Browsing by Author "Parker, Bruce C."

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    Cryopreservation of eukaryote algae
    Beaty, Myron H. (Virginia Tech, 1991-12-01)
    In an attempt to expand the knowledge of the diversity of algal taxa that are capable of successful recovery after freezing to and thawing from -196°C, 365 algal strains representing 13 algal classes were studied using various cryoprotectants at several concentrations. A cryopreservation protocol involving culturing the algae under low light (17-22 μE m⁻² s⁻¹) on semisolid (I % agar) media, controlled cooling at 1°C min⁻¹, rapid thawing, and the return of cultures to agar media was developed. This protocol produced successful recovery of >77% (283) of the algal strains tested. Of the 283 successfully cryopreserved strains comprising 240 species (68 genera), >220 species (34 genera) were cryopreserved for the first time. In addition, preliminary data suggest that some relationships exist among proposed systematic evolutionary lines, environmental preferences, cryoprotectants, and the organism's cryopreservability.
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    Development of a diet for rearing juvenile freshwater mussels
    Gatenby, Catherine M. (Virginia Tech, 1994-04-15)
    Over 100 species of freshwater mussels (Unionidae) are endangered or threatened in the United States, and another dozen species support a declining commercial harvest of shells for the cultured pearl industry in Asia. Because of these Significant declines in abundance, a study was undertaken to develop a diet for rearing juvenile mussels, with the goal of long-term propagation of rare species. Three trials were conducted to test various tri-algal and commercial diets and to determine the influence of silt in survival and growth of the rainbow mussel (Villosa iris) and giant floater (Pyganodon grandis). After 45 days post-metamorphosis, juvenile V. iris fed algae with silt exhibited a two-fold increase in shell length (532 μm), and 63.5% survival. Juvenile P. grandis exhibited similar results at 45 days post-metamorphosis. In comparison, all juvenile mussels fed algae without the presence of silt exhibited no increase in shell length after 45 days post-metamorphosis. However, survival varied between species. Survival after 45 days was 5.0% for V. iris and 43.3% for P. grandis. P. grandis is probably more tolerant of a variety of environmental conditions. Analysis of covariance showed that growth rate over time (120 days) of P. grandis was significantly greater than that of V. iris. Shell lengths of P. grandis juveniles fed algae in the substrates kaolin, sterilized silt, sterilized silt plus Aqua Bacta-Aid, and bacteria-colonized silt were Similar, indicating that bacteria were not essential to juvenile digestion or nutrition. Shell lengths of V. iris juveniles fed algae in kaolin or algae in bacteria-colonized silt also were similar after 60 days. Juvenile mussels appear to be pedal-feeding for approximately 120 ± 30 days, depending on the species; hence, silt probably serves as a physical substratum for pedal-feeding mussels to collect food particles. Subsequent tests indicated that growth was significantly correlated with algae high in oils which contain polyunsaturated fatty acids (PUFA). V. iris juveniles fed a tri-algal diet, consisting of Neoehloris oleoabundans~ Phaeodactylum tricornutum, and Bracteacoccus grandis (NPB), with silt substratum showed the best growth over time. Individuals achieved a mean shell length of 1747 μm and had 30.0% survival after 140 days postmetamorphosis. All other tri-algal diets tested enhanced growth over the commonly used green tri-algal mix of Chlorella, Ankistrodesmus, and Chlamydomonas (CAC), and all algae diets enhanced growth over a silt-only diet. Commercial yeast diets did not support growth. After 272 days post-metamorphosis, V. iris fed CAC in silt achieved a maximum shell length of 4520 μm (17-fold increase in length), with a mean length of 2968 μm and approximately 5% survival. After 195 days postmetamorphosis, P. grandis achieved a maximum shell length of 7846 μm (22- fold increase in length), with a mean of 4877 μm and approximately 12% survival. Results of all feeding trials indicate that algae are a suitable food source for rearing early juvenile freshwater mussels. A tri-a1gal diet high in oils resulted in greater growth than all other diets tested. Resident bacteria in riverine sediments were not essential to growth and survival of juvenile mussels. Silt provided some nutritional value, but primarily served as a physical substratum for pedal-feeding juveniles.
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    Development of an Algal Diet for Rearing Juvenile Freshwater Mussels (Unionidae)
    Beck, Kevin Moran (Virginia Tech, 2001-05-10)
    Feeding selectivity by the rainbow mussel (Villosa iris) was examined for three age groups; 2-3 days old, 50-53 days old, and 3-6 years old. The mussels were fed an algal diet consisting of Scenedesmus quadricauda (22.3 - 44.5 μm), Nannochloropsis oculata (2.8 – 8.1 μm), and Selenastrum capricornutum (3.6 – 8.5 μm) in equal cell densities. The change in relative abundance of each algal species within feeding chambers over a 5 hr feeding trial was used to discern selectivity. At the conclusion of the feeding trials, the gut contents of mussels were analyzed for preferential ingestion. The mussels selected for N. oculata and S. capricornutum over S. quadricauda (p < 0.05). This may be an indication of particle size-dependent selection. Feeding trials also suggest that selectivity by the rainbow mussel does not change with age. Gut content analyses showed a preferential ingestion of algae, in the sequence N. oculata, S. capricornutum, then S. quadricauda. The suitability of two algal diets, S. quadricauda and N. oculata, for rearing captive juveniles of V. iris in 145-L recirculating culture systems was compared. Juveniles were fed their assigned diet at a density rate of approximately 30,000 cells/ml for 42 days, and sampled weekly for percent survival and shell length. Regardless of diet, juvenile survival decreased rapidly after 21 days, and growth did not exceed approximately 450 μm. High mortality rates and slow growth of juveniles was likely due to inadequate diets. Juveniles that were fed S. quadricauda lacked chlorophyll coloration in their guts, indicating that the juveniles did not ingest this species of algae. Colonies of S. quadricauda were likely too large for the juveniles to ingest. The gut content of juveniles fed N. oculata showed chlorophyll coloration, indicating that the juveniles ingested this species, but N. oculata may have been difficult for the juveniles to assimilate. Under the culture conditions provided, survival and growth did not compare favorably to those of other studies with V. iris. Newly metamorphosed juveniles of V. iris were reared in 145-L recirculating culture systems containing sediment (< 600 μm) of two depths, 5 mm and 15 mm. Mussels were fed a bi-algal diet of Nannochloropsis oculata and Neochloris oleoabundans. Survival differed significantly between treatments (p=0.04), and was higher for juveniles reared in 5 mm of sediment over a 40-day period. Growth was not significantly different between treatments. After 40 days, juveniles achieved a mean length of approximately 578 μm in both treatments. Survival and growth of juveniles compared favorably to those of other culture studies using juveniles of V. iris. A shallow layer of sediment is recommended for the culture of juvenile mussels.
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    Development of methodology for community level toxicity testing using the fathead minnow seven day survival-growth impairment test
    Lauth, John R. (Virginia Tech, 1990-12-05)
    Single species toxicity tests are widely used to assess the potential effects of a toxicant on aquatic life. Increasingly, it is necessary to understand how the results of these tests relate to toxicant effects in natural communities. This dissertation presents the methodology and validation for a community level toxicity test that bridges the gap between single species tests and natural community responses. The research involved control of environmental parameters, improvement of feeding regimes and testing of the final community. The results are presented as four separate papers. The first paper addresses the development and validation of a standardized reconstituted water for culturing and toxicity testing of algae, cladocerans, a rotifer and two fish species. The next two papers address the substitution of the food source currently used in the fathead minnow survival-growth impairment test (Artemia) with a freshwater food source (the rotiter, Brachionus calyciflorus). Along with the alga Chlorella vulgaris (producer), B. calyciflorus (primary consumer) and the fathead minnow larvae (secondary consumer) comprise a three level food chain that was used to address trophic level interactions (feeding reduction and growth impairment) in the final phase of this research. The end result is an experimental procedure in which environmental parameters (water quality, temperature, etc.) and trophic structure parameters (Le. producer and primary consumer density) can be controlled well enough to insure that any shifts in community structure can be attributed to toxicant related effects.
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    Dynamic systems analysis of fossil dinoflagellates from the Atlantic Coastal Plain, USA
    Cawley, Jon Clayton (Virginia Tech, 1996-07-05)
    Dynamic Systems modeling suggests that complex coastal dinoflagellate biosystems can be modeled using environmental parameters such as temperature, salinity, and bulk nutrient levels. The former Salisbury Embayment of northern Virginia and Maryland is modeled here, using STELLA I and FORTRAN models based on physical oceanography and temperature, salinity, and nutrient conditions of the modern Yellow Sea. In these models, dinoflagellate assemblages are predicted based on environmental conditions associated with depth. Cluster analyses of fossil dinoflagellate frequency data from Tertiary Pamunky Group (Aquia and Nanjemoy Formations) of the Salisbury Embayment produce 17 discrete groupings. Samples within the Salisbury fossil cluster groups are statistically similar (via ANOVA analysis), but not the same. Therefore they represent paleocommunity types rather than paleocommunities. Although individual sinofiagellate species recur in similar environmental settings, the paleocommunity types do not appear to repeat. In the past, such associations have been used as depth indicators. It is suggested here that they relate to estuarine, nearshore, and offshore coastal regions because of the temperature, salinity, and nutrient conditions of each. In the modern Yellow Sea, nearshore and offshore regions are separated by discrete lateral fronts in some areas, and by gradational regions of mixing in others. Both types of water mass boundaries are modeled in this study. Results suggest that evidences that discrete water mass boundaries might have occurred between some fossil dinoflagellate associations. Circulation patterns of the Salisbury Embayment may have been roughly similar to those of the modern Yellow Sea.
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    Ecological and taxonomic studies of ectomycorrhizal fungi associated with Aspen
    Cripps, Cathy Lynn (Virginia Tech, 1995-04-05)
    A discrete aspen clone was sampled for ectomycorrhizal sporocarps over 4 years in an area impacted by copper mining in Butte, Montana. Locations of sporocarps were noted and species identified. A majority of the mycorrhizal fungi found in the aspen stand were early colonizers or species characteristic of disturbed sites, including Inocybe lacera, Laccaria laccata, Paxillus vernalis, and Tricholoma sclapturatum. Ectomycorrhizal rootlets were sampled to determine if above ground species reflected the abundance and distribution of species below ground. Over 94% of the mycorrhizae were identified to species by morphology and RFLP analysis, and 91% (excluding Cenococcum-type) were species which fruited. One fourth of the mycorrhizae were Paxillus vernalis which produced one sporocarp in 4 years. Fruitings exhibited a clustered “edge effect" at the canopy perimeter, in contrast to their mycorrhizae, which were found throughout the stand. The unusual vertical distribution of mycorrhizae to a depth of 48 cm, with few in the top 16 cm of soil is most likely due to moisture, nutrient, and organic matter considerations. Mycorrhizal members of the Cortinariaceae were an important component of the mycoflora of Populus tremuloides in Montana. Species of the mycorrhizal genus Inocybe, which is not well known in North America, were particularly prevalent in the aspen stands near Butte. Thirteen of the 16 species of Inocybe that occurred with aspen in these areas were in the Cortinatae group, having smooth spores, thick-walled pleurocystidia, and a cortina. Several of the species have previously been reported with aspen in Europe. A majority of the 16 species were linked for the first time to aspen in North America. This is the first report of I. flavella, I. longispora, and I. pseudodestricta from North America.
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    Ecology of algal mats and their role in the formation of stromatolites in Antarctic dry valley lakes
    Wharton, Robert A. (Virginia Polytechnic Institute and State University, 1982)
    Algal mats comprised primarily of Phormidium frigidum Fritsch, Lyngbya martensiana Menegh., and several species of pennate diatoms are found in the below-ice benthic regions of Lakes Bonney, Chad, Hoare, Fryxell, and Vanda, southern Victoria Land, Antarctica. Mats are also found in the littoral moats and ice-covers of several lakes, and in cryoconite holes on Canada Glacier. Variations in temperature, light, oxygen, salinity, and nutrient levels between lakes and different habitats in the same lake result in differences in species composition, morphology, biomass, and photosynthetic pigment content of the mats. Algal mats are trapping and binding sediment, and precipitating minerals, particularly calcite. Mats are removing organic and inorganic matter from the arheic lakes via transfer through the icecovers or by incorporation into the sediments. Some of the algal mats are laminated, organosedimentary structures and can be considered stromatolitic. Depending upon ambient and subsequent environmental conditions non-columnar, columnar, and pinnacle-shaped stromatolites are forming, some of which are partially lithified. If environmental variables (i.e. low light intensity, lack of burrowers or browsers, and relative lack of turbulence) associated with these stromatolites do not vary significantly, it is probable that they may result in a lacustrine carbonate sedimentary deposit.
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    Effects of copper on benthic communities in artificial microcosms
    Comeaux, Jay Louis (Virginia Tech, 1996-04-05)
    Due to perceived shortcomings in some aspects of hazard assessment for chemicals administered to aquatic systems, experiments were conducted to determine the effects of copper on various ecological parameters in artificial streams and microcosms. Effects investigated were colonization and growth of periphyton communities in artificial streams, community composition and nutritional content of periphyton in these streams, leaf conditioning and nutritional content in laboratory microcosms, and nutritional suitability of these leaves to a shredding macroinvertebrate. Main effects observed in periphyton growth experiments were significant reduction in substrate colonization due to copper treatment, which led to significantly lower standing biomass in treated streams. Observed growth rates were generally similar between control streams and copper treated streams. Light treatments did not affect periphyton responses to copper. Community composition of the periphyton was affected by 2.5 μg/L copper. Periphyton phosphorus and nitrogen contents were not affected by copper treatment. Conditioning rate of leaves was significantly decreased by 50 μg/L copper treatments in some cases. Leaf phosphate and nitrogen contents were not significantly affected by copper treatment. Significant differences in nutritional suitability of copper-treated leaves to a shredding macroinvertebrate were not detected. These experiments suggest that aquatic primary producers are more sensitive to copper than heterotrophs. Additionally, adverse effects on periphyton were observed at concentrations well below measures of chronic toxicity to organisms dependent on periphyton as a trophic resource and the chronic criteria for copper. As such, greater emphasis should be placed on the sensitivities of periphyton communities in future copper criteria determination.
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    Effects of temperature on aquatic organism sensitivity to selected chemicals
    Cairns, John Jr.; Buikema, Arthur L. Jr.; Heath, Alan G.; Parker, Bruce C. (Water Resources Research Center, Virginia Polytechnic Institute and State University, 1978)
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    Energy Reserves in Native Freshwater Mussels (Bivalvia:Unionidae) with and without Attached Zebra Mussels: Effects of Food Deprivation
    Patterson, Matthew Alan (Virginia Tech, 1998-06-05)
    This project evaluated the feasibility of salvaging zebra mussel-infested freshwater mussels from their native habitat by determining 1) how zebra mussel infestation affects unionid feeding and body condition, 2) how starvation in quarantine affects body condition of unionids, and 3) what feeding regime maintain unionid condition in quarantine. The effects of zebra mussel infestation on two mussel species were evaluated through glycogen analyses of mantle tissue and gut content analysis. Specimens of Amblema p. plicata (Say, 1817) and Quadrula p. pustulosa (I. Lea, 1831), collected from a heavily infested reach of the Ohio River in 1996, had significantly lower (p<0.05) glycogen levels than specimens collected from a low-infestation reach upstream. In 1996 and 1997, heavily infested Amblema p. plicata and Quadrula p. pustulosa had significantly less (p<0.01) organic matter and fewer algal cells in their guts than lightly infested specimens. In addition, gut contents of individual A. p. plicata contained significantly less (p<0.05) organic matter and fewer algal cells than the combined gut contents of all zebra mussels (18-33 mm in length) attached to their shells. Gut analyses also revealed significant diet overlap between native unionids and infesting zebra mussels. Thus, competitive interactions or interference by zebra mussels likely reduced unionid ingestion and consequently reduced glycogen stores. During quarantine, unionids salvaged from a lightly infested area and starved for 30 days had glycogen levels that declined dramatically. After 30 days without supplemental feeding, mean glycogen levels of A. p. plicata declined 85%, and mean glycogen levels of Q. p. pustulosa declined 70%. Thus, feeding of unionids is necessary to maintain their condition during lengthy quarantine. To determine the best feeding regime for unionids in quarantine, assimilation efficiencies and carbon budgets were established for the rainbow mussel, Villosa iris (Lea, 1829), using radio-labelled cultures of Neochloris oleoabundans (Chantanachat and Bold 1962) at three cell concentrations. Assimilation efficiencies for Villosa iris at 100,000cells/ml, 10,000 cells/ml, and 1,000 cells/ml were similar (45-56%); however, regardless of these similarities, assimilation efficiencies from this study indicate that Neochloris oleoabundans is readily assimilated (~50% AE) by Villosa iris . In addition, total assimilation was maximized at 100,000cells/ml, which indicates that Villosa iris has the greatest amount of energy available for growth, reproduction, and maintenance of condition in captivity at this cell concentration. During a second quarantine experiment, specimens were provided with 100,000cells/ml of N. oleoabundans twice per day. Initial mean glycogen levels for Amblema p. plicata (9.4 + 2.4 mg/g) and Quadrula p. pustulosa collected from ORM 175.5 in July 1997 were not significantly different (p>0.3) than the mean glycogen levels of A. p. plicata and Q. p. pustulosa collected from the same site in July 1996. Glycogen stores of unionids entering quarantine, therefore, were similar in both the starvation and controlled feeding experiments. After 7, 14, and 30 days of controlled feeding in quarantine, mean glycogen levels of A. p. plicata and Q. p. pustulosa did not change significantly (p>0.1). Thus, quarantine protocol for salvaged native mussels should include the feeding of algae to captive specimens to sustain glycogen levels prior to relocation.
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    Evaluating the Feasibility of Rearing Juvenile Freshwater Mussels in a Flow-Through Pond System at White Sulphur Springs National Fish Hatchery
    Mummert, Andrea Karina (Virginia Tech, 2001-12-13)
    A flow-through pond at White Sulphur Springs National Fish Hatchery was evaluated as culture environment for juvenile freshwater mussels of Villosa iris and Lampsilis fasciola. Survival did not differ significantly (p = 0.1910) over 93 d for V. iris cultured with silt (mean 49.8% ± SD 14.5) and without (mean 32.9% ± SD 11.7). Survival differed significantly (p <0.0001) between juveniles of V. iris (mean 49.8% ± SD 14.5 at age 93 d) and L. fasciola (mean 6.3% ± SD 4.5 at age 86 d). This may indicate that the pond failed to meet requirements of L. fasciola, or may have resulted from microhabitat variables. Growth did not differ significantly between species (p = 0.1315). Villosa iris reached a mean length of 1.81 mm ± SD 0.67, and L. fasciola 1.78 mm ± SD 0.78. Water quality parameters remained within suitable ranges, and planktonic algal densities were between 2850 - 6892 cells/mL. Survival of V. iris and growth of both species compares favorably to previous culture attempts. Juveniles of V. iris and L. fasciola were exposed to ammonium chloride solutions for 96 h in static renewal conditions at 12°C and 20°C. Calculating LC50 values with the Trimmed Spearman-Karber method, juveniles of L. fasciola (mean 96 h LC50 of 0.26 mg/L NH3-N) were significantly more tolerant of unionized ammonia than juveniles of V. iris (mean 96 h LC50 of 0.11 mg/L NH3-N). The only organisms with reported LC50 values lower than those seen for V. iris juveniles were Ceriodaphnia dubia and Hyella azteca.
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    Experiments to culture juvenile freshwater mussels in small tanks, floating containers and sediment beds
    Yang, Cheng-liang (Virginia Tech, 1996)
    Freshwater mussel culture has become an attractive enterprise because of its application for restoring depleted freshwater mussel populations, for rearing adults to support shell and cultured pearl industries, and for environmental monitoring and assessment. This study focused on testing indoor and outdoor culture techniques to rear newly metamorphosed juveniles of the rainbow mussel (Villosa iris). Tanks and floating containers were used outdoors, and sediment beds and floating containers were used in indoor culture experiments. Culture experiments with indoor sediment beds produced modest growth rates and variable survival rates for up to 4 months. Shell lengths of juveniles increased from 0.38 - 0.41 mm to 0.93 - 3.22 mm, 1.45 - 7.05 times original size; survival rates ranged from 1.27 % to 51.0 %. Experiments with indoor floating containers resulted in an increase of juvenile shell lengths from 0.38 - 0.40 mm to 0.86 - 2.07 mm, an 86 - 207 % increase; survival rates were 23.3 % to 27.0 % after 3 months. All indoor culture experiments combined water flow, inoculation of algae, fertilization, lighting and a pre-operation phase. Experimental results suggested that indoor floating container culture was a useful method to rear newly metamorphosed juvenile mussels, and the indoor sediment bed culture technique may also be suitable with modification, especially if filamentous algae can be controlled. Both outdoor tank and floating container culture experiments yielded poor results, which were probably caused by unsuitable culture conditions. Differences in juvenile growth rates (P < 0.001) and survival (P < 0.001) between floating container experiments I and II, which used the same culture techniques, were attributed to differences in culture conditions; water temperature (P < 0.001), dissolved oxygen (P < 0.01) and hardness (P < 0.01). Water temperature also contributed to a higher growth (P < 0.001) and survival rate (P < 0.001) in sediment bed culture II. The extensive occurrence of filamentous algae on sediments affected results and caused lower growth (P < 0.001) and survival rates (P <0.001) of juveniles in the sediment bed culture experiment III, IV and V. Finally, absence of water flow may have influenced growth and survival of juvenile V. iris, a naturally riverine species. Lack of currents near the bottom of tank and floating containers where juveniles resided likely contributed to complete mortality of juveniles in the outdoor culture experiments.
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    Hydrogeologic Controls on Lake Level at Mountain Lake, Virginia
    Roningen, Jeanne Marie (Virginia Tech, 2011-04-22)
    Mountain Lake in Giles County, Virginia, has a documented history of severe natural lake-level changes involving groundwater seepage [Jansons, 2004] that extend over the past 4200 years [Cawley, 1999], and as of December 2010 the lake was about 2% full by volume. Situated in the Valley and Ridge physiographic province on the axis of a plunging anticline and straddling contacts between three upper Ordovician and lower Silurian formations, the lake is one of two natural lakes in Virginia. A daily water balance, geophysical surveying with dipole-dipole electrical resistivity, and chemical sampling have shed light on the nature of flow to and from the lake, including: 1) the steady nature of net groundwater outflow, 2) the seasonal response to precipitation of a forested first-order drainage system in fractured rock, 3) the influence of a fault not previously discussed in literature regarding the lake, and 4) the possibility of flow pathways through karst features. Results from a water balance indicate steady lake drainage and significant recharge when vegetation is dormant, particularly during rain-on-snow melt events. The resistivity profiles display a highly heterogeneous subsurface and reveal low-resistivity areas that suggest flow pathways to and from the lake. Well logs, satellite images, and outcrop observations appear to confirm the presence of a fault to the east of the lake. Chemical evidence suggests that karst features may be present in the upper Reedsville-Trenton formation underlying the lakebed.
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    Identification and characterization of odorous metabolites produced by selected freshwater algae
    Rashash, Diana M. C. (Virginia Tech, 1994)
    The occurrence of taste-and-odor problems that are caused by algal metabolites in water supplies has been well documented. Several commonly occurring odor-producing algae were selected and cultured for this research. Initial studies involved the algal cells and cell-free media from cultures grown under fairly optimal conditions. Gas chromatography-mass spectrometry (GC-MS) and flavor profile analyses (FPA) were performed to identify the organic compounds produced by the algae and their respective odors. Three of the algal cultures underwent additional studies that investigated the effects of selected changes in culture conditions on both population growth and compound production. Experimental variables included nitrogen concentration (ammonium, nitrate, and nitrite), phosphorus concentration, light intensity, and temperature. Parametric and nonparametric analyses were performed to identify the environmental factors that had a significant effect on algal production, accumulation, and release of taste-and-odor compounds. The organic compounds were extracted from both the algal cells and the cell-free media. Continuous liquid-liquid extraction and Kuderna-Danish concentration (CLLE-KD) was an effective and reliable method for the isolation and concentration of a broad range of organic compounds. The plot of flavor profile analysis (FPA) results obtained for odor standards adhered to the Weber-Fechner Law (W-F) over the range of concentrations evaluated. The odor intensities of algal cultures were generally lower than the odor intensities predicted from the W-F plot of the compound standards. Masking of the odor associated with one compound by the odor associated with another was observed. Odors produced by young algal cultures (e.g., low population densities) were detected in FPA samples at compound concentrations below the limits of detection by GC-MS. Anabaena laxa retained most of the geosmin it produced within the algal cells. Phormidium sp. produced more 2-methylisoborneol (MIB) than geosmin, and the alga retained only a relatively small amount of either compound within the cells. Synura petersenii produced more 2t,4c,7c-decatrienal than 2t,6c-nonadienal, and large fractions of the concentrations produced were retained within the algal cells. Various combinations of nutrient reduction, early algal-bloom within-reservoir treatment, and removal of algal cells prior to oxidation were suggested as likely methods by which odor problems may be reduced.
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    Investigations of eutrophication in Mountain Lake, Giles County, Virginia
    Beaty, Myron H., 1963-; Parker, Bruce C. (Virginia Water Resources Research Center, Virginia Polytechnic Institute and State University, 1994-07)
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    Investigations of freshwater surface microlayers
    Hatcher, Roger Francis, 1945-; Parker, Bruce C. (Water Resources Research Center, Virginia Polytechnic Institute and State University, 1974)
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    Limnological investigations of a natural, subalpine lake in the early stages of eutrophication: Mountain Lake, Giles County, Virginia
    Beaty, Myron H. (Virginia Tech, 1995-04-01)
    Comprehensive year-round limnological investigations of Mountain Lake, Virginia were conducted from November 1992 through October 1994. Monthly physical, chemical, and biological measurements suggest that this ecosystem has shifted toward a more eutrophic condition. A trend in whole lake mean annual orthophosphate-phosphorus and inorganic nitrogen increases have occurred over the past decade, although primary productivity, cell densities, and chlorophyll a values indicate no consistent trends. Hypolimnetic oxygen deficits, however, have continued to increase over time, and in October 1994 the first measure of anoxic deep water was observed. Concurrently with the chemical changes, shifts in macrophytes and phytoplankton have occurred. Most notably were reductions in Nitella megacarpa and Dinobryon spp., an increase in Ceratophyllum sp., and a summer dominance of Sphaerocystis schroeteri and Aphanocapsa_ elachista. These two species represent algal classes, Chlorophyceae and Cyanophyceae, which have also increased in relative abundance and seasonal persistence in Mountain Lake. Nutrient addition studies conducted in 1994 indicated limiting concentrations of both phosphorus and inorganic nitrogen during most periods of thermal statification. Significant increases in primary productivity occurred within 48 hrs with the addition of K₂HPO₄ and/or NH₄NO₃ in the pico-, nano-, and microplankton size classes. The smaller size fractions (picoand nanoplankton) responded more strongly to the N enrichment, whereas the microplankton responded more with the P enrichment. In all cases, ammonium-N was the preferred inorganic nitrogen source during these Studies, as suggested from earlier studies of methylamine uptake in this lake. Studies of the importance of various phytoplankton size classes (pico-, nano-, micro-, and macro-) during thermal stratification indicated that the microphytoplankton were the most important size class in cell number, cell diversity, and contributed ~95% of the total primary productivity. The picophytoplankton were second in importance constituting ~5% of total primary productivity, whereas the relatively small numbers of nano- and macrophytoplankton contributed little primary productivity. This finding contrasts to many other oligotrophic ecosystems where the pico- and nanophytoplankton have demonstrated significantly greater importance. Increasing nutrient concentration, increasing hypolimnetic oxygen deficit, and shifting phytoplankton community structure suggest that Mountain Lake is entering the early stages of eutrophication. Continuation of increasing nutrient loads in this natural lake will potentially further shift this ecosystem toward eutrophic conditions.
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    Occurrence and distribution of human bacterial pathogens in Virginia surface waters
    Wendt, Stephen L.; Parker, Bruce C.; Falkinham, Joseph O. III (Virginia Water Resources Research Center, Virginia Polytechnic Institute and State University, 1979)
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    Physio-morphological effects of abrupt thermal stress on diatoms
    Lanza, Guy R. (Virginia Tech, 1971-08-31)
    Introduction: Increased temperature as a stress factor in aquatic environments has recently received much attention. Human population growth accompanied by expanded demands for electrical energy has resulted in increased construction of power generating facilities. Conventional fossil fuel power plants are being built to produce many times the electricity of those built in previous years. Nuclear power plants, not economically feasible in small sizes, are being constructed to generate even more electrical energy per unit than the new conventional units. Nuclear power facilities produce heat less efficiently and, thus, require approximately fifty percent more cooling per BTU than usual methods (Kolflat, 1968). Increased exposure of populations and communities of aquatic organisms to thermal pollution can thus be anticipated when natural water systems are utilized as a cooling source. The majority of research effort relative to the effects of heated waste waters on aquatic systems has been directed towards macro- as opposed to micro-organisms. While the use of microorganisms in general pollution monitoring is not a nevi concept; for examples see Kolkwitz and Marsson (1908); Butcher (1947); Fjerdingstad (1962), most of the existing effort has been in the area of correlation of species to various polluted situations. The major disadvantages of such approaches as well as the use of populations and communities of microorganisms in pollution monitoring are discussed in Cairns and Lanza (1971) and Cairns, etc. (submitted)... Vita removed Nov. 30, 2011. GMc
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    Physiological adaptations of microorganisms to high oxygen in two oligotrophic lakes
    Mikell, Alfred Thomas (Virginia Polytechnic Institute and State University, 1984)
    Dissolved oxygen at four times normal saturation inhibited growth and metabolism of summer planktobacteria in surface waters of alpine oligotrophic Mountain Lake (Giles County, Virginia). Data included viable colony counts, D-[U-¹⁴C]glucose incorporation into extractable lipid of colonies, and respiration-assimilation of D-[U-¹⁴C]glucose by lake water samples. Significant (P<0.05) differences were not detected in either colony counts or ¹⁴C-lipid when superoxide dismutase (30 U ml⁻¹) or catalase (130 U ml⁻¹) were added to the medium. The upper waters of Lake Hoare, Antarctica, contain dissolved oxygen at ≥42 mg liter⁻¹ (=HDO). HDO did inhibit D-[U-¹⁴C]glucose assimilation-respiration compared with normal atmospheric dissolved oxygen (=ADO) in Lake Hoare water. D-[U-¹⁴C]glucose was assimilated and respired optimally at 12°C in Lake Hoare. Colony formation was inhibited in both lakes. Colonies represented <1% of the fluorochrome-stained direct counts in Lake Hoare. Lake Hoare planktobacteria were smaller than the planktobacteria in Mountain Lake. ATP size fractionation revealed that 39% of ATP biomass was <0.5 Hm in Lake Hoare. Five microbial isolates were selected from Lake Hoare by growth under very high oxygen (=VHO, 4.6x in situ HDO, 55 lb in⁻² of added oxygen). One isolate was selected under ADO from shallow benthic mat underlying HDO waters. Isolates were examined for physiological characteristics which might enhance their survival in the HDO environment. While HDO incubation produced <36% of ADO incubated CFU, VHO was more selective producing <1%. Bacterial isolates were motile Gram negative rods, catalase and oxidase positive, differing in their growth response to temperature and nutrient concentration. One VHO isolate was a yeast. HDO reduced the maximal cell density in three isolates tested at higher nutrient concentrations, however, all three exhibited less repression as nutrients were lowered from 1000-10 mg liter⁻¹ in comparison to ADO grown controls. One isolate actually produced a cell density 3x that of the ADO control. Four of five bacterial isolates demonstrated HDO inducible superoxide dismutase (SOD). The inducible and constitutive SOD were the manganese type and had the same electrophoretic mobilities in respective isolates. All VHO isolates contained carotenoids. Pigmentation of the bacterial isolates differed due to the types and relative proportions of the constituent carotenoids. A carotenoid-negative mutant of one isolate grown under HDO exhibited a lengthened lag phase, decreased growth rate, maximal cell density and thereafter increased lysis compared to the same ADO grown strain and the carotenoid containing parent strain. The mutant and parent strain produced catalase and indistinguishable specific activities of SOD. Microorganisms in the high oxygen Lake Hoare waters may be protected from oxygen toxicity by the lake’s oligotrophic nature as well as a combination of cellular defenses.