Thesis (M.S.)--University of New Orleans, 2005. / Title from electronic submission form. "A thesis ... in partial fulfillment of the requirements for the degree of Master of Science in Dept. of Geology and Geophysics"--Thesis t.p. Vita. Includes bibliographical references.

xiv, 154 p. : ill. A print copy of this title is available through the UO Libraries. Search the library catalog for the location and call number. / The polychaete worm Owenia collaris (Family Oweniidae) is found in soft sediment habitats along the northeastern Pacific coast, particularly within bays and estuaries. Seasonally, these small tubeworms spawn gametes freely into the water column where they develop into planktotrophic mitraria larvae. After three to four weeks at ambient temperatures, they undergo a dramatic metamorphosis and return to the bottom. The reproductive and larval biology of a population of O. collaris in Coos Bay, OR was investigated over several years. The development of this polychaete has several unusual features, including a stomodeum not derived from the blastopore and continued proliferation of trochoblast descendents, producing simple cilia on monociliated cells. The description of larval and juvenile structures provided morphological characteristics useful for distinguishing this species from the congener O. fusiformis . The consequences of the unusual larval morphology of O. collaris (i.e. simple cilia, convoluted ciliated band) were investigated by comparing the feeding performance and growth of this species with those of invertebrate larvae representative of the more typical tornaria-type larval forms found in deuterostomes and trochophore-type larval forms found in the lophotrochozoa. Feeding and growth patterns were similar in the convergent mitraria and deuterostome larval forms. In an experiment designed to test the relationship between abiotic factors and the seasonal reproduction, the onset of breeding was cued by photoperiod, but seasonal trends in temperature, alkalinity, food availability for larvae, and salinity may drive reproductive patterns as well. Within the Coos Bay estuary, the intertidal distribution of O. collaris is related to adult salinity tolerances. Low salinity limits horizontal distribution and also reduces potential for reproduction. Most life-history stages are tolerant of a wide range of temperatures, both higher and lower than those typically seen in Coos Bay. There is little evidence to support the hypothesis that sediment characteristics limit distribution within the bay, although settling juveniles show some preference for small grain sizes and may not be able to recruit to mudflats that completely lack these size fractions.

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.

A great deal of work has been done on the ecology of the intertidal some of South African by the Zoology Department of the University of Cape Town under the direction of Professor T.A. Stephenon. As a result of this a number of valuable papers have been published dealing with the plants and animals of the zone, their ecology, lateral and vertical distribution and so on. Stephenon has, in three papers (1939, 1944,1947), dealt with general results and conclusions drawn from this survey. This work dealt entirely with the biotic between tidelevels, i.e., from the sublittoral fringe upward. it did not take into account the sublittoral, that part of the shallow coast which is perpetually submerged at all tides.

Hypoxia occurs when the dissolved oxygen concentrations in water fall below 2 mg/L, and negative impacts to flora and fauna can result. In this study, sediment core and water column measurements were collected and processed through several laboratory and field methods to better understand the biogeochemistry of Weeks Bay (WB), AL. Results show that salinity, temperature, and dissolved oxygen fluctuate on a diurnal cycle. Results also show a significant difference in water column and sediments between different years and sites. The western side of WB was found to more likely to go hypoxic than other portions. Conclusions of this research include that major differences in the water column are shown during a diurnal cycle, but sediments appear to be less dynamic. The implications of this work include WB hypoxia tendency is heterogeneous over space and time. However the sediments, although important, indicate that the pelagic and benthic components are decoupled.

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N/A / Thesis / Bachelor of Arts (BA)

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