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) 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

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 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

Large-scale bloom of Akashiwo sanguinea in the Northern California current system in 2009

Significant seabird mortality on the Oregon (OR) and Washington (WA) coast in 2009 has been attributed to a massive bloom of the dinoflagellate Akashiwo sanguinea (K. Hirasaka) G. Hansen & Ø. Moestrup. Initial, albeit limited, observations suggested this bloom began in WA and reached OR waters through southward transport. Here, we explore a combination of remote sensing products and an exceptional latitudinal dataset of plankton counts collected in the surfzone and offshore in OR and WA coastal waters. Records of satellite ocean color for this period support the new finding that blooms were concurrent in OR and WA waters, with no evidence for latitudinal propagation as had been previously suggested. Plankton analyses further indicate that there was a rapid and synchronized increase of A. sanguinea between late August and mid-September of 2009 along wide swaths of the OR and WA coasts. Bloom onset occurred during a prolonged quiescent and warm period in late August–early September, near the end of the March–October upwelling phase. An upwelling event in October likely contributed to foam production through vertical mixing of A. sanguinea rich waters. Bloom intensity peaked earlier and at higher levels in WA waters as compared to OR with cell concentrations exceeding 1.5 x 10⁶ cells L⁻¹ (WA) and ~350,000 cells L⁻¹ (OR). In OR samples, A. sanguinea cells comprised upwards of 90% of dinoflagellate cell counts and ~30% of total phytoplankton cells. At some locations, A. sanguinea persisted well into November–December of 2009, during which time satellite sea surface temperature records indicated anomalously warm surface waters (up to ~5°C greater than climatological means). Taken together, the data reveal a HAB event of a magnitude unprecedented in over a decade of observations. We hypothesize that these blooms originated from either a cryptic cyst bed and/or a pelagic seed bank of viable vegetative cells.Keywords: Upwelling, Seabird mortality, Cysts, Akashiwo sanguinea, HABS, Harmful algal blooms, Surf zone, DinoflagellatesKeywords: Upwelling, Seabird mortality, Cysts, Akashiwo sanguinea, HABS, Harmful algal blooms, Surf zone, Dinoflagellate

Monitoring Oregon Coastal Harmful Algae: Observations and implications of a harmful algal bloom-monitoring project

The accumulation of domoic acid (DA) and saxitoxins (STX), phycotoxins produced by some species of Pseudo-nitzschia and Alexandrium, respectively, in coastal food webs are a focus of research on the West Coast of the United States due to the deleterious effects they have on coastal ecosystems and economies. Results are presented from the 2007–2012 Monitoring Oregon Coastal Harmful Algae (MOCHA) project, the Oregon coast's first HAB monitoring and research program. Both historical toxin databases and more detailed case-study observations of individual HAB events are compiled to provide the first detailed overview of HAB occurrence in this region. These results are also presented in the context of informing future HAB monitoring in this and other upwelling regimes affected by STX and DA. A 2009–2010 warming event was associated with the greatest HAB activity during the MOCHA project, including anomalously high sea surface temperatures and shellfish harvesting closures due to STX and DA in 2009 and 2010, respectively. In regards to HAB monitoring, it is shown that (1) razor clams are a more sensitive indicator of DA than mussels; (2) water column concentrations of particulate domoic acid greater than 10³ng L⁻¹ can be used as a threshold for early-warning of shellfish DA toxicity and (3) approximately bi-weekly, or shorter, monitoring of Alexandrium in the surf zone and/or offshore can provide advance notice of STX contamination of shellfish. Both of the latter two metrics gain added value when coupled with local wind stress, a proxy of downwelling/relaxation events that facilitate greater interaction between offshore blooms and shellfish.Keywords: Oregon coast, Saxitoxin, Domoic acid, Alexandrium, Harmful algal bloom, Pseudo-nitzschi

Phytoplankton composition from sPACE: Requirements, opportunities, and challenges

Ocean color satellites have provided a synoptic view of global phytoplankton for over 25 years through near surface measurements of the concentration of chlorophyll a. While remote sensing of ocean color has revolutionized our understanding of phytoplankton and their role in the oceanic and freshwater ecosystems, it is important to consider both total phytoplankton biomass and changes in phytoplankton community composition in order to fully understand the dynamics of the aquatic ecosystems. With the upcoming launch of NASA\u27s Plankton, Aerosol, Clouds, ocean Ecosystem (PACE) mission, we will be entering into a new era of global hyperspectral data, and with it, increased capabilities to monitor phytoplankton diversity from space. In this paper, we analyze the needs of the user community, review existing approaches for detecting phytoplankton community composition in situ and from space, and highlight the benefits that the PACE mission will bring. Using this three-pronged approach, we highlight the challenges and gaps to be addressed by the community going forward, while offering a vision of what global phytoplankton community composition will look like through the “eyes” of PACE

WhiteAngelicqueCEOASLarge-ScaleBloom.pdf

Significant seabird mortality on the Oregon (OR) and Washington (WA) coast in 2009 has been attributed to a massive bloom of the dinoflagellate Akashiwo sanguinea (K. Hirasaka) G. Hansen & Ø. Moestrup. Initial, albeit limited, observations suggested this bloom began in WA and reached OR waters through southward transport. Here, we explore a combination of remote sensing products and an exceptional latitudinal dataset of plankton counts collected in the surfzone and offshore in OR and WA coastal waters. Records of satellite ocean color for this period support the new finding that blooms were concurrent in OR and WA waters, with no evidence for latitudinal propagation as had been previously suggested. Plankton analyses further indicate that there was a rapid and synchronized increase of A. sanguinea between late August and mid-September of 2009 along wide swaths of the OR and WA coasts. Bloom onset occurred during a prolonged quiescent and warm period in late August–early September, near the end of the March–October upwelling phase. An upwelling event in October likely contributed to foam production through vertical mixing of A. sanguinea rich waters. Bloom intensity peaked earlier and at higher levels in WA waters as compared to OR with cell concentrations exceeding 1.5 x 10⁶ cells L⁻¹ (WA) and ~350,000 cells L⁻¹ (OR). In OR samples, A. sanguinea cells comprised upwards of 90% of dinoflagellate cell counts and ~30% of total phytoplankton cells. At some locations, A. sanguinea persisted well into November–December of 2009, during which time satellite sea surface temperature records indicated anomalously warm surface waters (up to ~5°C greater than climatological means). Taken together, the data reveal a HAB event of a magnitude unprecedented in over a decade of observations. We hypothesize that these blooms originated from either a cryptic cyst bed and/or a pelagic seed bank of viable vegetative cells.Keywords: HABS, Harmful algal blooms, Seabird mortality, Surf zone, Dinoflagellates, Akashiwo sanguinea, Upwelling, Cyst

WhiteAngelicqueCEOASLarge-ScaleBloom_Corrigendum.pdf

Significant seabird mortality on the Oregon (OR) and Washington (WA) coast in 2009 has been attributed to a massive bloom of the dinoflagellate Akashiwo sanguinea (K. Hirasaka) G. Hansen & Ø. Moestrup. Initial, albeit limited, observations suggested this bloom began in WA and reached OR waters through southward transport. Here, we explore a combination of remote sensing products and an exceptional latitudinal dataset of plankton counts collected in the surfzone and offshore in OR and WA coastal waters. Records of satellite ocean color for this period support the new finding that blooms were concurrent in OR and WA waters, with no evidence for latitudinal propagation as had been previously suggested. Plankton analyses further indicate that there was a rapid and synchronized increase of A. sanguinea between late August and mid-September of 2009 along wide swaths of the OR and WA coasts. Bloom onset occurred during a prolonged quiescent and warm period in late August–early September, near the end of the March–October upwelling phase. An upwelling event in October likely contributed to foam production through vertical mixing of A. sanguinea rich waters. Bloom intensity peaked earlier and at higher levels in WA waters as compared to OR with cell concentrations exceeding 1.5 x 10⁶ cells L⁻¹ (WA) and ~350,000 cells L⁻¹ (OR). In OR samples, A. sanguinea cells comprised upwards of 90% of dinoflagellate cell counts and ~30% of total phytoplankton cells. At some locations, A. sanguinea persisted well into November–December of 2009, during which time satellite sea surface temperature records indicated anomalously warm surface waters (up to ~5°C greater than climatological means). Taken together, the data reveal a HAB event of a magnitude unprecedented in over a decade of observations. We hypothesize that these blooms originated from either a cryptic cyst bed and/or a pelagic seed bank of viable vegetative cells.Keywords: Surf zone, HABS, Akashiwo sanguinea, Upwelling, Seabird mortality, Cysts, Dinoflagellates, Harmful algal bloom

Monitoring Oregon Coastal Harmful Algae: Observations and implications of a harmful algal bloom-monitoring project

AbstractThe accumulation of domoic acid (DA) and saxitoxins (STX), phycotoxins produced by some species of Pseudo-nitzschia and Alexandrium, respectively, in coastal food webs are a focus of research on the West Coast of the United States due to the deleterious effects they have on coastal ecosystems and economies. Results are presented from the 2007–2012 Monitoring Oregon Coastal Harmful Algae (MOCHA) project, the Oregon coast's first HAB monitoring and research program. Both historical toxin databases and more detailed case-study observations of individual HAB events are compiled to provide the first detailed overview of HAB occurrence in this region. These results are also presented in the context of informing future HAB monitoring in this and other upwelling regimes affected by STX and DA. A 2009–2010 warming event was associated with the greatest HAB activity during the MOCHA project, including anomalously high sea surface temperatures and shellfish harvesting closures due to STX and DA in 2009 and 2010, respectively. In regards to HAB monitoring, it is shown that (1) razor clams are a more sensitive indicator of DA than mussels; (2) water column concentrations of particulate domoic acid greater than 103ngL−1 can be used as a threshold for early-warning of shellfish DA toxicity and (3) approximately bi-weekly, or shorter, monitoring of Alexandrium in the surf zone and/or offshore can provide advance notice of STX contamination of shellfish. Both of the latter two metrics gain added value when coupled with local wind stress, a proxy of downwelling/relaxation events that facilitate greater interaction between offshore blooms and shellfish