Qualitative and quantitative sampling was conducted along a 165 km reach of the river from PRKM 269.4 near Dryden, VA to PRKM 104.8 near Harrogate, TN. Twenty-nine species were observed throughout the entire river, and the highest diversity of 23 species was collected at PRKM 152.6. Mussel abundances (mussels/person-h and mussels/m2) ranged from 0.33 to 21.98 mussels/person-h and 0.00 to 2.24 mussels/m2. Recent recruitment (individuals < 40 mm, depending on the species) was observed for 15 species, including the endangered Epioblasma brevidens, Lemiox rimosus, and Quadrula intermedia. The greatest number of species (6) with evidence of recent recruitment also was found at PRKM 152.6. Data from the quantitative survey were used to simulate several sampling protocols that could be used to develop a long-term monitoring program for the Powell River. Five sites, PRKMs 197.9, 171.4, 159.6, 152.6, and 129.4, were selected for long-term monitoring because of high mussel densities and species richness. Six sampling protocols were simulated using the statistical program MONITOR to determine which protocols, if any, could monitor statistically significant changes in mussel abundance at rates + 10%. Each of the simulated sampling protocols lasted between 15 and 30 y, and employed quantitative sampling at 3 to 5 y intervals. None of the sampling protocols simulated during this study were able to detect declines in mussel abundance < 10%. Two sampling programs were able to detect increases in mussel abundance > 6% when the level of significance was > 0.10, and four sampling programs were able to detect a density increase of > 8% when the level of significance was 0.05. Despite the inability to monitor declines in mussel abundances, a long-term monitoring program is needed for the Powell River. Because qualitative sampling has been repeatedly shown to document species presence more effectively than quantitative sampling, it should be used to monitor changes in species presence and distribution. Quantitative sampling should be employed to monitor juvenile recruitment and changes in size-class structure of populations. Quantitative sampling also should be conducted to monitor overall mussel abundance at sites. Despite the inability to statistically detect changes in mussel density in the Powell River, quantitative sampling can provide valuable information, and the data collected can be used to qualitatively monitor changes in total density at sites. Both species share a similar distribution in the Powell River. Eighteen specimens of Quadrula sparsa were collected between PRKM 230.9 and 152.6, and 68 individuals of Q. intermedia were collected between PRKM 230.9 and 129.4. The highest density of each species was collected at PRKM 152.6, and recent recruitment was observed at PRKMs 152.6 and 153.4. Fresh-dead and relic shells of both species were thin-sectioned to determine individual growth rate and life span. These species complete the majority of their growth during the first 10 y of life, and likely live for a total of 40 to 50 y. One gravid female of Q. intermedia was collected during this study, but no gravid females of Q. sparsa were observed. / Master of Science

Epioblasma capsaeformis, commonly named the oyster mussel, once occupied thousands of miles of stream reaches, but has now been reduced in range to small, isolated populations in a few river reaches. Due to this significant decline in population numbers, a study was conducted to develop a diet for propagating this endangered species under captive conditions. Oyster mussel juveniles were collected from several sites on the Clinch River and sacrificed for gut content and biochemical composition analyses in summer. Feces and pseudofeces from live river-collected juveniles were examined seasonally for algae, detritus, and bacteria to qualitatively determine diet of specimens. Two feeding trials also were conducted in this study to evaluate effect of diet (commercial and non-commercial diets), on growth and survival of oyster mussel juveniles. From examination of gut contents, fecal and pseudofecal samples, it was apparent that algae and a significant amount of detritus (~90%) composed wild juvenile diets. E. capsaeformis juveniles (1-3 y of age) could have fed on particles up to 20 µm in size and seemed they were mostly ingesting particles within the 1.5-12 µm size range. Protein content of sacrificed juveniles ranged from 313 to 884 mg/g and was highly variable. Glycogen content ranged from 49-171 mg/g. Caloric content of four juveniles ranged from 2,935.10 to 4,287.94 cal/g, providing a preliminary baseline range for future energetic studies on freshwater mussels. Growth was significantly higher in those juveniles fed the triple concentration algae-mix (62,076 cells/ml) than all other diets tested in trial 1. Results of both feeding trials indicated that survival of juvenile oyster mussels was enhanced when fed an algal diet supplemented by bioflocs. / Master of Science

Declining unionid populations in the Clinch River are of concern due to the high endemism in the diverse fauna of the Cumberlandian region. Increase in agricultural and mining activities, as well as in industry and urbanization, are coupled with unionid declines throughout the watershed. In many reaches of the Clinch River, mussel populations exist which fail to show recruitment suggesting that this is the weak link in the complex life cycle. Two possible factors which could endanger the sensitive juvenile stage are the presence of sediment toxicants or adult Corbicula fluminea in the depositional areas, the preferred habitat of the juveniles. Before investigating the impacts of these factors, it was necessary to characterize the relationship of the juveniles with the sediment they inhabit. Observations of feeding behavior using videotape, dye studies in a feeding chamber, and gut content analysis were used to determine mechanisms of feeding, the primary food source, and the origin of substances taken up by juveniles. Exposure to sediment came not only through direct contact, but also through filtration of interstitial water and sediment-associated fine particulate organic matter. Juveniles used pedal locomotory and pedal sweep feeding behaviors to facilitate movement of particles into the pedal gape. Intermittent sediment toxicity was found in laboratory bioassays using Daphna magna and Chironomus riparius. These data, along with fluctuating metals in the Clinch River sediments, indicated that acute insults existed from which recovery would depend on the frequency, intensity and duration of the events. Field studies revealed that the intermittent toxicity is reflected in the community structure of benthic macroinvertebrates and impairs growth of juvenile unionids in-situ studies. The intermittent toxicity which may be associated with rain events impairs stream biota and may prevent recruitment of juvenile unionids. The presence of adult C. fluminea in sediments was found to decrease juvenile unionid growth and recovery from test sediments and to increase mortality and resuspension of juveniles into the water column. Both the presence of sediment-bound toxicants and C. fluminea may be contributing to unionid bivalve declines in the Clinch River, Virginia. / Ph. D.

No description available.

No description available.

Primers for 10 polymorphic DNA microsatellite loci were developed and characterized for the endangered oyster mussel Epioblasma capsaeformis from the Clinch River, TN. Microsatellite loci also were amplified for individuals collected from the following additional populations or species: (1) E. capsaeformis from Duck River, TN; (2) E. florentina walkeri from Indian Creek, upper Clinch River, VA; (3) E. florentina walkeri from Big South Fork Cumberland River, TN; and (4) E. torulosa rangiana from Allegheny River, PA. Allelic diversity ranged from 9-20 alleles/locus, and averaged 13.6/locus for all 5 populations investigated. Average expected heterozygosity (HE) per locus ranged from 0.78-0.92, and averaged 0.86. A genetic characterization of extant populations of E. capsaeformis and E. florentina walkeri was conducted to assess taxonomic validity and to resolve conservation issues related to recovery planning. These mussel species exhibit pronounced phenotypic variation, and are difficult to characterize phylogenetically using DNA sequences. Monophyletic lineages, congruent with phenotypic variation among species, were obtained only after extensive analysis of combined mitochondrial (1378 bp of 16S, cytochrome-b, ND1) and nuclear (515 bp of ITS-1) DNA sequences. In contrast, analysis of variation at 10 hyper variable DNA microsatellite loci showed moderate to highly divergent populations based on FST values, which ranged from 0.12-0.39. Quantitative genetic variation was observed in fish host specificity, with transformation success of glochidia of E. capsaeformis significantly greater (p<0.05) on the greenside darter Etheostoma blennioides, and that of E. f. walkeri significantly greater (p<0.05) on the fantail darter E. flabellare. Lengths of glochidia differed significantly (p<0.001) between species, with sizes ranging from 241-272 μm. Underwater photographs of mantle-pads and micro-lures of female mussels documented fixed phenotypic variation between species. The texture and color of the mantle-pad of E. capsaeformis is smooth and bluish-white, while that of E. f. walkeri is pustuled and brown, with tan mottling. Based on extensive molecular, morphological, and life history data, a population of E. capsaeformis from the Duck River, TN is described and proposed as a separate species, and a population of E. f. walkeri from the upper Clinch River, VA is described and proposed as a separate subspecies. Genetic management guidelines were developed to assess taxonomic status, genetic variation of donor-recipient populations targeted for augmentation, and field and laboratory protocols to maximize genetically effective population size, minimize genetic changes in captive-reared progeny, and prevent the release of juvenile mussels into non-native drainages. A pragmatic approach to species recovery is advocated; one that incorporates the principles of conservation genetics into breeding programs, but prioritizes the immediate demographic needs of critically endangered mussel species. / Master of Science

No description available.

This research examined how an invasive macrofouling organism, the Eurasian zebra mussel (Dreissena polymorpha), alters benthic communities in a riverine ecosystem. Controlled field experiments using artificial substrates showed that macroinvertebrate abundance is significantly enhanced within Dreissena beds, and that the physical habitat provided by mussel shells has a greater impact on macroinvertebrate abundance than biological factors (e.g., food provided by mussel biodeposits). Data collected at field sites before and after the establishment of dense Dreissena colonies suggested that these colonies alter macroinvertebrate communities on hard substrates primarily by enhancing populations of deposit-feeding organisms (e.g., amphipod crustaceans) and predators (e.g., flatworms), and by displacing fauna that are poorly adapted to interstitial substrate (e.g., large gastropods, net-spinning caddisfly larvae). Freshwater sponges were the only organisms found to compete successfully with Dreissena for hard substrate; sponge overgrowth caused significant local mortality of zebra mussels at all sites where sponges were abundant. / The capacity for Dreissena to displace native freshwater mussels (Family Unionidae) in the St. Lawrence River was examined over a four year period by quadrat sampling at selected sites. Dreissena preferentially colonized unionid mussels in the river. Mean infestation loads (number of zebra mussels per unionid mussel) in the St. Lawrence were 10-100 times lower than in the Great Lakes,.but resulted in similar high mortality. Severe declines in unionid species richness and abundance occurred in areas of the river that supported dense Dreissena populations ($>$4,000 mussels/m$ sp2).$ Analysis of data from the Great Lakes-St. Lawrence River system suggests that mass mortality and extirpation of unionid populations typically occurs within 4-5 years following initial colonization of unionids by Dreissena, and that Dreissena infestation will increase the future tate of extinction of North American unionids by nearly 10-fold.

No description available.

No description available.