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Oral | Posters


Oral Presentations

 

 

Day: 2, Session: 2, Talk: 1

Molecular Phylogenetic Analysis of the Devil Crayfish Group, with Elevation of Lacunicambarus to Generic Rank and a Re-description of the Devil Crayfish, Lacunicambarus diogenes comb. nov.

MAEL G. GLON, Roger F. Thoma, Chris A. Taylor, Marymegan Daly and John V. Freudenstein

As North American crayfish biodiversity becomes increasingly imperiled, the lack of a well-resolved, underlying taxonomic framework impedes conservation efforts. The taxonomy of the family Cambaridae has historically been based on morphology, but recent studies using molecular phylogenetic techniques have revealed taxonomic inconsistencies including a polyphyletic genus Cambarus. Here, we take a step towards increasing the taxonomic resolution of Cambaridae by investigating a group of primary burrowing crayfishes which were historically part of the Cambarus subgenera Lacunicambarus and Tubericambarus. This group, which we provisionally call the Devil Crayfish Group (DCG) because it contains the Devil Crayfish (Cambarus diogenes), has a complicated taxonomic history and is in need of revisionary work to inform conservation assessments. In this study, we test the hypothesis that the DCG forms a monophyletic clade through phylogenetic analyses of mitochondrial DNA sequence data from multiple specimens of the eight DCG species and from a broad sample of taxa representing approximately 70% of the species in what is currently recognized as Cambarus. We find that seven of the eight species from the DCG form a well-supported, monophyletic clade that is distinct from the remainder of what has traditionally been recognized as Cambarus. Although we were not successful in resolving the backbone of our phylogeny with high confidence, our analyses place the DCG as sister to a clade consisting of taxa from the genera Creaserinus, Faxonius, and Barbicambarus. Based on our results and on unique morphological and ecological characteristics of the DCG, we split seven of the eight DCG species from Cambarus and place them in Lacunicambarus, which we elevate to generic rank. We also redescribe the devil crayfish sensu stricto (Lacunicambarus diogenes comb. nov.) and designate a neotype for the species to facilitate subsequent revisionary work.

 

 

Day: 2, Session: 3, Talk: 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: 3

Modeling Effects of Crayfish Invasion and Drought on Crayfish Population Dynamics

Leah Bayer, Robert Fournier and DANIEL D. MAGOULICK

Crayfish play a crucial ecological role and are often considered a keystone species within freshwater ecosystems. However, North American crayfish species face several environmental and ecological threats including limited natural ranges, invasive species, and intensified drought. Demographic models can allow examination of population dynamics of a targeted species under a wide variety of disturbance scenarios. Here, we model the population dynamics of crayfish species with varied theoretical life histories and assess their responses to biological invasions and drought. We used RAMAS-Metapop to construct stage-based demographic metapopulation models parameterized using vital rates from established literature sources. Our models explored the population viability of four theoretical species under eleven disturbance scenarios and calculated estimates of terminal extinction risk, median time to quasi-extinction, and metapopulation occupancy. Our models indicate that populations respond differentially to disturbance based on life history. However, both r- and K-selected species appear to be highly susceptible to decline when faced with the additive effects of reduced carrying capacity due to invasion and reduced vital rates due to drought. By constructing models that explore a broad array of life histories and disturbance regimes, we hope to provide managers with tools to develop generalized, widely-applicable conservation strategies.

 

 

Day: 2, Session: 3, Talk: 5

Using Maximum Entropy Modeling to Predict Suitable Habitat Locations for the Cutshin Crayfish (Cambarus taylori)

ERIC TIDMORE and Zachary J. Loughman

The Cutshin Crayfish (Cambarus taylori) is a recently described species endemic to the Middle Fork of the Kentucky River basin that lies within the anthracite coal fields of Eastern Kentucky. As C. taylori has a restricted range in an area heavily impacted by extractive industry, a conservation assessment is warranted. The goal of this study was to predict suitable habitat locations for C. taylori through use of maximum entropy modeling (MaxEnt). The Middle Fork of the Kentucky River’s crayfish fauna was last surveyed during the summer of 2014. The occurrence data from this study coupled with landscape scale environmental variables—such as stream order and land use data—was used to create the model. The mean area under the receiver operating characteristic curve (AUC) value was 0.971, showing the model had high predictive accuracy. Stream order and stream sinuosity had the highest contribution to the model showing that C. taylori prefers 3rd and 4th order streams with low sinuosity. To test the accuracy of the model, ten high probability and ten low probability sites were surveyed. C. taylori was captured in ten of the twenty sites, eight of which were considered high probability for C. taylori presence.

 

 

Day: 2, Session: 4, Talk: 1

Illegal Export of Australian Freshwater Crayfish – Intercepted Shipments: A Case of Euastacus

James M. Furse

The unique, and often remarkable, nature of the native flora and fauna of Australia is well known. Many of these native Australian species are highly attractive, desirable and sought-after by private collectors, but also commercial interests known to include the pet/aquarium, and restaurant and gourmet food trades. Live export of native Australian wildlife (i.e. amphibians, birds, mammals, reptiles) for commercial purposes is prohibited under any circumstances. Live export of some invertebrates, fish and plants may be permitted (for commercial purposes), if they originate from approved sources or programs (i.e. captive breeding, aquaculture, or wildlife trade/wildlife trade management plans). For non-commercial purposes live exports of native flora and fauna is permitted (e.g. research, education), but as with any type of native species export, this is strictly regulated. Illegal export of Australian native flora and fauna is a most serious (and Federal) offence: penalties can be very serious indeed. Despite this, it is well established that there is illegal and ongoing "leakage" of native Australian flora and fauna. The freshwater crayfish fauna of Australia is both unique, remarkable, and well known in the aquarium trade. In some regions of the World this fauna is also evidently known in the restaurant and gourmet food trade. Illegal export(s) of native species of freshwater crayfish have previously occurred, and ongoing illegal exports of these animals are suspected, and sadly also expected. This talk will briefly outline the rules and regulations limiting live exports of native Australian flora and fauna, and outline case(s) of apparent illegal exports of Australian freshwater crayfish. A recent case where an illegal shipment of Euastacus was intercepted, and seized, in Australia will be discussed. This discussion will include information on the species that was intercepted, the intended geographical destination, destination-industry and why such activities pose a very serious threat to such species. Other details surrounding the intercepted shipment will be outlined as may be appropriate.

 

 

Day: 2, Session: 4, Talk: 2

Invasive Rusty Crayfish (Orconectes rusticus) Populations in North America are Infected with the Crayfish Plague Disease Agent (Aphanomyces astaci)

LAURA MARTÍN-TORRIJOS, David Buckley, Ignacio Doadrio, Annie Machordom and Javier Diéguez-Uribeondo

European freshwater crayfish are currently included in the IUCN Red list as threatened. In the Iberian Peninsula, the native species (i.e., the white–clawed crayfish, Austropotamobius pallipes) has experienced a drastic decline since 1973. Currently, the implemented management strategies of these species require a better understanding of the patterns of genetic diversity. In this study, we assessed the levels and patterns of the genetic variation by analyzing the largest number of populations of the whole distributional range of the WCC in the Iberian Peninsula. The two ribosomal mitochondrial markers applied (Cytochrome Oxidase subunit I and rDNA 16S genes) indicated high levels of genetic variability, which are significantly geographically structured in three main genetic groups, i.e., two corresponding to Northern and one to Central-Eastern Iberian Peninsula). The diversity found includes new private haplotypes, and reveals WCC populations (i.e., Southern and Central European WCC populations), may be result of the ancient palaeogeographic events, such as geographic barriers, and the Last Maximum Glacial scenario (LMG) (i.e., isolation in glacial refugia). Current conservation and management programs for the WCC in the Iberian Peninsula should take into account these three phylogeographic areas as essential management units in order to preserve the maximum genetic diversity.

 

 

Day: 2, Session: 4, Talk: 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: 2, Session: 4, Talk: 5

The Distribution and Conservation Status of the White Colour Morph of the Northern Clearwater Crayfish (Faxonius propinquus) in Lake Simcoe, Ontario, Canada

PREMEK HAMR and Mark Hoel

The rare and endemic white morph of Faxonius propinquus was first identified and described in 1978 by Dunham and Jordan who also subsequently documented the presence and distribution of the other various species and two other colour morphs of F. propinqqus in Lake Simcoe in Southern Ontario. Since then, no further research has been conducted on these populations, and the lake has been invaded by the introduced Rusty crayfish (Faxonius rusticus). The present study documents the decline and the present distribution of not only the rare white morph but also the other resident native species (O. virilis) which also appears to display several unusual colour morphs in Lake Simcoe. The decline of all three morphs of Faxonius propinquus as well as the impact of the F. rusticus expansion in the lake were assessed through surveys during the summers of 2015, 2016 and 2017. The significance of the results is discussed with respect to the conservation status and the future management of native crayfishes in Lake Simcoe.

 

 

Day: 3, Session: 2, Talk: 3

Crayfish, Conservation, and the Coalfields: A Case Study in the Initiation of a Crayfish Conservation Effort in North America

Zachary J. Loughman

Crayfishes have been recognized as one of the most imperiled animal groups on the planet internationally now for more than a decade. Conservation efforts in Europe and Australia have been many, and respective governments on both continents and their associated conservation agencies have been quick to recognize and protect pockets of diversity and specific highly imperiled species. In North America, most recent efforts have occurred via state level conservation agencies, which when said agencies have effective, forceful legal power, garner extensive protection for crayfish. Not all state level agencies are created equal, and when agencies lack enforcement power, crayfishes and other imperiled species can be eliminated in the names of progress. In these situations, listing as a federally imperiled species becomes paramount for protection of said taxa and their associated current and potential habitat. Cambarus callainus (Big Sandy Crayfish) and Cambarus veteranus (Guyandotte River Crayfish) are two Central Appalachian endemic species of tertiary burrowing crayfish whose populations have experienced drastic declines due to excess sedimentation and other stressors allied with extractive industries and development of riparian corridors. In 2014, a status assessment was written by the United State Fish and Wildlife Service (USFWS) based on work completed by astacological workers prior to that time, which indicated that water quality threats associated with coal mining, development, and off-road vehicle tourism were likely pressures to both species ability to persist in the coal fields of Kentucky, Virginia, and West Virginia, and in the case of C. veteranus, West Virginia only. In 2015, a range-wide assessment was completed for both species that involved visiting every historical location as well as over 100 new sample locations. Resultant of this work, current data was acquired that identified the principal current threats to both taxa had not changed, and possibly had gotten worse, which ultimately was used in addition to previous workers data to justify listing both species federally. On April 7th, 2016 C. callainus was listed as threatened and C. veteranus was listed as endangered. Beginning in the spring of 2017, an aggressive conservation campaign was initiated involving federal, nonprofit, and state level conservation agencies to gather data that ultimately will be used to conserve and protect both species. Captive rearing protocols, life history studies of C. callainus and C. veteranus as well as their crayfish associates, telemetry studies, and crayfish community analysis in addition to the creation of a response team for spills associated with extractive industry was created. In addition to research efforts, development of educational workshops for biologists working in the coalfields was also undertaken and initiated in the spring of 2016. Here in a review and case study will be provided detailing this process and the hope for its ultimate utilization in the preservation and future conservation of these highly imperiled central Appalachian endemics.

 

 

Day: 3, Session: 2, Talk: 4

Hunting Crayfish Plague with eDNA – And Making Use of the Results

LENNART EDSMAN, Anna Aspán, Patrik Bohman, Karin Enfjäll, Tomas Jansson, Stein Johnsen, Jenny Monsén, Daniel Nilsson, Johannes Rusch, David Strand, Rune Svensson, Øystein Toverud and Trude Vrålstad

In River Billan that starts in Norway and runs into Sweden, there has been a thriving population of the critically endangered native noble crayfish (Astacus astacus). The population has been good enough to support a sustainable, local, small scale fishery in both countries. Starting in August 2016 dead crayfish were found in the lower part of the river. The dying crayfish were analysed and the cause of death was crayfish plague (Aphanomyces astaci). Illegal introduction of the chronic crayfish plague carrying signal crayfish (Pacifastacus leniusculus) was suspected to be the reason for the plague outbreak, since this has happened numerous times in the neighbourhood. Intensive monitoring with baited traps and by electrofishing was conducted in both countries but no signal crayfish was found. Cages with noble crayfish were put out to monitor survival. The noble crayfish death by crayfish plague progressed upstream the river. On a rainy day in September 2017 we sampled 5 locations in River Billan in search for crayfish plague environmental DNA. The localities stretched from the outlet furthermost downstream up to the furthermost upstream location by the Norwegian border. Duplicate samples of 5 L was filtered on-site onto sterile glass fibre filters at each location. The samples were then analysed and presence/absence of eDNA from crayfish plague was analysed with qPCR. All samples for the four downstream locations were positive for crayfish plague. The furthermost upstream location was however negative for plague. Soon after 88 noble crayfish where caught with electrofishing in the upper part location of the river where no crayfish plague DNA had been found in the samples. They were transferred to a quarantine in a crayfish farm 200 km away, and the crayfish are still alive and healthy in the pond 7 months later, so the salvage action was successful. They can be used in the future for breeding and for restoration of the noble crayfish population in River Billan.

 

 

Day: 3, Session: 3, Talk: 2

Comparisons of Enzymatic Thermal Optima Among Narrowly and Broadly Distributed Crayfish Species

HISHAM ABDELRAHMAN, James A. Stoeckel and Jacob T. Westhoff

Previous researchers have shown that extraregional invasive crayfish possess certain biological and ecological traits that facilitate their ability to successfully invade large areas in distant regions, whereas extralimital invaders tend to remain localized and occupy smaller ranges. Physiological optima may provide additional explanatory power for realized and potential range of crayfish species. In this study, we tested for differences in enzymatic thermal optima among multiple crayfish species with narrow (i.e., Faxonius marchandi, ~2,800 km2) to broad (i.e., F. virilis, >11 million km2) native and invasive ranges. We hypothesized that species with broad ranges would be thermal generalists relative to species confined to limited ranges. To test this hypothesis, we generated thermal performance curves of respiratory enzymes in the electron transport system (ETS) for 12 individuals of each species. Optimal thermal range was defined as the temperature range within which ETS enzyme activity was within 10% of the maximum observed value. Preliminary results show that the wide-ranging, invasive F. virilis has a broader thermal optima, and higher individual variation, than a localized invader – F. neglectus – or narrow endemics such as F. eupunctus or F. marchandi. Furthermore neither the thermal optima, nor the optimal range of the localized invader – F. neglectus - was significantly different than that of an endemic (F. eupunctus) within the invaded range. Results thus far suggest that underlying physiology may provide important clues as to which species have the potential to spread broadly and which species may be limited to a relatively narrow range. Additional species are currently being analyzed to better assess the robustness of these conclusions.

 

 

Day: 3, Session: 3, Talk: 4

Normal Biochemistry of the Murray Crayfish Euastacus armatus (Parastacidae)

Martin Asmus, Shane Raidal and MAGGIE J. WATSON

Haemolymph samples were collected from wild and captive held adult male and female Murray Crayfish Euastacus armatus. Haematological analyses were performed in order to determine reference values for this species including protein, albumin, globulin, creatine kinase, aspartate transaminase, glutamate dehydrogenase, glucose, gamma-glutamyltransferase, potassium, sodium, calcium, phosphate, chloride, uric acid, cholesterol, amylase and bile acids. Additionally, protocols for measurements of phenoloxidase and prophenoloxidase (part of the non-specific immune system in crayfish which leads to the melanisation and sclerotisation in stressed animals) are being trialled. Alterations from these reference values can be used to determine stress and disease state of the crayfish. These tests are being used to monitor the health and stress levels of Murray Crayfish intended for use in a large-scale translocation of crayfish from healthy populations to areas of the Murray River that no longer support crayfish. Murray crayfish populations in affected parts of the river dropped by 81% in 2010–11 due to hypoxic water events.

 

 

Day: 3, Session: 3, Talk: 6

Body Size in Freshwater Crayfish: An Intercontinental Comparison

Alaistair M. M. Richardson

The independent evolution of the astacoidean and parastacoidean crayfish in the Northern and Southern Hemispheres provides an opportunity to compare their characteristics. The comparison can be sharpened by comparing the crayfish faunas of Australia and North America, having roughly similar areas and lying at comparable latitudes. Size data were collected from the literature for 230 North American and 125 Australian species, and were compared directly and in terms of the species' burrowing habits. The Australian fauna includes several much larger species, and while the modal body size is very similar in the two faunas, the North American modal size class, and also the entire fauna, is dominated by tertiary burrowers, the Australian by primary ones. Further, Australian primary burrowers are smaller on average. The factors influencing these differences are discussed.

 

 

Day: 3, Session: 3, Talk: 7

Burning Down the House: Effects of Prescribed Burning and Mechanical Vegetation Treatments on Primary Burrowing Crayfish Densities

SUSAN B. ADAMS and Scott G. Hereford

Prior to widespread anthropogenic habitat alteration, primary burrowing crayfishes along the Gulf of Mexico Coastal Plain in southern Mississippi and Alabama presumably occupied predominantly open pine savannas, prairies, and bogs. Among other alterations, European settlement brought increasing fire suppression and intensive pine production. The Mississippi Sandhill Crane National Wildlife Refuge was “established in 1975…to protect the critically endangered Mississippi sandhill cranes [Grus canadensis pulla] and their unique, and itself endangered, wet pine savanna habitat.” The cranes require open meadow or pine savanna habitat, now created and maintained via prescribed burning, or when burning is precluded, via mechanical treatment. The US Fish and Wildlife Service (FWS) became interested in how these land management actions affect other at-risk species, including the primary burrowing crayfishes on the refuge: Creaserinus spp. and Procambarus fitzpatricki. In 2016, we initiated a study to survey crayfishes on the refuge and to begin examining how the land management influences burrowing crayfish densities. Crayfishes were surveyed by trapping and dipnetting in perennial and intermittent water bodies and by excavating and trapping from burrows. Burrower density among management classes was addressed by surveying burrow densities in quadrats along six transects on three plot types: regularly burned, regularly mechanically treated, and infrequently managed. We collected six species, including four only from water bodies: Cambarellus diminutus, Procambarus shermani, P. clarkii, and Faxonella clypeata. Procambarus fitzpatricki, considered at-risk by the FWS, was collected from burrows but also from small, isolated, intermittent pools in prairies and savannas. The most abundant burrower was identified as Creaserinus oryktes; however, taxonomic uncertainty creates enormous difficulty in distinguishing C. oryktes (not considered at-risk) from C. danielae (considered at-risk). Preliminary results indicate that burrowers were more abundant in burned or mulched plots than in infrequently managed plots. Confounding factors include interactions between site moisture and burn frequency/intensity and between ease of locating burrows and vegetation density.

 

 

Day: 5, Session: 3, Talk: 1

Geographical Variation in Size and Growth in the Giant Freshwater Crayfish, Astacopsis gouldi. Deductions from a Large Opportunistic Database

ALASTAIR M. M. RICHARDSON and Todd Walsh

A tagging program on the Tasmanian giant freshwater crayfish, Astacopsis gouldi, has been carried out since 1998, using PIT tags since 2007. Almost 600 animals, ranging from 20-215 mm carapace length, have been tagged and around 2500 captures recorded from 123 localities on 62 rivers across the species' range. Comparisons of length-weight relationships and growth are made between the discrete western and eastern ranges of the species, and between populations living in nutrient-poor and nutrient-rich waters. Animals from the eastern range are slightly lighter for a given weight than western animals. Growth is marginally slower in animals from nutrient-poor waters. Individual growth histories are available for 26 animals, some of which have been recaptured up to 6 times, over as long as 10 years. Growth rates vary considerably within river populations, suggesting that there may be fast- and slow-growing animals within the same population. Gompertz growth models showed lower growth rates and asymptotes for the nutrient-poor population, but their usefulness was affected by the limited size at known age data. Models suggested that animals of 220 mm CPL may be 60-70 years old.

 

 

Day: 5, Session: 3, Talk: 5

A New Technique for Determining Crayfish Population Demographics

JOSHUA MOUSER, Jason Glover and Shannon K. Brewer

Aging organisms provides crucial population demographic information such as growth, recruitment, and mortality. Crustaceans are typically aged via indirect techniques, such as length-frequency histograms and mark recapture. Indirect techniques are limited to the populations and specific study period, do not provide an actual age, and histograms are inaccurate for older age classes with fewer individuals. In contrast, direct techniques rely on calcified structures, but often the individual must be sacrificed. Recent work has demonstrated that the gastric mill, located in the stomach of crustaceans, may be useful for obtaining direct age estimates. Therefore, our objective was to determine if a common North American crayfish species could be reliably aged using gastric mill ossicles. We collected approximately 100 adult and 300 age-0 (<13 mm carapace length) ringed crayfish Faxonius neglectus from streams in the Ozark Highlands ecoregion. Gastric mills were extracted from the crayfish, separated, cleaned, sectioned, and mounted on a microscope slide. Each crayfish was aged independently by three different readers and a consensus age was reached if there were discrepancies. For a subset of individuals, two readers aged each ossicle independently to determine which ossicle provided the most consistent age estimates. We compared length-frequency histograms from field collections to our direct age estimates. All three ossicles showed consistent growth bands, but the zygocardiac and mesocardiac ossicles had superior readability. Crayfish age estimates ranged from zero to ten years, whereas the length-frequency histograms suggested eight year classes. Our age estimates did not match length-frequency histograms well, especially after year 4. Independent age estimates from each of the paired zygocardiac ossicles were similar. Our results suggest that ringed crayfish may live to be much older than five years as generally accepted, and aging crayfish directly may improve the age bias reflected in histograms. Future work will focus on validating that bands correspond to one year of growth, environmental effects on band deposition, and if daily bands are deposited in age-0 crayfish.


 

Poster Presentations

 

 

POSTER 51

Investigating the Role of Dishonest Signals of Strength in Interspecific Fights Between Two Arizona Crayfish

ZACK A. GRAHAM and Michael J. Angilletta

Crayfish use their claws to defend territories and routinely engage in combat with competitors. Usually, the crayfish with smaller claws retreats without fighting, even though large claws are not necessarily strong ones. This dishonesty enables crayfish to obtain resources without being a true threat to opponents. The importance of dishonest signals of strength has been demonstrated in intraspecific crayfish fights. But distributions of crayfish often overlap and competition with other crayfish species is expected. Therefore, to understand the role of dishonest signaling in interspecific competition, I observed the fighting behavior of the two invasive Arizona crayfish species; the virile crayfish (Orconectes virilis) and the red swamp crayfish (Procambarus clarkii). I predict that dishonest signals of strength will influence interspecific fights in a similar manner to intraspecific fights. My results demonstrate the importance of investigating dishonest signals of strength in multiple crayfish species. Additionally, I propose that future analysis of dishonest signals may have important implications regarding crayfish invasions.

 

 

POSTER 54

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.

 

 

POSTER 57

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.

 

 

POSTER 60

Identification of Pathogens Causing Porcelain Disease in North America: Call for Samples

EMILY IMHOFF

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.

 

 

POSTER 61

Are Soil Properties Good Predictors in Distribution Modelling for Three European Crayfish?

CONSTAN?A MIHAELA ION, Andrei Dornik and Lucian Pârvulescu

Niche-based species distribution models (SDMs) using different algorithms (like generalized linear model, MaxEnt, random forest) are largely used in various applications for many species of plants and animals. By far, the most used variables for modelling are bioclimatic variables, but also slope, land use, vegetation cover and soil are sometimes considered. Several soil properties are now available at regional and global level, with suitable spatial resolution for SDMs. We therefore aim to increase our understanding on how these soil properties affect spatial distribution of crayfish species. We used a database consisting of 470 presence and absence locations in Romania for three European species of crayfish (Austropotamobius torrentium, Astacus leptodactylus and A. astacus), to extract information from several soil properties layers (grid type at 250 m resolution at seven standard depths) obtained from ISRIC - World Soil Information. Analyzing soil texture, 3000 randomly selected points from the study area were grouped mainly into five soil textural classes (silty clay, clay loam, silty clay loam, loam and silt loam), while crayfish presence points fell only in loam and clay loam. Using SDM we found that soil properties are good predictors for the current distributions of the three investigated crayfish species. For A. leptodactylus, the predicted distribution covers low plains up to the hills, while for A. astacus it ranges from higher plains, over foothills and tablelands and into lower altitude units of the Carpathian Mountains. A. torrentium predicted distribution is clearly restricted to the foothill region. The analysis based on crayfish abundance pointed out that there is a positive response to clay content and soil bulk density, and a negative response to sand content as well as to coarse fragments for all investigated crayfish species. We speculate that the burrows integrity against the erosion along the shorelines might be the explanation of these results, challenging new perspectives in further ecological approaches.

 

 

POSTER 68

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.

 

 

POSTER 69

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.

 

 

POSTER 72

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.

 

 

POSTER 74

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.

 

 

POSTER 76

A New Species of Faxonius Crayfish from the Red River System of Kentucky and Tennessee

ERIN T. BLOOM, Brittany McCall, Guenter A. Schuster and Rebecca E. Blanton

Faxonius barrenensis is a crayfish endemic to the Green River system of Kentucky and Tennessee and is closely related to F. mirus, which is restricted to Tennessee River tributaries in Tennessee and Alabama. A morphologically similar but undescribed crayfish, Faxonius sp., occurs in the Red River system (Cumberland River) of Kentucky and Tennessee. Whether the latter represents a disjunct population of F. barrenensis or F. mirus, or alternatively, a distinct, species is unknown. Furthermore, whether the shared morphological traits reflected shared ancestry or convergence has not been tested. We used molecular and morphological data, including two mitochondrial (COI and 16s) and two nuclear (28s and GAPDH) genes and a standard suite of phenotypic measurements and meristics to examine phylogenetic relationships and the taxonomic status of Faxonius sp. relative to F. barrenensis, F. mirus and other Faxonius. Results from the concatenated and individual gene datasets supported a close relationship among the three focal taxa, implying their gross morphological similarities likely reflect recent shared ancestry. In all mitochondrial and combined gene trees, Faxonius sp. was recovered as a genetically divergent clade from F. barrenensis and F. mirus. Additionally, Faxonius sp. is phenotypically distinguished from F. barrenensis and F. mirus based on several characteristics. Given these findings, we propose Faxonius sp. represents a distinct species of crayfish that is closely related to F. mirus and F. barrenensis. However, our data does not resolve which of the latter is its sister species; additional molecular markers are needed to resolve this question. The new species has only been collected at four different localities within the Red River system (Cumberland), three of those located on the Ft. Campbell Army Base along the Tennessee/Kentucky state line. Several other streams have been searched, but no other populations have been identified, suggesting it has a small range and warrants conservation concern.


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