xv, 151 p. : ill. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / The sea anemone Metridium senile occurs along a salinity gradient in the South Slough Estuary, Oregon, where it is subjected to frequent and sometimes large fluctuations in salinity. This study determined how hypo-osmotic stress contributes to the survival and distribution of this population. In the laboratory, chronic exposure ofM. senile to 50% and 75% seawater for twenty-eight days resulted in partial regulation of volume and magnesium ions. Anemones transplanted to the field exhibited increased mortality and partial regulation of volume, osmolality, and magnesium ions with decreased salinity during the wet season (December-February) and less regulation during the dry season (June-August). This pattern of physiological tolerance coincides with observed trends of seasonal abundance and distribution. Previous studies describe M senile as a marine osmoconformer, however this estuarine population is able to withstand moderate hypo-osmotic stress through partial regulation of tissue osmolality and magnesium ions. / Committee in Charge: Dr. Craig M. Young, Chair; Dr. Nora B. Terwilliger; Dr. Steven S. Rumrill; Dr. Caren E. Braby

The South Slough Estuary is located off Coos Bay along the southern coast of Oregon. It is divided into two channels that meet and continue to Coos Bay at the Charleston Harbor. There are six major contributing streams to South Slough. After rainfall events, the level of coliform bacteria in the slough increases because of stream bacteria loading. This is due to cattle grazing in the drainage areas, failed septic systems from private homes, and sewage sludge applied to the County landfill, which drains into the slough. The Oregon Health Division has enforced a Sanitation Management Plan for Commercial Shellfish Harvesting in South Slough that specifies closure of commercial shellfish harvesting for certain rainfall and flood events. The purpose of this study is to analyze and improve the current understanding of the hydraulics and water quality of the South Slough Estuary. This was achieved by calibrating the South Slough using the water quality model CEQUAL- W2. It was calibrated for the following parameters water surface elevations, velocity, temperature and total dissolved solids. A management analysis was also done analyzing the transport of bacteria and a conservative tracer. Model predictions for water surface elevations at one of the monitoring sites, Hinch Road Bridge, was significantly lower than measured elevations. There was an excellent correlation of velocity, and reasonable timing of peaks due to tidal effects. Model predictions for temperature and total dissolved solids match measured values well. To improve the accuracy of the model the following was recommended; install a raingage in the South Slough, measure temperature and constituent concentrations at inflow locations, survey the S4 current meter, new soundings performed of the Winchester Creek arm and at the Hinch Road Bridge gaging station, and investigate the possibility of an obstruction near the Hinch Road Bridge gaging station.

ix, 73 leaves : ill. ; 28 cm Typescript Thesis (M.S.)--University of Oregon Includes vita and abstract Bibliography: leaves 71-73 Another copy on microfilm is located in Archives University of Oregon theses, Dept. of Biology, M.S., 1982

x, 53 leaves : ill., map ; 29 cm Notes Typescript Thesis (M.S.)--University of Oregon, 1986 Includes vita and abstract Bibliography: leaves 48-53 Another copy on microfilm is located in Archives

Typescript. Includes vita and abstract. Bibliography: Includes bibliographical references (leaves 90-96). Description: xii, 96 leaves : ill. ; 29 cm.

Typescript. Includes vita and abstract. Bibliography: Includes bibliographical references (leaves 87-100). Description: xiii, 100 leaves : ill. ; 29 cm.

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

xvii, 175 leaves : ill. ; 29 cm Notes Typescript Thesis (Ph. D.)--University of Oregon, 2002 Includes vita and abstract Includes bibliographical references (leaves 150-175) Another copy on microfilm is located in Archives

ix, 119 leaves : ill., maps ; 28 cm Notes Typescript Thesis (Ph. D.)--University of Oregon, 1985 Includes vita and abstract Bibliography: leaves 108-119 Another copy on microfilm is located in Archives

Typescript. Includes vita and abstract. Bibliography: Includes bibliographical references (leaves 77-80). Description: xii, 80 leaves : ill. ; 29 cm. / The lower distributional limits (fronts) of callianassid shrimp populations were observed at five sites in South Slough, Coos Bay estuary, Oregon. Fronts at four sites exhibited similar shoreward-seaward movements while the remaining site showed drastic population reductions. Shrimp density and body size were found to be significantly greater above than below the front. There was no consistent pattern found in grain size or interstitial water content across the front. In a controlled predator-exclusion experiment, resulting shrimp densities were not significantly different among treatments. Front shifts showed no pattern in response to treatments. These results imply that fish predation is not responsible for front placement. Trawls taken on both sides of the front produced similar densities of a predatory fish, Leptocottus armatus. Because predation pressure was calculated to be roughly equal above and below the front, Leptocottus is not expected to be responsible for position and movements of these fronts.