Redband trout density was examined in three forested streams in central Oregon at two scales, pool channel unit and microhabitat. Two streams were in roadless areas and one was in a "highly managed" watershed. At the larger spatial scale, trout displayed a seasonal shift in habitat use from early to late summer. There was a positive correlation between trout density and pool structural complexity during summer base flow. The association was intensified throughout the summer as stream flow continued to drop. The structural complexity of each pool was quantified using an index integrating structural variability and depth. Twenty-two pools were divided into microhabitats, or pool subunits with similar characteristics using a qualitative classification scheme describing different structural elements comprising the pool habitat. Microhabitat was partitioned between fry and older trout throughout the summer: Fry generally used stream margins, backwaters, and shallow areas; whereas, trout one year and older used deep areas (depth greater that 0.5 m) and cover associated with substrate and wood. The use of cover by trout one year and older doubled from June to August. This change in use was coupled with the increased association with structural complexity at the channel unit scale. The large substrate and wood that provided cover also increased the structural complexity of the pool. As trout increased their use of cover, their densities increased in more complex pools. Man-made log weir pools in a simplified stream were evaluated for their structural complexity and compared to the shallow natural pools in the same reach. Log weir pools had greater average depth, but were less complex than natural pools, and could maintain a similar density of trout. The structural complexity in natural pools appears to compensate for their shallow depth. Log weir pools enhanced with placement of a rootwad supported higher densities of trout. Addition of a rootwad provided microhabitats associated with cover that were lacking in weir pools without other structures added. When using instream construction to create pool habitat, complex structure that provides microhabitats associated with cover is more effective at holding higher densities of fish under late summer low flow conditions. / Graduation date: 1996

Population size of Clavibacter michiganensis subsp. sepedonicus in potato cv Russet Burbank and plant response as affected by drought were assessed in a greenhouse experiment. Water deficit stress and no stress treatments, and inoculum densities of 0 or 2 X 10��� cfu C. m. sepedonicus/seed piece were arranged factorially. Stem populations of C. m. sepedonicus were significantly lower in the water deficit stress treatment compared to the non-stressed treatment at every sampling date in both experiments. In seven of the eight harvests the number of C. m. sepedonicus cells/g of stem tissue for the water deficit stress treated, infected plants was a factor of 10 lower than the non-stressed treatment. Foliar symptoms of bacterial ring rot were not observed, but symptoms developed in tubers. Compared to the noninoculated control inoculum reduced aerial biomass from 12 to 21% and tuber yield from 15 to 38% in samples taken four times after the drought was terminated. Reduction of these same variables due to water deficit stress ranged from 17 to 21% and 15 to 41%, respectively, compared to the non-stressed control. Therefore, both water deficit stress and C. m. sepedonicus had similar effects on growth and tuber yield of potato. / Graduation date: 1995

Habitats for juvenile chinook salmon (Oncorhynchus tshawytscha) were observed at a high flow during the spring of 1989 and at a low flow during the spring of 1991 in the lower American River of California. Parameters of microhabitats in eight macrohabitats were measured. Mean column water velocity and total water depth variables were used to statistically compare juvenile chinook salmon microhabitat distributions between and among macrohabitat type/reach and flow combinations. Using mean column water velocity and total water depth as independent variables, each macrohabitat type/reach appeared to be unique. Mean column water velocity seemed to be a better descriptor of juvenile chinook salmon habitat selection than was total water depth. Riffles appeared to be the preferred macrohabitats for large non-schooling chinook salmon at both flow levels. Root wads, woody debris, and submerged terrestrial vegetation were utilized extensively and provided a significant cover for schooling chinook salmon during the high flow period. Habitat utilization by chinook salmon appears to be influenced by nonhydraulic variables. Application of models in current instream flow studies need to include factors such as water temperature and aquatic insect production. / Graduation date: 1993

Rainbow trout were exposed to aluminum at pH 7.25 and 8.25 and four hardnesses (10, 30, 80, and 120 ppm CaCO₃) for 96 hours in a continuous-flow system and mortality and aluminum accumulation in the gills were determined. Temperature, pH, and dissolved oxygen were measured daily for each treatment. Dissolved and total aluminum concentrations and hardness were determined following exposure periods of 48 and 96 hours. Aluminum was most toxic at pH 8.25, and was more toxic at lower than at higher hardnesses. Water hardness provided a significant protective effect against aluminum-induced mortality (p < 0.05), and there were no significant effects for water hardness on gill accumulation at either of pH. At pH 7.25 no mortalities occurred under any conditions. At pH 8.25, the accumulation of aluminum in gill tissues was higher than for pH 7.25 following exposure for 96 hours. In addition, aluminum concentration and exposure time had a significantly cumulative effect on fish mortality (p < 0.05). Possible mechanisms for aluminum toxicity and the accumulation of aluminum in the gills of rainbow trout were attributed to the forms and solubilities of aluminum species at different pH values. Competition between Ca²⁺ and aluminum for binding sites on the gills likely influenced aluminum toxic action. / Graduation date: 1992

Ball State University LibrariesLibrary services and resources for knowledge buildingMasters ThesesThere is no abstract available for this thesis.

Temperature, conductivity, and Aeromonas hydrophila density were determined bimonthly at six sites in the White River drainage system, Delaware County, Indiana, from April, 1984 through December, 1984. Fish were collected from four of the six sites. Fish were identified to species, examined for gross pathology, and their blood collected. Titers against A. hydrophila antigen 157 were determined for all carp (Cyprinus carpio) captured. Certain carp serum samples were also tested against three additional A. hydrophila antigens.Aerononas hydrophila densities appeared to be related to temperature and conductivity, primary producers, and runoff/effluent. Aeromonas hydrophila densities were higher in areas affected by urban runoff/ effluent than in areas affected by rural runoff/effluent. Aeromonas hydrophila densities increased as one progressed through the city of Muncie.Only five percent of all fish captured exhibited signs of gross pathology. Diseased fish typically demonstrated low titers against antigen 157. Several A. hydrophila serotypes were apparently infectious for the carp studied. Thirty-two percent of the carp sampled exhibited a positive titer response against antigen 157. Considerable variation in titer response existed between individuals.Ball State UniversityMuncie, IN 47306

Skin and blubber tissue samples were collected from two hundred and six freeranging Heaviside’s dolphins (Cephalorhyncus heavisidii) during January through June of 2008, 2009, and 2010, along the coast of South Western Africa, to be analyzed for heavy metal concentration levels. Inductively coupled mass spectrometry (ICP-MS) was used to determine sample solution concentrations of all metals (aluminum, arsenic, cadmium, chromium, copper, iron, lead, manganese, mercury, nickel, selenium and zinc). Data provided by this thesis is the first reference of its kind for this species (Cephalorhyncus heavisidii), which is one of the least-known cetacean species in the world. In addition to baseline heavy metal concentration information for the Heaviside’s dolphin, meaningful population structural and ecological information was obtained. A level of site fidelity or specific movement pattern across certain sites was indicated by the presence of different concentration levels across individuals sampled in different areas, especially adjacent areas. With an investigation into the potential sources of the marine heavy metal contamination, it was deduced that these sources contributed to each site’s unique and characteristic toxicological and hydrological profile as reflected by the bioaccumulation patterns seen in this study. It was confirmed by this study that bioaccumulation levels are a meaningful and novel measure of population structure. Potential evidence of differences in bioaccumulation patterns between sexes was observed in this study, as well. Although not definitive, a difference in metabolism, heavy metal elimination, or ranging pattern between males and females was suggested by the results. Variation in the results suggests a deepened level of complexity in the physiological and ecological aspects of trace elements accumulation and detoxification in the tissue of an apex predator like the Heaviside’s dolphin. Finally, a general assessment of health implications for the species was established, and it was found that Heaviside’s dolphins have higher than average mammalian trace element concentrations, and higher than average concentrations as specifically compared with other odontocetes. Further research using a larger sample size and using internal organs will provide more insight and a deeper understanding of the novel information presented here. / published_or_final_version / Biological Sciences / Master / Master of Philosophy

abstract / Biological Sciences / Doctoral / Doctor of Philosophy

No description available.

Microorganisms are increasingly used in toxicological studies to determine potential environmental impacts of xenobiotic compounds. A multi-stage laboratory model was developed to facilitate the examination of environmental impacts of selected pollutants on fundamental cycling processes inherent to aquatic ecosystems, namely, the degradation of organic substances and nitrogen transformations under aerobic conditions. A microbial association representative of riverine ecosystems was enriched for, isolated and cultured within the model. Characterisation of the microbial association were undertaken. Scanning electron microscopy and bright field microscopy revealed that a diverse heterogenous community of microorganisms had established within the model. Successional metabolic events, namely organic carbon catabolism, ammonification of organic nitrogen and the process of nitrification were differentiated in time and space with the microbial association integrity still being retained. The establishment of a microbial association within the model was primarily dependent on: dilution rates, specific growth rates and interactions between microorganisms and the prevailing environmental conditions. Growth-rate independent populations of microorganisms established within the model and were thought to contribute significantly to the metabolic processes within the model. Nitrifying activity was identified as a rate-limiting process within the model. Following separation of metabolic events, the ecotoxicological impacts of phenol and 2,4-dichlorophenol on the association were assessed. The biological oxidation of ammonia through to nitrate (nitrification) was found to be a sensitive indicator of perturbation. The model was found to be suitable for testing both acute and chronic intoxication by pollutant compounds as well as for biodegradation testing and the possible evaluation of ecotoxicological impacts of wastewater treatment plants. The main disadvantages of the model arose from its operational complexity, its empirical nature and its impracticality for screening large numbers of compounds. A bioassay based on the inhibition of ammonium oxidation was developed in order to fulfil the requirements for a simple and rapid test protocol for the initial screening of perturbant compounds. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1996.