6/06/2017  |   11:00 - 11:15   |  305A

DIET OF THE CRAYFISH OF THE SUSQUEHANNA RIVER Two nonnative crayfish species, rusty crayfish (Orconectes rusticus) and the Allegheny crayfish (O. obscurus), are currently found in the Susquehanna River. In 2015 we hand collected crayfish from among 6 sites spanning almost 115 river miles. Thirty stomachs were dissected from similarly sized individuals at each of the six sites; two of the sites had only Allegheny crayfish present, and the remainder had rusty crayfish. On average 49% of the stomachs examined contained food across all sampled sites, but at the individual sites this ranged from 27 to 77%. Aquatic macroinvertebrates comprised most of the observed prey, and in particular mayflies. The other food item was unknown plant material. The 174 total individual stomachs ranged from 5-17 taxa, indicating substantial breadth among prey groups. We found 10 genera of mayflies represented in the stomachs, but Leucrocuta was the dominant genus. Most surprisingly, however, was our discovery of many prey species within the stomachs entirely intact. These findings suggests that these crayfish were engulfing their prey whole.

Michael Bilger (Primary Presenter/Author), Susquehanna University, mdbilger@verizon.net;


Brian Mangan ( Co-Presenter/Co-Author), Kings College, brianmangan@kings.edu;


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6/06/2017  |   11:30 - 11:45   |  305A

HABITAT AND TROPHIC NICHE DIFFERENTIATION WITHIN A UNIONID COMMUNITY. Within dense communities of functionally similar organisms significant competition for shared resources is anticipated, driving these organisms to partition into distinct niches to reduce competition. However, within species-rich unionid mussel communities it appears that species often occupy highly overlapping niche volume. We studied the food and habitat portioning in diverse unionid communities to better understand community assembly. Unionid niches have proven difficult to identify due to an inability to accurately determine what food resources they are assimilating and habitats characteristics they prefer. To investigate habitat niches we conducted spatially-explicit (each quadrat had a GPS point associated with it) quantitative mussel surveys paired with a suite of environmental measures (e.g. flow velocity, sediment temperature, hyporheic connectivity, sediment particle size distribution). Resource assimilation was quantified by employing combined stable-isotope and fatty-acid analyses, to examine the nutritional resources being exploited; we also used scanning electron microscopy to examine unionid gill physiology across species. Considerable variability was observed interspecifically and intraspecifically in resources utilization and habitat occupation, though some species were found occupying narrower less variable niches suggesting specialization by those species.

Brian van Ee (Primary Presenter/Author), University of Alabama, bcvanee@gmail.com;


Carla L. Atkinson ( Co-Presenter/Co-Author), University of Alabama, carlalatkinson@gmail.com;


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6/06/2017  |   11:45 - 12:00   |  305A

THE FINE SCALE HABITAT PREFERENCE OF FRESHWATER MUSSEL, WESTRALUNIO CARTERI, IN SOUTH-WEST AUSTRALIA Freshwater mussels are key ecological generalists in aquatic communities. Westralunio carteri is the only freshwater mussel species in south-west Australia. The fine scale distribution of adult mussels of this species within river reaches has been investigated using quadrat searches and modelled against a range of environmental factors. A total number of 604 mussels were found in eight different rivers at a mean density of 32.4±5.8 individuals/m2. The distribution of W. carteri was highly aggregated with a Lloyd’s patchiness index of 3.72. A model averaging approach indicated that the most important factors explaining mussel distribution were substrate grain size, water depth and the size of benthic debris, with fine silt, shallower water and larger debris favoured by this species. Juvenile mussels may have different habitat preferences than adult mussels and further studies are required to investigate this.

Le Ma (Primary Presenter/Author), Murdoch University, Vicenk.Male@gmail.com;


Alan Lymbery ( Co-Presenter/Co-Author), Murdoch University, A.Lymbery@murdoch.edu.au ;


David Morgan ( Co-Presenter/Co-Author), Murdoch University, D.Morgan@murdoch.edu.au ;


Stephen Beatty ( Co-Presenter/Co-Author), Murdoch University, S.Beatty@murdoch.edu.au;


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6/06/2017  |   12:00 - 12:15   |  305A

POPULATION GENETIC STRUCTURE AND PATERNITY OF THE THREERIDGE MUSSEL (AMBLEMA PLICATA) IN SOUTHEAST OKLAHOMA ASSESSED USING MICROSATELLITES. Several anthropogenic factors have led to substantial declines in North America’s freshwater mussel populations over the last century. A greater understanding of mussel dispersal abilities and population structure is imperative to improve conservation strategies. Since impoundments restrict fish movement and reduce gene flow in mussels, we predicted that genetic structuring may exist between populations upstream and downstream of impoundments. We evaluated genetic structure and paternity of a common, host-generalist mussel species (Amblema plicata) in the Little River in southeast Oklahoma using nine polymorphic microsatellite loci. We genotyped a total of 270 individuals from nine mussel beds distributed throughout the Little River. The programs STRUCTURE and ML-Relate were used to examine genetic structure and relatedness (i.e. paternity), respectively. Results from this study will have important conservation implications by providing a better understanding of the dispersal capabilities of host-generalist mussel species and the number of males contributing to broods. Understanding mussel population structuring can improve mussel conservation strategies by informing management where mussels should be reintroduced and which mussel beds are the most genetically diverse, and therefore of potential priority for protection.

Patrick Olson (Primary Presenter/Author), University of Oklahoma, olso7823@ou.edu;


Caryn C. Vaughn ( Co-Presenter/Co-Author), University of Oklahoma, carynvaughn@gmail;


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