Sediment was fertilized with f/2 algal growth medium in situ and in the laboratory daily for one week. Sampling strategy incorporated two intertidal heights and two sites. Experiments were done in August and January. No significant changes in chlorophyll a or diatom community structure were observed after ten days of growth in either the field or the laboratory experiments. Laboratory experiments also showed slightly increased gross primary production (p<.10) and increased oxygen uptake (p<.01) associated with nutrient enrichment. Unlike planktonic diatoms, sediment-associated diatoms in Yaquina Bay show no nutrient limitation. Thus other factors probably control diatom growth in these sediments such as light intensity, photoperiod, intertidal height, sediment stability and organic content, and animal consumption. / Graduation date: 1982

Sediment samples were collected from eight sampling sites along the Yaquina Estuary, Oregon from Yaquina Bay to Elk City near the head of the estuary. Samples were collected in November 1973, February 1974, May 1974 and August 1974 from two or three intertidal levels depending on the magnitude of the intertidal area exposed at low tide. Concurrent sediment and water samples were obtained for the determination of water temperature, salinity, sediment size, and percentage of organic carbon and cabonate in each sample. Incident light and exposure period data were obtained for the sampling year. A total of 36,564 diatoms identified and counted in 71 samples was separated into 390 taxa (species or varieties). Of the 390 taxa, 31%, representing 30% of the total cell count, could not be identified from available literature. The relative abundance values of the taxa were utilized for the comparisons of several community composition parameters (the Information measure, Simpson's diversity index, redundancy, niche breadth, and a measure of similarity) which were used for comparisons of spatial and temporal distributions of sediment-associated diatom assemblages within the estuary. Multivariate analyses (clustering, disciminant analysis, principal components, canonical correlation) of species and environmental data were employed to analyze the distribution of sediment-associated diatom assemblages relative to the sampling strategy and to environmental gradients. The distribution of sediment-associated diatoms in Yaquina Estuary was regulated primarily by mean salinity and characteristics of the sediment. Above Yaquina Bay the prominent taxa exhibited overlapping distributions along the salinity gradient to a location in brackish water where the mean salinity was approximately 5°/oo. Here, a relatively sharp discontinuity in the diatom flora existed which appeared to be the product of the biochemical and biophysical mechanisms involved in osmotic regulation of mesohalobian and oligohalobian assemblages. Relatively large disparities in the structure of sediment-associated diatom assemblages were found within relatively small local areas of Yaquina Bay. These differences were attributed to the properties of the sediment, Responses of the diatom assemblages to light intensity, temperature and exposure to intertidal emergence were not obvious. Approximately one-half of the numerical variation in the diatom flora apparently was related to factors other than the physical and chemical variables considered in this study. Comparisons of previous distributional surveys in Yaquina Estuary indicated that the diatom flora associated with the sediments was dissimilar in species composition to proximal epilithic, epiphytic and planktonic diatom assemblages. Species diversity was generally high throughout the intertidal sediments, irrespective of tidal height and season, while redundancy was generally low. High diversity values may represent contamination of samples, behavioral-physiological adaptations of the sediment flora, or the spatial heterogeneity of intertidal sediments. / Graduation date: 1977

Sediments from 21 Oregon lakes were analyzed for seven metals (Fe, Mn, Zn, Cu, Co, Ni, V) in three forms (exchangeable, organic+sulfides, and oxyhydroxides+ oxides+ carbonates) using a sequential fractionation procedure. The summer epilimnetic filterable concentration of an eighth (Mo) was also determined. Sedimentary diatom remains and summer phytoplankton populations of the lakes were correlated with the 22 metal parameters and with conservative water chemistry parameters, estimators of lake productivity, and watershed geology. Both the sedimentary metals and the two populations of primary producers correlated best with the ecoregions of Omernik and Gallant (1986). A number of species possessed correlations with specific trace metal extractions or ratios of those extractions. Bloom-forming Anabaenas strongly correlated with sedimentary organic and filterable epilimnetic nickel. Possible Ni limitation of this group was observed in one Cascade lake (Lava). The ratio of organic nickel to cobalt appeared to control the abundance of several sedimentary diatoms. Organic vanadium strongly correlated with a number of diatoms, particularly in the genera, Cyclotella and Fragilaria. Possible V pollution was observed in one lake (Woahink), and frustule remains of C. stelligera significantly increased with increasing total sedimentary V concentrations there. Zinc was the trace metal most frequently found to apparently limit diatom growth. Diatoms may have developed three different responses to Zn limitation; the three groups have been labelled affinity-, velocity-, and (possibly) storage- specialists following Sommer (1985). Possible Zn pollution was observed in two lakes (Oswego and Clear). Phytoplankton and sedimentary diatoms weakly correlated with sedimentary iron by comparison to Ni, V, or Zn. Few strong relationships were observed with manganese, copper, or cobalt. No statistically significant correlations were found with molybdenum, and few correlations between a conservative chemical parameter and a species of phytoplankton were found. There was poor correlation between trace metal concentrations and lake productivity, despite frequently observed correlations between individual species and particular trace metal fractions. These findings suggest that variations in absolute trace metal concentrations, and/or ratios, may be important factors for controlling species distribution, but have relatively little influence upon lake primary productivity or standing stocks.

Typescript. Includes vita and abstract. Bibliography: Includes bibliographical references (leaves 91-99). Description: xi, 99 leaves : ill., maps ; 29 cm.

Typescript. Includes vita and abstract. Bibliography: Includes bibliographical references (leaves 84-88). Description: x, 88 leaves : ill. ; 29 cm. / Along the Oregon coast blooms of Pseudo-nitzschia spp. have been an almost annual occurrence since monitoring began in the late 80's. This study looks at the distribution of Pseudo-nitzschia spp., in relation to meteorological and oceanographic conditions. A series of transects (1995-98) were done in Coos Bay and over the adjacent continental shelf under a variety of oceanographic conditions. An intense sampling program was undertaken in June 1998, with simultaneous nearshore and in bay (Coos Bay) sampling, including a nearshore grid, 24 hour anchor station in the bay, and an in bay incoming tide drift study. The results suggest that blooms develop nearshore after upwelling events. In conditions of relaxed upwelling highest cell concentrations were found immediately adjacent to the coast in surface and mid-depth waters. At stations in Coos Bay, Pseudonitzschia spp. concentrations increased with the incoming tide. Nearshore phytoplankton populations were transported into the bay, initially in the more saline bottom waters, but were rapidly mixed throughout the water column by the turbulent flow in the channels. On ebbing tides there was a reduced number of phytoplankton in the water column, possibly indicating consumption by in bay filter feeders or sinking and deposition on the bottom.

Typescript. Includes vita and abstract. Bibliography: Includes bibliographical references (leaves 60-63). Description: xii, 63 leaves ; 29 cm.

Typescript. Includes vita and abstract. Bibliography: Includes bibliographical references (leaves 79-83). Description: viii, 83 leaves : ill., map ; 29 cm.