The effects of alongshore variability in topography (banks and capes) and spatial variability in the wind forcing, including the wind-stress curl, on coastal ocean circulation are studied using a combination of observations and model simulations. Satellite sea surface temperature observations are used to describe the seasonal evolution of temperature fronts...
Temperature, salinity, and dissolved oxygen concentration
measured in an estuary were analyzed to determine if the effects of
coastal upwelling could be observed and used to effectively monitor
the degree of upwelling.
Hydrographic data collected weekly at a point four miles from
the entrance of Yaquina Bay (Buoy 15) were...
The distribution patterns of quartz and opal contents and the distribution
patterns of radiolarian assemblages, in the sediments of the
southeastern Pacific, are largely controlled by both the surface winds
and the mixed-layer oceanic circulation. The distribution pattern of
quartz is related to eolian and ice-rafted transport, as well as...
A finite difference scheme is employed to solve the
integral form of the momentum, continuity and heat
equations, for a two layer ocean bounded by a coastline.
The momentum equations include the turbulent dynamics and
the time-dependent and nonlinear terms in both the
cross-shelf and alongshelf directions. The system of...
A cruise of the R/V Yaquina off Oregon during June and July of
1968 provided data for a study of the relationships of hydrographic
and chemical parameters to estimates of biological activity. The
emphasis was on carbon and nitrogen reservoirs. Phytoplankton pigments,
nitrogen and C/N ratio were used along with...
A method is described for determining the absolute dynamic topography of the sea surface. Using hydrographic and wind data obtained in 1963, the surface topography and the horizontal and vertical mass transports off the southeast Arabian coast during the summer monsoon are calculated. As indicated by the calculations, upwelling occurs...
The relationship between sea level and wind stress in a region of
known upwelling was studied for an eleven-month period during
1933-34.
Sea level data, obtained from observations taken by the Coast and
Geodetic Survey, were processed to remove astronomic tidal constituents
and inverted barometer effect. Regression analysis was used...
Understanding how large-scale processes (>100 kms) influence ecological communities is currently a major focus in ecology. In marine systems, coastal upwelling, a large-scale oceanographic process in which surface water pushed offshore by winds is replaced by cold, nutrient-rich water from depth, appears to cause variation in rocky intertidal communities. Along...
The Oregon upwelling system is a region of high biomass and primary
productivity as well as strong mesoscale variability. In order to examine the
interaction of physical forcing and ecosystem dynamics, four 3-week sampling
cruises were conducted in the Oregon upwelling system as part of the Northeast
Pacific Global Ocean...
Diatom floral analysis of 116 sediment surface samples obtained off Peru reveals a boundary in the sediments between coastal upwelling influenced sediments and sediments outside the highly productive realm. Sinuous patterns of relative abundance for meroplanktic species (Actinocyclus octonarius, Actinoptychus senarius, and Cyclotella striata/stilorum) may preserve the meander-like patterns of...
The Oregon continental shelf waters are typically characterized by four to five major upwelling events that occur between May and October. The upwelled water is rich in nutrients, which fuels an increase in phytoplankton biomass. The onset of El Nino, however, can disrupt the normal physical processes along the Oregon...
Hydrographic observations were made over the continental shelf and slope off Oregon during the 1973 Coastal Upwelling Experiment (CUE-II) from three ships: R/V OCEANOGRAPHER, R/V THOMAS G. THOMPSON, and R/V YAQUINA. This report contains the observations made on four YAQUINA cruises between June and August 1973 (Table I). Observations were...
This dissertation focuses on the importance of pelagic subsidies in the Northeast Pacific to rocky shore community regulation. My results document the patterns of pelagic subsidy supply, determine if those subsidies are correlated with community structure, and examine if community regulation differs between areas of high- and low-subsidies. Understanding how...
Within systems characterized by substantial spatial and temporal variability, abundances of organisms tend to be higher in localized areas. Within the northern California Current system, the identification of such marine, biological hotspots would be of great importance to resource managers, conservationists, and research planners, and is consequently a growing area...
The effects of wind forcing on coastal ocean circulation are studied using a
numerical modeling approach. The first region of interest is on the North Carolina
shelf, where the Coastal Ocean Processes (CoOP) Inner Shelf Study (ISS) took place
during August - November 1994. ISS observations are used to initialize,...
The objectives of this dissertation were to describe the complex oceanographic conditions around the Galápagos Archipelago (eastern equatorial Pacific), their seasonal variability, and their effects on patterns of cetacean occurrence. The physical and ecological factors leading to a plume of high phytoplankton biomass in the wake of the Galápagos were...
Past studies of the Oregon and Washington coast have shown a rapid change in the coastal ocean conditions with the onset of upwelling in spring. This process, called the spring transition marks the change from winter to summer conditions along the west coast of Unites States. To examine the interannual...
Temperature, salinity, density and turbulent dissipation profiles measured using the Rapid Sampling Vertical Profiler during the Coastal Transition Zone Experiment, July 1988.
In this report we will present vertical sections of temperature, salinity and sigma-t from both CTD and bottle casts made on legs 1-5 of the R/V Eastward during JASON, and from CTD casts made on legs 1, 2 and 4 of the R/V Melville and legs .2 and 4 of...
The area near Point Arguello has long been recognized as a location of strong
upwelling. A tongue of biologically active waters was observed in the earliest studies of
this region (Sverdrup and Allen, 1939). More recently, satellite estimates of chlorophyll by
the Coastal Zone Color Scanner (CZCS) on Nimbus-7 have...
Coastal-based high-frequency (HF) radar systems are an increasingly used tool for measuring surface currents in the coastal ocean. These systems provide a spatial and temporal resolution not achievable with other methods. Standard-range sites typically generate hourly maps of surface currents on a 2km grid extending approximately 50km from shore while...
Various methods of presenting and mathematically describing particle
size distribution are explained and evaluated. The hyperbolic
distribution is found to be the most practical but the more complex
characteristic vector analysis is the most sensitive to changes in
the shape of the particle size distributions.
Particle size distribution, nutrient concentrations,...
In eastern boundary current upwelling ecosystems, mesoscale circulation features such as eddies and upwelling filaments play a prominent role in the transfer of water and the associated plankton from the productive nearshore to the oligotrophic deep sea. The relationship between mesoscale circulation, zooplankton distributions, and the across-shelf transport of coastal...
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...
Two bloom-detection products were developed for the Oregon coast that describe the relative percent change observed between successive pairs of 8-day chlorophyll-a (CHL) and fluorescence line-height (FLH) products obtained from the MODerate Resolution Imaging Spectroradiometer aboard the Aqua spacecraft (MODIS-Aqua). The CHL[subscript dev] and FLH[subscript dev] products, respectively, were optimized...
Marine fish are subject to direct and indirect oceanographic variations operating at short and long time scales. In this study feeding habits and long-term growth condition of several groundfish species of the Pacific Northwest are examined to understand the relationship between variations in the fish's biological and life history components...
The influence of large-scale processes on natural communities has become one of the central issues of modern ecology. I combined field and laboratory studies to investigate the effects of variation in coastal upwelling on rocky intertidal communities along the central Oregon coast. I examined whether the growth of intertidal barnacles...
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...
Most climate change predictions focus on the response of individual species to changing local conditions and ignore species interactions, largely due to the lack of a sound theoretical foundation for how interactions are expected to change with climate and how to incorporate them into climate change models. Much of the...
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)...
The high productivity of Eastern Boundary Upwelling Ecosystems (EBUE), some of the most productive ecosystems in the globe, is attributed to the nutrient rich waters brought up through upwelling. Climate change scenarios for coastal upwelling systems, predict an intensification of coastal upwelling winds. Associated with intensification in upwelling are biogeochemical...
Foundation species are important components of ecosystems because they provide habitat and ameliorate stressful conditions for residents. This thesis considers the role of surfgrasses (Phyllospadix spp.) as dynamic foundation species on the coast of Oregon in two studies. Chapter 2, which presents an observational survey of two Phyllospadix congeners, investigates...
Summertime, wind-driven upwelling off the Oregon coast delivers nutrient rich water to the surface that fuels the autotrophic production of particulate organic carbon (POC). This POC can be transported horizontally by fluid motions and vertically by sinking to the bottom where it can be entrained in the benthic boundary layer...
In the summer of 2007, a biophysical experiment was conducted to identify physical processes that determine the delivery of invertebrate larvae and juvenile rockfish to rocky intertidal and kelp forest communities in northern Monterey Bay, California. The experiment was sponsored by the Partnership for Interdisciplinary
Studies of Coastal Oceans (PISCO)...
This dissertation investigates the context-dependency of species interactions between seagrass and macroalgae in upwelling-influenced estuaries. In all coastal systems, nutrient loading is multidirectional, resulting from mostly freshwater and marine inputs. The directionality of nutrient inputs may affect the rate of supply of organic matter to the system. In systems where...
The multifaceted role of the environment in regulating the structure and dynamics of biological communities has long fascinated ecologists and motivated much debate and research. Now, in a time of accelerated global changes due to human impacts, the need to understand how the environment shapes communities has gained new urgency....
Small pelagic fish represent a critical trophic link between plankton and large predators in marine upwelling ecosystems such as the California Current System. Populations of these fish are highly variable over time and are characterized by extreme fluctuations in abundance, which have significant ecosystem impacts. The causes driving
this instability...
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...
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...
Recruitment of larvae from the plankton is an important determinant of
community structure in marine systems. In populations of many marine species,
recruitment determines the basic demographic parameters of immigration, emigration,
and reproduction. Moreover, the effect of recruitment as an "ecological subsidy" can
determine the strength of interactions among species...