Growth of mussels under laboratory conditions was examined under various food regimes in different water types and temperatures. Growth was less than would be useful as an indicator and comparisons with field exposures were of minimal value. The effects of organophosphates on bivalves were examined via toxicity tests, tissue concentration, and by controlling exposure through the use of physical constraints. Upper temperature tolerance of both bivalve species was examined with respect to different acclimation temperatures and organophosphate exposures. Deviations from control exposures occurred at some temperatures. Copper effectively lowered the mean heat coma temperatures of C. fluminea at some concentrations, however, chlorine exposures did not alter heat coma temperature.

From 2006-2011, four population reintroduction techniques were applied to three sites within a reach of the upper Clinch River in Virginia designated suitable for population restoration of the federally endangered oyster mussel (Epioblasma capsaeformis). These techniques were: 1) translocation of adults (Site 1), 2) release of laboratory-propagated sub-adults (Site 1), 3) release of 8-week old laboratory-propagated juveniles (Site 2), and 4) release of stream-side infested host fishes (Site 3). Demographic data were collected in 2011 and 2012 by systematic quadrat and capture-mark-recapture sampling to assess reintroduction success, evaluate reintroduction techniques, and compare survey approaches for monitoring freshwater mussels. Estimates of abundance and density of translocated adults ranged from 450-577 individuals and 0.09-0.11/m2 in 2011, and 371-645 individuals and 0.07-0.13/m2 in 2012. Estimates of abundance and density of laboratory-propagated sub-adults ranged from 1,678-1,943 individuals and 0.33-0.38/m2 in 2011, and 1,389-1,700 individuals and 0.27-0.33/m2 in 2012. Additionally, three recruits were collected at Site 1. No E. capsaeformis were collected at Sites 2 and 3. Capture-mark-recapture sampling produced similar mean point estimates as systematic quadrat sampling, but with typically more precision. My results indicated that the release of larger individuals (>10 mm) is the most effective technique for restoring populations of E. capsaeformis, and that systematic quadrat and capture-mark-recapture sampling have useful applications in population monitoring that are dependent on project objectives. Systematic quadrat sampling is recommended when the objective is to simply estimate and detect trends in population size for species of moderate to larger densities (>0.2/m2). Capture-mark-recapture sampling should be used when objectives include assessing a reintroduced population of endangered species or at low density, obtaining precise estimates of population demographic parameters, or estimating population size for established species of low to moderate density (0.1-0.2/m2). The ability to grow endangered juveniles to larger sizes in captivity requires improving grow-out culture methods of laboratory-propagated individuals. A laboratory experiment was conducted to investigate the effects of temperature (20-28 C) on growth and survival of laboratory-propagated juveniles of the Cumberlandian combshell (Epioblasma brevidens), E. capsaeformis, and the wavyrayed lampmussel (Lampsilis fasciola) in captivity. Results indicated that 26 C is the optimum temperature to maximize growth of laboratory-propagated juveniles in small water-recirculating aquaculture systems. Growing endangered juveniles to larger sizes will improve survival in captivity and after release into the wild. As a result, hatcheries can reduce the time that juveniles spend in captivity and thus increase their overall production and enhance the likelihood of success of mussel population recovery efforts by federal and state agencies, and other partners. / Master of Science

The habitat requirements of western freshwater mussels, Anodonta, Gonidea, and Margaritifera, remain unclear despite their imperiled status. Freshwater mussels provide a series of ecosystem services including habitat enhancement, substratum stabilization, nutrient cycling, and water clarification, which makes their loss from aquatic ecosystems particularly detrimental. To improve the efficacy of restoration actions targeting these organisms, I used random forest modeling to investigate the biotic and abiotic factors influencing mussel density and distribution throughout a 55-kilometer (km) segment of the Middle Fork John Day River (MFJDR), in northeastern Oregon. Data was collected to characterize the occurrence of mussels with respect to the hierarchical, hydrogeomorphic structure of habitat within reaches of varying valley confinement and channel units nested within these reaches. Data regarding functional habitat features were also included to ensure that models included the wide range of characteristics that mussels need from their environment. By collecting data at both the reach and channel unit scale, I was able to investigate how mussel densities and distributions vary with spatial scale and other biophysical parameters. Throughout the study area, Margaritifera density exhibited a unimodal distribution with respect to river km, while Anodonta and Gonidea density showed a negative relationship with river km and exhibited higher densities downstream. The large scale, longitudinal trends of Margaritifera were related to hydrogeomorphic characteristics at the reach scale, while less than half of the longitudinal variation in Anodonta and Gonidea were explained by hydrogeomorphic and water quality parameters. At the channel unit scale, all mussel genera responded to the patchy variation in physical habitat characteristics, particularly habitat factors that indicated more stable parts of the channel. Overall, physical habitat characteristics such as woody debris, emergent aquatic vegetation, coarse substratum, and channel morphology were more important than hydraulic, biotic, and chemical variables. These results suggest that at both the reach and channel unit scales, mussel density and distribution are influenced by high flow refugia and the hierarchical structuring of hydrogeomorphic habitat characteristics. These results will assist mussel restoration efforts by providing specific guidance about the types of physical habitat conditions that are suitable for mussels.

Propagation and culture has been accepted as an approved aquaculture method for resource managers to enhance and recover freshwater mussel populations. Although juveniles can be produced readily for many mussel species, achieving high growth and survival in the laboratory remains difficult. The goal of my project was to improve growth and survival of juvenile mussels by comparing diets, algae concentration, and culture systems. The first objective determined a suitable diet for feeding juvenile northern riffleshell, Epioblasma torulosa rangiana, a species listed as federally endangered. Three algal diets were evaluated to determine differences in growth and survival of juveniles of E. t. rangiana. After 60 d, mean survival on Phytofeast, Shellfish Diet, and WSSNFH mix were 75.1 (95% CI: 72.2 to 78.0), 78.9 (95% CI: 74.5 to 83.2), and 85.0 (95% CI: 80.6 to 89.3) percent, respectively. WSSNFH mix had the highest survival which was significantly different from Phytofeast (p=0.01).  Mean shell lengths were 2.37 mm (95% CI: 2.27 to 2.47), 2.62 mm (95% CI: 2.52 to 2.72), and 3.11 mm (95% CI: 3.01 to 3.22), respectively.  Juvenile length on all three diet treatments was significantly different from each other (p<0.0001), with the WSSNFH mix exhibiting the highest growth, and Phytofeast with the lowest growth. My second objective evaluated the effect of algal concentration (cells mL-1) on growth and survival of juveniles of E. t. rangiana and mucket, Actinonaias  ligamentina. After 60 d, mean survival of E. t. rangiana for the low (30,000 cells mL-1), medium (80,000 cells mL-1), and high (140,000 cells mL⁻¹) algal concentrations were 39.1 (95% CI: 30.7 to 47.4), 20.7 (95% CI: 12.8 to 28.6), and 12.7 (95% CI: 4.82 to 20.5) percent, respectively (p<0.01). Mean shell lengths were 1.58 mm (95% CI: 1.49 to 1.66), 1.30 mm (95% CI: 1.19 to 1.40), and 1.01 mm (95% CI: 0.936 to 1.08), respectively (p<0.0001).  Mean survival of A. ligamentina for the low, medium, and high algae concentrations were 46.8 (95% CI: 35.2 to 58.4), 24.6 (95% CI: 15.1 to 34.0), and 10.7 (95% CI: 5.45 to 15.9) percent, respectively (p<0.01). Significant differences were observed between the low feed concentration versus the medium and high feed concentrations. Mean shell lengths for the low, medium, and high concentrations were 1.15 mm (95% CI: 1.08 to 1.22), 0.994 mm (95% CI: 0.930 to 1.06), and 0.833 mm (95% CI: 0.770 to 0.896), respectively. All concentrations were significantly different, and the low concentration had the highest mean shell length (p<0.0001). The third objective compared the performance of three recirculating aquaculture systems for rearing juvenile mussels >5 mm. Mean incremental length of juveniles of E. t. rangiana at 60 d in Pans, Buckets, and Upwellers was 1.19 mm (95% CI: 0.746 to 1.62), 1.05 mm (95% CI: 0.608 to 1.49), and 2.07 mm (95% CI: 1.63 to 2.51), respectively. Incremental lengths were significantly higher in the Upwellers (p=0.03). The mean lengths for Bucket and Pan systems were not significantly different from each other (p=0.54).  Percent survival of juveniles for the Pans, Buckets, and Upwellers were 91.7 (95% CI: 87.4 to 96.0), 90.0 (95% CI: 80.6 to 99.4), and 100 (95% CI: 100 to 100), respectively. Survival in the Upwellers was significantly higher than in the Buckets (p=0.018). Survival of juveniles in the Pan system and Upwellers were not significantly different from each other (p=0.05).  Mean growth for A. ligamentina was 1.96 mm (95% CI: 1.03 to 2.9), 0.88 mm (95% CI: 0.048 to 1.80), and 2.46 mm (95% CI: 1.537 to 3.38), respectively (p=0.07). Mean percent survival of juveniles of Actinonaias ligamentina in the Pans, Buckets, and Upwellers were 100 (95% CI: 100 to 100), 86.7 (95% CI: 74.0 to 99.4), and 100 (95% CI: 100 to 100), respectively.   Survival of A. ligamentina in the Upwellers was significantly higher than in Buckets (p<0.0001).  Juvenile survival in the Pan system and Upwellers was not significantly different (p=0.998). Results indicate that the Upweller culture system supported the highest growth and survival in culturing E. t. rangiana and A. ligamentina. / Master of Science

Seasonality estimates based on archaeological shellfish remains have been an important component of settlement pattern reconstruction. Investigations of this nature allow researchers to place prehistoric people on the landscape at points in space at different times of the year. Many of the previous seasonality studies, however, have focused on marine species from coastal sites, with little attention given to freshwater locales, especially ones in the Mississippi Delta. To address that disparity, this study examines freshwater mussel “season of capture” via analysis of stable oxygen isotope ratios in specimens recovered from two Late Woodland sites located along the Yazoo River, Mississippi. As freshwater mussel shells are composed of aragonite, a metastable form of calcium carbonate (CaCO3), they can suffer greatly from the impact of meteoric diagenesis. Because of this, samples must be evaluated for diagenesis prior to any geochemical analysis taking place. Archaeological shell samples were examined via thin-section petrography and scanning electron microscopy (SEM). Visual analysis indicated pristine aragonite microstructure and crystallography in all archaeological shell samples, and confirmed their suitability for isotope analysis. Vetted shells were then micromilled across accretionary growth bands, and analyzed for their oxygen isotope signatures. Isotope profiles were then interpreted for their individual “season of capture”, and oscillation patterns for 22 shell specimens indicated mussels were being collected in all four seasons. These data support the view that at least some portion of the human population at both sites engaged in shellfishing activities year-round, indicating sedentary populations at both locales. The shell assemblages were also investigated for the purpose of informing modern conservation efforts (i.e., “applied zooarchaeology”). Nearly 24,000 valves were analyzed taxonomically, yielding the presence of 37 species, of which 24 represented new river records for the Yazoo River. These data provide a valuable historical perspective, cataloging communities as they existed prior to extensive modern impacts, thus representing an ecological baseline to be compared with modern populations. Though modern data are extremely limited for the river, the study revealed it once supported a diverse mussel community containing numerous species currently considered rare, endangered, or extinct in Mississippi.

In 1998, a tanker truck overturned on U.S. Route 460 in Tazewell County, Virginia, releasing approximately 5110 L of Octocure 554-revised, a rubber accelerant, into an unnamed tributary approximately 162 m from its confluence with the Clinch River. The spill killed nearly all aquatic life in the river, including three species of federally endangered mussels, for 11 km downstream. The restoration plan developed after the spill included community outreach to complement the physical, on-site restoration effort. Although numerous studies have been made of the aquatic resources in the upper Clinch River, Tazewell County, Virginia, there had been no prior assessment of the local residents' knowledge, attitudes, and opinions about the natural resources in this biodiversity hotspot. I surveyed residents of Tazewell County, Virginia to assess their baseline knowledge about the upper Clinch River watershed, endangered mussels, aquatic conservation, and water quality issues. The survey response rate was 42%. Survey respondents were aware that mussels are present in the Clinch River watershed, but were not aware of their imperiled status or the ecosystem services that mussels perform. On average, respondents expressed stronger moralistic, naturalistic, and ecologistic than negativistic and utilitarian attitude orientations toward endangered freshwater mussels. Respondents considered water quality important and expressed support for mussel restoration. However, respondents indicated that the presence of mussel populations might negatively impact economic development of the county. Local community leaders and conservation educators, when interviewed to explore their opinions on conservation of aquatic resources, placed high value upon the Clinch River's water quality. They also have sought information regarding water quality and the Clinch River from local organizations and agencies and/or have developed a relationship with them as a result of their long-term presence in the community. The majority of respondents believed that human impacts contribute to species decline, but human impacts may not be the primary contributor to such decline. Respondents indicated that governmental and nongovernmental conservation agencies and organizations can assist localities by providing additional funding opportunities, seminars, and training sessions. Tazewell County conservation educators focus broadly on water resources of the county. Conservation educators wised that adults and teenagers displayed greater interest in conservation issues and that local governments were involved more actively in conservation. Overwhelmingly, educators believed that forming and fostering partnerships is the most effective way to inform audiences about conservation. Barriers to conservation education faced by educators include lack of funding, audience apathy, and/or audience negativity. Nearly all respondents indicated that balance between conservation and development currently exists or that achieving such a balance should be a goal of the local government. Survey and interview results were used to develop specific outreach recommendations to generate community support for mussel restoration and aquatic conservation in Tazewell County. Recommendations for the Certus Spill Outreach Plan include: frame mussel outreach messages in a broader aquatic ecosystem context in order to emphasize the human connection to aquatic ecosystems, communicate positive messages about conservation with decision-makers, regularly communicate positive messages about conservation in the local press, and partner with the local school system and agencies that have established positive images in the towns and county. / Master of Science

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