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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: 2, Talk: 3

Cambarus aff. dubius, a New Species of Crayfish (Decapoda: Cambaridae) Endemic to the Pre-glacial Teays River Valley in West Virginia, USA

DAVID A. FOLTZ II., Nicole M. Sadecky, Greg A. Myers, James W. Fetzner Jr., Stuart Welsh, G. Whitney Stocker, Mael G. Glon and Roger F. Thoma

A new species of crayfish, Cambarus aff. dubius, new species, is described from the preglacial Teays River Valley of Cabell, Kanawha, Lincoln, Mason, and Putnam counties, West Virginia. The species was previously considered to be part of the Cambarus dubius complex (Jezerinac et al. 1995). Loughman et al. 2015 restricted C. dubius to an orange color morph found in central and northern portions of the Allegheny Mountains and Appalachian Plateau in central West Virginia, western Maryland, and southcentral Pennsylvania. The new species described herein can be distinguished from all other members of Cambarus by a double row of cristiform tubercles on the palm, an open areola with two rows of punctations, and a consistent blue coloration.

 

 

Day: 2, Session: 2, Talk: 4

Examination of Morphological Variation in Faxonius jeffersoni Populations Indicates the Presence of a Species Complex

Zachary L. Couch

Faxonius jeffersoni Rhoades is a poorly known member of the crayfish family Cambaridae currently found in six small stream systems in Jefferson, Oldham, and Bullitt counties in Kentucky, USA. Fitzpatrick (1967) was the first to report morphological variation in gonopod sculpturing, rostrum width, and areola width between populations of F. jeffersoni found in the Beargrass and Pond Creek drainages in Jefferson and Bullitt counties. During qualitative and quantitative surveys conducted as a part of this study from 2007–2010 throughout Kentucky, examination of several morphological characteristics indicate that F. jeffersoni may represent multiple species. Examined specimens of F. jeffersoni from the Beargrass (n=48) and Goose Creek (n=15) drainages possess a gonopod with terminal elements (equal in length) that are 26.51% (0.026) and 26.62% (0.019) of the total length of the gonopod, respectively, lack a shoulder below the central projection, and typically exhibit a smooth mandibular margin. Specimens of F. jeffersoni examined from the Pond Creek (n=21) and Abrams Run (n=6) drainages are typically characterized by having a gonopod with terminal elements (the central projection being longer than the mesial process) that are 31.93% (0.019) and 31.54% (0.026) of the total length of the gonopod, respectively, possess a shoulder on the gonopod below the central projection, and typically exhibit a dentate mandibular margin. A median carina is often observed in larger specimens from the Pond Creek and Abrams Run drainages but was always found to be lacking from examined specimens from the Beargrass and Goose Creek drainages. This study reports the findings of preliminary morphometric analyses collected to clarify the taxonomic status of F. jeffersoni. Additional data collection and analysis is ongoing. However, results of morphometric analyses conducted to date suggests that the population of F. jeffersoni found in the Pond Creek and Abrams Run drainages represents a new species. As the current range of the species resides in a largely urban watershed, these initial findings are encouraged for use by resource managers to begin to reassess the conservation status of the F. jeffersoni species complex and consider its need for legal protection at the state and federal levels.

 

 

Day: 2, Session: 3, Talk: 1

Assessing Crayfish Habitat Requirements: A Proposed Method for Determining Habitat Breadth in Lotic Ecosystems

CHRISTOPHER A. TAYLOR and Christopher J. Rice

Lotic ecosystems in the central and eastern United States can be highly variable in habitat structure, ranging from shallow riffles to deep pools. These same ecosystems harbor a highly endemic and threatened crayfish fauna. Understanding habitat requirements for rare species is fundamental for effective conservation, yet habitat descriptions for many of these species rely solely on data from easily accessed sampling locations. We tested a new sampling method for collecting the narrowly endemic Coldwater Crayfish (Faxonius eupunctus) in the southern Missouri Ozarks by utilizing SCUBA in deep, largely non-wadeable pools. Our methods allowed for unbiased and repeatable sampling within and across sites and for the collection of rigorous data on crayfish density and habitat associations. By combining our proposed pool sampling method with wadable riffle sampling, we expanded the known habitat requirements for the Coldwater Crayfish. Data from pool sampling increased known suitable ranges for temperature and substrate size for the species. Our work also found agreement between both habitat types for physcial habitat variables exhibiting significant relationships with Coldwater Crayfish density. Using mulitple sampling methods has long been known to increase the accuracy of community inventory sampling given differences in microhabitat use by community members. Our work demonstrates that employing multiple sampling methods can increase the accuracy of habitat requirements for rare crayfish species.

 

 

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: 6

Crayfish Conservation in Southern England

JEN NIGHTINGALE, Grainne McCabe, Gareth Jones and Paul Stebbing

The white-clawed crayfish, Austropotamobius pallipes has suffered severe declines within the south west of England, where the first signal crayfish, Pascifastcus leniusculus farms were established in the 1970s. In response to this decline, The South West Crayfish Partnership (SWCP) was formed in 2008; comprising Bristol Zoological Society, Buglife, Cefas, the Environment Agency, Wildlife Trusts and Associates. The SWCP implements landscape scale, strategic conservation for A. pallipes, in an attempt to safeguard the future of this species in South West England. The conservation effort has four strands: 1. Ark sites: established throughout the south west England, for translocation of the most highly threatened white-clawed crayfish populations and captive-bred reintroductions. 2. Crayfish captive breeding facility: established at Bristol Zoo, which provides plague-free A. pallipes brood stock for ark site release, wild supplementations, research and outreach. 3. Communication strategy: running in tandem with the other three elements, targeting key audiences such as anglers, restaurants, students, school children and zoo visitors. 4. Invasive crayfish control – trialing different control techniques specifically targeting the signal crayfish. The presentation will cover the key elements of this conservation programme, evaluating its success to date and discuss the research elements that run in tandem with all of these conservation strands.

 

 

Day: 2, Session: 3, Talk: 7

Introduced and Then Almost Forgotten: Invasive Crayfish (Procambarus clarkii and Cherax quadricarinatus) in Costa Rica, Central America - Preliminary Results

JUAN CARLOS AZOFEIFA SOLANO, Ingo S. Wehrtmann, Fresia Villalobos-Rojas, Raquel Romero-Chaves and Adrián García-Rodríguez

Costa Rica harbors a remarkable diversity of freshwater native decapods, including 15 crab species (Pseudothelphusidae) and more than 21 species of caridean shrimps (Atyidae and Palaemonidae). Crayfish (Astacoidea) are not part of the native freshwater decapod fauna of the country. However, during the last century, two crayfish species were introduced: Procambarus clarkii in the Reventazón basin (Caribbean slope) in the 1970's, and Cherax quadricarinatus in the Tempisque basin (Pacific slope) in the 1980's. Both species have been recognized as invasive species in many other countries, and there is broad evidence suggesting its negative impact on native species, ecosystem functioning, and even human activities. Despite the potential threat of these crayfish species for the Costa Rican freshwater environments, very limited information is available about their occurrence in the country. Therefore, it is imperative to document the current distribution of both species and to assess their possible effects on the freshwater ecosystems in Costa Rica. We initiated a study aimed to explore the presence of these invasive crayfish species in Costa Rican streams and lakes and to provide information about their feeding ecology. So far, we have collected P. clarkii in two locations, outside the Reventazón basin were it was initially introduced, and belonging to the Pacific slope. More than 160 specimens have been analyzed, ranging in size from 6.5 to 78.1 mm total length. The predominant food item found at the stomachs was unidentified plant detritus, followed by filamentous plants, fragments of chironomid and Ephemeroptera larvae, and plastic. Our collections revealed two new locations for C. quadricarinatus in Costa Rica: one of them a stream in the Caribbean slope, and the other in the Arenal Lake, the largest reservoir in Costa Rica. The size of the collected specimens (n=7) ranged from 45.1 to 92.2 mm total length. Currently, both crayfish species inhabit both Caribbean and Pacific slopes in Costa Rica. It remains to be studied whether these species dispersed naturally or if they were locally introduced by humans. Since both species have been introduced in Costa Rica and the Central American region, the results of the study aim to raise awareness about the possible impacts of these crayfish species on the native flora and fauna of the local freshwater ecosystems, and to develop recommendations for the implementation of management programs.

 

 

Day: 2, Session: 4, Talk: 2

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

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

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

 

 

Day: 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: 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: 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 (CO2) are being investigated as potential chemical controls for invasive crayfish integrated pest management programs. Adult Red Swamp Crawfish (RSC; Procambarus clarkii) were exposed in the laboratory to CO2, cypermethrin, and pyrethrin; adult Virile Crayfish (VC; Faxonius virilis) were exposed to cypermethrin and pyrethrin. Test temperatures for CO2 trials and chemical toxicity tests were 10 and 24°C. A shuttle box was used to determine if crayfish avoided inhabiting an area with CO2-enriched water. Preliminary results of the CO2 trials suggest that RSC were more active in the 24°C trials (n = 150 crossings) compared to the 10°C (n = 75 crossings), but crayfish showed no preference for left or right sides of the shuttle box during the 30-min baseline portion of the trials. Crayfish response to the infusion of CO2 were similar for both temperatures; crayfish moved away from the CO2 side and remained on the non-CO2 side for the remainder of the 30-min trial. Crayfish avoided chambers with a CO2 concentration of about 114 mg/L. Static 24-hr toxicity tests will be conducted to determine lethal concentrations of cypermethrin and pyrethrin to RSC and VC, with and without the effect of turbidity. Pilot field trials will be conducted in <0.4 hectare research ponds (CO2), artificial burrows (cypermethrin and pyrethrin) and retention basins (cypermethrin or pyrethrin) in Michigan and Alabama, during summer and fall 2018. Results will provide resources managers with best practices for the application of CO2 to enhance mechanical and biological control methods and for the application of chemicals based on chemical sensitivity of crayfish.

 

 

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: 4, Talk: 1

Origin and Speciation of the Marbled Crayfish

FRANK LYKO

Marbled crayfish are a globally expanding population of parthenogenetically reproducing freshwater crayfish. They are closely related to the sexually reproducing slough crayfish, Procambarus fallax, which is native to the southeastern United States. However, reproductive incompatibility and substantial genetic differences suggest that the marbled crayfish should be considered an independent species (Procambarus virginalis). We have recently established a draft assembly of the marbled crayfish genome. We are now using comparative whole-genome sequencing to clarify the origin and speciation of marbled crayfish and I will discuss our available data.


 

Poster Presentations

 

 

POSTER 55

Development of a Captive Rearing Protocol for Threatened & Endangered Appalachian Crayfish

CHRISTOPHER VOPAL, Emmy Delekta and Zachary J. Loughman

In 2016, two Appalachian endemic species were federally listed by the United States Fish & Wildlife Service: Cambarus callainus (Big Sandy Crayfish) and Cambarus veteranus (Guyandotte River Crayfish), which are listed as threatened and endangered respectively. Both species were listed due to limited and declining ranges caused by various anthropogenic activities, especially those causing stream sedimentation. Captive propagation can be used as a tool for crayfish conservation by helping to restore the native range of a species or improving their fecundity within their current range. Over a ten week period, 120 young-of-the-year (YOY) Cambarus chasmodactylus (New River Crayfish), a surrogate species for C. callainus and C. veteranus, were raised in individual cells to compare (1) growth and (2) survival on two different diets. They were fed every other day, with half (60) raised on trout diet pellets (TD) and the other half raised on blood worms (BW). Results showed more YOY growth with BW (17.3% growth) than with TD (13.6% growth). Increased survival was also observed with BW (84.5% survival) when compared to the TD (70.5% survival). Our results may be influenced by the ease and ability for the crayfish to forage on the blood worms and may also have a higher nutritional value in comparison to the TD. Our findings suggests a BW diet may be more effective in the captive rearing of Camabrus crayfish. Using information gathered from this study, a modified protocol will be used for a new study beginning July 2018 for C. callainus and Cambarus smilax (Greenbrier Crayfish). This modified protocol will compare three diets (bloodworm, detritus, and bloodworm/detritus) in the growth and survival of YOY C. callainus and C. smilax in a six month period.

 

 

POSTER 58

An Assessment of Cambarus spicatus, Broad River Spiny Crayfish

RILEY W. AULICK and Zachary J. Loughman

The Broad River Spiny crayfish, Cambarus spicatus, is endemic to the Broad River and some of its tributaries. Few life history studies of C. spicatus have caused the IUCN to list it as data deficient. The goal of this study was to determine the impacts of land development on the distribution of C. spicatus. In the summer of the 2017, the West Liberty University Crayfish Conservation Research Lab surveyed the Catawba watershed in North Carolina and the Broad and Saluda watersheds in South Carolina in search of C. spicatus. A standard protocol of ten seine hauls per riffle was implemented in one hundred and twenty-three streams. Dip nets were used in addition to seines to survey the banks of the streams. ArcMap, an application of ArcGIS, was utilized by adding layers such as land cover and a buffer around each collection area which provided land type percentages for each survey site. Six individuals from four sites in North Carolina and one individual from South Carolina were collected out of a total of one-hundred and twenty-three sites. According to the models, C. spicatus was least likely to be found in areas developed for agriculture and urban development. This study provides strong evidence that land development is negatively impacting C. spicatus distribution. Additional studies are needed throughout the species range to make a final determination that land development has a negative impact on C. spicatus.

 

 

POSTER 63

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.

 

 

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 71

A Night of Devastation: Natural and Life History Observations of an En-masse Single Night Collection of Fallicambarus devastator

ZACHARY W. DILLARD, Katie Scott, Nicole M. Sadecky, Luke K. Sadecky and Zachary J. Loughman

Due to their fossorial tendencies, primary burrowing crayfish are the most difficult behavioral group of crayfish to study in-situ. In this study we elucidated both natural and life history aspects and intraspecific behaviors from a collection of 111 individual Fallicambarus devastator collected in Angelina County, Texas, on the night of May 15th, 2015. We also intend to emphasize the importance of environmental cues on collection success. Significant amounts of precipitation occurred during the days prior to collection efforts, resulting in the majority of burrows to be flooded on the day of collection. All animals were collected either traversing the landscape or captured at the portal of their burrow. Behaviors observed included excavation, respiration, feeding, and interspecific interactions. The majority of animals observed were adults, with juveniles noticeably absent on the surface. Life history observations included evidence of synchronous alteration to reproductive form in males, as well as sexually-dependent chelae morphometric ratios. Fallicambarus devastator meristically displayed sexual dimorphism between form I male and female chelae, with form I chelae having longer propodus length and greater palm widths compared to the squamous and shorter chelae of females. Understanding the significance of studying these animals in favorable conditions is of paramount importance to the quality of future primary burrowing crayfish research.

 

 

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.

 

 

POSTER 78

Morphometric and Genetic Evidence of Population Heterogeneity in the Narrow-clawed Crayfish from Belarus

KAROLINA ŚLIWIŃSKA, Agata Mruga?a, Molotkov V. Dimitry, Radek Šanda and Anatoly V. Alekhnovich

The narrow-clawed crayfish, Astacus leptodactylus (Eschscholtz, 1823) is one of the two native European crayfish species in Belarus. Although it is a widespread species of high economic importance in this country, the recent expansion of the invasive alien crayfish species endanger the sustainability of its stocks within Belarus. Nevertheless, A. leptodactylus taxonomical status is under debate across its whole range, and it is currently considered as a species complex. Indeed, the occurrence of various morphological forms within its native range has been extensively described in early scientific literature. Moreover, based on molecular data, A. leptodactylus populations have been recently divided into European and Asian lineages; a division confirmed also by comparative morphological analyses of genetically distinct Armenian and Croatian populations. Yet detailed information on the diversity of narrow-clawed crayfish remains still scarce, especially in its native distribution range. Therefore, our study aimed to evaluate the diversity of A. leptodactylus within two different drainages (Baltic and Black Sea) in Belarus, based on morphological (multivariate statistics) and genetic (mtDNA COI gene) analyses. As a result of molecular analyses, the studied populations were clustered into two distinct phylogroups, corresponding to the previously published A. leptodactylus lineages. Furthermore, the multivariate morphometric analyses confirmed this clustering, and indicated that variability of studied populations is especially expressed in abdomen and cephalothorax parameters. The obtained results suggest that A. leptodactylus may have a double origin within the territory of Belarus, and therefore, provide important information for the conservation and management of this native crayfish species.

 

 

POSTER 79

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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