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: 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: 5
Using Maximum Entropy Modeling to Predict Suitable Habitat Locations for the Cutshin Crayfish (Cambarus taylori)
ERIC TIDMORE and Zachary J. Loughman
The Cutshin Crayfish (Cambarus taylori) is a recently described species endemic to the Middle Fork of the Kentucky River basin that lies within the anthracite coal fields of Eastern Kentucky. As C. taylori has a restricted range in an area heavily impacted by extractive industry, a conservation assessment is warranted. The goal of this study was to predict suitable habitat locations for C. taylori through use of maximum entropy modeling (MaxEnt). The Middle Fork of the Kentucky River’s crayfish fauna was last surveyed during the summer of 2014. The occurrence data from this study coupled with landscape scale environmental variables—such as stream order and land use data—was used to create the model. The mean area under the receiver operating characteristic curve (AUC) value was 0.971, showing the model had high predictive accuracy. Stream order and stream sinuosity had the highest contribution to the model showing that C. taylori prefers 3rd and 4th order streams with low sinuosity. To test the accuracy of the model, ten high probability and ten low probability sites were surveyed. C. taylori was captured in ten of the twenty sites, eight of which were considered high probability for C. taylori presence.
Day: 2, Session: 3, Talk: 6
Crayfish Conservation in Southern England
JEN NIGHTINGALE, Grainne McCabe, Gareth Jones and Paul Stebbing
The white-clawed crayfish, Austropotamobius pallipes has suffered severe declines within the south west of England, where the first signal crayfish, Pascifastcus leniusculus farms were established in the 1970s. In response to this decline, The South West Crayfish Partnership (SWCP) was formed in 2008; comprising Bristol Zoological Society, Buglife, Cefas, the Environment Agency, Wildlife Trusts and Associates. The SWCP implements landscape scale, strategic conservation for A. pallipes, in an attempt to safeguard the future of this species in South West England. The conservation effort has four strands: 1. Ark sites: established throughout the south west England, for translocation of the most highly threatened white-clawed crayfish populations and captive-bred reintroductions. 2. Crayfish captive breeding facility: established at Bristol Zoo, which provides plague-free A. pallipes brood stock for ark site release, wild supplementations, research and outreach. 3. Communication strategy: running in tandem with the other three elements, targeting key audiences such as anglers, restaurants, students, school children and zoo visitors. 4. Invasive crayfish control – trialing different control techniques specifically targeting the signal crayfish. The presentation will cover the key elements of this conservation programme, evaluating its success to date and discuss the research elements that run in tandem with all of these conservation strands.
Day: 2, Session: 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: 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: 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: 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: 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: 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: 5
Hunting Missouri’s Rarest Crayfish Using eDNA and Visual Surveys: A First Look at the Natural History of the Caney Mountain Cave Crayfish
ROBERT J. DiSTEFANO, David C. Ashley, Shannon K. Brewer and Joshua B. Mouser
Stygobitic (cave) crayfishes are regarded as the most imperiled crayfishes in the U.S. and Canada. The Caney Mountain Cave Crayfish (Faxonius stygocaneyi), discovered in 1998, is known from only a single population in Mud Cave in the Caney Mountain Conservation Area (CMCA) of southern Missouri. It is listed as “critically imperiled” by the state of Missouri and “threatened” by the American Fisheries Society. We conducted the first study of F. stygocaneyi to gather preliminary data on its natural history and population, and to locate possible additional populations. We visited Mud Cave on 14 occasions (at least once each season) between 2014 and 2018. Visual surveys along a transect of inundated (wet) and non-inundated (mud) habitat were conducted during most visits except late April-May 2017 when the cave was flooded. Supplemental baited trapping was also performed intermittently. Water samples (2 L at two Mud Cave locations) were taken on each of 7 visits in 2017 and 2018. Water and air temperatures were recoded for most of 2014-2016. We captured a total of 23 (carapace length, 15.0-47.0 mm, average: 27.2 mm) and observed an additional 42 F. stygocaneyi, including the first-ever records of juveniles (August 2016 and 2017) and an ovigerous female (August 2016). Multiple visual searches of the known five other caves and three springs at CMCA detected no F. stygocaneyi. In addition to water samples from Mud Cave, we also collected and filtered multiple water samples from Onyx, and Bear Hollow caves, and three springs thought to be in the same drainage in 2017-2018. We developed primers and probes to amplify F. stygocaneyi DNA from those samples. Study results were limited by use of non-invasive sampling methods, high turbidity, flooding on some occasions, and what appears to be a small population. Yet we observed four times more crayfish compared to the previous 17 years since the species’ discovery, and collected the first biological data. Visual and eDNA sampling of adjacent caves and springs suggest the species could be endemic to only Mud Cave.
Day: 3, Session: 4, Talk: 1
Chemical Control Trials for Invasive Crayfish Infestations
ANN L. ALLERT, Kim T. Fredricks and James A. Stoeckel
Few chemical control tools are available for management of invasive crayfish infestations. Cypermethrin, pyrethrin, and carbon dioxide (CO
Day: 3, Session: 4, Talk: 2
Investigation of the Salinity Tolerance and Life History of the Hammock Island Crayfish, Procambarus lunzi, in South Carolina, USA
ELIZABETH B. UNDERWOOD and Michael R. Kendrick
There are currently 38 confirmed species of freshwater crayfish in South Carolina, with nine of these found in the Sea Island/Coastal Marsh physiographic province (A.K.A. 'near-coastal zone') of the state. This includes Procambarus troglodytes, Procambarus lunzi, and the invasive Procambarus clarkii, among others. Crayfish in the near-coastal zone of South Carolina face numerous threats, including habitat destruction, invasive species, coastal flooding, sea-level rise, and storm surge. Sea level rise and storm surge events will likely lead to the salinization of near-coastal habitats, affecting crayfish that inhabit these wetlands. One crayfish species that will likely be affected by such salinization is the hammock (or hummock) island crayfish, Procambarus lunzi, which is the only crayfish known to inhabit hammock islands of South Carolina. Hammock islands are near-coastal upland features often consisting of maritime forest and depressional freshwater wetlands that are surrounded by salt marsh. Due to the isolated nature of its habitat and proximity of P. lunzi to the coast, potential conservation and management actions will need to consider how this species will respond to the effects of sea-level rise. The objectives of this research were to 1) Determine the salinity tolerance of 3 Procambarus species (P. lunzi, P. troglodytes, and P. clarkii) and 2) Assess life history of P. lunzi on a hammock island in South Carolina. For salinity tolerance trials of Procambarus lunzi, 32 individuals were collected from hammock island wetlands (salinities ranged from 0.3 to 7.0 psu) and exposed to one of two treatment conditions, 0 or 30 psu. Mean percent survival at the end of the first trial was 18.75%. It was hypothesized that the crayfish may have been previously stressed from high-salinity habitat conditions on the island and a second experimental trial was conducted. Crayfish from the first trial's 0 psu treatments (n=16) were kept in freshwater and fed every other day for two weeks. They were then placed in either 0 or 30 psu treatment tanks with each salinity treatment being replicated twice. Mean percent survival at the end of the seven-day trial was 100% at 0 psu, and 87.5% at 30 psu. Similar experiments were conducted with P. troglodytes and P. clarkii, and survival at 30 psu was 63% and 56%, respectively. The life history of P. lunzi is currently being assessed by re-sampling of a population on a hammock island. During each sampling event, post-orbital carapace length, sex, and reproductive state are recorded. Hourly measurements of temperature and salinity are also being recorded at the study location. A total of 50 crayfish have been sampled in December 2017 and February 2018 (30 females, 20 Form II males, and 0 Form I males) and salinities ranged from 3 to 6 psu. Although it is unclear how increased salinity affects fitness of these species, the findings in this study (high survivorship of Procambarus in high-salinity laboratory conditions and the collection of Procambarus lunzi from mesohaline wetlands), suggest that Procambarus is able to survive extended periods of increased salinities.
Day: 3, Session: 4, Talk: 3
Epigenetic Regulation in the Marbled Crayfish
VITOR COUTINHO CARNEIRO, Anny Gatzmann, Cassandra Falckenhayn and Frank Lyko
The all-female marbled crayfish (Procambarus virginalis) attracted the attention of the scientific community due to its 'self-cloning' capacity. The obligatory parthenogenetic reproduction provided interesting research opportunities and also established a potent ecological threat. Despite its identical DNA, this model has an extraordinary variety in appearance and behaviour between isogenic batchmates reared in the same environment. This suggests that epigenetic mechanisms play a key role in marbled crayfish phenotypic variation. Our group has recently annotated the draft genome of the marbled crayfish, which revealed a conserved, functional and versatile DNA methylation system for epigenetic regulation. We have also used whole-genome bisulfite sequencing, RNA-seq and ATAC-seq for a comprehensive analysis of multiple individuals and tissues. Our results provide a novel concept for how methylation-dependent regulation of gene expression may facilitate the phenotypic adaptation and invasive spread of this animal.
Day: 3, Session: 4, Talk: 4
Effect of an Analgesic at Environmental Concentration on Crayfish Locomotion and Cardiac Physiology
FILIP LOŽEK, Iryna Kuklina, Tomáš Randák, Pavel Kozák, Petr Císař and Miloš Buřič
There is an increasing evidence on ecological and biological impacts of pharmaceutical pollution (e.g., antidepressants, anxiolytics, psycholeptics and analgesics) on aquatic organisms. Tramadol is an example of opioid analgesic frequently used treating chronic and acute pain. In order to investigate long-time effects of tramadol at environmentally relevant of 1 ?g L-1 on signal crayfish Pacifastacus leniusculus as an important participent of the predator-prey relationships, cardiac activity (heart rate, HR) and behavior (locomotion) were evaluated under repeated stimuli of a natural stressor (i.e., hemolymph) as an odor of injured conspecific 4 times within 3 weeks of tramadol exposure and 4 times within following 2 weeks of depuration period. For evaluation of crayfish primary physiological and ethological reactions to the stressor, the data within half an hour prior to and half an hour post stressor addition were used. A significant increase of the HR after stressor application was found, as well as there was a significant difference between tramadol free (control) and tramadol exposed groups. However there was no statistical difference in the locomotion of both control and exposed crayfish recorded before and after stressor application. According to the discovered shifts in crayfish cardiac physiology under long-term exposure to tramadol at non-lethal concentration, the significance of these shifts will need further detailed investigations.
Day: 5, Session: 2, Talk: 1
Crayfish Chimney Function: Airflow, Oxygen, and Pheromones
JAMES A. STOECKEL, Hisham Abdelrahman, Mary Szoka, David Blersch and Jeremiah Davis
Most burrowing crayfish build chimneys. However, chimneys are often present only seasonally, located only over a single burrow opening, or completely absent, suggesting that they are periodically constructed for specific function and purpose(s). In this study we use a combination of field and wind-tunnel experiments to investigate function and purpose of Cambarus c.f. polychromatus chimneys. Field trials with smoke bombs and natural burrows showed that air flow is a major outcome of chimney construction. In a typical burrow complex, smoke was drawn in through three non-chimney openings, traveled ~0.5 m underground to the groundwater level, and then back up to the surface and exited through the chimney. Smoke was not drawn through the burrow when the chimney was removed. Chimneys appear to drive airflow through burrows by creating temperature differentials with non-chimney openings, and/or pressure differentials related to wind blowing across chimney and non-chimney entrances (Bernouli’s Principle). Wind tunnel trials with model burrows showed that air velocity through burrows was highest when chimneys were upwind of chimneyless openings. Air velocity through burrows also increased with increasing chimney height and increasing wind speed. Ongoing field studies suggest that need for increased oxygen is not likely the primary purpose driving crayfish to build chimneys to draw air through burrows. Individuals that were freshly molted or brooding, representing two life-history stages that require the most oxygen, were only found in plugged and chimneyless burrows, respectively. Alternatively, based on results of this and previous studies, we hypothesize that an important outcome of increased airflow through and out the burrows is dispersal of pheromones to facilitate intraspecific communication between adults during the reproductive season, and subsequent recruitment of young to conspecific burrow colonies.
Day: 5, Session: 2, Talk: 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: 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: 3, Talk: 3
Observations of Chelae Injury in Two Crayfish Species in Three Sinuous Rills
CHESTER R. FIGIEL JR.
Crayfish often lose or autotomize limbs (e.g., chelae) during agonistic conflicts. This defense mechanism increases the probability of surviving the encounter, however can result in long-term functional and energetic costs. For example, chela autotomy influences crayfish competitive ability, foraging time, capacity to obtain mates, and modifies crayfish distribution and behavior. Biotic factors (e.g., population density or predators), as well as abiotic factors (e.g., refugia or habitat complexity) can influence the frequency of injury. In this study, I investigated the prevalence of chela injury (loss or partially regenerated chelae) in two crayfish species (Cambarus striatus and Procambarus spiculifer) that were collected in three sinuous rills (Mountain Creek (MC), Liberty Bell Creek (LB), and Cascade Branch (CB)) in west central Georgia, USA over a four year period. My objectives were to determine if injury was similar among sites, among crayfish species, or varied with time of year. Additionally, within a species my objectives were to examine whether injury differed in crayfish size classes or sex. Cambarus striatus were collected in each of the three streams with the percent injured as follows: MC 15.5%, n = 579; LB 16.3%, n = 1555; and CB 21.3%, n = 1159. There were significantly more injuries from crayfish collected at CB than at the other two streams (p < 0.05). This was most likely driven by the greater percent of injuries in the juvenile size classes (6.0 mm to 15.9 mm carapace length (CL)): CB (24.5%) compared to the similar size classes at LB (16.6%) and MC (15.0%). The frequency of injury between males (18.2%), females (20.0%), or juveniles (19.0%) did not differ significantly nor were there significant differences between Form I (15.6%) and Form II (18.9) males (p > 0.05). Of the 590 C. striatus crayfish having an injury, approximately 13% of these crayfish had both chelae injured. Procambarus spiculifer were collected in each of the three streams (however only 3 individuals were collected at LB so data were not used for that site). The percent injured for P. spiculifer differed significantly between MC 12.1%, n = 727; and CB 23.7%, n = 169 (p < 0.05). There were a greater percent of injuries in the larger adult size classes (> 31.0 mm CL = 26.4%) compared to smaller size classes (< 31.0 mm CL = 9.9%). The frequency of injury among males (13.8%) and females (15.9%) did not differ significantly, however differed from the percent of injured juvenile crayfish (7.3%). Of the 126 P. spiculifer crayfish having an injury, approximately 12% of these crayfish had both chelae injured. The percent of injured crayfish captured varied widely from month to month for both species and no discernable pattern emerged through time. Given the level of injury in these populations, it is vital to understand how injury influences population dynamics of these two species with differing ecological needs and lifestyles.
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.
Day: 5, Session: 4, Talk: 3
Crustacyanin Genes of Cambarus Crayfish
PAUL R. CABE, Morgan Trimas, Jeronimo Reyes-Olmedo and Christian Kim
Decapod crustaceans, including crayfish, exhibit a tremendous range of coloration. These various colors are all produced by a combination of diet-derived carotenoid pigments with proteins coded by the crustacyanin genes, a crustacean-specific evolutionary innovation. In general, peptides from two different crustacyanin genes, crustacyanin A and crustacyanin C, combine in multi-unit proteins with carotenoids, shifting the absorption spectra of carotenoids to produce a range of colors. Despite their evolutionary and ecological importance, little is known about these genes in crayfish. We attempted to determine the sequence of these genes in Cambarus longulus and Cambarus bartonii (family Cambaridae) using an RNA-seq approach. RNA was extracted from tissues on the inner surface of the carapace (endocuticle, epithelium, hypodermis) and converted to cDNA. The cDNA pool was sequenced on the Illumina platform, yielding more than 7 million paired-end reads per species, which were assembled into transcripts. These transcripts were searched using crustacyanin sequences from other decapods. The sequence data suggest there are three different crustacyanin A genes in these species which differ primarily in non-coding regions. Using primers designed from these sequences, we were able to amplify these genes directly from genomic DNA, which confirmed the transcript sequences and revealed the presence of short introns. Likewise, the data also suggest both species have several distinct crustacyanin C genes. Direct knowledge of the sequence of these genes opens the possibility for comparative study of these evolutionary important genes in crayfish of the family Cambaridae.
Day: 5, Session: 4, Talk: 4
Detectable Effects of Impoundments on the Genetic Structure of Crayfish (Faxonius spp.) in Alabama 43-Years After Dam Closure
ZANETHIA C. BARNETT, Ryan C. Garrick, Clifford A. Ochs and Susan B. Adams
Numerous freshwater species have highly fragmented populations due to barriers created by impoundments. Dams and impoundments can prevent or reduce dispersal by physically blocking movement of individuals, reducing floodplain-river connectivity, and creating a lentic zone and tail waters unfavorable to stream organisms. The loss of longitudinal and lateral connectivity can lead to population isolation, failed recruitment, and local extinction. Using population genetic analyses, we assessed fragmentation of crayfish populations caused by impoundments in the southern Appalachians, a global center of crayfish diversity and a region with numerous impoundments. We sampled one unimpounded and two impounded streams. Six to 10 sites were sampled along each stream between 2015 and 2017, with at least four sites sampled up- and downstream of impoundments. Faxonius erichsonianus and F. validus, two of the most abundant and widespread species in the streams, were collected for genetic analyses. For all individuals, a portion of the mitochondrial cytochrome oxidase subunit I (COI) gene was amplified via polymerase chain reaction, and sequenced. Analyses of F. erichsonianus are in progress. Faxonius validus genetic diversity was lower in unimpounded than impounded streams. Local populations of F. validus up- versus downstream of impoundments differed genetically from one another, but up- and downstream populations in the unimpounded stream did not differ. Directionality of gene flow analyses indicated that in the unimpounded stream, F. validus individuals moved both up and downstream. However, as expected, this connectivity was asymmetric, with greater gene flow originating from upstream sources. Notably, whereas downstream gene flow occurred in both impounded streams, upstream gene flow occurred in only one of these streams. Overall, the magnitude of genetic connectivity among local populations was higher in unimpounded than impounded streams.
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.
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.
Identification of Pathogens Causing Porcelain Disease in North America: Call for Samples
Porcelain disease refers to the appearance of certain symptoms in crayfish, primarily a white opacity of the musculature. The disease is usually slow-progressing but believed to be fatal in all cases. In crayfish it is typically caused by microsporidians of the Thelohania genus. However, the symptoms may also be caused by members of other genera. Species identifications are currently made by morphology and more importantly through genetic techniques. Porcelain disease is well documented in European and Australian crayfish populations, but has not been well-studied in North America where anecdotal evidence suggests it occurs at a low rate in wild crayfish populations. I hope to acquire samples of infected crayfish from field researchers in North America to identify the species of microsporidians causing the disease on this continent. I am looking for assistance with this project from any researchers in North America who encounter visibly-infected crayfish and are willing to provide a tissue sample for investigation. Sampling kits will be made available for any willing participants.
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.
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.
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.
Soft Serve: The Interactive Biology of the Queen Snake (Regina septemvittata) and Its Specialized Crayfish Prey in Northern West Virginia, USA.
DAN T. MEYER and Zachary J. Loughman
Coevolution of crayfishes and other animals is well documented in the literature. In North America, several species of vertebrates and invertebrates have been documented utilizing the burrows of various crayfish species. Crawfish Frogs (Lithobates areolatus), Hines Emerald Dragonflies (Somatochlora hineana), Kirtland's snakes (Clonophis kirtlandii) and Eastern Massasauga (Sistrurus catenatus) all utilize crayfish burrows during key if not all aspects of their life history and experience declines when burrowing crayfish colonies are destroyed. Several species of animals have also been documented as crayfish dietary specialists. Hellbender salamanders (Cryptobranchus) have long been known to rely heavily on crayfishes as forage. Several sports fish, including but not limited to black basses (Micropterus salmoides), sunfishes (Centrarchidae), catfishes (Siluriformes), and brown trout (Salmo trutta) also feed heavily upon crayfish during all facets of their life history. Arguably one of the most specialized of all North American crayfish dietary obligates could be the Queen Snake (Regina septemvittata). This small natricine snake occurs throughout the Appalachian, Piedmont, Midwest, and Ozarkian region of North America, and feeds exclusively on freshly molted crayfish. Queen Snakes have experienced precipitous declines over much of the western portion of their range, though seem to remain common throughout much of Appalachia. Historically, herpetologists studying Queen Snakes have studied the snake's movement patterns, reproductive biology, and life history, but have not delved deeply into this species feeding biology. Snakes will be captured and any food boluses present in snakes will be collected by palpation of the stomach region. Monthly crayfish life history sampling will be performed in our study streams to determine the molt frequency of Cambarus carinirostris and Faxonius obscurus, which co-occur and serve as forage for queen snakes. Snakes will be captured throughout their activity period and all regurgitated crayfish will be identified to species if possible, measured and weighed, and put into a designated size cohort based on crayfish life history sampling. Our goal is to determine if Queen Snakes rely heavily on a single species of crayfish, or rely on different crayfishes during peak molt periods, as well as determine if anyone size of crayfish experience predation over another. The ultimate outcome of this research will be a better understanding of this predators interaction with it crayfish prey, and provide valuable information for its future conservation.
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.
A New Species of Faxonius Crayfish from the Red River System of Kentucky and Tennessee
ERIN T. BLOOM, Brittany McCall, Guenter A. Schuster and Rebecca E. Blanton
Faxonius barrenensis is a crayfish endemic to the Green River system of Kentucky and Tennessee and is closely related to F. mirus, which is restricted to Tennessee River tributaries in Tennessee and Alabama. A morphologically similar but undescribed crayfish, Faxonius sp., occurs in the Red River system (Cumberland River) of Kentucky and Tennessee. Whether the latter represents a disjunct population of F. barrenensis or F. mirus, or alternatively, a distinct, species is unknown. Furthermore, whether the shared morphological traits reflected shared ancestry or convergence has not been tested. We used molecular and morphological data, including two mitochondrial (COI and 16s) and two nuclear (28s and GAPDH) genes and a standard suite of phenotypic measurements and meristics to examine phylogenetic relationships and the taxonomic status of Faxonius sp. relative to F. barrenensis, F. mirus and other Faxonius. Results from the concatenated and individual gene datasets supported a close relationship among the three focal taxa, implying their gross morphological similarities likely reflect recent shared ancestry. In all mitochondrial and combined gene trees, Faxonius sp. was recovered as a genetically divergent clade from F. barrenensis and F. mirus. Additionally, Faxonius sp. is phenotypically distinguished from F. barrenensis and F. mirus based on several characteristics. Given these findings, we propose Faxonius sp. represents a distinct species of crayfish that is closely related to F. mirus and F. barrenensis. However, our data does not resolve which of the latter is its sister species; additional molecular markers are needed to resolve this question. The new species has only been collected at four different localities within the Red River system (Cumberland), three of those located on the Ft. Campbell Army Base along the Tennessee/Kentucky state line. Several other streams have been searched, but no other populations have been identified, suggesting it has a small range and warrants conservation concern.
The Crayfish Morphology Database: Developing an Online Platform for Maintaining and Sharing Specimen Data and Images Used in the Descriptions of New Crayfish Species
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.
Assessing Metals-Mining Impacts to Stream Ecosystems Using Crayfish
ANN L ALLERT, Danielle Cleveland, Christopher Schmitt, Robert J. DiStefano, John Weber, David Mosby and Eric Gramlich
Quantifying injury to aquatic natural resources caused by the release of contaminants is essential for pursuing damage claims from responsible parties within the context of the U.S. Natural Resource Damage Assessment framework. Natural resource trustees, including U.S Fish and Wildlife Service and state conservation agencies, assess physical, chemical and biological metric and endpoints when pursuing claims. Studies conducted in Missouri’s lead mining districts have evaluated the direct effects of metals mining on native crayfish species as well as indirect effects related to their structural and functional roles in Ozark Mountain ecosystems. Crayfish were found to be indicator or sentinel species due to their site fidelity, abundance, and sensitivity to metals. Crayfish densities were significantly lower at sites downstream from mining areas compared to sites upstream for mining-impacted sites. Crayfish are important food items for predatory fishes and riparian wildlife, which may be at risk from dietary exposure to metals in crayfish. Results from our study have contributed to recovery of funds for stream habitat restoration and for status assessments for potentially threatened or endangered crayfish species residing in mining-impacted watersheds.
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