ix, 62 leaves : ill. ; 29 cm Notes Typescript Thesis (M.S.)--University of Oregon, 1987 Includes vita and abstract Bibliography: leaves 59-62 Another copy on microfilm is located in Archives

Typescript. Includes vita and abstract. Bibliography: Includes bibliographical references (leaves 45-47). / Rhithropanopeus harrisii is an introduced Atlantic crab in Coos Bay, Oregon. In Coos Bay, it occurs only in the uppermost estuary where salinities are seasonally low (<1 0/00). Rhithropanopeus occurs at higher salinities in its native range, and tolerates higher salinities in the laboratory. A native crab, Hemigrapsus oregoneos1s, occurs in the estuary, but not as far up into the oligohaline and freshwater zones as Rb1tbcopanopeus. In laboratory experiments, adult Hem1grapsus consume juvenile Rhithropanopeus. Hemjgrapsus is significantly more aggressive than Rhithropanopeus. The absence of juvenile Rhithropanopeus at field sites where both species occur suggests that field interactions may be occurring. Taken together, these results and observations suggest that there may be a dynamic zone in the estuary where the distribution of Rhithropanopeus is restricted by Heroigrapsus. Rhithropanopeus may find a refuge from Hemigrapsus in the oligohaline-freshwater Zones of the estuary, such that Hemigrapsus may be exerting selective pressure on the Rhithropanopeus population favoring freshwater adapted individuals.

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.

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

The Olympia oyster, Ostrea lurida. was overharvested in the early 20th century and is now the focus of restoration efforts in estuaries along the west coast of North America. These efforts would be aided by a better understanding of larval abundance patterns, settlement behavior, and post-settlement performance of oysters in estuaries throughout its range. In Coos Bay, Oregon, all three of these components of the oyster life cycle were investigated at multiple sites. Like adult oysters, larvae were restricted to the upper portion of the bay, although larvae were supplied to sites in the upper bay where settlement was low. Settlement and post-settlement growth was highest at sites of high adult density. These results indicate that in O. lurida, as in many other marine invertebrates, the adult population is subject to bottlenecks at the larval and juvenile stage that can vary spatially. This thesis contains previously unpublished co-authored material. / 2014-12-16

The recent rise of inner shelf hypoxia in the California Current System has caused concern within the scientific community, sparking a surge in studies addressing the issue. While regional studies of hypoxia abound, relatively little attention has been focused on the smaller coastal estuarine systems in the Pacific Northwest. Here, we present results from Coos Bay, a small, highly seasonal estuary on the southern Oregon coast. Due to wide fluctuations in freshwater input, Coos Bay exhibits characteristics of a salt-wedge type estuary in the winter, a well-mixed estuary in the summer, and a partially-mixed estuary during times of moderate discharge. Despite a strong coupling with coastal waters, we did not find evidence for pervasive hypoxia in Coos Bay. The primary drivers of variability in dissolved oxygen levels in the estuary are upwelling wind stress, residence time, and in situ biologic processes.

xiv, 158 p. / Print copies of this title are available through the UO Libraries under the call number: SCIENCE QL444.M34 D38 2006; OIMB QL444.M34 D38 2006 / The Australasian burrowing isopod (Sphaeroma quoianum) was discovered in Coos Bay, Oregon in 1995. After approximately ten years, S. quoianum has become a common member of the intertidal community and appears to be accelerating shoreline erosion. Surveys, density measurements, and a field experiment were conducted to determine the intertidal distribution, density, and substratum preference of this bioeroder within Coos Bay. Results were compared to two Australian embayments (Port Phillip Bay and the Tamar Estuary) to examine how the ecology of S. quoianum differs. In all bays examined, isopod presence was dependent upon salinity and densities varied between substrata (marsh bank, wood, and friable rock). Densities in marsh banks and friable rock were significantly higher within Coos Bay than the Australian embayments surveyed. In experimental trials, S. quoianum greatly preferred wood to other substrata. The wide distribution and high densities S. quoianum attains have clear environmental and economic implications.

x, 62 leaves : ill. ; 29 cm Notes Typescript Thesis (M.S.)--University of Oregon, 1987 Includes vita and abstract Bibliography: leaves 54-62 Another copy on microfilm is located in Archives

xviii, 160 p. : ill. (some col.) / Salt marshes are intertidal communities dominated by halophytic vascular plants that are subjected periodically to tidal inundation. These species have developed various adaptations to this stress, including tolerances of fluctuating salinity, extended periods of inundation and intervals of anoxic conditions. The marshes are divided into zones of different plant communities based on species' tolerances of ambient estuarine conditions. Abiotic stresses change along the estuarine salinity gradient (marine to riverine), potentially altering development and composition of plant communities. Abiotic gradients associated with tides are not the only factors that contribute to development of plant community composition in salt marshes. Both negative (competition) and positive (facilitation) biological interactions are also important. Factors that influence community structure in salt marshes, particularly on the eastern North American seaboard, have been well studied. In contrast, salt marshes along the Oregon coast are smaller and more discrete and have received comparatively little attention. The community structure and seed bank composition of six marshes along an estuarine salinity gradient were evaluated. Four major community types dominated marshes that varied in the salinity of inundating tidal waters. Community types were relatively consistent throughout the estuary despite the distances between the marshes. Unlike the emergent plant communities, marsh seed bank composition was more similar within a marsh than within a community type. The low and high marsh community types were separated by a distinct boundary in the marine marshes. Although abiotic factors influence the physical separation of communities, competitive interactions commonly determine the upper limit of a species. In Metcalf marsh, however, the upper boundary for two dominant low marsh species was not determined by competition with the high marsh dominant species. Positive biotic interactions between seedlings and existing vegetation in a community are important factors in determining species distributions, particularly in stressful estuarine environments. In salt marshes, where abiotic stress can be harsh, presence of existing vegetation can ameliorate these conditions and enhance germination and seedling establishment. However, interaction between seedlings and the emergent marsh community was highly competitive, though germination of one species was enhanced in the presence of existing vegetation. This dissertation includes un-published co-authored material. / Committee in charge: Dr. Scott Bridgham, Chairperson; Dr. Richard Emlet, Advisor; Dr. Steven Rumrill, Member; Dr. Alan Shanks, Member; Dr. Gregory Retallack Outside Member