants and animals. By far, the most used variables for modelling are bioclimatic variables, but also slope, land use, vegetation cover and soil are sometimes considered. Several soil properties are now available at regional and global level, with suitable spatial resolution for SDMs. We therefore aim to increase our understanding on how these soil properties affect spatial distribution of crayfish species. We used a database consisting of 470 presence and absence locations in Romania for three European species of crayfish (Austropotamobius torrentium, Astacus leptodactylus and A. astacus), to extract information from several soil properties layers (grid type at 250 m resolution at seven standard depths) obtained from ISRIC - World Soil Information. Analyzing soil texture, 3000 randomly selected points from the study area were grouped mainly into five soil textural classes (silty clay, clay loam, silty clay loam, loam and silt loam), while crayfish presence points fell only in loam and clay loam. Using SDM we found that soil properties are good predictors for the current distributions of the three investigated crayfish species. For A. leptodactylus, the predicted distribution covers low plains up to the hills, while for A. astacus it ranges from higher plains, over foothills and tablelands and into lower altitude units of the Carpathian Mountains. A. torrentium predicted distribution is clearly restricted to the foothill region. The analysis based on crayfish abundance pointed out that there is a positive response to clay content and soil bulk density, and a negative response to sand content as well as to coarse fragments for all investigated crayfish species. We speculate that the burrows integrity against the erosion along the shorelines might be the explanation of these results, challenging new perspectives in further ecological approaches.
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.
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.
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.
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.
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