Hydrographic, tidal, and meteorological data collected near Newport, Oregon, were analyzed to determine the relative contributions of temperature, salinity, and air pressure variations to the recorded departures of sea level from mean sea level. Nearshore the steric and recorded sea levels exhibited a similar seasonal oscillation, with high sea levels in winter and low sea levels in summer. Analysis of the steric topography indicated the presence of two distinct regions off Oregon, one extending from shore to 45 nm, and the other from 65 nm offshore to seaward of NH 165. The seasonal oscillations of sea level were approximately six months out of phase in the two regions. The nearshore region was greatly influenced by upwelling and local runoff, while the offshore region was dominated by the Columbia River plume which flows south during the summer months. Redacted for privacy Steric departures were of greater magnitude than air pressure departures, but no single dominant cause of sea level oscillation could be identified, thus justifying the labeling of this region as a transition zone from steric to pressure dominance in sea level determination. Thermal and haline components of the steric departure were shown to be of comparable magnitude and in phase. The range of steric departures was approximately 16 cm, a figure compatible with ranges reported for stations of similar latitude. / Graduation date: 1973

Graduation date: 1973

An inexpensive method for calibrating an infrared analyzer to measure varying ranges of carbon dioxide partial pressures (Pco₂) is described. A discussion is made of the hydrographic (temperature, salinity, and sigma-t) and chemical (dissolved oxygen, AOU, Pco₂ pH, and nutrients) variables that were observed along the Newport hydrographic line in March and June 1971. A winter storm in late March led to an inshore feature of doming isolines. Indications of early seasonal upwelling and photosynthesis were also observed. June conditions were characterized by a deteriorated upwelling regime and an inshore phytoplankton bloom. The Columbia River plume was also driven abnormally close (65 kilometers) to shore by southwesterly winds. Chemical variables as observed in the Columbia and Willamette Rivers in June, 1971 are compared to data from a study made in December, 1968. A large gradient in Pco₂ and temperature is observed in the Willamette River approximately 3.5 kilometers upstream from the confluence in June, but not in December. This observation is related to the seasonal flow patterns of the two rivers. Chemical variables in the Columbia River are influenced by seasonal phytoplankton activity, but oxidation of organic matter is the predominating factor in the Willamette River. Pco₂ values calculated from pH and alkalinity measurements agreed to ± 5 percent with directly measured Pco₂ values in the Columbia River. / Graduation date: 1973

Graduation date: 1975

Sediments of a portion of the central Oregon shelf between 17 and 339 m have been examined for modern foraminifera. Eighty-three samples were collected from 33 stations along three traverses located between 43° 16'N and 43° 50'N. One hundred fifty-five benthic and nine planktonic species are recognized. Fifty-six benthic species occur with a frequency of more than two percent in at least one sample. Benthic species are grouped into four distinct bathymetric faunas. Elphidiella hannai and Buccella spp. are indicative of Fauna A (17-50 m). Fauna B (50-100 m) is characterized by Buliminella elegantissima and Elphidium magellanicum. In the rocky area off Cape Arago Cassidulina californica, C. limbata, Cibicides fletcheri, and C. lobatulus become dominant. Spiroplectammina biformis, Textularia earlandi, and Trifarina angulosa are important species of Fauna C (100-175 m). Abundant species of Fauna D (175-339 m) include Eggerella advena, Epistominella exigua, and Uvigerina juncea. Species diversity increases offshore to a maximum of about 35 benthic species near 100 m and then decreases slightly with depth. Standing crop is low nearshore, rises to a maximum of approximately 300 specimens per 20 cm³ between 125 and 150 m, and then declines. Total benthic population reaches a maximum of approximately 6000 specimens per sample between 150 and 175 m. Values then decrease to about 2000 specimens at 339 m. A maximum of 15 to 20 percent live benthic specimens occurs near 50 m. Planktonic foraminifera constitute less than ten percent of the total population. Maximum percentages generally occur shoaler than 100 m, while maximum specimens per sample occur at the deepest stations. Porcelaneous specimens do not exceed six percent of the benthic population. Agglutinated foraminifera are more abundant than calcareous specimens deeper than 100 m. The frequency of occurrence of a species may vary by as much as 25 percentage points from samples collected approximately 15 cm apart. Statistical analysis of selected species indicates that sampling density was not too close along any one traverse, although the traverses possibly could have been spaced farther apart. Miscellaneous biofacies trends indicate that: thecamoebians are most abundant between 50 and 125 m; statoliths and otoliths occur most frequently between 75 and 2OO m; highest ostracod values are found between 25 and 150 m; and radiolarians generally exceed foraminifera deeper than 250 m. / Graduation date: 1967

During eleven cruises conducted off the Oregon continental slope from April 1973 to March 1975, approximately 1600 specimens of the majid crab Chionoecetes tanneri Rathbun were collected. A time sequence of size frequency histograms and bivariate plots of allometric measurements were used to determine size classes, population structure, growth and age at maturity of C. tanneri from the Oregon coast. Adult sex ratios and sex ratios for each of the juvenile size classes were computed. Bivariate plots of carapace width and cheliped length for males and carapace width and abdomen width for females defined nine size classes for juvenile males and eight size classes for juvenile females. The morphogenic relationship between differential cheliped length and gonad maturity in males and differential abdomen width and gonad maturity in females (Watson, l970a; Brown and Powell, 1972) allowed determination of minimum size at maturity of 118 mm carapace width for male C. tanneri and 85 mm carapace width for female C. tanneri. Mean carapace widths for adult males (142.7 mm) and adult females (102.5 mm) collected for this study compare well with those given by Pereyra (1972). Mean carapace width increase for each molt for all juvenile size classes was computed to be 26.14%. When size classes were equated to molt groups a linear regression (Time = -2.94 + 0.81 (Carapace width)), based on progression of carapace width modes through time, predicts age at maturity to be from five to six years. A highly significant departure from a 1:1 sex ratio for adults, of 2.41 females per 1 male, is consistent with reports for other members of the genus Chionoecetes (Hilsinger, 1975). / Graduation date: 1976

Two beaches with significant differences in grain size and thus in beach profile morphology and response to wave conditions were studied on the Oregon coast. Gleneden Beach, just south of Siletz Spit and Lincoln City, has a median grain size of 0.36 mm (medium sand) and a steep beach face slope, while Devil's Punchbowl Beach has a median grain size of 0.23 mm (fine sand) and low concave-up beach face slope. Eleven beach profile surveys were obtained at Gleneden Beach and twelve at Devil's Punchbowl Beach between August 1976 and April 1977; on average once every two weeks during spring tides. Gleneden Beach showed the typical change from a swell profile with a wide berm that prevails during summer months to a storm profile with little or no berm that exists during the stormy winter months. This transition occurred in August and September, being completed by early November. The finer-grained Devil's Punchbowl Beach also showed general erosion during the fall. However, a transition from a swell profile to a storm profile is not as clear there as the beach has little berm, even in mid-summer, and always has a concave-up appearance typical of the winter storm profile. Gleneden Beach and Devil's Punchbowl Beach did not always agree in their responses to the changing wave conditions. One may be eroding at the same time the other is accreting. These differences in response to changing wave conditions appear to result from their differences in grain size. Volume changes of the erosion or deposition at the two beaches were computed from successive beach profiles. The coarser-grained Gleneden Beach showed larger changes in erosion and deposition, the maximum erosion being 0.71 m³ per meter of profile length, while the finer-grained Devil's Punchbowl Beach showed a maximum erosion of 0.25 m³ per meter of profile length. Attempts were made at relating the erosion or deposition and the volumes of erosion/deposition to the wave breaker heights and deep-water wave steepness that occurred between the beach profile sequences. There is only a vague relationship between the volumes of beach erosion/deposition and the wave heights, the probability of erosion increasing and the volume of sand eroded increasing with increasing wave breaker heights. The maximum wave heights that occur during the time interval appear to be most important to the volume of erosion, erosion volumes being large if storm breaker heights reach 5 to 6 meters or greater. Deposition prevails when the average breaker heights fall below 4 meters and storms are limited to breaker heights less than 5 meters. The deep-water wave steepness shows little relationship to the erosion or deposition volumes, indicating that the wave period is not as important a parameter as the wave height to beach erosion. / Graduation date: 1977

The overriding goal of this study was to provide first order estimates of dilution and tidal flushing of waste discharges released hypothetically into various Oregon estuaries during critical low flows and tides. Causal relationships between discharged wastes and subsequent estuarine response were studied. Various approaches to determine the assimilative capacity of tidal estuaries were described and applied to ten of Oregon's estuaries for which limited hydraulic flow information was available. This study mainly focused on the well-mixed condition common to most of Oregon's estuaries. The characteristics of the estuary used in the calculations were: tidal volumes, river flow, topography, and salinity information. Comparison of results from the modified tidal prism method and fraction of freshwater method for determining tidal flushing was made. Stommel's and Thomann's one-dimensional model was used to predict the spatial pollutant distribution from a waste outfall discharging into an estuary. Flushing rates in an overmixed estuary were determined using Gibson's method as well as flushing times calculation for a marina-like small basin. / Graduation date: 1976

Observations of wind, currents, sea level and hydrography obtained during the 1972 Coastal Upwelling Experiment (CUE-I) are described. Only phenomena with periods longer than a day are considered. One section describes the changes observed during a period of variable winds in early July 1972. Another describes a ribbon of relatively cool water observed early in the upwelling season and attributes its existence to advection of Subarctic water by the coastal jet associated with upwelling. A third section describes the seasonal development of the upwelling regime between April and October 1972. These studies are combined with other studies of CUE-I data to provide a partial description of the upwelling regime which is compared to the conceptual model developed prior to CUE-I. It is concluded that the vertical and onshore velocity fields are as yet largely unknown. The alongshore velocity field includes southward surface flow with a coastal jet, a persistent vertical shear with deeper velocities northward relative to the surface and high coherence with the wind and sea level at periods of several days. A poleward undercurrent is observed, but it may not be an integral part of the upwelling regime. The hydrography has a strong seasonal cycle. Differences between any two sections between April and October l972 are smaller than between any of these and a section occupied in January 1973. Oscillations in the wind with periods of several days cause significant changes in the region inshore of 10 km and in the upper 20 m further offshore. Subsurface temperature observations are not coherent with the wind at periods of several days. / Graduation date: 1974

Patterns of beach erosion and accretion due to jetty construction are examined for the coast of Oregon. All jetty systems are included with the exception of those on the Columbia River, making a total of nine systems. All evidence indicates that these areas of the Oregon coast are experiencing a seasonal reversal in the sand drift, but with a zero or near zero net drift over a several years time span. Thus, shoreline changes resulting from jetty construction are not the usual examples of jetties blocking a net drift as found in southern California and elsewhere. In general, accretion of the shoreline took place adjacent to the jetties following their construction, both to the north and south. This accretion resulted mainly from the embayment formed between the jetty and the pre-jetty shoreline, the embayment becoming filled until the shoreline is straight and again in equilibrium with the waves such that there is a zero net sand drift. In some cases, as at the entrance to Yaquina Bay, the jetties are oblique to the trend of the shoreline and so produced a protected zone from the waves where accretion could occur. Sand for the accretion adjacent to the jetties was derived from beach erosion at greater distances from the jetties. The severity of the erosion depended on the total amount of sand required for the beach accretion to a new equilibrium, and the length of beach that was undergoing erosion. When only a short stretch of beach occurs to one side of the jetties, as at Bayocean Spit, then the resulting erosion was particularly severe, in that case leading to the breaching of the spit. A computer model is developed to simulate the shoreline changes that occurred following construction of the jetties on the Siuslaw River mouth. The model demonstrates deposition next to the jetty to fill the embayment created by the jetty, and erosion at greater distances from the jetty. The shoreline advances of the model agreed closely with the actual shoreline changes found in surveys following jetty construction. / Graduation date: 1976