Abstracts

IAA22 Book of Abstracts (PDF)

Meeting Program/Schedule (PDF)

 

 VIEW MEETING PROGRAM ONLINE

 

 

LIST OF MEETING ABSTRACTS

NOTE: You may quickly navigate to a name you are looking for by clicking a letter below (first letter in their lastname).

ALL A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Oral | Posters


Oral Presentations

 

 

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: 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: 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: 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: 2, Session: 4, Talk: 6

100+ Years Since Ortmann: Conservation and Distribution of Crayfishes of the Upper Ohio River Basin in Pennsylvania

TANYA N. KHAN, David A. Lieb and Zachary J. Loughman

Crayfishes in North America face numerous anthropogenic stressors such as urbanization, extractive industries, and introduction of non-native crayfish species. In 1906, Arnold Ortmann published his survey of crayfishes of Pennsylvania, where he found only native populations. Comparing Ortmann’s work to more recent investigations of southeastern Pennsylvania crayfishes has revealed the presence of five non-native species which have destabilized historic populations. Given these findings, there are reasons to be concerned about the status of crayfish populations in the Upper Ohio River Basin in Pennsylvania, where three native species historically occur: Cambarus carinirostris (Rock Crawfish), Cambarus robustus (Big Water Crayfish), and Faxonius obscurus (Allegheny Crayfish). The goal of this study was to assess changes in crayfish fauna of western Pennsylvania since the 1906 survey. In addition, we set out to determine if abiotic factors influence presence of the three native species. Using standardized sampling of 10 seine hauls/site, we conducted surveys of 256 sites in the Upper Ohio River drainage, with a focus on collection of epigean species. Site covariates including physiochemical and physical habitat data (utilizing the Qualitative Habitat Evaluation Index, QHEI) were obtained at 175 sampled sites. Presence and absence data of each species were analyzed using logistic regression modeling to fit single covariate or additive-effects models of stream habitat, water quality, or presence/absence of other crayfish species. Crayfishes were found at 79% of 102 historical sites and 97% of 163 new sites. To date, only one non-native population of Faxonius rusticus (Rusty Crayfish) has been discovered in the North Branch of Slippery Rock Creek. These collections represent approximately 60% of the survey, with remaining collections to occur in 2018. Model results show correlations of: Faxonius obscurus presence to a global model (containing 8 covariates), temperature + conductivity, and temperature + pH; Cambarus carinirostris presence to temperature + substrate; and Cambarus robustus presence to pool quality + substrate and temperature + substrate. Preliminary data suggests that crayfish fauna in western Pennsylvania has remained moderately stable over the last century, though the presence of a non-native crayfish population indicates the need for continued monitoring. Efforts in Pennsylvania must focus on prevention and management of the spread of non-native species to preserve the native crayfish populations that remain.

 

 

Day: 3, Session: 1, Talk: 3

STURE ABRAHAMSSON MEMORIAL LECTURE: Crayfish Color Patterns: Their Overlooked Significance

Guenter A. Schuster

Crayfish colors and color patterns have not been well studied. Horton H. Hobbs, Jr. and others, in descriptions of new species, mostly relied on verbal color pattern descriptions. This began to change with the publication of Raymond Bouchard's late 1980s color poster entitled "America's Crayfish." Since then, crayfish books and color posters representing crayfishes from several states and countries have been published. Now, color photographs are usually included in new species descriptions. State and federal agencies, as well as NGOs, are commonly using color photographs of crayfishes for conservation purposes. This talk addresses the North American cambarid crayfish fauna research on vision, and how color patterns might be useful to crayfishes. It will also address how these color patterns could provide important insight into the biology, behavior, taxonomy and systematics of crayfishes.

 

 

Day: 3, Session: 2, Talk: 2

The Louisiana Crawfish History Summary, The Last Fifty Years

JAY V. HUNER, Robert P. Romaire, C. Greg Lutz, Albert P. Gaude III., James W. Avault Jr., W. Ray McClain and Mark G. Shirley

The Louisiana USA crawfish industry has two commercial sources of crawfish, Procambarus spp., a wild harvest, mostly from the Atchafalaya River Basin (ARB) in the south-central area of the state, and a cultivated harvest from aquaculture ponds, located primarily in the southwestern area of the state. The combined harvest in 2016 was 135.2 MT with aquaculture accounting for 91%. The modern crawfish aquaculture industry originated in the early 1960s when low water during the ARB spring flood resulted in a poor harvest. State biologists worked with farmers in the Mississippi River alluvial valley and the southwestern prairie area to cultivate crawfish in purpose built impoundments and rice field impoundments. Area in crawfish culture increased from 4,050 ha in 1968 to 90,050 ha in 2017. Aquaculture accounted for 40-60% of annual harvest until the year 2000 and thereafter accounted for 70-95%. Changes in the hydrology of the ARB have largely accounted for declining wild crawfish harvests. The dominant species is Procambarus clarkii, the red swamp crawfish. Some Procambarus zonangulus, the southern white river crawfish, are harvested. Three major events impacted the Louisiana crawfish industry. First, import of crawfish products from the Peoples’ Republic of China beginning in the mid-1990s lowered prices. Second, an insecticide applied to rice fields used to cultivate crawfish in 1999-2001, combined with historical record summer drought which negatively impacted reproduction, led to widespread crop failure. Third, White Spot Shrimp Virus (WSSV), highly lethal to Procambarus spp. became widely distributed in both wild and cultured crawfish crops. Initially, competition from Chinese crawfish products had a negative impact on the Louisiana crawfish industry. However, over time imports led to development of new domestic markets and industry wide quality control practices. The highest crawfish production cost is harvesting – labor and bait. Crawfish are harvested in mesh traps that must be tended manually. Mechanized harvest boats have reduced the time necessary to tend traps but trapping is still highly inefficient. Initially, cut rough fish was the common bait, and later grain-based manufactured baits were developed but are relatively ineffective during colder months of the November/December – May/June seasons. A short-lived soft-shelled crawfish industry involving as many as 150 farmers developed in the 1980s. Despite good acceptance of the product, profits were low and entrepreneurs left the trade. No more than three producers remain today. Crawfish are cultivated by simulating the cool season wet, warm season dry hydrology of Louisiana. This works so well with rice farming that 75% of crawfish area is integrated with rice. The agricultural community refers to this landscape as working wetlands. The food rich system attracts predaceous, omnivorous, and vegetarian species of birds in great numbers. As a result, the National Audubon Society has designated the southwestern Louisiana region as an Important Bird Area of Global Importance. However, concerns about bird impacts on crawfish crops remain.

 

 

Day: 3, Session: 2, Talk: 3

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

Zachary J. Loughman

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

 

 

Day: 3, Session: 2, Talk: 5

A Nonnative Crayfish (Faxonius virilis) Use of an Eel Ladder, Potomac River Drainage, USA

STUART WESLH and Zachary J. Loughman

Fish passage facilities for reservoir dams have been used to restore habitat connectivity within riverine networks by allowing upstream passage for native species. These facilities may also support the spread of invasive species, an unintended consequence and potential downside of upstream passage structures. We documented dam passage of the invasive virile crayfish, Faxonius virilis, at fish ladders designed for upstream passage of American eels, Anguilla rostrata, in the Shenandoah River drainage, USA. Ladder use and upstream passage of 11 virile crayfish occurred during periods of low river discharge (<30 cubic meters per second) and within a wide range of water temperatures from 9.0–28.6°C. Virile crayfish that used the eel ladders had a mean carapace length and width of 48.0 mm and 24.1 mm, respectively. Our data demonstrated the use of species-specific fish ladders by a non-target non-native species, which has conservation and management implications for upstream passage facilities and the spread of aquatic invasive species.

 

 

Day: 3, Session: 3, Talk: 2

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

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

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

 

 

Day: 3, Session: 3, Talk: 3

Multi-method Inference of Temperature Tolerance and Preference for a Native and an Invasive Crayfish

JACOB T. WESTHOFF, Chris Rice, Hisham Abdelrahman and James A. Stoeckel

Conservation and management of crayfishes can be informed through a greater understanding of crayfish thermal ecology, especially as it relates to the suitability of thermal habitats for native and invasive crayfish. We used a combination of behavioral and enzymatic endpoints to estimate temperature preference, optimal respiratory enzyme tolerance (ORET), and critical thermal maximum (CTM) for the imperiled native Coldwater Crayfish (Faxonius eupunctus) and the invasive Ringed Crayfish (Faxonius neglectus). Significant differences in these parameters would allow for thermal partitioning of space and thus enhance the probability of coexistence. Crayfish used in CTM and preference tests were acclimated at one of four temperatures (10, 15, 20, 25°C) for two weeks prior to testing, whereas ETS assays used crayfish acclimated at 21°C. Estimates of CTM were 33.9°C for F. eupunctus and 33.2°C for F. neglectus. Mixed linear model analysis of CTM data showed no difference between species or genders, but a strong effect of acclimation temperature (p-value < 0.01). Mixed linear model analysis using likelihood ratio tests indicated F. eupunctus preferred slightly colder water (19.6°C) than did F. neglectus (21.3°C; p-value = 0.03). That analysis also identified a significant difference (p-value = 0.01) between males (20.3°C) and females (21.0°C), but acclimation temperature and the interaction between gender and species were not significant. Mean ORET did not differ between F. eupunctus (28.4°C) and F. neglectus (28.5°C), but did differ from a third congener, Faxonius marchandi (29.7°C), based on two-way ANOVA results. For all species, ORET was higher than organismal thermal preference estimates, but lower than CTM, suggesting it may provide a useful breakpoint for managers. Management strategies should target temperature regimes that approach but do not exceed OET to increase the frequency of optimal temperature occurrences while minimizing the risk of exposing crayfish to their thermal maxima. Across all estimated metrics, F. eupunctus and F. neglectus differed by less than 2°C, indicating that significant biological difference is unlikely. Thus, habitats suitable for the native F. eupunctus will also be thermally available to the invasive F. neglectus, thereby increasing the opportunity for interaction and negative population effects.

 

 

Day: 3, Session: 3, Talk: 6

Body Size in Freshwater Crayfish: An Intercontinental Comparison

Alaistair M. M. Richardson

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

 

 

Day: 3, Session: 4, Talk: 3

Epigenetic Regulation in the Marbled Crayfish

VITOR COUTINHO CARNEIRO, Anny Gatzmann, Cassandra Falckenhayn and Frank Lyko

The all-female marbled crayfish (Procambarus virginalis) attracted the attention of the scientific community due to its 'self-cloning' capacity. The obligatory parthenogenetic reproduction provided interesting research opportunities and also established a potent ecological threat. Despite its identical DNA, this model has an extraordinary variety in appearance and behaviour between isogenic batchmates reared in the same environment. This suggests that epigenetic mechanisms play a key role in marbled crayfish phenotypic variation. Our group has recently annotated the draft genome of the marbled crayfish, which revealed a conserved, functional and versatile DNA methylation system for epigenetic regulation. We have also used whole-genome bisulfite sequencing, RNA-seq and ATAC-seq for a comprehensive analysis of multiple individuals and tissues. Our results provide a novel concept for how methylation-dependent regulation of gene expression may facilitate the phenotypic adaptation and invasive spread of this animal.

 

 

Day: 5, Session: 2, Talk: 6

Simultaneous eDNA Monitoring of the Host-pathogen Complex Pacifastacus leniusculus and Aphanomyces astaci Under Varying Environmental Conditions

JOHANNES C. RUSCH, David A. Strand, Charlotte Laurendz, Stein I. Johnsen, Lennart Edsman and Trude Vrålstad

In 2016 the North-American signal crayfish Pacifastacus leniusculus was included in the list of Invasive Alien Species of concern to the European Union. In Norway the species is black-listed and rated as a high-risk species, and eradication has been carried out whenever feasible. This is because it is a chronic carrier of the oomycete Aphanomyces astaci, which is lethal to all European freshwater crayfish species and listed among the 100 worst invasive species. Environmental DNA (eDNA) methodology is now being used on a wide variety of target species and on many different platforms including targeted PCR and broad spectred sequencing methods. Detection and monitoring of invasive, endangered and elusive species is commonly performed using species specific quantitative real-time PCR (qPCR) or droplet digital PCR (ddPCR), and has proved useful for targeting species of specific concern. Recently eDNA monitoring of A. astaci has been implemented in the national crayfish plague surveillance in Norway. For the carrier of the crayfish plague, the signal crayfish, a qPCR assay for eDNA detection has also been published recently. In this study, we present simultaneous eDNA monitoring of the host-pathogen complex P. leniusculus - A. astaci under varying environmental conditions both in aquarium and field experiments. We used the published qPCR assays for both species and redesigned them so they can be run as a duplex ddPCR assay. We compared water samples by means of qPCR and ddPCR from two lakes in Sweden and Norway with different signal crayfish population densities and A. astaci prevalence in the population. We also studied eDNA emission from the host-pathogen couple in aquarium-experiments with A. astaci positive signal crayfish held at different densities, temperatures and feeding regimes. Samples were obtained by filtering water (1 & 5 L) on-site through glass fibre filters. These were subsequently analysed using the species-specific qPCR and ddPCR assays for the respective targets. The concentrations of detectable eDNA copies of the two targets are influenced differently and by several factors, including population density of the crayfish, pathogen prevalence, temperature, and turbidity including microbiological activity in the water. They are therefore subject to significant fluctuation. Thus, there seems to be no straightforward correlation between eDNA copy-number and crayfish density and the probability of detecting one target rather than the other varies according to different conditions. Therefore, for a reliable monitoring of crayfish plague (A. astaci) and signal crayfish alone or together, the simultaneous monitoring concept for both targets is recommended.

 

 

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: 4

The Development and Application of a Commercially Viable and User Friendly Environmental DNA (eDNA) Methodology for the Conservation of the Endangered White-Clawed Crayfish

CHRISTOPHER TROTH and Michael J. Sweet

Over the last thirty years, in the UK and Europe the endangered indigenous white-clawed crayfish (Austropotamobius pallipes) has suffered extensive population decline due to the introduction of competitive and disease carrying non-native species. Detection of these now isolated populations is becoming more difficult using established and often destructive or invasive traditional ecological survey techniques. The recent emergence of molecular species detection, defined by the term ‘environmental DNA – eDNA’ has proven to be a valid additional cost-effective method to traditional surveys for many aquatic species worldwide. Here we develop an eDNA based method for the non-invasive detection of A. pallipes; inferring fast species presence or absence data within freshwater habitats. Working alongside stakeholders, commercial organisations, ecologists and end-user groups in the UK we have validated this method for use as a commercially available tool, through careful design and assessment of all variables and limitations that are known to effect eDNA. This has enabled the validation of the technique in ‘real world’ conservation and commercial based settings. Primary trials into the potential quantification of white-clawed crayfish biomass using eDNA have had success with high and medium densities of crayfish in controlled environments. However, at lower natural densities quantification attempts were more varied. We also present the analysis of two different, commonly used sample collection methods to identify the most suitable and commercially applicable technique for effective detection of A. pallipes which may depend on the goal of each individual study. In this paper we report our findings on A. pallipes distribution and abundance in both lotic and lentic habitats using eDNA, incorporating two different approaches to sample collection. We also explore the variation of eDNA detection rates through the seasons, to determine if eDNA could be used for the detection of A. pallipes all year round, or during the more active summer season of crayfish activity. Coupled with further research into the rate of eDNA decay over time, and sample collection methodology choice we can we can now apply these methods in the field successfully taking all major limitations into account to get the most out of A. pallipes detection using non-invasive eDNA techniques. Using feedback from end-users we can now provide a basis for the commercial development and use of eDNA for crayfish, providing a more accessible detection method which will allow for more citizen science within this field to contribute to a greater conservation effort of the white-clawed 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 56

Assessing Rarity Patterns in Crayfish at Multiple Spatial Scales Using Scale-area Curves

JOHN W. JOHANSEN, Hayden T. Mattingly, Christopher A. Taylor and Guenter A. Schuster

Identification of at-risk species often relies mostly on range size, particularly for poorly studied species. Although this provides a relatively efficient method for identifying species of conservation concern, it may lead to an inaccurate assignment of conservation status. For example, many species occupy small native ranges but are locally abundant and temporally stable. Additionally, extinction processes operate at different spatial-scales. Scale-area curves provide a framework that examines rarity at multiple spatial scales, and thus, can lead to development of more impactful conservation strategies. Using a well-vetted database of Alabama crayfish collections, we used measures of area of occupancy to construct scale-area curves and assess rarity patterns for lotic crayfishes at two spatial scales: 1 km2 and 100 km2. Area of occupancy (AOO) is a measure of range size that varies depending on the spatial-scale of interest. For each species, AOO was estimated by counting the number of occupied cells in nested grids at increasing user-defined areas. In addition to AOO, the degree of range fragmentation was determined for each species from the slope of the scale-area curve at each spatial scale. Principle components analysis was used to identify scale-specific patterns of rarity. For example, at the 1 km2 spatial scale, we identified 5 groups of species based on AOO and degree of range fragmentation while at the 100 km2 scale six groups were identified. At the 1 km2 scale, several state imperiled species (S2) had higher levels of fragmentation than many critically imperiled species (S1). This indicates the lower ranked (S2) species may actually be more susceptible to loss of local populations due to increased range fragmentation. Accordingly, understanding metapopulation dynamics and maintaining habitat connectivity should be a priority for this subset of state imperiled (S2) species. This demonstrates the need to examine multiple variables and spatial scales in prioritizing species of conservation concern, particularly for those species that lack basic biological and ecological data beyond range size.

 

 

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 64

Influence of Climate Warming on the Ecological Impacts of Invasive Crayfishes

VICTORIA CHICATUN and Anthony Ricciardi

Aquatic systems in temperate regions are particularly sensitive to temperature change, which can cause seasonal stress for cold-water adapted species and hospitable conditions for warm-water invaders. Altered thermal regimes may mediate the ecological impacts of non-native species by affecting their abundance and per capita effects, causing shifts in predator-prey dynamics and competitive dominance over native species. High-impact invaders tend to exhibit higher functional responses (maximum feeding rates) than functionally-similar native taxa. It has also been shown that individuals' maximum feeding rates are inversely proportional to the deviation from their environmental optima and could potentially be used a performance metric for invasive species across a thermal gradient. My research investigates the effects of water temperature and population latitude on prey consumption and competitive dominance by invasive (Faxonius rusticus) and native (F. virilis) crayfishes in the Great Lakes basin. For this, I have planned a series of lab experiments comparing functional responses and outcomes of competitive interactions across temperatures (based on projected warming scenarios for the lower Great Lakes) to test the prediction that native species will exhibit lower maximum feeding rates than invaders and that increasing temperatures will result in competitive dominance of southern species over northern species.


Oral Presentations from IAA22

Day 1

  
  
  

Poster Presentations

General Assembly

Meeting Photo Gallery

There are currently no photos from this meeting to display.

 

 

Member Login

Forgot Your Password?

Recover PW

Enter the e-mail address you used to
create your IAA account.
Return to Login
Back to Top