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: 2
Female Form Alternation in American Cambarid Species
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: 3
Modeling Effects of Crayfish Invasion and Drought on Crayfish Population Dynamics
Leah Bayer, Robert Fournier and DANIEL D. MAGOULICK
Crayfish play a crucial ecological role and are often considered a keystone species within freshwater ecosystems. However, North American crayfish species face several environmental and ecological threats including limited natural ranges, invasive species, and intensified drought. Demographic models can allow examination of population dynamics of a targeted species under a wide variety of disturbance scenarios. Here, we model the population dynamics of crayfish species with varied theoretical life histories and assess their responses to biological invasions and drought. We used RAMAS-Metapop to construct stage-based demographic metapopulation models parameterized using vital rates from established literature sources. Our models explored the population viability of four theoretical species under eleven disturbance scenarios and calculated estimates of terminal extinction risk, median time to quasi-extinction, and metapopulation occupancy. Our models indicate that populations respond differentially to disturbance based on life history. However, both r- and K-selected species appear to be highly susceptible to decline when faced with the additive effects of reduced carrying capacity due to invasion and reduced vital rates due to drought. By constructing models that explore a broad array of life histories and disturbance regimes, we hope to provide managers with tools to develop generalized, widely-applicable conservation strategies.
Day: 2, Session: 3, Talk: 4
Comparison of Traditional Crayfish Trapping and eDNA Monitoring of Noble Crayfish Astacus astacus
DAVID A. STRAND, Stein Ivar Johnsen, Johannes C. Rusch and Trude Vrålstad
During the past decade, the environmental DNA (eDNA) methodology has become an important non-invasive tool to monitor freshwater microorganisms and macroorganisms. From a single water sample, it is possible to detect several species of interest or even whole communities. eDNA studies have been applied to a wide range of aquatic organisms, including freshwater crayfish. eDNA can be used to reveal elusive species, such as alien invasive species at an early stage or rare and endangered species. While eDNA is a great tool for revealing the presence or absence of freshwater organisms, it is not always a clear relationship between eDNA copy numbers and the density of the species of interest. In this study, we have developed a species-specific Taqman MGB assay that targets the COI region of noble crayfish mitochondrial DNA. The eDNA assay is optimised for both quantitative real-time PCR (qPCR) and digital droplet PCR (ddPCR). Further, we have surveyed several lakes with varying crayfish densities using both traditional crayfish trapping (baited traps) and eDNA monitoring. In each lake, several water samples were filtered on site for eDNA capture, followed by trapping (baited traps) along the same shoreline. In one of the lakes, we also surveyed one site with both methods monthly from June to October to monitor seasonal variation of crayfish trapping and eDNA abundance in the water. Relative crayfish density (CPUE – crayfish per trap night) varied from 0.08 to 17.6 in the surveyed lakes. The water samples is in the process of being analysed for eDNA of noble crayfish using both qPCR and ddPCR technology. Using these results, we will compare the traditional cage trapping of noble crayfish (CPUE) with eDNA monitoring to evaluate if eDNA can be used to give an estimate of relative density of freshwater crayfish in a lake. We will also compare the results from qPCR with ddPCR to evaluate the pros and cons of the two approaches. The results will be presented at the IAA22 conference.
Day: 2, Session: 3, Talk: 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: 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: 3
The Life History of Cambarus veteranus Faxon 1914 (Decapoda: Cambaridae) in the Clear Fork of the Guyandotte River, WV, USA
NICOLE SADECKY and Zachary J. Loughman
Cambarus veteranus Faxon, 1914 (Guyandotte River Crayfish), is an endangered, narrow endemic, residing in just two streams in the southern coalfields of West Virginia. A life history study was initiated for C. veteranus in Clear Fork of the Guyandotte River, Wyoming County, West Virginia to gather basic life history information needed for future conservation efforts. Monthly collections began June 2017 and continued through May 2018. Two 400-meter stream reaches were designated as life history study sites with two different 100-meter sub-reaches sampled each month. Specimens, regardless of species, were collected, sexed, and molt stage determined. Preliminary results suggest an importance of water temperature on crayfish capture with December yielding considerably higher capture rates of C. veteranus in comparison to other species collected. Form I males are ever present and reach their highest density in early winter. Pre-glaired females reached their highest densities in October and December with glaired females present nearly every month. A single ovigerous female was collected, bearing just two stage 4 juveniles, during the November sampling event. Three ovigerous females bearing stage 4 juveniles were subsequently collected during the March sampling event, thus suggesting overwintering with young. Molting events were observed between September and October with pre-molting individuals present in September and freshly molted individuals present in October. Additionally, molting events occurred in March with pre-molting individuals present as well as freshly molted individuals and in May with the majority of the population observed in the soft or fresh molt state. Providing life history information for C. veteranus will assist in conservation efforts and possible repatriation of C. veteranus in the future. Additionally, life history information for C. veteranus can be compared to closely related species that are often used as a surrogate for C. veteranus in captive rearing studies.
Day: 2, Session: 4, Talk: 5
The Distribution and Conservation Status of the White Colour Morph of the Northern Clearwater Crayfish (Faxonius propinquus) in Lake Simcoe, Ontario, Canada
PREMEK HAMR and Mark Hoel
The rare and endemic white morph of Faxonius propinquus was first identified and described in 1978 by Dunham and Jordan who also subsequently documented the presence and distribution of the other various species and two other colour morphs of F. propinqqus in Lake Simcoe in Southern Ontario. Since then, no further research has been conducted on these populations, and the lake has been invaded by the introduced Rusty crayfish (Faxonius rusticus). The present study documents the decline and the present distribution of not only the rare white morph but also the other resident native species (O. virilis) which also appears to display several unusual colour morphs in Lake Simcoe. The decline of all three morphs of Faxonius propinquus as well as the impact of the F. rusticus expansion in the lake were assessed through surveys during the summers of 2015, 2016 and 2017. The significance of the results is discussed with respect to the conservation status and the future management of native crayfishes in Lake Simcoe.
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: 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: 2, Talk: 4
Hunting Crayfish Plague with eDNA – And Making Use of the Results
LENNART EDSMAN, Anna Aspán, Patrik Bohman, Karin Enfjäll, Tomas Jansson, Stein Johnsen, Jenny Monsén, Daniel Nilsson, Johannes Rusch, David Strand, Rune Svensson, Øystein Toverud and Trude Vrålstad
In River Billan that starts in Norway and runs into Sweden, there has been a thriving population of the critically endangered native noble crayfish (Astacus astacus). The population has been good enough to support a sustainable, local, small scale fishery in both countries. Starting in August 2016 dead crayfish were found in the lower part of the river. The dying crayfish were analysed and the cause of death was crayfish plague (Aphanomyces astaci). Illegal introduction of the chronic crayfish plague carrying signal crayfish (Pacifastacus leniusculus) was suspected to be the reason for the plague outbreak, since this has happened numerous times in the neighbourhood. Intensive monitoring with baited traps and by electrofishing was conducted in both countries but no signal crayfish was found. Cages with noble crayfish were put out to monitor survival. The noble crayfish death by crayfish plague progressed upstream the river. On a rainy day in September 2017 we sampled 5 locations in River Billan in search for crayfish plague environmental DNA. The localities stretched from the outlet furthermost downstream up to the furthermost upstream location by the Norwegian border. Duplicate samples of 5 L was filtered on-site onto sterile glass fibre filters at each location. The samples were then analysed and presence/absence of eDNA from crayfish plague was analysed with qPCR. All samples for the four downstream locations were positive for crayfish plague. The furthermost upstream location was however negative for plague. Soon after 88 noble crayfish where caught with electrofishing in the upper part location of the river where no crayfish plague DNA had been found in the samples. They were transferred to a quarantine in a crayfish farm 200 km away, and the crayfish are still alive and healthy in the pond 7 months later, so the salvage action was successful. They can be used in the future for breeding and for restoration of the noble crayfish population in River Billan.
Day: 3, Session: 3, Talk: 2
Comparisons of Enzymatic Thermal Optima Among Narrowly and Broadly Distributed Crayfish Species
HISHAM ABDELRAHMAN, James A. Stoeckel and Jacob T. Westhoff
Previous researchers have shown that extraregional invasive crayfish possess certain biological and ecological traits that facilitate their ability to successfully invade large areas in distant regions, whereas extralimital invaders tend to remain localized and occupy smaller ranges. Physiological optima may provide additional explanatory power for realized and potential range of crayfish species. In this study, we tested for differences in enzymatic thermal optima among multiple crayfish species with narrow (i.e., Faxonius marchandi, ~2,800 km2) to broad (i.e., F. virilis, >11 million km2) native and invasive ranges. We hypothesized that species with broad ranges would be thermal generalists relative to species confined to limited ranges. To test this hypothesis, we generated thermal performance curves of respiratory enzymes in the electron transport system (ETS) for 12 individuals of each species. Optimal thermal range was defined as the temperature range within which ETS enzyme activity was within 10% of the maximum observed value. Preliminary results show that the wide-ranging, invasive F. virilis has a broader thermal optima, and higher individual variation, than a localized invader – F. neglectus – or narrow endemics such as F. eupunctus or F. marchandi. Furthermore neither the thermal optima, nor the optimal range of the localized invader – F. neglectus - was significantly different than that of an endemic (F. eupunctus) within the invaded range. Results thus far suggest that underlying physiology may provide important clues as to which species have the potential to spread broadly and which species may be limited to a relatively narrow range. Additional species are currently being analyzed to better assess the robustness of these conclusions.
Day: 3, Session: 3, Talk: 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: 3, Talk: 7
Burning Down the House: Effects of Prescribed Burning and Mechanical Vegetation Treatments on Primary Burrowing Crayfish Densities
SUSAN B. ADAMS and Scott G. Hereford
Prior to widespread anthropogenic habitat alteration, primary burrowing crayfishes along the Gulf of Mexico Coastal Plain in southern Mississippi and Alabama presumably occupied predominantly open pine savannas, prairies, and bogs. Among other alterations, European settlement brought increasing fire suppression and intensive pine production. The Mississippi Sandhill Crane National Wildlife Refuge was “established in 1975…to protect the critically endangered Mississippi sandhill cranes [Grus canadensis pulla] and their unique, and itself endangered, wet pine savanna habitat.” The cranes require open meadow or pine savanna habitat, now created and maintained via prescribed burning, or when burning is precluded, via mechanical treatment. The US Fish and Wildlife Service (FWS) became interested in how these land management actions affect other at-risk species, including the primary burrowing crayfishes on the refuge: Creaserinus spp. and Procambarus fitzpatricki. In 2016, we initiated a study to survey crayfishes on the refuge and to begin examining how the land management influences burrowing crayfish densities. Crayfishes were surveyed by trapping and dipnetting in perennial and intermittent water bodies and by excavating and trapping from burrows. Burrower density among management classes was addressed by surveying burrow densities in quadrats along six transects on three plot types: regularly burned, regularly mechanically treated, and infrequently managed. We collected six species, including four only from water bodies: Cambarellus diminutus, Procambarus shermani, P. clarkii, and Faxonella clypeata. Procambarus fitzpatricki, considered at-risk by the FWS, was collected from burrows but also from small, isolated, intermittent pools in prairies and savannas. The most abundant burrower was identified as Creaserinus oryktes; however, taxonomic uncertainty creates enormous difficulty in distinguishing C. oryktes (not considered at-risk) from C. danielae (considered at-risk). Preliminary results indicate that burrowers were more abundant in burned or mulched plots than in infrequently managed plots. Confounding factors include interactions between site moisture and burn frequency/intensity and between ease of locating burrows and vegetation density.
Day: 3, Session: 4, Talk: 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 (CO
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: 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: 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: 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: 2
Population Characteristics of Red Swamp Crayfish Procambarus clarkii from Two Hydrologically Different Large River-floodplain Systems in Southeast Louisiana
ALEXA BALLINGER and Christopher Bonvillain
Anthropogenic modifications to large river-floodplain systems can sever natural water sources, alter annual flood pulses, and disrupt population dynamics of aquatic biota. The Atchafalaya River Basin (ARB) and the upper Barataria Estuary (UBE) in southeast Louisiana are separated by only 25 km and historically shared a similar hydrologic regime. Currently, the ARB receives an annual flood pulse from the Mississippi River that typically inundates floodplain habitats in the spring and dewaters in summer, providing access to floodplain spawning and foraging habitats and environmental cues for crayfish life cycle activities. In contrast, anthropogenic modifications to the UBE have eliminated an annual riverine flood pulse from the Mississippi River and large precipitation events are now the only drivers of floodplain inundation. The purpose of this project is to compare population characteristics of red swamp crayfish Procambarus clarkii between the ARB and UBE, two hydrologically different large river-floodplain ecosystems. P. clarkii were sampled every two weeks in the ARB and UBE during the 2017 and 2018 crayfish seasons. Sex, carapace length, and male reproductive form were recorded for all captured crayfish and catch per unit effort (CPUE) was determined as the number of crayfish per trap. Water quality was recorded at all sample sites on every sample date and hemolymph samples were collected from P. clarkii at all sample locations to determine hemolymph protein concentration. During the 2017 crayfish season, mean P. clarkii CPUE (3.81 ± 0.21) and carapace length (43.41 ± 0.71 mm) were higher in the ARB compared to the UBE (1.42 ± 0.34; 35.86 ± 0.49 mm). Additionally, ARB mean P. clarkii hemolymph protein concentration (5.1 ± 0.1 g/100 mL) was slightly higher than individuals from the UBE (4.8 ± 0.09 g/100 mL). These results indicate that the modification or absence of a flood pulse can have adverse effects on crayfish populations, threatening the ecological and economical importance of this species in river-floodplain ecosystems. The results from this research will provide a foundation for assessment of future anthropogenic modifications to river-floodplain hydrology and its effect on local aquatic biota.
Day: 5, Session: 4, Talk: 2
Monitoring Indigenous and Invasive Crayfish and Other Aquatic Species Using Educational Citizen Science and Environmental DNA
SUNE AGERSNAP, Steen Wilhelm Knudsen, Peter Rask Møller, Marie Rathcke Lillemark and Pernille Hjorth
The use of environmental DNA (eDNA) extracted from water samples is a promising tool for early and non-invasive detection of invasive and indigenous crayfish and other aquatic species. However, regular monitoring of large freshwater areas with eDNA are still quite labour intensive. In this presentation I will present preliminary results and experiences from Natural History Museum of Denmark’s citizen science based education program “DNA & LIFE”, where high school students, collect and analyse eDNA samples with the newest species-specific assays and methods. They work in a special DNA-laboratory with high procedural standards that has been established for education. This gives scientists an easy access to a high number of water samples from all over Denmark. At the moment in our “Real Science” project, students work together with scientist to develop and test new assays. During the development of the crayfish assays published in Agersnap et al. 2017. DNA and LIFE did some of the initial testing in 2015 on water samples, and has afterwards tested several waters for crayfish. Since DNA and LIFE started in 2014 more than 6,000 students have collected and analysed eDNA samples from more than 450 lakes and streams covering all of Denmark. And more than 40 different species-specific assays have been tested on freshwater and marine samples. These results can be beneficial to other scientific institutions who want to combine eDNA monitoring with scientific based, educational citizen science.
Day: 5, Session: 4, Talk: 3
Crustacyanin Genes of Cambarus Crayfish
PAUL R. CABE, Morgan Trimas, Jeronimo Reyes-Olmedo and Christian Kim
Decapod crustaceans, including crayfish, exhibit a tremendous range of coloration. These various colors are all produced by a combination of diet-derived carotenoid pigments with proteins coded by the crustacyanin genes, a crustacean-specific evolutionary innovation. In general, peptides from two different crustacyanin genes, crustacyanin A and crustacyanin C, combine in multi-unit proteins with carotenoids, shifting the absorption spectra of carotenoids to produce a range of colors. Despite their evolutionary and ecological importance, little is known about these genes in crayfish. We attempted to determine the sequence of these genes in Cambarus longulus and Cambarus bartonii (family Cambaridae) using an RNA-seq approach. RNA was extracted from tissues on the inner surface of the carapace (endocuticle, epithelium, hypodermis) and converted to cDNA. The cDNA pool was sequenced on the Illumina platform, yielding more than 7 million paired-end reads per species, which were assembled into transcripts. These transcripts were searched using crustacyanin sequences from other decapods. The sequence data suggest there are three different crustacyanin A genes in these species which differ primarily in non-coding regions. Using primers designed from these sequences, we were able to amplify these genes directly from genomic DNA, which confirmed the transcript sequences and revealed the presence of short introns. Likewise, the data also suggest both species have several distinct crustacyanin C genes. Direct knowledge of the sequence of these genes opens the possibility for comparative study of these evolutionary important genes in crayfish of the family Cambaridae.
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.
Investigating the Role of Dishonest Signals of Strength in Interspecific Fights Between Two Arizona Crayfish
ZACK A. GRAHAM and Michael J. Angilletta
Crayfish use their claws to defend territories and routinely engage in combat with competitors. Usually, the crayfish with smaller claws retreats without fighting, even though large claws are not necessarily strong ones. This dishonesty enables crayfish to obtain resources without being a true threat to opponents. The importance of dishonest signals of strength has been demonstrated in intraspecific crayfish fights. But distributions of crayfish often overlap and competition with other crayfish species is expected. Therefore, to understand the role of dishonest signaling in interspecific competition, I observed the fighting behavior of the two invasive Arizona crayfish species; the virile crayfish (Orconectes virilis) and the red swamp crayfish (Procambarus clarkii). I predict that dishonest signals of strength will influence interspecific fights in a similar manner to intraspecific fights. My results demonstrate the importance of investigating dishonest signals of strength in multiple crayfish species. Additionally, I propose that future analysis of dishonest signals may have important implications regarding crayfish invasions.
History of Spring River Crayfish (Faxonius roberti) Collections in the Strawberry River, Arkansas
BRIAN K. WAGNER
The Spring River Crayfish (Faxonius roberti) was recently distinguished from the Coldwater Crayfish (Faxonius eupunctus). It encompasses former F. eupunctus range in the Spring and Strawberry river drainages of Missouri and Arkansas. The species was first detected in the Strawberry River basin in a tributary stream in 1972 and the main river in 1974, neither of which have yielded specimens in more recent sampling efforts. The next reported observation was in 2006 from the main stem at a low water crossing 17.6 km downstream. A 2010-11 range-wide study of F. eupunctus only collected 4 individuals from one site in the basin using a quantitative kick-seine method that was much more effective in the other basins, suggesting a much lower abundance in the Strawberry. Additional effort in 2011 utilizing snorkeling and hand capture of crayfish was able to extend the documented range downstream an additional 14.3 km from the 2006 collection. Beginning in 2016 efforts began to attain a more detailed understanding of the species' range in this river by kayaking between access points and conducting snorkel searches by 2-3 divers at every 2nd to 3rd riffle encountered. These efforts documented 8 additional sites, including one 9 km upstream of the 2006 site. In 2017 efforts continued by making kayak trips above and below the area surveyed in 2016, requiring kayaking back to the put-in point at the end of the survey. In the upstream collection this included searching an additional 2 km above the site of the 1974 collection, but did not locate any occupied sites in this direction. Downstream searches were more productive, extending the occupied stream reach by 17.1 km. Combined this documents that F. roberti currently occupies at minimum 15 sites over a 40.4 km section of the Strawberry River.
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.
Crayfishes of the Potomac River Basin in Pennsylvania
AUDREY M. SYKES, David A. Lieb and Zachary J. Loughman
Arnold Ortmann was the first zoologist to critically review the crayfishes of Pennsylvania in the late 1800’s. Resultant of his work, Ortmann published The Crawfishes of Pennsylvania and The Crawfishes of Western Pennsylvania, two seminal works that are still relevant to this day. While extensive sampling in eastern Pennsylvania has occurred over the past two decades, western Pennsylvania’s crayfishes have received little scientific attention since Ortmann’s efforts. To rectify this dearth of information, intensive sampling of western Pennsylvania was initiated in the summer of 2014. This effort has been continuous for the past four years throughout the area using Ortmann’s work as a reference point in determining what constituted native fauna assemblage and the presence of invasive species. The ultimate goal of this project is to document both the native and invasive fauna of the Potomac Watershed in Pennsylvania. The historic faunal assemblage consists of Faxonius obscurus, Faxonius limosus, and Cambarus bartonii. Two invasive species, Faxonius rusticus and Faxonius virilis, have been reported in the Potomac Watershed downstream in Maryland. Pennsylvania’s portion of the Potomac Watershed will be sampled and reported in May of 2018. Over 100 sites will be sampled utilizing a protocol developed for the greater WPA Crayfish Survey by the West Liberty University’s Crayfish Conservation Lab. At each site, ten seine hauls will be employed in 125-meter stream reach, where the best available habitat will be surveyed first, followed by mediocre, and finally subpar habitat. In addition to a standard WPA Crayfish Datasheet, a Qualitative Habitat Evaluation Index Form (QHEI) will be completed at each site. This data will be used in the determination of habitat covariates associated with each species presence in the Potomac Watershed. All animals collected will be vouchered and assessed into the West Liberty University Astacology Collection.
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.
An Assessment of Cambarus spicatus, Broad River Spiny Crayfish
RILEY W. AULICK and Zachary J. Loughman
The Broad River Spiny crayfish, Cambarus spicatus, is endemic to the Broad River and some of its tributaries. Few life history studies of C. spicatus have caused the IUCN to list it as data deficient. The goal of this study was to determine the impacts of land development on the distribution of C. spicatus. In the summer of the 2017, the West Liberty University Crayfish Conservation Research Lab surveyed the Catawba watershed in North Carolina and the Broad and Saluda watersheds in South Carolina in search of C. spicatus. A standard protocol of ten seine hauls per riffle was implemented in one hundred and twenty-three streams. Dip nets were used in addition to seines to survey the banks of the streams. ArcMap, an application of ArcGIS, was utilized by adding layers such as land cover and a buffer around each collection area which provided land type percentages for each survey site. Six individuals from four sites in North Carolina and one individual from South Carolina were collected out of a total of one-hundred and twenty-three sites. According to the models, C. spicatus was least likely to be found in areas developed for agriculture and urban development. This study provides strong evidence that land development is negatively impacting C. spicatus distribution. Additional studies are needed throughout the species range to make a final determination that land development has a negative impact on C. spicatus.
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.
Exploring the Limit and Beyond of Hypoxia: Behavioural-driven Conservation of an Ancestral Legacy of Freshwater Crayfish
LUCIAN PÂRVULESCU, Adrian Neculae, Eva Kaslik, Claudia Zaharia, Zanethia Barnett, Marcelo M. Dalosto, James M. Furse, Tadashi Kawai, Sandro Santos and Ovidiu I. Sîrbu
Freshwater crayfish burrowing is not simply sheltering, but an active and conscious behavior in which the animal invests considerable time and energy. As aerobic organisms, crayfish are often recorded as being related to high levels of dissolved oxygen. Approaches considering the in-burrow requirements of oxygen are scarce. We monitored the respiratory behavior and survival under acute hypoxia under controlled conditions in the laboratory of ten ecologically and phylogenetically dissimilar species of crayfish from different geographical locations (5 species of Cambaridae, 3 of Astacidae and 2 of Parastacidae). We found that primary burrowing species (Parastacus brasiliensis and Cambarus striatus) cannot tolerate severe hypoxia, whereas secondary and tertiary burrowing species (Faxonius limosus, F. etnieri, Procambarus vioscai, Cambaroides japonicus, Austropotamobius torrentium, Astacus leptodactylus, A. astacus and Cherax quadricarinatus) were not only able to withstand prolonged anoxia, but also able to remain active for up to 40 hours after reaching zero-oxygen conditions. Using nonlinear regression tools applied to the available experimental data, we estimated the critical values of the dissolved oxygen levels which characterize the transition from aerobic to anaerobic respiration for each species found tolerating the anoxia. Based on the diffusion-convection transport and the experimentally determined oxygen consumption function, we developed a mathematical model describing the time-dependent changes of the dissolved oxygen concentration which takes into account both aerobic and anaerobic respiratory processes for A. leptodactylus and O. limosus in a virtual burrow filled with water. We further validated our models by comparing numerical simulations with laboratory measurements for different geometries of burrows. Excluding a region at the entrance, the mathematical predictions for a normal day-night cycle of a crayfish inside a (virtual) burrow show that the water-dissolved oxygen inside the burrow reaches anoxia levels within hours. We speculate that the ability of crayfish to cope with oxygen shortages might be a phylogenetic legacy from their ancestors, lobsters, known to encounter low levels of oxygen in deep waters. Most probably, the primary burrowing species lost this ability since the oxygen diffusion is much faster in fossorial burrows, and thus leading to weaker conservation of the specific mechanisms during evolution. These results challenge the current behavioral and physiological knowledge of crayfish, and might drive new perspectives on the ecology, conservation and even evolutionary processes.
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.
Dispersal and a Large River: Patterns of Genetic Diversity in an Imperiled, Small-stream Adapted Crayfish, Cambarus pristinus
BROOKE A. GRUBB, John W. Johansen and Rebecca E. Blanton
Crayfishes are a diverse group of freshwater decapods. Many North American crayfishes have small geographic ranges and are considered imperiled due to a variety of factors that threaten their persistence. Several factors, including fragmented habitats and corridor quality, affect dispersal ability and gene flow. Decreases in gene flow among populations can contribute to increasing genetic drift and inbreeding depression, which leads to a loss of genetic variability within populations and can reduce the adaptive potential of a species. Cambarus pristinus (Pristine Crayfish) has a small range on the Cumberland Plateau of Tennessee, where it occupies small tributaries of the Caney Fork River and lower order (<4th) reaches of the mainstem Caney Fork. Because the majority of the mainstem is larger than 4th order, it may limit dispersal and gene flow among populations of the different tributary systems. To examine contemporary and historic levels of genetic structure across the Caney Fork River mainstem, chelae from 20-30 individuals from two localities in each tributary will be collected. DNA extracted from the muscle of the chelae will be used to examine patterns of genetic structure using 20 microsatellite loci amplified from species-specific primers and the mitochondrial COI gene. Preliminary data summarizing progress on microsatellite primer optimization and locus identification and genetic structure among populations based on the COI gene will be presented and discussed.
The Life History of Cambarus robustus
GREGORY A. MYERS, David J. Foltz II., Emmy M. Delekta and Zachary J. Loughman
Crayfishes are the third most imperiled taxa in North America and are valuable keystone species in freshwater ecosystems. Cambarus veteranus is a narrow endemic in West Virginia recently listed by the U.S. Fish and Wildlife service as endangered. Cambarus robustus is a common species of crayfish that's closely related to C. veteranus, making it a suitable surrogate for investigations into the life history of C. veteranus. From June 2016 to July 2017, a collection of thirty individual C. robustus was made monthly. Gender, reproductive form, morphometric data (TCL, AbL, AbW, ChL, PaW), and natural history observations were recorded for each individual. When ovigerous females were encountered, they were placed in 80% EtOH and taken back to the lab where eggs were counted. A single ovigerous female was collected with a full load of eggs (n=94). Male C. robustus reached sexual maturity at 30.8mm TCL, and females reached sexual maturity at 37.3mm TCL. Brooding females were encountered invariably in a very specific microhabitat that may be pertinent to the conservation of this species. The results of this study will be useful for future life history studies of Cambarus, including imperiled taxa such as C. veteranus.
A Night of Devastation: Natural and Life History Observations of an En-masse Single Night Collection of Fallicambarus devastator
ZACHARY W. DILLARD, Katie Scott, Nicole M. Sadecky, Luke K. Sadecky and Zachary J. Loughman
Due to their fossorial tendencies, primary burrowing crayfish are the most difficult behavioral group of crayfish to study in-situ. In this study we elucidated both natural and life history aspects and intraspecific behaviors from a collection of 111 individual Fallicambarus devastator collected in Angelina County, Texas, on the night of May 15th, 2015. We also intend to emphasize the importance of environmental cues on collection success. Significant amounts of precipitation occurred during the days prior to collection efforts, resulting in the majority of burrows to be flooded on the day of collection. All animals were collected either traversing the landscape or captured at the portal of their burrow. Behaviors observed included excavation, respiration, feeding, and interspecific interactions. The majority of animals observed were adults, with juveniles noticeably absent on the surface. Life history observations included evidence of synchronous alteration to reproductive form in males, as well as sexually-dependent chelae morphometric ratios. Fallicambarus devastator meristically displayed sexual dimorphism between form I male and female chelae, with form I chelae having longer propodus length and greater palm widths compared to the squamous and shorter chelae of females. Understanding the significance of studying these animals in favorable conditions is of paramount importance to the quality of future primary burrowing crayfish research.
Noninvasive Ground Penetrating Radar Investigation of Fallicambarus fodiens Subsurface Habitations
ZACHARIAH SEAMAN and Harvey Henson
Ground penetrating radar (GPR) is a geophysical technique that uses electromagnetic energy to image and identify subsurface objects and structures. This methodology has been used in areas such as geology, archaeology and engineering; however, recent research has applied these geophysical methods within the zoological community. Several studies have discussed the utility and benefit of using GPR to image wombat burrows, badger setts, gopher tortoise burrows, and pocket gopher tunnels. Our team sought to determine if below ground structures constructed by burrowing crayfish could be imaged noninvasively, despite their comparatively smaller burrow sizes. In previous research, imaging crayfish burrows were a challenge when data collection occurred in clay derived soils. However, given the proper timing of rainfall and ground water infiltration, imaging of crayfish related structures in a silt loam soil regardless of burrow size is possible. Our studied species, the Digger Crayfish (Fallicambarus fodiens), was located and observed in southern Illinois, and 3D GPR scans were conducted and collected. The preliminary data show various subsurface anomalies where crayfish burrows (i.e. crayfish chimneys) were observed above ground. These anomalies were interpreted as subsurface structures created by crayfish activity.
Morphometric and Genetic Evidence of Population Heterogeneity in the Narrow-clawed Crayfish from Belarus
KAROLINA ŚLIWIŃSKA, Agata Mruga?a, Molotkov V. Dimitry, Radek Šanda and Anatoly V. Alekhnovich
The narrow-clawed crayfish, Astacus leptodactylus (Eschscholtz, 1823) is one of the two native European crayfish species in Belarus. Although it is a widespread species of high economic importance in this country, the recent expansion of the invasive alien crayfish species endanger the sustainability of its stocks within Belarus. Nevertheless, A. leptodactylus taxonomical status is under debate across its whole range, and it is currently considered as a species complex. Indeed, the occurrence of various morphological forms within its native range has been extensively described in early scientific literature. Moreover, based on molecular data, A. leptodactylus populations have been recently divided into European and Asian lineages; a division confirmed also by comparative morphological analyses of genetically distinct Armenian and Croatian populations. Yet detailed information on the diversity of narrow-clawed crayfish remains still scarce, especially in its native distribution range. Therefore, our study aimed to evaluate the diversity of A. leptodactylus within two different drainages (Baltic and Black Sea) in Belarus, based on morphological (multivariate statistics) and genetic (mtDNA COI gene) analyses. As a result of molecular analyses, the studied populations were clustered into two distinct phylogroups, corresponding to the previously published A. leptodactylus lineages. Furthermore, the multivariate morphometric analyses confirmed this clustering, and indicated that variability of studied populations is especially expressed in abdomen and cephalothorax parameters. The obtained results suggest that A. leptodactylus may have a double origin within the territory of Belarus, and therefore, provide important information for the conservation and management of this native crayfish 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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