Search

Search Results

• 1. [Article] Iron, nutrient, and phytoplankton distributions in Oregon coastal waters

  Copyrighted by American Geophysical Union.

  Citation × Citation Citation Abstract Copy Title: Iron, nutrient, and phytoplankton distributions in Oregon coastal waters Author: Wheeler, Patricia A., Chase, Zanna, Marra, John, van Geen, Alexander, Kosro, P. Michael, 1951- Copyrighted by American Geophysical Union. Title: Iron, nutrient, and phytoplankton distributions in Oregon coastal waters Author: Wheeler, Patricia A., Chase, Zanna, Marra, John, van Geen, Alexander, Kosro, P. Michael, 1951- Copyrighted by American Geophysical Union. Close

• 2. [Article] Distribution and variability of iron input to Oregon coastal waters during the upwelling season

  Copyrighted by American Geophysical Union.

  Citation × Citation Citation Abstract Copy Title: Distribution and variability of iron input to Oregon coastal waters during the upwelling season Author: Schwartz, Roseanne, Hales, Burke, Chase, Zanna, Cowles, Timothy J., van Geen, Alexander Copyrighted by American Geophysical Union. Title: Distribution and variability of iron input to Oregon coastal waters during the upwelling season Author: Schwartz, Roseanne, Hales, Burke, Chase, Zanna, Cowles, Timothy J., van Geen, Alexander Copyrighted by American Geophysical Union. Close

• 3. [Article] Temporal variation of hydrological exchange and hyporheic biogeochemistry in a headwater stream during autumn

  This is the author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by The North American Benthological Society and can be found at: http://www.freshwater-science.org/Journal.aspx. As ...

  Citation × Citation Citation Abstract Copy Title: Temporal variation of hydrological exchange and hyporheic biogeochemistry in a headwater stream during autumn Author: Ribot, Miquel, Marti, Eugenia, Sabater, Francesc, Argerich, Alba This is the author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by The North American Benthological Society and can be found at: http://www.freshwater-science.org/Journal.aspx. As of 2012, the Journal of the North American Benthological Society is called Freshwater Science and is published by The Society for Freshwater Science. Title: Temporal variation of hydrological exchange and hyporheic biogeochemistry in a headwater stream during autumn Author: Ribot, Miquel, Marti, Eugenia, Sabater, Francesc, Argerich, Alba This is the author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by The North American Benthological Society and can be found at: http://www.freshwater-science.org/Journal.aspx. As of 2012, the Journal of the North American Benthological Society is called Freshwater Science and is published by The Society for Freshwater Science. Close

• 4. [Article] Atmosperic CO₂ uptake by a coastal upwelling system

  Copyrighted by American Geophysical Union.

  Citation × Citation Citation Abstract Copy Title: Atmosperic CO₂ uptake by a coastal upwelling system Author: Takahashi, Taro, Hales, Burke, Bandstra, Leah M. Copyrighted by American Geophysical Union. Title: Atmosperic CO₂ uptake by a coastal upwelling system Author: Takahashi, Taro, Hales, Burke, Bandstra, Leah M. Copyrighted by American Geophysical Union. Close

• 5. [Article] Analysis of particulate organic matter distribution along surface waters of the California Current

  Water samples along the Washington, Oregon and California coastline were collected using high resolution sampling and analyzed to determine particulate organic carbon and nitrogen concentrations. Over ...

  Citation × Citation Citation Abstract Copy Title: Analysis of particulate organic matter distribution along surface waters of the California Current Author: Welch, Kylie Water samples along the Washington, Oregon and California coastline were collected using high resolution sampling and analyzed to determine particulate organic carbon and nitrogen concentrations. Over 28 days during August 2011, nearly 1500 samples were collected aboard the R/V Wecoma (W1108C) using a semi-automated filtration system. Additional subsurface samples were collected from CTD casts. In-situ measurements of temperature, salinity, chlorophyll fluorescence, and beam attenuation were combined with the data from individual samples to provide a near-synoptic, spatial distribution of particulate organic matter along the California Current. Marked contrasts in the concentrations and compositions of particulate organic matter were observed among different water masses along the margin, including those directly affected by Columbia River discharge, recently upwelled near-shore waters, and filaments associated with mesoscales eddies. My results demonstrate the utility of high-resolution sampling techniques can be integrated with remote sensing approaches to better understand physical-biological interactions in the coastal ocean. Title: Analysis of particulate organic matter distribution along surface waters of the California Current Author: Welch, Kylie Water samples along the Washington, Oregon and California coastline were collected using high resolution sampling and analyzed to determine particulate organic carbon and nitrogen concentrations. Over 28 days during August 2011, nearly 1500 samples were collected aboard the R/V Wecoma (W1108C) using a semi-automated filtration system. Additional subsurface samples were collected from CTD casts. In-situ measurements of temperature, salinity, chlorophyll fluorescence, and beam attenuation were combined with the data from individual samples to provide a near-synoptic, spatial distribution of particulate organic matter along the California Current. Marked contrasts in the concentrations and compositions of particulate organic matter were observed among different water masses along the margin, including those directly affected by Columbia River discharge, recently upwelled near-shore waters, and filaments associated with mesoscales eddies. My results demonstrate the utility of high-resolution sampling techniques can be integrated with remote sensing approaches to better understand physical-biological interactions in the coastal ocean. Close

• 6. [Article] Variability in mesoscale circulation and its effects on zooplankton distribution in the Northern California Current

  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 ...

  Citation × Citation Citation Abstract Copy Title: Variability in mesoscale circulation and its effects on zooplankton distribution in the Northern California Current Author: Keister, Julie Eileen 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 taxa and biomass in the California Current System was studied using data collected as part of the U.S. Global Ocean Ecosystems Dynamics (GLOBEC) Northeast Pacific Program. Sea surface height from >13 years of satellite altimeter data was used to characterize the spatial and temporal variability in mesoscale circulation in the northern California Current (35°N-49°N) and explore mechanisms of variability. High spatial and temporal variation in mesoscale energy occurred. Energy was not strongly linked to upwelling winds, but did correspond to climate indices, indicating that basin-scale processes play a role in controlling the circulation. CTD casts, zooplankton net tows, and Acoustic Doppler Current Profiler (ADCP) velocities collected during a research cruise conducted in summer 2000 off Oregon and northern California were used to describe the effects of mesoscale circulation on distributions of zooplankton. During the cruise, a filament of the coastal upwelling jet extended seaward of Cape Blanco (42.8°N) resulting in the displacement of coastal zooplankton to >100 km off the continental shelf. Velocities and standing stocks of zooplankton were used to estimate seaward transport of 0.5 Sv in the upper 100 m of the filament, in which zooplankton biomass averaged ~20 mg carbon/m³. That offshore transport equated to >900 metric tons of carbon each day, and 4-5x10⁴ tons over the 6-8 week lifetime of the circulation feature. Although the flux represented a small portion (<2%) of the shelf zooplankton biomass, the transport resulted in an offshore "hot-spot" in which biomass was 3-4X higher than in the surrounding ocean. Distributions of early life history stages of euphausiids indicated that retention of coastal populations may be strongly affected by the offshore advection. Finally, satellite sea surface temperature (SST) and sampling conducted during five summers were used to explore variability in the relationship between mesoscale circulation features and distributions of zooplankton. Circulation patterns differed among cruises and were reflected in zooplankton distributions. Circulation features resulted in the occurrence of cold surface water and coastal taxa offshore, but species abundances and presence/absence of taxa at specific locations were not predictable from satellite SSTs. These results are relevant to studies of ecosystem dynamics and the global carbon cycle because mesoscale circulation plays an important role in the seaward transport of carbon, retention and loss of taxa from the continental shelf, and creation of offshore structure which may be exploited by upper trophic level organisms. Title: Variability in mesoscale circulation and its effects on zooplankton distribution in the Northern California Current Author: Keister, Julie Eileen 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 taxa and biomass in the California Current System was studied using data collected as part of the U.S. Global Ocean Ecosystems Dynamics (GLOBEC) Northeast Pacific Program. Sea surface height from >13 years of satellite altimeter data was used to characterize the spatial and temporal variability in mesoscale circulation in the northern California Current (35°N-49°N) and explore mechanisms of variability. High spatial and temporal variation in mesoscale energy occurred. Energy was not strongly linked to upwelling winds, but did correspond to climate indices, indicating that basin-scale processes play a role in controlling the circulation. CTD casts, zooplankton net tows, and Acoustic Doppler Current Profiler (ADCP) velocities collected during a research cruise conducted in summer 2000 off Oregon and northern California were used to describe the effects of mesoscale circulation on distributions of zooplankton. During the cruise, a filament of the coastal upwelling jet extended seaward of Cape Blanco (42.8°N) resulting in the displacement of coastal zooplankton to >100 km off the continental shelf. Velocities and standing stocks of zooplankton were used to estimate seaward transport of 0.5 Sv in the upper 100 m of the filament, in which zooplankton biomass averaged ~20 mg carbon/m³. That offshore transport equated to >900 metric tons of carbon each day, and 4-5x10⁴ tons over the 6-8 week lifetime of the circulation feature. Although the flux represented a small portion (<2%) of the shelf zooplankton biomass, the transport resulted in an offshore "hot-spot" in which biomass was 3-4X higher than in the surrounding ocean. Distributions of early life history stages of euphausiids indicated that retention of coastal populations may be strongly affected by the offshore advection. Finally, satellite sea surface temperature (SST) and sampling conducted during five summers were used to explore variability in the relationship between mesoscale circulation features and distributions of zooplankton. Circulation patterns differed among cruises and were reflected in zooplankton distributions. Circulation features resulted in the occurrence of cold surface water and coastal taxa offshore, but species abundances and presence/absence of taxa at specific locations were not predictable from satellite SSTs. These results are relevant to studies of ecosystem dynamics and the global carbon cycle because mesoscale circulation plays an important role in the seaward transport of carbon, retention and loss of taxa from the continental shelf, and creation of offshore structure which may be exploited by upper trophic level organisms. Close

• 7. [Article] Above and Below : Oregon Coastal Phytoplankton Bloom Dynamics from Sea and Space

  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 ...

  Citation × Citation Citation Abstract Copy Title: Above and Below : Oregon Coastal Phytoplankton Bloom Dynamics from Sea and Space Author: McKibben, S. Morgaine 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 satellites) are applied to investigate phytoplankton bloom dynamics from event to regional and climate scales along the Oregon coastal region, a productive eastern boundary upwelling regime. Chapters 2 and 3 investigate patterns in, and mechanisms behind, Oregon coastal harmful algal blooms (HABs). Chapter 2 presents the temporal and spatial occurrence of HAB events in this region and investigates ecological conditions associated with them. Elevated HAB activity was observed in 2009-2010 and coincided with anomalously warm ocean conditions, specifically a brief change in the Pacific Decadal Oscillation (PDO) to a warm phase and a coincident El Nino event. Through these analyses, key parameters came to the forefront as informative to future monitoring efforts such as wind stress, a metric for when putative blooms may move on/off shore, particulate dissolved domoic acid in surface waters, and the abundance of Alexandrium spp. which appear to be strongly predictive of potential saxitoxin contamination of shellfish. Chapter 3 provides the first evidence of climatic regulation of domoic acid in shellfish over the past 20 years in the Northern California Current regime. The timing of elevated domoic acid and changes in plankton communities are found to be strongly related to warm phases of the PDO and the Oceanic Nino Index, an indicator of El Nino events. Based on these findings, a risk assessment model is developed to forecast bloom events. Chapter 4 explores patterns in the surface (horizontal) and depth (vertical) distribution of phytoplankton based on the universal autotrophic pigment chl-a. Results were considered with respect to season (upwelling or downwelling) and region (high chl-a nearshore to low chl-a offshore). Applications of glider-based primary productivity models to evaluating satellite-based estimates of ocean primary productivity are discussed. The research presented in this dissertation shows the power of long-term ocean observations from a variety of vantage points to describe the patterns and processes in the vast ocean that affect the tiniest of Earth's photosynthetic life. Title: Above and Below : Oregon Coastal Phytoplankton Bloom Dynamics from Sea and Space Author: McKibben, S. Morgaine 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 satellites) are applied to investigate phytoplankton bloom dynamics from event to regional and climate scales along the Oregon coastal region, a productive eastern boundary upwelling regime. Chapters 2 and 3 investigate patterns in, and mechanisms behind, Oregon coastal harmful algal blooms (HABs). Chapter 2 presents the temporal and spatial occurrence of HAB events in this region and investigates ecological conditions associated with them. Elevated HAB activity was observed in 2009-2010 and coincided with anomalously warm ocean conditions, specifically a brief change in the Pacific Decadal Oscillation (PDO) to a warm phase and a coincident El Nino event. Through these analyses, key parameters came to the forefront as informative to future monitoring efforts such as wind stress, a metric for when putative blooms may move on/off shore, particulate dissolved domoic acid in surface waters, and the abundance of Alexandrium spp. which appear to be strongly predictive of potential saxitoxin contamination of shellfish. Chapter 3 provides the first evidence of climatic regulation of domoic acid in shellfish over the past 20 years in the Northern California Current regime. The timing of elevated domoic acid and changes in plankton communities are found to be strongly related to warm phases of the PDO and the Oceanic Nino Index, an indicator of El Nino events. Based on these findings, a risk assessment model is developed to forecast bloom events. Chapter 4 explores patterns in the surface (horizontal) and depth (vertical) distribution of phytoplankton based on the universal autotrophic pigment chl-a. Results were considered with respect to season (upwelling or downwelling) and region (high chl-a nearshore to low chl-a offshore). Applications of glider-based primary productivity models to evaluating satellite-based estimates of ocean primary productivity are discussed. The research presented in this dissertation shows the power of long-term ocean observations from a variety of vantage points to describe the patterns and processes in the vast ocean that affect the tiniest of Earth's photosynthetic life. Close

• 8. [Article] A modeling study of shelf circulation off northern California in the region of the Coastal Ocean Dynamics Experiment : response to relaxation of upwelling winds

  copyrighted by American Geophysical Union

  Citation × Citation Citation Abstract Copy Title: A modeling study of shelf circulation off northern California in the region of the Coastal Ocean Dynamics Experiment : response to relaxation of upwelling winds Author: Gan, Jianping, Allen, John S. copyrighted by American Geophysical Union Title: A modeling study of shelf circulation off northern California in the region of the Coastal Ocean Dynamics Experiment : response to relaxation of upwelling winds Author: Gan, Jianping, Allen, John S. copyrighted by American Geophysical Union Close

• 9. [Article] Development of satellite bloom detection products for coastal Oregon

  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) ...

  Citation × Citation Citation Abstract Copy Title: Development of satellite bloom detection products for coastal Oregon Author: McKibben, S. Morgaine 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 to detect bloom onset via satellite in a region typified by high-frequency biological variability at the time scale of days and persistent cloud cover. Daily CHL[subscript dev] and FLH[subscript dev] imagery highlights the geographic locations of greatest temporal change observed between weekly average CHL or FLH products over time, providing a way to track the onset and advection of algal blooms. "Bloom indices" based on CHL[subscript dev] and FLH[subscript dev] were developed as a temporal metric of regional-scale bloom events. Comparison of these indices to in situ mooring data collected off the central Oregon coast from summer 2009 through winter 2010 demonstrated successful detection of all upwelling-induced bloom events, plus a late-season harmful algal bloom associated with wind relaxation and warming surface waters. During summer and autumn of 2009, significant correlation was observed between blooms detected by the CHL[subscript dev] and FLH[subscript dev] indices and two in situ metrics of upwelling-favorable conditions: 1) temperature, with temporal lags of -1 (r=-0.41) and 0 days (r=-0.45), respectively, and wind stress, with temporal lags of +2 (r=-0.25 and -0.41, respectively). Consistent with the regional oceanography, winds were shown to be dominant drivers of observed blooms during the summer and autumn. Winter 2009 through spring 2010 yielded high-variability bloom indices, due to frequent, variable cloud coverage, and no significant correlation was observed between the indices and in situ data. Coupled with physical proxies collected via satellite or in situ, these products provide an excellent foundation for remote bloom detection in Oregon’s coastal waters and regions with similar biological and physical conditions. Title: Development of satellite bloom detection products for coastal Oregon Author: McKibben, S. Morgaine 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 to detect bloom onset via satellite in a region typified by high-frequency biological variability at the time scale of days and persistent cloud cover. Daily CHL[subscript dev] and FLH[subscript dev] imagery highlights the geographic locations of greatest temporal change observed between weekly average CHL or FLH products over time, providing a way to track the onset and advection of algal blooms. "Bloom indices" based on CHL[subscript dev] and FLH[subscript dev] were developed as a temporal metric of regional-scale bloom events. Comparison of these indices to in situ mooring data collected off the central Oregon coast from summer 2009 through winter 2010 demonstrated successful detection of all upwelling-induced bloom events, plus a late-season harmful algal bloom associated with wind relaxation and warming surface waters. During summer and autumn of 2009, significant correlation was observed between blooms detected by the CHL[subscript dev] and FLH[subscript dev] indices and two in situ metrics of upwelling-favorable conditions: 1) temperature, with temporal lags of -1 (r=-0.41) and 0 days (r=-0.45), respectively, and wind stress, with temporal lags of +2 (r=-0.25 and -0.41, respectively). Consistent with the regional oceanography, winds were shown to be dominant drivers of observed blooms during the summer and autumn. Winter 2009 through spring 2010 yielded high-variability bloom indices, due to frequent, variable cloud coverage, and no significant correlation was observed between the indices and in situ data. Coupled with physical proxies collected via satellite or in situ, these products provide an excellent foundation for remote bloom detection in Oregon’s coastal waters and regions with similar biological and physical conditions. Close

• 10. [Article] High-resolution sampling of particulate organic carbon in a coastal upwelling system

  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 ...

  Citation × Citation Citation Abstract Copy Title: High-resolution sampling of particulate organic carbon in a coastal upwelling system Author: Holser, Rachel R. 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 (BBL). POC can be transformed during transport by heterotrophic metabolism, thus changing its concentration and composition. To better understand the dynamics of POC within the water column of this highly variable system, we developed a semi-automated filtration system that, when coupled to a towed profiling/sampling vehicle, allowed us to collect POC samples at higher spatial and temporal resolution than previously possible. During late May of 2009 we used this system to collect around 400 POC samples from two cross-shelf transects off the central Oregon coast spanning the ranges between BBL and surface mixed layer, and shelfbreak to shoreline. These samples were collected in conjunction with in-situ measurements of temperature, salinity, chlorophyll fluorescence, optical backscatter, and beam attenuation coefficients. Analyses of both the optical and bulk measurements indicate the presence of three distinct particle pools. The first pool is rich in POC and shows elevated fluorescence and beam-c relative to optical backscatter. The second pool is elevated in both fluorescence and optical backscatter, and is rich in POC relative to beam-c. The third pool is depleted in POC and shows proportionately elevated backscatter. Using variations in the optical properties of these three particle pools, we created multiple POC – beam-c calibrations, which allowed us to derive high-resolution POC distributions within the water column. This derived distribution indicates a decoupling between sediment and carbon in the BBL, and an unanticipated elevation of POC in the mid water column. Title: High-resolution sampling of particulate organic carbon in a coastal upwelling system Author: Holser, Rachel R. 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 (BBL). POC can be transformed during transport by heterotrophic metabolism, thus changing its concentration and composition. To better understand the dynamics of POC within the water column of this highly variable system, we developed a semi-automated filtration system that, when coupled to a towed profiling/sampling vehicle, allowed us to collect POC samples at higher spatial and temporal resolution than previously possible. During late May of 2009 we used this system to collect around 400 POC samples from two cross-shelf transects off the central Oregon coast spanning the ranges between BBL and surface mixed layer, and shelfbreak to shoreline. These samples were collected in conjunction with in-situ measurements of temperature, salinity, chlorophyll fluorescence, optical backscatter, and beam attenuation coefficients. Analyses of both the optical and bulk measurements indicate the presence of three distinct particle pools. The first pool is rich in POC and shows elevated fluorescence and beam-c relative to optical backscatter. The second pool is elevated in both fluorescence and optical backscatter, and is rich in POC relative to beam-c. The third pool is depleted in POC and shows proportionately elevated backscatter. Using variations in the optical properties of these three particle pools, we created multiple POC – beam-c calibrations, which allowed us to derive high-resolution POC distributions within the water column. This derived distribution indicates a decoupling between sediment and carbon in the BBL, and an unanticipated elevation of POC in the mid water column. Close