IAA22 Book of Abstracts (PDF)
Meeting Program/Schedule (PDF)
LIST OF MEETING ABSTRACTS
NOTE: You may quickly navigate to a name you are looking for by clicking a letter below (first letter in their lastname).
Day: 2, Session: 1, Talk: 4
HOST COUNTRY LECTURE:
An Overview of U.S. Crayfish Conservation in State Agencies and a Plan to Reverse CRAWnic Neglect
Robert J. DiStefano
Crayfish conservation can be accomplished in the United States (U.S.) by federal government, state governments, universities, non-governmental organizations (i.e., The Nature Conservancy), professional societies (e.g., American Fisheries Society), local governments, and private citizens. State fish and wildlife agencies are charged with protecting and managing each state’s aquatic resources, yet crayfish have historically received little attention from them. This is largely due to state funding formulas that rely heavily on sales of recreational licenses (fishing, hunting, etc.), and perceived responsibility of agencies to be more responsive to that segment of the public who buy licenses. Missouri is unique in having established a state conservation program for crayfish decades ago. The program has produced substantial research data on crayfish species distributions, ecology and threats, especially for imperiled and endemic species. It has yielded several conservation actions (e.g., regulations, education products and activities). I will reference Missouri as one possible model for establishing and maintaining a state government (or regional government elsewhere) crayfish conservation program that involves government staff, but also partners from academia and some stakeholder groups. I will conclude by providing a brief update about states’ involvement in U.S. crayfish conservation.
Day: 2, Session: 3, Talk: 2
Variations in Morphology and Physiology of Introduced Populations of the Virile Crayfish Faxonius virilis
Jennifer Weber, Hisham Abdelrahman, James A. Stoeckel and Brian Helms
Many introduced organisms have high levels of variation in morphology, physiology, and behavior, presumably conferring a selective advantage when establishing viable populations in novel habitats. Faxonius virilis (Virile or Northern Crayfish) is native to the northern and midwestern portions of the United States and southern Canada, but has been introduced throughout the continental United States and Europe. Previous work has demonstrated F. virlis and congeners possess morphological variation that is predictable among different habitats. We tested whether observed morphological variation, quantified with geometric morphometrics (GMM) and gill surface area calculation , was associated with physiological patterns, quantified with closed respirometry, in an introduced population of F. virilis from the Cahaba River in central Alabama, USA. We used 36 individual adult F. virilis (13 male, 19 female) for respirometry trials and subsequent GMM analysis. There were no sex differences in respiration or shape patterns. Using a Regulator Index calculated from curves derived from respirometry trials, we found that the total surface area of the gill filaments increased, the RI score increased, indicating that individuals who utilized regulatory strategies also had more surface area available for gas exchange. Further, crayfish could be broadly grouped as regulators, conformers, and undetermined in regards to their respiratory strategies. Crayfish shape between these 3 groups was significantly different, with regulators generally showing a broader carapace, conformers showing a narrower more fusiform carapace, and the undetermined group displaying a shape intermediate between regulators and conformers. These data suggest that F. virilis possesses physiological variation that corresponds to morphological variation, traits which may be attributable to the success of this species in novel habitats. Whether these respiration and morphological patterns hold across other species is yet to be determined.
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: 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: 1
Illegal Export of Australian Freshwater Crayfish – Intercepted Shipments: A Case of Euastacus
James M. Furse
The unique, and often remarkable, nature of the native flora and fauna of Australia is well known. Many of these native Australian species are highly attractive, desirable and sought-after by private collectors, but also commercial interests known to include the pet/aquarium, and restaurant and gourmet food trades. Live export of native Australian wildlife (i.e. amphibians, birds, mammals, reptiles) for commercial purposes is prohibited under any circumstances. Live export of some invertebrates, fish and plants may be permitted (for commercial purposes), if they originate from approved sources or programs (i.e. captive breeding, aquaculture, or wildlife trade/wildlife trade management plans). For non-commercial purposes live exports of native flora and fauna is permitted (e.g. research, education), but as with any type of native species export, this is strictly regulated. Illegal export of Australian native flora and fauna is a most serious (and Federal) offence: penalties can be very serious indeed. Despite this, it is well established that there is illegal and ongoing "leakage" of native Australian flora and fauna. The freshwater crayfish fauna of Australia is both unique, remarkable, and well known in the aquarium trade. In some regions of the World this fauna is also evidently known in the restaurant and gourmet food trade. Illegal export(s) of native species of freshwater crayfish have previously occurred, and ongoing illegal exports of these animals are suspected, and sadly also expected. This talk will briefly outline the rules and regulations limiting live exports of native Australian flora and fauna, and outline case(s) of apparent illegal exports of Australian freshwater crayfish. A recent case where an illegal shipment of Euastacus was intercepted, and seized, in Australia will be discussed. This discussion will include information on the species that was intercepted, the intended geographical destination, destination-industry and why such activities pose a very serious threat to such species. Other details surrounding the intercepted shipment will be outlined as may be appropriate.
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: 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: 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: 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: 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: 2, Talk: 5
A Nonnative Crayfish (Faxonius virilis) Use of an Eel Ladder, Potomac River Drainage, USA
STUART WESLH and Zachary J. Loughman
Fish passage facilities for reservoir dams have been used to restore habitat connectivity within riverine networks by allowing upstream passage for native species. These facilities may also support the spread of invasive species, an unintended consequence and potential downside of upstream passage structures. We documented dam passage of the invasive virile crayfish, Faxonius virilis, at fish ladders designed for upstream passage of American eels, Anguilla rostrata, in the Shenandoah River drainage, USA. Ladder use and upstream passage of 11 virile crayfish occurred during periods of low river discharge (<30 cubic meters per second) and within a wide range of water temperatures from 9.0–28.6°C. Virile crayfish that used the eel ladders had a mean carapace length and width of 48.0 mm and 24.1 mm, respectively. Our data demonstrated the use of species-specific fish ladders by a non-target non-native species, which has conservation and management implications for upstream passage facilities and the spread of aquatic invasive species.
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: 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: 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: 2
Biogeographic Differences in the Tradeoff Between Foraging and Predator Avoidance Across Native and Non-native Populations of Two Crayfish
LINDSEY REISINGER, Mael G. Glon and Lauren M. Pintor
There is growing evidence that the traits and impacts of species may diverge during the process of biological invasions; however, we still lack a general understanding of how the invasion process affects animal behavior. We used a biogeographic approach to compare foraging and antipredator behavior across a reciprocal invasion (an invasion in which each species was introduced to the native range of the other) of virile (Faxonius virilis) and rusty crayfish (F. rusticus). We hypothesized that the invasion process would select for bold, active individuals that allocate more time to foraging and less time to defense than their native counterparts. We used laboratory experiments to examine crayfish boldness, activity, and foraging voracity and mesocosm experiments to examine shelter use and predator avoidance behavior in response to a predatory fish. The intraspecific variation we observed was often greater in magnitude than interspecific variation, offering new evidence that ecologically important behaviors can vary substantially across the range of a species and may differ between native and non-native populations. Virile crayfish from native populations (Wisconsin, USA) were bolder, more active, and more voracious foragers than those from the species’ non-native range (Indiana, USA), and also displayed reduced antipredator behavior. Rusty crayfish from non-native populations (Wisconsin, USA) also displayed reduced antipredator behavior compared to their native counterparts (Indiana, USA). These results suggest that there is a tradeoff between foraging and predator avoidance in crayfish. Counter to our hypothesis, crayfish behavior did not consistently vary across species based on whether the population was native or non-native. Increased investment in foraging in Wisconsin could be an adaptation to the shorter growing season, and reduced boldness and activity in non-native virile crayfish could be an adaptation to avoid interactions with competitively superior rusty crayfish. Because foraging voracity and predator avoidance are ecologically important traits, the substantial divergence in behavior we observed across the geographic range of each species is likely to alter the ecological impacts of these crayfish on freshwater ecosystems.
Day: 5, Session: 2, Talk: 6
Simultaneous eDNA Monitoring of the Host-pathogen Complex Pacifastacus leniusculus and Aphanomyces astaci Under Varying Environmental Conditions
JOHANNES C. RUSCH, David A. Strand, Charlotte Laurendz, Stein I. Johnsen, Lennart Edsman and Trude Vrålstad
In 2016 the North-American signal crayfish Pacifastacus leniusculus was included in the list of Invasive Alien Species of concern to the European Union. In Norway the species is black-listed and rated as a high-risk species, and eradication has been carried out whenever feasible. This is because it is a chronic carrier of the oomycete Aphanomyces astaci, which is lethal to all European freshwater crayfish species and listed among the 100 worst invasive species. Environmental DNA (eDNA) methodology is now being used on a wide variety of target species and on many different platforms including targeted PCR and broad spectred sequencing methods. Detection and monitoring of invasive, endangered and elusive species is commonly performed using species specific quantitative real-time PCR (qPCR) or droplet digital PCR (ddPCR), and has proved useful for targeting species of specific concern. Recently eDNA monitoring of A. astaci has been implemented in the national crayfish plague surveillance in Norway. For the carrier of the crayfish plague, the signal crayfish, a qPCR assay for eDNA detection has also been published recently. In this study, we present simultaneous eDNA monitoring of the host-pathogen complex P. leniusculus - A. astaci under varying environmental conditions both in aquarium and field experiments. We used the published qPCR assays for both species and redesigned them so they can be run as a duplex ddPCR assay. We compared water samples by means of qPCR and ddPCR from two lakes in Sweden and Norway with different signal crayfish population densities and A. astaci prevalence in the population. We also studied eDNA emission from the host-pathogen couple in aquarium-experiments with A. astaci positive signal crayfish held at different densities, temperatures and feeding regimes. Samples were obtained by filtering water (1 & 5 L) on-site through glass fibre filters. These were subsequently analysed using the species-specific qPCR and ddPCR assays for the respective targets. The concentrations of detectable eDNA copies of the two targets are influenced differently and by several factors, including population density of the crayfish, pathogen prevalence, temperature, and turbidity including microbiological activity in the water. They are therefore subject to significant fluctuation. Thus, there seems to be no straightforward correlation between eDNA copy-number and crayfish density and the probability of detecting one target rather than the other varies according to different conditions. Therefore, for a reliable monitoring of crayfish plague (A. astaci) and signal crayfish alone or together, the simultaneous monitoring concept for both targets is recommended.
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: 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: 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.
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.
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.
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.
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.
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.
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.
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.
Meeting Photo Gallery
There are currently no photos from this meeting to display.