Thursday, June 8, 2017
09:00 - 10:30

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09:00 - 09:15: / 305A EFFECT OF STREAM PERMANENCE ON PREDATION RISK OF LOTIC CRAYFISH BY RIPARIAN AND AQUATIC PREDATORS

6/08/2017  |   09:00 - 09:15   |  305A

EFFECT OF STREAM PERMANENCE ON PREDATION RISK OF LOTIC CRAYFISH BY RIPARIAN AND AQUATIC PREDATORS Given the importance of crayfish in stream ecosystems, gaining insight into the role of stream permanence in maintaining predator-prey interactions is critical. Our objectives were to 1) determine the influence of stream permanence and season on crayfish predation and 2) assess the role of stream permanence and crayfish density on the presence of predators, while accounting for imperfect detection. We conducted surveys of crayfish density, fish presence, mammalian scat, and environmental variables within 10 intermittent and 10 permanent streams in the Ozark Highlands. We used occupancy modeling and logistic regression to assess the relationship between predator presence, crayfish density, and environmental variables. The relative frequency of occurrence of crayfish prey was greater in permanent streams than in intermittent streams. Raccoons had the highest detection probability whereas American mink and river otter had low detection probabilities. River otter occupancy was positively associated with intermittent streams whereas centrachid, raccoon, and American mink occupancy was negatively associated with intermittent streams. Hydrologic variability associated with climate change may alter crayfish predation risk and could have widespread implications for aquatic biota and predator-prey interactions.

Daniel Magoulick ( Co-Presenter/Co-Author), University of Arkansas, danmag@uark.edu;


Allyson Yarra (Primary Presenter/Author), University of Arkansas, allysonyarra@gmail.com;


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09:15 - 09:30: / 305A LIFE-HISTORY AND POPULATION BIOLOGY OF CRAYFISH IN THREE SINUOUS RILLS IN WEST CENTRAL GEORGIA

6/08/2017  |   09:15 - 09:30   |  305A

LIFE-HISTORY AND POPULATION BIOLOGY OF CRAYFISH IN THREE SINUOUS RILLS IN WEST CENTRAL GEORGIA I sampled stream-dwelling crayfish at monthly intervals over a 3-year period in three headwater streams (order 1-2) originating in Franklin D. Roosevelt (Georgia) state park. Crayfish were collected by dip nets and modified minnow traps in contrasting habitats: gravel/rocky riffles; gravel/sandy runs; and gravel/sandy pools. Physical parameters measured at each collection time were temperature and dissolved oxygen, while pH, hardness, alkalinity, ammonia nitrate, and chloride were measured 4 times per year. Crayfish carapace length and width, and right chela length and width were recorded and crayfish sex and crayfish injury (e.g., chela autonomy) were noted. I collected over 3,500 crayfishes consisting of three species, Cambarus howardi (GA state-listed as threatened), C. striatus, and Procambarus spiculifer. Life-history attributes such as timing of reproduction and free swimming juveniles will be discussed. As data is still being collected, information on sex ratios, sexual dimorphism, fecundity, and frequency of injury is being compiled and will be presented. Recognizing the distinct patterns of these crayfish life history strategies will improve understanding of the biology and ecology of these understudied organisms.

Chester R. Figiel, Jr. (Primary Presenter/Author), U.S. Fish and Wildlife Service, chester_figiel@fws.gov;


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09:30 - 09:45: / 305A ON THE PROVENANCE OF AN ORCONECTES POPULATION IN THE JAMES RIVER BASIN, VIRGINIA

6/08/2017  |   09:30 - 09:45   |  305A

ON THE PROVENANCE OF AN ORCONECTES POPULATION IN THE JAMES RIVER BASIN, VIRGINIA We investigated the origin of a Virginia population of Orconectes crayfish population found in the upper James River and a small portion of the upper Roanoke River basins in western Virginia. This population was first noticed by several researchers, and although the precise identity and provenance of the population was unclear, genetic evidence suggested links to Orconectes populations in the Ozark region of Missouri and Arkansas. We tested the hypothesis that it was native to both regions or native to one region and introduced to the other using genetic data. We sequenced a portion of the mitochondrial cytochrome oxidase I gene and NADH dehydrogenase 2 gene from individuals across the known range in Virginia, and compared them to sequences from several Orconectes species from Arkansas and Missouri. For both genes, the Virginia populations were completely devoid of sequence variation, strongly suggesting an introduced population of recent origin. These sequences were closest to samples of Orconectes ozarkae from south-central and southwestern Missouri.

Morgan Trimas (Primary Presenter/Author), Washington & Lee University, trimasm18@mail.wlu.edu;


Sarah Clifford ( Co-Presenter/Co-Author), Washington & Lee University, cliffords19@mail.wlu.edu;


Zachary Loughman ( Co-Presenter/Co-Author), West Liberty University, zloughman@westliberty.edu;


Paul Cabe ( Co-Presenter/Co-Author), Washington & Lee University, cabep@wlu.edu;


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09:45 - 10:00: / 305A PINCHY PATCHES: EXPLORING THE ASSEMBLY OF SYMBIOTIC METACOMMUNITIES

6/08/2017  |   09:45 - 10:00   |  305A

PINCHY PATCHES: EXPLORING THE ASSEMBLY OF SYMBIOTIC METACOMMUNITIES Crayfish and their ectosymbiotic annelid worms (Order: Branchiobdellida) engage in a density-dependent cleaning symbiosis that shifts between mutualism and parasitism. This shift provides us with an effective tool to study the nature of symbiosis. Our current work utilizes metacommunity theory, which describes the interactions between spatially disparate communities of organisms, to model and predict these symbiotic interactions. A metacommunity is a community of communities, groups of interacting organisms that affect each other through dispersal. Traditionally, this framework has been used to study communities along connected environmental patches. However, if we consider a host crayfish to be a patch, we can use this framework to study how host controls and symbiont interactions with the host and each other affect the structure of the symbiont communities on each crayfish. Data from a field survey at Sinking Creek in Newport, VA have provided us with insights on how the worm communities develop after a disturbance event (such as the crayfish molting), as well as information on the worm communities on crayfish of different sizes, and how they change throughout the year.

Philip McElmurray (Primary Presenter/Author), Virginia Tech, pmac@vt.edu;


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


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


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10:00 - 10:15: / 305A PRELIMINARY RESULTS OF A LIFE HISTORY STUDY OF THE SOUTHERN PLAINS CRAYFISH, PROCAMBARUS SIMULANS (CRUSTACEA: DECAPODA), FROM WEST-CENTRAL TEXAS

6/08/2017  |   10:00 - 10:15   |  305A

PRELIMINARY RESULTS OF A LIFE HISTORY STUDY OF THE SOUTHERN PLAINS CRAYFISH, PROCAMBARUS SIMULANS (CRUSTACEA: DECAPODA), FROM WEST-CENTRAL TEXAS This study was undertaken to better understand the life history strategy of the southern plains crayfish, Procambarus simulans, from the Concho River drainage of west-central Texas. The population, inhabiting three temporarily contiguous pools along an approximately 5.5km reach of Dry Lipan Creek, an ephemeral tributary of the Concho River near Mereta, Texas was monitored within the first ten days of each month starting in April of 2016 and continuing through March of 2017. Specimens were collected, using minnow traps or burrow excavation, sexed, measured and then released. Males were determined as either form I (breeding) or II (non-breeding). Also, morphometric measurements of carapace length and width, abdomen length and width, chelae length, palmar width, and dactyl length were taken for each specimen. Both Form I and Form II males were observed consistently throughout the study; ovigerous females were observed only during September. Young-of-the-year were observed in both October and November. As water levels within the pools dropped during the winter months, specimens were less readily collected. The largest sample size (n=31) was observed in August and the smallest sample size (n=2) in January.

Michael Lucero (Primary Presenter/Author), Angelo State University, mlucero2@angelo.edu;


Ned Strenth ( Co-Presenter/Co-Author), Angelo State University, ned.strenth@angelo.edu;


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10:15 - 10:30: / 305A THE DILUTION EFFECT IN A MUTUALISM: EFFECTS OF HOST DENSITY AND HOST DIVERSITY ON ECTOSYMBIONT ABUNDANCE

6/08/2017  |   10:15 - 10:30   |  305A

THE DILUTION EFFECT IN A MUTUALISM: EFFECTS OF HOST DENSITY AND HOST DIVERSITY ON ECTOSYMBIONT ABUNDANCE The dilution effect describes the effect of host diversity on parasite proliferation—with greater host diversity, parasite prevalence per host is lower due to a higher probability of parasites encountering unsuitable hosts. No previous research has examined whether host dilution affects mutualistic symbionts. Using the crayfish-branchiobdellidan worm mutualism, we performed an experiment investigating the effect of host density (1 vs 2 Cambarus chasmodactylus per aquarium) and host diversity (1 C. chasmodactylus paired with 1 Orconectes cristavarius) on branchiobdellidan (Cambarincola ingens) abundance. Worm numbers decreased over time on C. chasmodactylus alone and in the treatment in which it was paired with O. cristavarius, the latter being a poor host for C. ingens. Worm numbers declined the least in the 2 C. chasmodactylus treatment. While increased host diversity may reduce levels of parasitism (a positive effect of increased biodiversity) it could have negative effects on the abundance of mutualistic symbionts depending on the quality of alternative hosts.

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


Gretchen Bailey ( Co-Presenter/Co-Author), Appalachian State University, baileygl@appstate.edu;


James Skelton ( Co-Presenter/Co-Author), University of Florida, skelto3@gmail.com;


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


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