More than half the North American freshwater mussel species in the family Unionidae (unionids) are imperiled or extinct. Alteration of rivers is considered a major contributor to unionid population declines. Losses could occur through disruption of the reproductive cycle. Unionid reproduction requires attachment of larva (glochidia) to host fishes; therefore, changes in the host fish community could alter the reproductive potential in unionid communities. There have been few attempts to compare reproductive success before and after alteration. I examined the pattern of glochidia use on two common host fishes, Lepomis megalotis and Cyprinella venusta, before and after alteration of the Tombigbee River. While both host species declined in the river, the number of glochidia per infested fish and proportion of infested fish increased post-impoundment in L. megalotis but not C. venusta. My results demonstrate the importance of considering reproductive changes as a driver of unionid mussel declines in North America.

The Powell River is located in southwestern Virginia and northeastern Tennessee, USA and supports a diverse freshwater mussel assemblage of 29 extant species. Throughout the river major ion and trace element concentrations have increased over the last several decades due to extensive surface coal-mining in the headwaters in Virginia. As watershed area affected by mining has increased, mussel populations have declined, especially in Virginia where populations have been severely reduced or extirpated. The upper watershed now has been extensively mined for coal, causing widespread effects on water and sediment quality. To investigate how mining may be affecting mussel populations, I first conducted a laboratory bio-assay to assess the effects of elevated major ions and the trace element nickel (Ni) on growth and survival of juvenile mussels, including one common species (Villosa iris) and one endangered species (Epioblasma capsaeformis). No significant differences in overall survival between treatments and control were observed for either species over a 70 day test period. Total growth was not significantly different between treatments and control for either species. However, overall growth varied significantly (p=0.009) between species, with V. iris (2.49 mm) exhibiting greater growth compared to E. capsaeformis (1.97 mm). Results suggest that major ion chronic toxicity alone or in combination with Ni at or below my test concentration is not a likely source of toxicity to juvenile mussels in the Powell River. Secondly, I conducted a field study in the Powell River using two cohorts of juveniles of Villosa iris to assess the effects of trace elements and PAH contamination related to mining on mussel survival and growth. Specific conductance was elevated throughout the Powell River, where site means ranged from 450 to 900 µS/cm. While mortality was high at all eight sites it was not significantly different among these sites (p>0.28); however, growth of juvenile mussels was significantly higher (p<0.001) in the lower river in Tennessee. Regression analysis showed significant relationships (p<0.001) of river kilometer with temperature, specific conductance, and aqueous major ion concentrations. A principal component analysis (PC) was conducted on all trace element data. Growth of Cohort 1 on Day 106 was best explained by the PC dominated by aqueous major ion concentrations (p<0.0001, R2= 0.65) and growth of Cohort 2 on Day 106 was best explained by specific conductance (p<0.0001, R2= 0.68). Growth of Cohort 2 at Day 423 was best explained by tissue trace element concentration PC1 and PC2 (p<0.0001, R2= 0.73). This study suggests major ions and select trace elements (Ba, Ni, Fe, Se, and Sr) in the Powell River are negatively affecting the growth of freshwater mussels and that the source of these contaminants is primarily from mining in the headwaters. / Master of Science / The Powell River is located in southwestern Virginia and northeastern Tennessee, USA and supports a diverse freshwater mussel assemblage of 29 extant species. Throughout the river major ion and trace element concentrations have increased over the last several decades. As watershed area affected by coal mining has increased mussel populations have declined, especially in Virginia where populations have been severely reduced or extirpated. The upper Powell River watershed has been extensively mined for coal, causing widespread decline in the river’s water and sediment quality. My study consisted of a laboratory and field exposure to assess the toxicity of the mining related contaminants, such as major ions, trace elements, and polycyclic aromatic hydrocarbons (PAHs) to freshwater mussels. Further, the study investigated the concentrations of these contaminants in the river and their effects on the survival and growth of exposed juvenile mussels. In my laboratory study, mussels of a common species (Villosa iris) and an endangered species (Epioblasma capsaeformis) showed no effect when exposed to a suite of major ions and the trace element Ni similar to levels measured in the Powell River. When juvenile Villosa iris were exposed in the Powell River at eight sites in Virginia and Tennessee, high rates of mortality were observed at all eight sites and growth of juveniles showed a significant spatial trend, with higher growth observed downstream in Tennessee. Water quality analysis revealed increased concentrations of major ions at all sites but concentrations of trace elements were generally below EPA water quality criteria. Further, many of the major ions and trace elements trended spatially with higher concentrations measured in the headwaters in Virginia and lower concentrations observed downstream in Tennessee. Statistical analysis revealed that major ions and trace elements (Ba, Ni, Fe, Se, and Sr) may have negatively affected growth of exposed mussels. This study revealed that laboratory conditions may not adequately be representing river conditions and that in the river major ions and trace elements likely are negatively effecting growth and survival of freshwater mussels. This study revealed that conditions in the Powell River likely are not suitable for mussel reintroduction and that mining is the main source of the contaminants in the river.

The Clinch River, Virginia is known for high aquatic biodiversity, particularly Unionidae which are declining at remarkable rates. Studies conducted on the mainstem have only addressed effects of point-source stressors (various toxic spills and effluents from the Clinch River Plant (CRP), Carbo, Virginia) that have been introduced into the Clinch River. It is hypothesized that the tributaries of the Clinch River deliver a variety of stressors to the mainstem, which may affect the diverse fauna. The aquatic health of 19 upper Clinch River tributaries, Virginia, was assessed via ecotoxicological ratings that indicated the least healthy catchments were associated with mining activity (Dumps, Russell and Coal Creeks). Tributaries were categorized by land use and mining streams were significantly different from agricultural and forested streams (F = 9.63, p<0.0001). Tributaries with ecotoxicological ratings (ETR) <80 from 100 were deemed suboptimal and thus studied further. Using identical response variables and upstream and downstream sites, resulting ETRs for nine streams indicated no model significance regarding land use, year, or site. Variability within treatments and low sampling sizes contributed to lack of significance, and results indicate that future studies need to be designed incorporating sites with analogous land use stressors. This first assessment of upper Clinch River tributaries indicates the catchments requiring remediation are Dumps, Russell and Coal Creeks, while tributaries requiring extensive evaluations are Big, Lick, Swords, Big Spring, Guest River, Cavitts and Middle Creeks. Tributaries that were deemed healthy (ETRs >80) were Big Stony, Copper, Indian, Stock, Little River and Cove Creeks. / Master of Science

Biological invasions are among the leading causes of species diversity loss; however, the impacts of invasion are context-dependent and can vary with the local environment. The mechanisms governing variation in impact and their relationship to specific abiotic and biotic factors remain largely unexplored. Recent local declines in native unionid mussels have been attributed to the invasion of North American lakes and rivers by the Eurasian zebra mussel ( Dreissena polymorpha), as a result of intense fouling of unionid shells by zebra mussels. My research investigated the role of abiotic and biotic factors in mediating the impact of zebra mussels on native mussels. I examined the impact of zebra mussels on unionids in a habitat thought to be suboptimal for zebra mussels and compared this to the impact observed in other invaded habitats. A predictive model relating fouling intensity to local environmental variables (calcium concentration, sediment particle size) was developed, and a predator-exclusion experiment was conducted to investigate the role of predation in mediating fouling intensity. Overall, I found that two abiotic factors of the local environment were significant predictors of fouling intensity and that relationships used to predict the impact of zebra mussels could be extended to a broader range of habitats.

No description available.

Thesis (Ph. D.)--University of Michigan, 1934. / Thesis note on label mounted on t.p.; also on p. [7]. Descriptive letterpress on versos facing the plates. eContent provider-neutral record in process. Description based on print version record. Bibliography: p. 78-83.

Thesis (Ph. D.)--University of Michigan, 1934. / Thesis note on label mounted on t.p.; also on p. [7]. Descriptive letterpress on versos facing the plates. Bibliography: p. 78-83.

Freshwater mussel propagation techniques were tested at the Virginia Department of Game and Inland Fisheries Aquatic Wildlife Conservation Center through a series of three experiments. Experiment 1 tested the suitability of a pond and raceway for rearing juvenile oystermussels (Epioblasma capsaeformis) and wavyrayed lampmussel (Lampsilis fasciola). This experiment was prematurely terminated due to predation on mussels by fathead minnows (Pimephales promelas). Experiment 2 evaluated growth and survival of juvenile rainbow mussels in outdoor troughs and indoor aquaria. There was no significant difference in survival or growth between the two systems. Experiment 3 used troughs similar to those in Experiment 2 to rear E. capsaeformis and L. fasciola under two silt regimes. Survival for Experiment 3 was significantly greater for L. fasciola. The comparison between silt regimes indicated that individuals in the high-silt treatment had better survival than those in the low-silt treatment. The difference between these 2 treatments may be a reflection of increased escapement in the low-silt treatment, which may have resulted from more frequent disturbance during sampling. Growth of L. fasciola was significantly greater than E. capsaeformis, and was greater in the low-silt treatment. A habitat survey of the Clinch River, Virginia was conducted from Blackford, Clinch River Kilometer (CRK) 478 to the Tennessee border, CRK 325. Physical characteristics identified in the survey were combined with water quality and impact source data to develop a habitat suitability index for freshwater mussels within this study reach. Model parameters were indexed and weighted to give a final suitability ranking. Habitat units having the highest overall ranking included: Nash Ford (CRK 449), Artrip (CRK 442), several riffles and runs below Carterton (CRK 417), upstream of Mill Island (CRK 389.5), and Pendleton Island (CRK 365), and Speers Ferry (CRK 333-325). Potential locations for habitat restoration projects and additional monitoring were also identified. / Master of Science

American Electric Power's (AEP) coal-fired Clinch River Plant, a power-generating facility in Carbo, Russell County, Virginia (USA), has impaired Clinch River biota through toxic spills in 1967 and 1970, and effluent copper (Cu) concentrations that were reported to have exceeded water quality criteria from 1985-1989. These impacts have provided impetus for many research projects addressing the absence of bivalves, including federally protected species of native mussels (Unionoidea), from sites influenced by CRP effluent. Modifications in CRP effluent during 1987 and 1993 drastically reduced Cu levels and warranted the present study, which assessed long-term biological recovery in Clinch River biota near the CRP. In 2000-2001, surveys of benthic macroinvertebrate communities and instantaneous measures of effluent toxicity did not foretell significant reductions in survivorship and growth of field-caged Asian clams (Corbicula fluminea) at sites downstream of the CRP. More importantly, these results indicated renewed toxicity in CRP effluent. Additional transplant studies using two enclosure types were conducted to isolate effects attributable to CRP effluent from the potentially confounding effects of substrate variability among study sites. While it was found that mean growth of clams was greatest in the enclosure that minimized substrate variability (p=0.0157), both enclosure types clearly distinguished significant impairment of survivorship and growth at sites downstream of the CRP discharge, and strengthened the association between impairment and CRP effluent. An intensive field investigation was undertaken to determine whether impairment observed in transplant studies extended to resident bivalves. During 2001-2002, densities and age structures of C. fluminea and distributions of mussels suggested that impairment indeed extended to resident bivalves for a distance of 0.5 to 0.6 km downstream of the CRP discharge. Impairment of bivalves was less evident below (1) a fly ash landfill and (2) coal mining activities and low-volume leachate from a bottom ash settling pond. With respect to long-term recovery, modifications in CRP effluent treatment have reduced Cu concentrations from an average of 436 mg/L in 1985-1989 to 13 mg/L in 1991-2002. Subsequently, Cu body burdens of Asian clams (Corbicula fluminea) transplanted within CRP influence have decreased from 442% of levels accumulated at reference sites in 1986, to 163% of these levels in 2002. The reduction in effluent Cu largely explains recovery of most benthic macroinvertebrate community parameters (e.g., richness, diversity) at influenced sites from levels that were typically less than 70% of reference levels, to levels that frequently range from 80 to greater than 100% of reference levels. Nevertheless, bivalves remain impaired downstream of the CRP; survivorship and growth of C. fluminea transplanted to CRP-influenced sites have typically been less than 40 and 20% of reference values, respectively. Furthermore, C. fluminea has seldom been encountered within CRP influence for nearly two decades. Likewise, native mussels remain absent within CRP influence, but recent surveys suggest their downstream distributions are more proximate to the CRP discharge than has been reported previously. A preliminary assessment of factors potentially contributing to toxicity revealed that (1) water reclaimed from settling basins for discharge with CRP effluent significantly impaired fecundity of ceriodaphnids at concentrations of 50%, (2) LC50 values for industrial treatment chemicals were misrepresented on Material Safety Data Sheets and consequently, were subject to misapplication by operators, (3) Cu concentrations of 96 mg/L significantly impaired growth of Asian clams in artificial stream testing, and (4) effluent Al exceeded acute and chronic water quality criteria, suggesting this ion should receive further consideration in future studies. / Master of Science

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