Modifications of an ocean model are described, as the objective for which the model was used changed to study the kinematics and dynamics of an eastern-boundary poleward undercurrent.
Phytoplankton are a sentinel class of organisms in the marine environment. Through their photosynthetic activity in sunlit waters worldwide, phytoplankton shape the health and productivity of marine ecosystems and impact the global climate. In this work a range of ocean sensing technologies (via ships, surf zone sampling, moorings, gliders, and...
Contiential margins on plate boundaries are complex systems with morphologies and characteristics dictated by the interplay of sediment deposition and erosion, tectonic faulting, folding, and strong ground motion generating mass wasting events. With ever increasing advances in high-resolution remote sensing techniques these systems are increasingly becoming illuminated.
A ~120 km...
Changes in environmental conditions in marine ecosystems could directly or indirectly influence distribution, abundance, settlement, and size at settlement of flatfish. Understanding species-specific and age-specific responses to environmental variability is important for managing commercially important flatfish stocks. Slope-spawning flatfish whose offspring rely on extensive drift from the slope (spawning) to...
Small pelagic fishes (SPF), such as anchovies and sardines, are ecologically important due to their large abundance and intermediate trophic position that links plankton production to upper trophic levels. They are also economically important, supporting large fisheries that contribute to one fourth of the world fish landings. Reproductive success in...
When adult spawning and juvenile settling locations of marine fishes are
geographically separated, their early life history stages must rely on transport and
their own behavior to move them toward suitable habitats for successful recruitment
to the juvenile phase. Variations in climate may reduce the availability of spawning
and juvenile...
Tropical coral reef ecosystems are very important from both the ecological and economical
points of view. However, they are also particularly fragile, and have been
declining in recent years in most regions of the world, since they are highly susceptible
to anthropogenic stressors operating at global scales (e.g., global warming...
Paleoclimate archives have revealed abrupt climate events that are superimposed on more gradual climate changes throughout the last glacial and deglacial periods. The underlying causes of such rapid climate changes are still poorly understood, but the strong expression of these events in northern hemisphere records likely points to climatic mechanisms...
Freshwater provided from river discharge influences the dynamics and circulation of most continental shelves around the world. It has profound effects on the transport and fate of materials and substances originated from rivers and estuaries, as well as on the ocean biogeochemistry and marine ecosystems. The effect of buoyancy forcing...
A three-part study was conducted into the impact of physiological and ecological variables on the net isotopic fractionation of hydrogen, α[subscript K₃₇], expressed in C₃₇ alkenones. First, alkenone-producer production, abundance, and export were characterized in the summertime Gulf of California and Eastern Tropical North Pacific using compound-specific, labeled in situ...
Wind-driven coastal upwelling brings subsurface water onto the central-Oregon shelf after the spring transition each year. This cold and salty source water is oxygen-poor, yet above the hypoxic threshold, dissolved oxygen < 1.4 ml l⁻¹. Once on the shelf, dissolved oxygen (DO) concentrations of upwelled near-bottom waters are modified by...
Antarctic Ice Sheet mass balance and, hence, sea level change is affected by the floating extensions of outlet glaciers and ice streams that take up about 44% of the coastline (Drewry et al., 1982) and are referred to as "ice shelves". Ice sheet mass loss accelerates when these ice shelves...
In order to evaluate the shallow stratigraphy along the southern Cascadia abyssal margin and northern California abyssal plain, CHIRP subbottom profiles capable of imaging individual turbidite beds in the upper tens of meters of the subsurface were collected. Reflectors imaged with the 3.5 kHz CHIRP subbottom data represent turbidite beds...
Quantifying the mass transport through marine sediments, and the geochemical response to such flow with numerical models has become a common and powerful approach for geochemical data interpretation. In this dissertation, I developed and applied transport-reaction models to unravel complex and interdependent reactions involving carbon, sulfur and silica transformations in...
Influences of tidal and slower (subtidal) oceanic flows over the continental shelf and slope off Oregon are studied using a high-resolution ocean circulation model and comparative model-data analyses. The model is based on the Regional Ocean Modeling System (ROMS), a fully nonlinear, three-dimensional model (using hydrostatic and Boussinesq approximations). The...
Analogous to ocean surface waves, waves in the ocean interior also experience steepening, breaking, and dissipation as they approach the coastline. Much less is known about this internal beach. In this work, extensive moored Acoustic Doppler Current Profiler and temperature/salinity data together with optical remote sensing are combined to describe...
Subduction zone earthquake and tsunami hazards affect tens of millions worldwide and the recurrence of these disasters can be evaluated with paleoseismic techniques, because earthquake cycles (and their supercycles) typically span many millennia. In these three chapters, I discuss a suite of analyses I use to evaluate the sedimentary record...
Euphausia pacifica, the North Pacific krill, is a key grazer in the California Current System and an important prey item for consumers such as salmon, seabirds, and whales. As a crucial link between phytoplankton and higher trophic levels, it is essential to understand both the behavior and bioenergetics of this...
The marine ecosystem provides a broad spectrum of services for a wide array of user groups. Such broad use of marine resources often results in use conflicts between ecosystem elements and human interests. To help mitigate these conflicts, the Bayesian Analysis for Spatial Siting (BASS) tool was developed to incorporate...
A new method is introduced for incorporating bathymetric uncertainty into predictions of nearshore and river flows (i.e., unstratified flows primarily forced by pressure and radiation stress gradients). The method involves the use of the ensemble Kalman filter (EnKF) as a parameter estimation scheme, where the parameter to be estimated is...
This paper details a method to compute absolute water velocity profiles from glider-based acoustic Doppler current profiler (ADCP) measurements based on the "shear method" developed for lowered ADCPs. The instrument is a 614-kHz Teledyne RDI ADCP integrated into the body of a Teledyne Webb Research Slocum Glider. Shear is calculated...
The influence of mesoscale ocean eddies on near-surface ocean temperature, surface stress and phytoplankton communities is investigated by collocating numerous satellite measurements along with vertical profiles of oceanic temperature and salinity to the interiors of eddies identified and tracked in altimetric sea surface height maps.
The surface currents associated with...
Understanding and modeling microbial responses and feedbacks to climate change is hampered by a lack of a framework in the pelagic environment by which to link local mechanism to large scale patterns. Where terrestrial ecology draws from landscape theory and practice to address issues of scale, the pelagic seascape concept...
Nearshore hypoxia within the Northern California Current (NCC) system is a seasonal phenomenon caused by coastal upwelling and occurs mainly during late-summer and early fall. The effects of low oxygen levels on fish and invertebrate communities, particularly during early-life history stages, however, are poorly known for this area. I investigated...
Pacific cod (Gadus macrocephalus) is an important species, both economically and ecologically in the Bering Sea and Aleutian Islands (BSAI). However, little is known about its spawning dynamics. To address this knowledge gap, I developed a gross anatomical maturity key for Pacific cod to assess temporal and spatial patterns of...
The rapid increase in atmospheric carbon dioxide (CO₂) over the last 250 years has led to the absorption of approximately 550 billion tons of anthropogenic CO₂ by the global ocean. This oceanic uptake of CO₂ has resulted in decreasing pH and alterations to carbonate chemistry, threatening many ecologically and economically...
The quantification and description of sea surface temperature (SST) is critically important because it can influence the distribution, migration, and invasion of marine species; furthermore, SSTs are expected to be affected by climate change. Recent research indicates that there has been a warming trend in ocean temperatures over the last...
This study investigated long-term (1961-2008) changes in albacore (Thunnus alalunga) abundance and distribution in relation to local environmental and large-scale climate indices in the Northeastern Pacific using time series and spatial analyses. Prior to the time series analysis, a wavelet analysis was conducted to examine nonrandom patterns of cyclical variability...
Deep-sea bamboo coral (Isidella sp.) SE000901A from the southern Oregon coast (water depth 1048m) provides a high-resolution record of variability of North Pacific Intermediate Water (NPIW) and carbon rain to the sea floor, related to coastal upwelling, from 1808 to 2000AD. Counting of annual layers in magnesium to calcium (Mg/Ca)...