No description available.

1 examined the temporal and spatial distribution of total ammonia nitrogen (TAN) and un-ionized ammonia (NH,) in sediment pore water and compared the temporal and spatial patterns of TAN and NH, in overlying surface water with those in pore water, to determine if they were reaching concentrations known to be deleterious to fingernail clams. Pore water was obtained by core extraction and subsequent centrifugation. TAN and NI-I3 in pore water were measured from May through December 1994, at ninety two sites in pool 8, upper Mississippi River, to a depth of five centimeters below the sediment-water interface. TAN and NH3 in pore water were significantly different among sampling dates; with the greatest concentrations occurring in the summer months. Tan and N1-I3 in pore water was significantly greater in impounded open water and backwater side channel habitats and least in main channel border habitat. Tan and NH3 in surface water were significantly less than those in pore water from all of the habitats studied. Analysis of sediment substrate physical features, found that fingernail clam density and occupance were correlated to texture, with fingernail clams preferring silt loam and loam textures. Analysis of the data determined fingernail clams have a preference for particular water depths. It was found that a positive correlation exists between the occurrence and abundance of may flies and fingernail clams. Additionally, this study found a positive correlation between the density of dead fingernail clams (as per empty shells) and the abundance of live fingernail clams. Sites that contained a mean NI-I, concentration below 36 ug/L possessed the largest numbers of fingernail clams. When the mean un-ionized ammonia was above 36 ug/l, fingernail clam density declined precipitously-- 36 ug/L NH3 is the concentration demonstrated to inhibit growth of fingernail clams in laboratory studies. Mean concentrations of NH, in pore water at sites containing fingernail clams was 40 ug/L and ranged from 3 to 100 ug/L. At sites where fingernail clams were nonexistent, NH3 ranged from 3 to 375 ug/L with a mean of 57 ugfL. Mean un-ionized ammonia concentrations at sites containing fingernail clams were significantly different from and consistently lower than sites without fingernail clams. / Department of Natural Resources and Environmental Management

No description available.

Coral reefs are important to sustain marine ecosystems and provide a reliable resource for studying past climate. Corals are increasingly challenged by changing environments. The marginal corals of Hong Kong provide a natural laboratory to study the combination of environmental conditions controlling coral distribution and growth. Salinity and pH were found to impact corals in studies of coral distribution, extension, and culture. Hong Kong corals have low extension rates (1.2-11.4 mm/yr) and do not colonize in areas of low in salinity and pH. Ten years of instrumental records showed extension related positively to summer salinity and dissolved oxygen. Winter seawater temperature was inversely related to extension, while chlorophyll a showed positive relationship in autumn and winter. Culture results show low salinity negatively impacted coral calcification, photosynthesis, and extension. Corals exhibited reduced growth, paling and bleached. In contrast, coral growth increased under high pCO2, but corals decalcified in dark indicating underlying mechanisms may be altering coral physiology. The boron isotope (δ11B) proxy in corals is able to reconstruct past seawater pH when the pH of the extracellular calcifying fluid (ECF) is considered. A pH offset (ΔpH) was recorded in reconstructed pHsw due to ion pumping to ensure the ECF is saturated with respect to aragonite. By incorporating carbon isotopes (δ13C) into the δ11B-ΔpH relationship, δ11B can be corrected to remove ECF processes and reconstruct seawater pH. Culture results indicated δ11Baxial from axial tip recorded pH similar to other studies while low salinity impacted δ11Bbasal at the base. The different relationship shown from the same colony within the same cultured conditions suggested vital effects with differing coral metabolisms. δ11Baxial and δ11Bbasal related to extension but insignificantly. The large isotopic offset between δ11Baxial and δ11Bbasal indicated different growth mechanisms could possibly affected boron incorporation. The δ11B variation within a coral colony suggested careful and precise sampling for pH reconstructions is important. / published_or_final_version / Earth Sciences / Doctoral / Doctor of Philosophy

published_or_final_version / Biological Sciences / Doctoral / Doctor of Philosophy

No description available.

No description available.

Graduation date: 1995

An extensive review of all the avoidance apparatus which have been used to date in chemical avoidance tests and also an analysis of the trends and needs for new improved designs led to the design of a new avoidance apparatus. The new apparatus is a viable tool for analyzing the behavioral responses of fish to potentially toxic effluents in three dimensions. The method is quick, sensitive and relatively easy to use if sufficient fish stock is available. / The variable parameters of the avoidance reaction were three: (a) the type of the pollutant, (b) the injection system, and (c) the concentration of the pollutant. / Statistical analysis for the experiments included preliminary calculations, time series analysis, analysis of variance and Duncan's tests. / Preliminary tests evaluated the general disposition of fish in the channel, the influence of a water acclimation jet and also the effects of noise, light and temperature. Experiments were performed to define the optimal number of fish per experiment, the influence of video analysis and also of variability, adaptability and continuity. / The types of pollutants used were D.S.S. (dodecyl sodium sulfate)--a well-known reference pollutant, polymers, monomers, a plating industrial effluent and its components (Cr, Ni, Fe). / For all of these, horizontal and vertical distributions were produced together with avoidance curves and avoidance reaction representations. / The role of the avoidance reaction in relation to lethal and sublethal levels has been defined; after the evaluation of synergism and antagonism phenomena, proposed adjustments for safe toxicant levels have been estimated.

Thesis (M.S. - Hydrology)--University of Arizona, 1982. / Includes bibliographical references (leaves 46-48).