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: 3
James W. Fetzner Jr. and Eric Dorfman
Day: 2, Session: 1, Talk: 4
HOST COUNTRY LECTURE:
An Overview of U.S. Crayfish Conservation in State Agencies and a Plan to Reverse CRAWnic Neglect
Robert J. DiStefano
Crayfish conservation can be accomplished in the United States (U.S.) by federal government, state governments, universities, non-governmental organizations (i.e., The Nature Conservancy), professional societies (e.g., American Fisheries Society), local governments, and private citizens. State fish and wildlife agencies are charged with protecting and managing each state’s aquatic resources, yet crayfish have historically received little attention from them. This is largely due to state funding formulas that rely heavily on sales of recreational licenses (fishing, hunting, etc.), and perceived responsibility of agencies to be more responsive to that segment of the public who buy licenses. Missouri is unique in having established a state conservation program for crayfish decades ago. The program has produced substantial research data on crayfish species distributions, ecology and threats, especially for imperiled and endemic species. It has yielded several conservation actions (e.g., regulations, education products and activities). I will reference Missouri as one possible model for establishing and maintaining a state government (or regional government elsewhere) crayfish conservation program that involves government staff, but also partners from academia and some stakeholder groups. I will conclude by providing a brief update about states’ involvement in U.S. crayfish conservation.
Day: 2, Session: 2, Talk: 1
Molecular Phylogenetic Analysis of the Devil Crayfish Group, with Elevation of Lacunicambarus to Generic Rank and a Re-description of the Devil Crayfish, Lacunicambarus diogenes comb. nov.
MAEL G. GLON, Roger F. Thoma, Chris A. Taylor, Marymegan Daly and John V. Freudenstein
As North American crayfish biodiversity becomes increasingly imperiled, the lack of a well-resolved, underlying taxonomic framework impedes conservation efforts. The taxonomy of the family Cambaridae has historically been based on morphology, but recent studies using molecular phylogenetic techniques have revealed taxonomic inconsistencies including a polyphyletic genus Cambarus. Here, we take a step towards increasing the taxonomic resolution of Cambaridae by investigating a group of primary burrowing crayfishes which were historically part of the Cambarus subgenera Lacunicambarus and Tubericambarus. This group, which we provisionally call the Devil Crayfish Group (DCG) because it contains the Devil Crayfish (Cambarus diogenes), has a complicated taxonomic history and is in need of revisionary work to inform conservation assessments. In this study, we test the hypothesis that the DCG forms a monophyletic clade through phylogenetic analyses of mitochondrial DNA sequence data from multiple specimens of the eight DCG species and from a broad sample of taxa representing approximately 70% of the species in what is currently recognized as Cambarus. We find that seven of the eight species from the DCG form a well-supported, monophyletic clade that is distinct from the remainder of what has traditionally been recognized as Cambarus. Although we were not successful in resolving the backbone of our phylogeny with high confidence, our analyses place the DCG as sister to a clade consisting of taxa from the genera Creaserinus, Faxonius, and Barbicambarus. Based on our results and on unique morphological and ecological characteristics of the DCG, we split seven of the eight DCG species from Cambarus and place them in Lacunicambarus, which we elevate to generic rank. We also redescribe the devil crayfish sensu stricto (Lacunicambarus diogenes comb. nov.) and designate a neotype for the species to facilitate subsequent revisionary work.
Day: 2, Session: 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: 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: 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: 2
The Louisiana Crawfish History Summary, The Last Fifty Years
JAY V. HUNER, Robert P. Romaire, C. Greg Lutz, Albert P. Gaude III., James W. Avault Jr., W. Ray McClain and Mark G. Shirley
The Louisiana USA crawfish industry has two commercial sources of crawfish, Procambarus spp., a wild harvest, mostly from the Atchafalaya River Basin (ARB) in the south-central area of the state, and a cultivated harvest from aquaculture ponds, located primarily in the southwestern area of the state. The combined harvest in 2016 was 135.2 MT with aquaculture accounting for 91%. The modern crawfish aquaculture industry originated in the early 1960s when low water during the ARB spring flood resulted in a poor harvest. State biologists worked with farmers in the Mississippi River alluvial valley and the southwestern prairie area to cultivate crawfish in purpose built impoundments and rice field impoundments. Area in crawfish culture increased from 4,050 ha in 1968 to 90,050 ha in 2017. Aquaculture accounted for 40-60% of annual harvest until the year 2000 and thereafter accounted for 70-95%. Changes in the hydrology of the ARB have largely accounted for declining wild crawfish harvests. The dominant species is Procambarus clarkii, the red swamp crawfish. Some Procambarus zonangulus, the southern white river crawfish, are harvested. Three major events impacted the Louisiana crawfish industry. First, import of crawfish products from the Peoples’ Republic of China beginning in the mid-1990s lowered prices. Second, an insecticide applied to rice fields used to cultivate crawfish in 1999-2001, combined with historical record summer drought which negatively impacted reproduction, led to widespread crop failure. Third, White Spot Shrimp Virus (WSSV), highly lethal to Procambarus spp. became widely distributed in both wild and cultured crawfish crops. Initially, competition from Chinese crawfish products had a negative impact on the Louisiana crawfish industry. However, over time imports led to development of new domestic markets and industry wide quality control practices. The highest crawfish production cost is harvesting – labor and bait. Crawfish are harvested in mesh traps that must be tended manually. Mechanized harvest boats have reduced the time necessary to tend traps but trapping is still highly inefficient. Initially, cut rough fish was the common bait, and later grain-based manufactured baits were developed but are relatively ineffective during colder months of the November/December – May/June seasons. A short-lived soft-shelled crawfish industry involving as many as 150 farmers developed in the 1980s. Despite good acceptance of the product, profits were low and entrepreneurs left the trade. No more than three producers remain today. Crawfish are cultivated by simulating the cool season wet, warm season dry hydrology of Louisiana. This works so well with rice farming that 75% of crawfish area is integrated with rice. The agricultural community refers to this landscape as working wetlands. The food rich system attracts predaceous, omnivorous, and vegetarian species of birds in great numbers. As a result, the National Audubon Society has designated the southwestern Louisiana region as an Important Bird Area of Global Importance. However, concerns about bird impacts on crawfish crops remain.
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: 4, Talk: 2
Investigation of the Salinity Tolerance and Life History of the Hammock Island Crayfish, Procambarus lunzi, in South Carolina, USA
ELIZABETH B. UNDERWOOD and Michael R. Kendrick
There are currently 38 confirmed species of freshwater crayfish in South Carolina, with nine of these found in the Sea Island/Coastal Marsh physiographic province (A.K.A. 'near-coastal zone') of the state. This includes Procambarus troglodytes, Procambarus lunzi, and the invasive Procambarus clarkii, among others. Crayfish in the near-coastal zone of South Carolina face numerous threats, including habitat destruction, invasive species, coastal flooding, sea-level rise, and storm surge. Sea level rise and storm surge events will likely lead to the salinization of near-coastal habitats, affecting crayfish that inhabit these wetlands. One crayfish species that will likely be affected by such salinization is the hammock (or hummock) island crayfish, Procambarus lunzi, which is the only crayfish known to inhabit hammock islands of South Carolina. Hammock islands are near-coastal upland features often consisting of maritime forest and depressional freshwater wetlands that are surrounded by salt marsh. Due to the isolated nature of its habitat and proximity of P. lunzi to the coast, potential conservation and management actions will need to consider how this species will respond to the effects of sea-level rise. The objectives of this research were to 1) Determine the salinity tolerance of 3 Procambarus species (P. lunzi, P. troglodytes, and P. clarkii) and 2) Assess life history of P. lunzi on a hammock island in South Carolina. For salinity tolerance trials of Procambarus lunzi, 32 individuals were collected from hammock island wetlands (salinities ranged from 0.3 to 7.0 psu) and exposed to one of two treatment conditions, 0 or 30 psu. Mean percent survival at the end of the first trial was 18.75%. It was hypothesized that the crayfish may have been previously stressed from high-salinity habitat conditions on the island and a second experimental trial was conducted. Crayfish from the first trial's 0 psu treatments (n=16) were kept in freshwater and fed every other day for two weeks. They were then placed in either 0 or 30 psu treatment tanks with each salinity treatment being replicated twice. Mean percent survival at the end of the seven-day trial was 100% at 0 psu, and 87.5% at 30 psu. Similar experiments were conducted with P. troglodytes and P. clarkii, and survival at 30 psu was 63% and 56%, respectively. The life history of P. lunzi is currently being assessed by re-sampling of a population on a hammock island. During each sampling event, post-orbital carapace length, sex, and reproductive state are recorded. Hourly measurements of temperature and salinity are also being recorded at the study location. A total of 50 crayfish have been sampled in December 2017 and February 2018 (30 females, 20 Form II males, and 0 Form I males) and salinities ranged from 3 to 6 psu. Although it is unclear how increased salinity affects fitness of these species, the findings in this study (high survivorship of Procambarus in high-salinity laboratory conditions and the collection of Procambarus lunzi from mesohaline wetlands), suggest that Procambarus is able to survive extended periods of increased salinities.
Day: 3, Session: 4, Talk: 3
Epigenetic Regulation in the Marbled Crayfish
VITOR COUTINHO CARNEIRO, Anny Gatzmann, Cassandra Falckenhayn and Frank Lyko
The all-female marbled crayfish (Procambarus virginalis) attracted the attention of the scientific community due to its 'self-cloning' capacity. The obligatory parthenogenetic reproduction provided interesting research opportunities and also established a potent ecological threat. Despite its identical DNA, this model has an extraordinary variety in appearance and behaviour between isogenic batchmates reared in the same environment. This suggests that epigenetic mechanisms play a key role in marbled crayfish phenotypic variation. Our group has recently annotated the draft genome of the marbled crayfish, which revealed a conserved, functional and versatile DNA methylation system for epigenetic regulation. We have also used whole-genome bisulfite sequencing, RNA-seq and ATAC-seq for a comprehensive analysis of multiple individuals and tissues. Our results provide a novel concept for how methylation-dependent regulation of gene expression may facilitate the phenotypic adaptation and invasive spread of this animal.
Day: 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: 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: 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: 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.
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.
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.
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.
Are Soil Properties Good Predictors in Distribution Modelling for Three European Crayfish?
CONSTAN?A MIHAELA ION, Andrei Dornik and Lucian Pârvulescu
Niche-based species distribution models (SDMs) using different algorithms (like generalized linear model, MaxEnt, random forest) are largely used in various applications for many species of plants and animals. By far, the most used variables for modelling are bioclimatic variables, but also slope, land use, vegetation cover and soil are sometimes considered. Several soil properties are now available at regional and global level, with suitable spatial resolution for SDMs. We therefore aim to increase our understanding on how these soil properties affect spatial distribution of crayfish species. We used a database consisting of 470 presence and absence locations in Romania for three European species of crayfish (Austropotamobius torrentium, Astacus leptodactylus and A. astacus), to extract information from several soil properties layers (grid type at 250 m resolution at seven standard depths) obtained from ISRIC - World Soil Information. Analyzing soil texture, 3000 randomly selected points from the study area were grouped mainly into five soil textural classes (silty clay, clay loam, silty clay loam, loam and silt loam), while crayfish presence points fell only in loam and clay loam. Using SDM we found that soil properties are good predictors for the current distributions of the three investigated crayfish species. For A. leptodactylus, the predicted distribution covers low plains up to the hills, while for A. astacus it ranges from higher plains, over foothills and tablelands and into lower altitude units of the Carpathian Mountains. A. torrentium predicted distribution is clearly restricted to the foothill region. The analysis based on crayfish abundance pointed out that there is a positive response to clay content and soil bulk density, and a negative response to sand content as well as to coarse fragments for all investigated crayfish species. We speculate that the burrows integrity against the erosion along the shorelines might be the explanation of these results, challenging new perspectives in further ecological approaches.
Habitat Associations of Endemic Crayfishes in the Meramec River Drainage: The Freckled Crayfish (Cambarus maculatus) and Belted Crayfish (Faxonius harrisonii).
Joe Chilton, Amanda E. Rosenberger and ROBERT J. DiSTEFANO
Understanding the habitat associations of rare species is important to make informed management and policy decisions. The Freckled Crayfish (Cambarus maculatus) and Belted Crayfish (Faxonius harrisonii) are two of Missouri’s rare and endemic crayfish species. Both species are listed as vulnerable on Missouri’s list of species and communities of conservation concern due to their limited range. Their native range is limited to the Meramec River drainage in eastern Missouri. We sampled 60 sites throughout the two species’ known range for presence and habitat variables. Replication was performed spatially within sites using kick-seines, drag seines, and visual timed-searches. Local- and landscape-scale habitat variables were evaluated for possible associations with the crayfishes through occupancy modeling with the R package “unmarked”. We found boulders and Strahler stream order were positive estimators of occupancy, while percent agriculture was negatively associated with the Freckled Crayfish. Belted Crayfish were associated with larger substrate size, increased embeddedness of substrate, and aquatic vegetation. This information will guide conservation managers in future projects and policy decisions regarding these two species.
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.
Analysis of Species-environmental Relationships with Variance Partitioning and Distance-based Moran Eigenvector Maps: Application for Crayfish Distribution and Community Models
WILLIAM R. BUDNICK, Sophia I. Passy and Michael D. Kaller
Advances in numerical ecology have developed robust modeling techniques that can include spatial information in analyses of species-environmental relationships. We demonstrate how variance partitioning and distance-based Moran eigenvector maps (dbMEM) can determine which spatial scales that environmental factors structure crayfish communities and distributions. We sampled 56 streams from 5 major Louisiana river drainages from 2013-2014. Variance partitioning with redundancy analyses of environmental factors and geographic spatial distances produced a poor model fit and great environmental-spatial covariance, which confounded interpretation. However, including orthogonal spatial variables obtained from dbMEM not only improved model fits, but elucidated which environmental variables constrained community composition across spatial scales, namely among drainages (broad scale), within drainages (intermediate scale) and within stream (small scale). Presence of sand, specific conductance, and stream depth were important community drivers across scales, but presence of clay and grassy banks were more locally important. Temperature, a climatic factor, was important at broad scales. Our methods provided valuable insight into the relevant scales of environmental influence on crayfish and it is our hope that we see wider adoption of these methods for future work.
Another Cautionary Tale of Numts: Multiple Different Copies of the COI Gene in the Camp Shelby Burrowing Crayfish (Fallicambarus gordoni)
JAMES W. FETZNER JR.
During a preliminary phylogeographic study conducted several years ago involving the Camp Shelby Burrowing Crayfish (Fallicambarus gordoni) it was noted that most of the generated COI barcode sequences were “messy” (i.e., contained multiple peaks at many sites along the length of the sequence), suggesting some sort of contamination was being co-amplified. This messy data was so prevalent (almost every specimen) that it ultimately eroded confidence in the base calls for the region sequenced and led to the termination of the project due to a very limited sequencing budget that had already been expended. In order to investigate the source of this contamination, COI PCR products from eight F. gordoni individuals (one from each sampled site), plus one specimen of another Fallicambarus species, were subsequently cloned. Eight individual colonies per individual were picked, amplified, and sequenced to see if the source of the contamination could be identified (i.e., as bacterial, human, pseudogene, or other). Checking the sequences using Genbank BLAST searches revealed that the sequences were most closely related to COI genes from the genus Fallicambarus, suggesting they are additional copies present within the genome, rather than contaminant DNA from an external source (i.e., bacterial). The results suggested that multiple different copies of the COI gene appear to be present within the genome of F. gordoni individuals, often containing multiple point mutations and/or length differences (=indels), which directly resulted in the messy sequences seen during the original project. In some cases, the sequences appeared to be pseudogenes because they often contained multiple stop codons. This study provides another cautionary tale about numts (nuclear copies of mitochondrial genes) and making sure they are accounted for when analyzing mitochondrial datasets in phylogeographic and systematic studies of freshwater crayfish.
Comparing the Efficacy of Conventional Funnel Versus Artificial Refuge Traps
NICOLA GREEN, Paul Stebbing, Matt Bentley, Demetra Andreou and Rob Britton
Many methods of controlling crayfish have been attempted but few target all life stages of the population. The most commonly used method, the funnel or baited trap, is known to be size and sex biased, making control attempts via this method ineffective. This study compared funnel traps with artificial refuge traps, which mimic crayfish habitat features and, because they do not ‘capture’ individuals, can be left in situ for long periods. Results from a two-year study on a lotic system indicate that the artificial refuge traps caught more crayfish and were more cost efficient than the funnel traps. They were also found to be unbiased with regard to sex and caught a far wider size range, including young of year crayfish, and high numbers of moulting and ovigerous individuals, providing useful information on life-history traits.
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.
The Crayfish Morphology Database: Developing an Online Platform for Maintaining and Sharing Specimen Data and Images Used in the Descriptions of New Crayfish Species
JAMES W. FETZNER JR.
A new online database, and associated website, are under development with the goal of capturing, maintaining and sharing a standard suite of morphological measurement data and specimen images used in the description of new freshwater crayfish species. The website is password protected, allowing authors to secure their project data under a user account that only they can access. Once published, their data could become available to the community. The site consists of eight tabbed web forms that capture information on field collections, geographic locality, and specimen-level morphological measurements broken out by major feature (e.g., Carapace, Rostrum, Chela, Gonopod, and ‘Miscellaneous’). A tab is also provided to upload specimen images captured from a variety of views. The database currently is set up for capturing data on North American taxa, but if there is interest from the community, this could be expanded to include other crayfish groups from around the globe. Measurement data can be entered automatically into the web form via a digital caliper connected to a computer, or entered manually. A standard set of photographic images can also be captured and annotated, and then uploaded to the project, making them available for side-by-side viewing, allowing for multiple specimen comparisons of various morphological features. Features such as simple statistical analyses of the data (counts, frequencies, etc.) still need to be implemented, but could be generated and output as a summary report. The full project data can also be output to Excel format to allow for more detailed statistical analyses. Most of the data presented in new species descriptions are just estimates of the mean and/or the range of values measured. Thus, all of the underlying data captured for each individual specimen in a study are often lost to science, unless the specimens have been designated as types. Having a repository for these types of data will help to make comparisons among species a lot easier in the future and will reduce the duplication of effort when making comparisons among multiple species.
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.
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