6/07/2017  |   09:00 - 09:15   |  305A

USE OF ENVIRONMENTAL DNA (eDNA) AND THE ELECTRON TRANSPORT SYSTEM (ETS) ASSAY TO ASSESS POPULATIONS OF INVASIVE Orconectes virilis IN THE SOUTHEASTERN UNITED STATES The virile crayfish (Orconectes virilis), is an upper mid-west North American species that has been broadly introduced, with southernmost introductions in the Cahaba River of Alabama. To better understand its current extent and predict future expansion, we are taking a two-pronged approach using eDNA techniques to assess presence/absence in streams, and ETS assays to assess thermal tolerance of the invader relative to congeneric natives. To date, we have developed and optimized general quantitative PCR (qPCR) markers to detect the presence of Orconectes spp. and specific qPCR markers to detect O. virilis and native O. erichsonianus at the species level. We have also developed and refined protocols using the ETS assay to assess differences in thermal tolerance between aquatic species. We are currently surveying Cahaba drainage streams for presence/absence of invasive and native crayfish and comparing thermal tolerances among O. virilis and native Orconectes spp. Results will be of great use in identifying streams at high-risk for future invasions, and native species likely to be impacted by the invader.

Hisham Abdelrahman (Primary Presenter/Author), School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, hisham@auburn.edu;


Mallary Clay ( Co-Presenter/Co-Author), Department of Biological Sciences, Auburn University, mclay@gps.edu;


Nathan Whelan ( Co-Presenter/Co-Author), US Fish and Wildlife Service, nathan_whelan@fws.gov;


Brian Helms ( Co-Presenter/Co-Author), Troy University, helmsb@troy.edu;


Jim Stoeckel ( Co-Presenter/Co-Author), Auburn University, jas0018@auburn.edu;


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6/07/2017  |   09:15 - 09:30   |  305A

HABITAT-MEDIATED MORPHOLOGICAL VARIATION IN INTRODUCED CRAYFISH POPULATIONS Evidence indicates that crayfish morphology can vary depending on environmental context. Introduced species may show more inter-population variation in morphology than native species, since morphological variation is considered a trait conducive to successful invasion. This higher level of trait variability can lead to highly localized populations. Orconectes virilis, an invasive crayfish in North American ecosystems, may display this elevated level of variation, making it a good model organism for testing this concept. Specimens were collected from lake and river habitats in the Cahaba River drainage of Alabama in the United States and multiple river drainages in the prairie provinces of Canada. Both traditional morphometric measurement and geometric morphometics were used to compare morphologies between “lake” and “river” populations. Comparing the length-to-width ratios of the areola between the groups, we found that lake dwelling crayfish tended to have a higher areola ratio than river dwellers. This suggests that the introduced populations are changing their morphology in response to their novel environment. Identifying these traits in known invasives may help predict which species have the potential to become invasive in the future.

Jennifer Weber (Primary Presenter/Author), Auburn University, jmw0030@auburn.edu;


Bronwyn Williams ( Co-Presenter/Co-Author), North Carolina Museum of Natural Sciences, bronwyn.williams@naturalsciences.org;


Brian Helms ( Co-Presenter/Co-Author), Troy University, helmsb@troy.edu;


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6/07/2017  |   09:30 - 09:45   |  305A

INTEGRATIVE TAXONOMY AND CRAYFISH CONSERVATION Effective conservation of biodiversity is highly dependent upon a robust taxonomic framework, which in turn is based on an understanding of the characteristics that define species limits. Historically, crayfish species have been delimited based on morphological variation; key taxonomic characters are assumed to differ among, but not within species. In recent years, molecular genetic data - primarily fragments of the mitochondrial genome - have become a common addition to taxonomic studies. In several of these studies, results of parallel morphological and molecular analyses have seemingly been at odds with each other. Such conflicts have been contentious, yet arise in large part from a lack of understanding of the mechanisms that underlie both morphological and molecular variation. Morphology and mitochondrial DNA are far from the only data types that can, and should, be used to aid in species delimitation. Indeed, there is a real need for an integrative approach to crayfish taxonomy in which molecular, morphological, biogeographical, behavioral, physiological, and ecological data together help define operational taxonomic units for effective conservation.

Bronwyn Williams (Primary Presenter/Author), North Carolina Museum of Natural Sciences, bronwyn.williams@naturalsciences.org;


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6/07/2017  |   09:45 - 10:00   |  305A

EFFECTS OF NATIVE AND INVASIVE SPECIES, SOURCE POPULATION, AND STREAM DRYING ON CRAYFISH POPULATION DYNAMICS AND ECOSYSTEM STRUCTURE AND FUNCTION Invasive crayfish are a significant threat to native endemic crayfish in the Ozark Highlands of Arkansas and Missouri, an area where stream drying is a prominent disturbance. Objectives of this study were to examine the effects of native and invasive crayfish source population, and stream drying on crayfish population dynamics and ecosystem structure and function. We performed a fully factorial mesocosm experiment with crayfish (native Orconectes eupunctus, invasive O. neglectus from AR, and invasive O. neglectus from KS) and stream drying (drying and control) treatments. Data were analyzed with two-way ANOVAs and negative binomial regressions. Crayfish growth was greatest in O. neglectus (AR) treatments. Chlorophyll a was greatest in O. neglectus (KS) treatments, although not significantly. Leaf decomposition was least in O. eupunctus treatments. Drying treatments reduced chlorophyll a, sedimentation, and Chironomidae abundance, and increased autotrophic index. Macroinvertebrate richness was greater in control than drying treatments except for O. neglectus (AR). Results from this study indicate that O. eupunctus and O. neglectus are not ecologically redundant and invasive species source population may differentially affect population dynamics and ecosystem structure and function.

Daniel Magoulick ( Co-Presenter/Co-Author), Arkansas Cooperative Fish and Wildlife Research Unit, University of Arkansas, danmag@uark.edu;


Nicole Graham (Primary Presenter/Author), University of Arkansas, negraham@uark.edu;


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6/07/2017  |   10:00 - 10:15   |  305A

DENSITY DEPENDENT EFFECTS OF INVASIVE CRAYFISH ON NATIVE CRAYFISH: INSIGHTS FROM MESOCOSM EXPERIMENTS The invasive virile crayfish (Orconectes virilis) is one of three invasive crayfish in Virginia, and may pose serious threats to native crayfish. Previous laboratory experiments showed that invasive virile crayfish could significantly reduce the survival of native Piedmont crayfish (Cambarus sp. C). However, it is hard to replicate natural conditions under laboratory settings due to the complexity of ecological interactions. We conducted field mesocosm experiments using 1250L tanks to find how different densities of invasive virile crayfish affect native Piedmont crayfish populations. After 43 days, we did not find significant differences of survival rates of crayfish among treatments (p = 0.446). We found significant differences of biomass change among treatments (p < 0.001) and between native and invasive crayfish (p < 0.01). Invasive crayfish grew much faster compared to native crayfish in allopatry. However, invasive crayfish growth was decreased when in sympatry with native species, probably due to competitive interactions. Additionally, native crayfish growth was decreased under high invasive crayfish density. Overall, this experiment suggests that invasive virile crayfish grow much faster than native Piedmont crayfish, and could negatively impact native crayfish growth in high density.

Sujan Henkanaththegedara (Primary Presenter/Author), Longwood University, sujan040@gmail.com;


Jonathan Milisci ( Co-Presenter/Co-Author), Longwood University, jonathan.milisci@live.longwood.edu;


Connor Perry ( Co-Presenter/Co-Author), Longwood University, connor.perry@live.longwood.edu;


David Conner ( Co-Presenter/Co-Author), Longwood University, david.conner@live.longwood.edu;


Jessica Hoak ( Co-Presenter/Co-Author), Virginia Tech, jessica.hoak@live.longwood.edu;


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6/07/2017  |   10:15 - 10:30   |  305A

DETERMINING HOW INVASION AFFECTS NATIVE HOSTS AND THEIR SYMBIONTS: A TALE OF CRAYFISH AND THEIR SYMBIOTIC WORMS A lot of attention has been directed towards understanding introduced species and their impacts on invaded systems. Less well studied is how invasion affects native hosts and their symbionts. Holarctic crayfish host diverse assemblages of symbiotic worms known as Branchiobdellida. These leach-like annelids are cleaning symbionts of crayfish with no free-living life stage, requiring a crayfish host for reproduction and dispersal. These assemblages vary based on crayfish genera. Species in the genus Cambarus derive health benefits from this symbiosis at intermediate worm abundance while many Orconectes species appear to be less tolerant of symbionts. Orconectes presence in crayfish communities has been shown to significantly reduce both Branchiobdellida density and richness. As many invasive crayfish species are Orconectes, differences in host symbiont tolerance may influence native symbiont diversity and abundance. To determine what effect invasion has had on both crayfish and Branchiobdellida communities, historic survey sites in the Mountain Lake region of Virginia were resampled. Combined with results from symbiont dispersal experiments, these results will help us to better understand a poorly studied aspect of invasion.

Spencer Bell (Primary Presenter/Author), University of Alabama, obscurus@vt.edu;


Robert Creed ( Co-Presenter/Co-Author), Appalachian State Universtiy, creedrp@appstate.edu;


Bryan Brown ( Co-Presenter/Co-Author), Virginia Tech, stonefly@vt.edu;


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