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Brian Bergamaschi (Former Employee)

Science and Products

Filter Total Items: 22
Satellite image of South San Francisco Bay

Remote Sensing of Mercury Pollution in South San Francisco Bay

San Francisco Bay has a long history of being subject to natural resources exploitation and pollution. Ongoing flux of contaminants into the bay, legacy pollution from the Gold Rush era and structural modifications still influence the natural ecosystem today. This project aims to map multiple forms (i.e. species) of mercury -- one of the major contaminants in the bay -- to help inform restoration...
By
Western Geographic Science Center
Remote Sensing of Mercury Pollution in South San Francisco Bay

Remote Sensing of Mercury Pollution in South San Francisco Bay

San Francisco Bay has a long history of being subject to natural resources exploitation and pollution. Ongoing flux of contaminants into the bay, legacy pollution from the Gold Rush era and structural modifications still influence the natural ecosystem today. This project aims to map multiple forms (i.e. species) of mercury -- one of the major contaminants in the bay -- to help inform restoration...
Learn More
Image Collage of Landsat, pollinator, and volcanologist

Assessing impacts of wildfire on water and habitat quality in downstream aquatic ecosystems using remote sensing

This project focuses on the downstream effects of wildfires on lakes, reservoirs, and coastal water within the larger context of the USGS project on Post-fire Hazards and Impacts to Resources and Ecosystems (PHIRE): Support for Response, Recovery, and Mitigation. The overall objective of this work is to leverage the historic satellite remote sensing record to provide insight on the impact of...
By
Ecosystems Mission Area, California Water Science Center
Assessing impacts of wildfire on water and habitat quality in downstream aquatic ecosystems using remote sensing

Assessing impacts of wildfire on water and habitat quality in downstream aquatic ecosystems using remote sensing

This project focuses on the downstream effects of wildfires on lakes, reservoirs, and coastal water within the larger context of the USGS project on Post-fire Hazards and Impacts to Resources and Ecosystems (PHIRE): Support for Response, Recovery, and Mitigation. The overall objective of this work is to leverage the historic satellite remote sensing record to provide insight on the impact of...
Learn More
Scientists aboard research vessel conduct water-quality mapping in support of wastewater-derived nutrients project

Biogeochemistry Group

The Biogeochemistry (BGC) Group uses an interdisciplinary approach to address surface water quality issues and food web dynamics throughout California, particularly in the Sacramento-San Joaquin Delta and San Francisco Bay.
By
California Water Science Center
Biogeochemistry Group

Biogeochemistry Group

The Biogeochemistry (BGC) Group uses an interdisciplinary approach to address surface water quality issues and food web dynamics throughout California, particularly in the Sacramento-San Joaquin Delta and San Francisco Bay.
Learn More
Map showing current San Francisco Bay-Delta water quality sampling station locations.

Sampling Locations for the Water Quality of San Francisco Bay Project

Since 1969, the Water Quality of San Francisco Bay Research and Monitoring Project has conducted water-column sampling along the deep channel of the San Francisco Bay-Delta system. Learn more about when and where we collect data.
By
Water Resources Mission Area, California Water Science Center
Sampling Locations for the Water Quality of San Francisco Bay Project

Sampling Locations for the Water Quality of San Francisco Bay Project

Since 1969, the Water Quality of San Francisco Bay Research and Monitoring Project has conducted water-column sampling along the deep channel of the San Francisco Bay-Delta system. Learn more about when and where we collect data.
Learn More
Scientist sample for clams aboard the R/V Polaris in North San Francisco Bay.

Sampling Methods for the Water Quality of San Francisco Bay Project

The Water Quality of San Francisco Bay Research and Monitoring Project measures changes in water quality along the deep channel of the San Francisco Bay-Delta system using submersible sensors and discrete water samples. Learn more about how we collect and measure water-quality data.
By
Water Resources Mission Area, California Water Science Center
Sampling Methods for the Water Quality of San Francisco Bay Project

Sampling Methods for the Water Quality of San Francisco Bay Project

The Water Quality of San Francisco Bay Research and Monitoring Project measures changes in water quality along the deep channel of the San Francisco Bay-Delta system using submersible sensors and discrete water samples. Learn more about how we collect and measure water-quality data.
Learn More
R/V David H. Peterson at the Redwood City dock.

Research Vessel David H. Peterson

The Research Vessel David H. Peterson begain service with the U.S. Geological Survey in 2015. Named after a founder of the Water Quality of San Francisco Bay Research and Monitoring Project, this vessel is a high-tech scientific platform for estuarine research. Learn more about how the R/V David H. Peterson makes our research possible.
By
Water Resources Mission Area, California Water Science Center
Research Vessel David H. Peterson

Research Vessel David H. Peterson

The Research Vessel David H. Peterson begain service with the U.S. Geological Survey in 2015. Named after a founder of the Water Quality of San Francisco Bay Research and Monitoring Project, this vessel is a high-tech scientific platform for estuarine research. Learn more about how the R/V David H. Peterson makes our research possible.
Learn More
Filter Total Items: 26

Phytoplankton Species Composition and Abundance in the Sacramento-San Joaquin River Delta: Microscopic Enumeration of USGS Samples, beginning in 2016 (ver. 2.0, December 2025) Phytoplankton Species Composition and Abundance in the Sacramento-San Joaquin River Delta: Microscopic Enumeration of USGS Samples, beginning in 2016 (ver. 2.0, December 2025)

This dataset contains multiple types of data characterizing phytoplankton in the Sacramento-San Joaquin Delta (California, USA). 1) Bright field microscopy was used to identify and enumerate phytoplankton community composition; 2) Epifluorescent microscopy was used to enumerate picophytoplankton (phytoplankton cells less than 2 microns in diameter) and, 3) a categorical visual index...
By
California Water Science Center

Cyanotoxins in the California Sacramento-San Joaquin Delta: Whole Water Cyanotoxin Samples Cyanotoxins in the California Sacramento-San Joaquin Delta: Whole Water Cyanotoxin Samples

This dataset is comprised of cyanotoxin concentrations from whole water cyanotoxin samples collected at water quality stations in the Sacramento-San Joaquin Delta, beginning in 2020. Cyanotoxin congeners were measured from whole water cyanotoxin samples within the cyanotoxin classes: microcystins, anatoxins, cylindrospermopsins, saxitoxins, anabaenopeptins, and nodularin. Concentrations...
By
California Water Science Center

Water quality and nutrient data from San Joaquin River and Stockton Waterfront, April and August 2024 Water quality and nutrient data from San Joaquin River and Stockton Waterfront, April and August 2024

This dataset records diel changes to water quality parameters, nutrients, and phytoplankton biomass in the south-eastern region of the Sacramento-San Joaquin Delta. Sampling occurred in August 2024 in the Stockton Waterfront (City of Stockton, San Joaquin County, California, USA) and San Joaquin River. Data was collected from approximately 6am to 9pm Pacific Standard Time on August 6, 13...
By
California Water Science Center

Assessing spatial variability of nutrients, phytoplankton, and related water quality constituents in the California Sacramento-San Joaquin Delta at the landscape scale: 2023 High resolution mapping surveys Assessing spatial variability of nutrients, phytoplankton, and related water quality constituents in the California Sacramento-San Joaquin Delta at the landscape scale: 2023 High resolution mapping surveys

Broad-area, high-resolution, boat-based water quality mapping surveys of the Sacramento-San Joaquin Delta and Suisun Bay (Delta) of California, USA were conducted under different environmental/flow conditions in May, July, and October of 2023. The spatial and temporal variability of nutrients, phytoplankton, and related water quality parameters were assessed. This dataset includes...
By
California Water Science Center

Cyanotoxins in the California Sacramento-San Joaquin Delta: Fixed Station Solid Phase Adsorption Toxin Tracking (SPATT) samplers Cyanotoxins in the California Sacramento-San Joaquin Delta: Fixed Station Solid Phase Adsorption Toxin Tracking (SPATT) samplers

This dataset is comprised of cyanotoxin concentrations in extracts from solid phase adsorption toxin tracking (SPATT) samplers deployed at fixed sampling stations in the Sacramento-San Joaquin Delta, beginning in 2020. SPATT samplers are a form of passive sampler constructed of adsorbent resin beads that concentrate cyanotoxins over time. Cyanotoxin congeners were measured from SPATT...
By
California Water Science Center

Above-water hyperspectral field spectroscopy measurements at Franks Tract in the Sacramento-San Joaquin Delta, California Above-water hyperspectral field spectroscopy measurements at Franks Tract in the Sacramento-San Joaquin Delta, California

Hand-held hyperspectral spectroscopy data were collected in 2022 in Franks Tract, a flooded area located in the central Sacramento-San Joaquin Delta of California. The data were collected from a boat and co-located within pixels from the Ocean Land Color Imaging (OLCI) sensor on the Sentinel-3A and 3-B satellites. Data from 16 sites within 7 OLCI pixels were collected on three days: July...
By
California Water Science Center
Filter Total Items: 111

Assessing environmental drivers and protist community dynamics that shaped the historic August 2022 Heterosigma akashiwo bloom in San Francisco Bay, California Assessing environmental drivers and protist community dynamics that shaped the historic August 2022 Heterosigma akashiwo bloom in San Francisco Bay, California

San Francisco Bay, California, typically has chlorophyll a (chl-a) concentrations below 10 µg L−1, despite nutrient loadings exceeding those in many estuaries with recurring harmful algal blooms (HABs). However, in August 2022 there was a Heterosigma akashiwo (raphidophyte) bloom with chl-a concentrations exceeding 450 µg L−1, resulting in widespread hypoxia and fish die-off. We used...
Authors
Schuyler Crain Nardelli, Keith Bouma-Gregson, David Senn, Daniel Killam, Ariella Chelsky, Erica S. Kress, Emily T. Richardson, Timothy Otten, Tamara E. C. Kraus, Brian A. Bergamaschi
By
California Water Science Center

An integrated sensor network and data driven approach to satellite remote sensing of dissolved organic matter An integrated sensor network and data driven approach to satellite remote sensing of dissolved organic matter

Traditional remote sensing retrieval models for water quality have historically relied on limited, localized data sets due to the prohibitive costs of extensive field campaigns and logistical challenges of collecting match-up data with satellite overpasses. As a result, these models often lack generalizability across seasons, tides, and sites. Furthermore, small field data sets limit the...
Authors
Dulcinea Marie Avouris, Erin L Hestir, Jacob Fleck, Jeffrey A. Hansen, Brian A. Bergamaschi
By
California Water Science Center

Identifying conditions associated with outliers produced by three different chlorophyll fluorometers: A comparison of instrumentation and development of correction formulae Identifying conditions associated with outliers produced by three different chlorophyll fluorometers: A comparison of instrumentation and development of correction formulae

Measurements of chlorophyll concentration reported by fluorometers (fChl) are used in environmental research and monitoring, as inputs to models, and in the interpretation of remote sensing data. Researchers and managers benefit from understanding how to interpret and ensure the accuracy of fChl data collected by in situ fluorometers. Although fChl values produced by different...
Authors
Emily T. Richardson, Tamara E. C. Kraus, Crystal Lee Sturgeon, Katy O’Donnell, Brian A. Bergamaschi
By
California Water Science Center

Estimating biogeochemical rates using a computationally efficient Lagrangian approach Estimating biogeochemical rates using a computationally efficient Lagrangian approach

Nutrient concentrations in many estuaries have increased over the past century due to increases in wastewater discharge and increased agricultural intensity, contributing to multiple environmental problems. Numerous biogeochemical and physical processes in estuaries influence nutrient concentrations during transport, resulting in complex spatial and temporal variability and challenges...
Authors
Edward Gross, Rusty Holleman, Wim Kimmerer, Tamara E. C. Kraus, Brian A. Bergamaschi, Scott Burdick-Yahya, David Senn
By
California Water Science Center

Assessing spatial variability of nutrients, phytoplankton, and related water-quality constituents in the California Sacramento–San Joaquin Delta at the landscape scale—2018 high resolution mapping surveys Assessing spatial variability of nutrients, phytoplankton, and related water-quality constituents in the California Sacramento–San Joaquin Delta at the landscape scale—2018 high resolution mapping surveys

Executive Summary This study examined the abundance and distribution of nutrients and phytoplankton in the tidal aquatic environments of the Sacramento–San Joaquin Delta (Delta) and Suisun Bay, comprising three spatial surveys conducted in May, July, and October of 2018 that used continuous underway high frequency sampling and measurements onboard a high-speed boat to characterize...
Authors
Brian A. Bergamaschi, Tamara E. C. Kraus, Bryan D. Downing, Elizabeth B. Stumpner, Katy O’Donnell, Jeffrey A. Hansen, Jeniffer Soto Perez, Emily T. Richardson, Angela M. Hansen, Alan Gelber
By
Water Resources Mission Area, California Water Science Center

Evaluation and refinement of chlorophyll-a algorithms for high-biomass blooms in San Francisco Bay (USA) Evaluation and refinement of chlorophyll-a algorithms for high-biomass blooms in San Francisco Bay (USA)

A massive bloom of the raphidophyte Heterosigma akashiwo occurred in summer 2022 in San Francisco Bay, causing widespread ecological impacts including events of low dissolved oxygen and mass fish kills. The rapidly evolving bloom required equally rapid management response, leading to the use of near-real-time image analysis of chlorophyll from the Ocean and Land Colour Instrument (OLCI)...
Authors
Raphael M. Kudela, David B. Senn, Emily T. Richardson, Keith Bouma-Gregson, Brian A. Bergamaschi, Lawrence Sim
By
Water Resources Mission Area, California Water Science Center

Non-USGS Publications**

Bergamaschi, B.A. and Hedges, J.I. (1995) A Multichambered Apparatus for HF Solvolysis Experiments - Reaction of Cellulose HF Solvolysis Products with Acetic-Acid and Acetic-Anhydride. Carbohydrate Research 267, 115-126. https://doi.org/10.1016/0008-6215(94)00279-O
Hedges, J.I., Bergamaschi, B.A. and Benner, R. (1994) Comparative Analyses of DOC and DON in Natural Water - Erratum (Vol 41, Pg 121, 1989). Marine Chemistry 46, 407-408. https://doi.org/10.1016/0304-4203(94)90035-3
Hedges, J.I., Bergamaschi, B.A. and Benner, R. (1993) Comparative Analyses of DOC and DON in Natural Water. Marine Chemistry 41, 121-134. https://doi.org/10.1016/0304-4203(93)90110-A
Hopkinson, C., Cifuentes, L., Burdige, D., Fitzwater, S., Hansell, D., Henrichs, S., Kahler, P., Koike, I., Walsh, T. and Bergamaschi, B. (1993) Measurement of Dissolved Organic Carbon and Nitrogen in Natural Waters - DON Subgroup Report. Marine Chemistry 41, 23-36. https://doi.org/10.1016/0304-4203(93)90103-U
Hedges, J.I. and Bergamaschi, B.A. (1992) Seawater Carbon Measurement. Nature 359, 202-202. https://doi.org/DOI 10.1038/359202a0

**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.

San Francisco Bay-Delta Water Quality, Nutrient, and Phytoplankton Mapping, 2018-2020-2021-2022-2023-2024 Comparison San Francisco Bay-Delta Water Quality, Nutrient, and Phytoplankton Mapping, 2018-2020-2021-2022-2023-2024 Comparison

San Francisco Bay-Delta Water Quality, Nutrient, and Phytoplankton Mapping, 2018-2020-2021-2022-2023-2024 Comparison
By
California Water Science Center

Bay- Delta Water Quality, Nutrient and Phytoplankton Mapping | US Geological Survey Bay- Delta Water Quality, Nutrient and Phytoplankton Mapping | US Geological Survey

Data visualization tool created for California's Bay-Delta Regional Monitoring Program. This web applicaton visualizes nutrients and phytoplankton spatially and temporally.
By
California Water Science Center
Heterosigma akashiwo in San Fracisco Bay

Heterosigma akashiwo in San Fracisco Bay

A new study by several scientists examines the environmental conditions that fueled a massive algal bloom in the San Francisco Bay. By analyzing water...

Read Article
CAWSC Biogeochemistry Group Expands its Monitoring of Water Quality in the Delta

CAWSC Biogeochemistry Group Expands its Monitoring of Water Quality in the Delta

The USGS California Water Science Center’s Biogeochemistry Group continues to address surface water quality issues and food web dynamics throughout...

Read Article
Scientists Assess Sediment Nutrient Storage and Release in California's Sacramento-San Joaquin Delta

Scientists Assess Sediment Nutrient Storage and Release in California's Sacramento-San Joaquin Delta

California Water Science Center scientists have begun the first comprehensive assessment of sediment nutrient inventories and fluxes in the Sacramento...

Read Article

Science and Products

Filter Total Items: 22
Satellite image of South San Francisco Bay

Remote Sensing of Mercury Pollution in South San Francisco Bay

San Francisco Bay has a long history of being subject to natural resources exploitation and pollution. Ongoing flux of contaminants into the bay, legacy pollution from the Gold Rush era and structural modifications still influence the natural ecosystem today. This project aims to map multiple forms (i.e. species) of mercury -- one of the major contaminants in the bay -- to help inform restoration...
By
Western Geographic Science Center
Remote Sensing of Mercury Pollution in South San Francisco Bay

Remote Sensing of Mercury Pollution in South San Francisco Bay

San Francisco Bay has a long history of being subject to natural resources exploitation and pollution. Ongoing flux of contaminants into the bay, legacy pollution from the Gold Rush era and structural modifications still influence the natural ecosystem today. This project aims to map multiple forms (i.e. species) of mercury -- one of the major contaminants in the bay -- to help inform restoration...
Learn More
Image Collage of Landsat, pollinator, and volcanologist

Assessing impacts of wildfire on water and habitat quality in downstream aquatic ecosystems using remote sensing

This project focuses on the downstream effects of wildfires on lakes, reservoirs, and coastal water within the larger context of the USGS project on Post-fire Hazards and Impacts to Resources and Ecosystems (PHIRE): Support for Response, Recovery, and Mitigation. The overall objective of this work is to leverage the historic satellite remote sensing record to provide insight on the impact of...
By
Ecosystems Mission Area, California Water Science Center
Assessing impacts of wildfire on water and habitat quality in downstream aquatic ecosystems using remote sensing

Assessing impacts of wildfire on water and habitat quality in downstream aquatic ecosystems using remote sensing

This project focuses on the downstream effects of wildfires on lakes, reservoirs, and coastal water within the larger context of the USGS project on Post-fire Hazards and Impacts to Resources and Ecosystems (PHIRE): Support for Response, Recovery, and Mitigation. The overall objective of this work is to leverage the historic satellite remote sensing record to provide insight on the impact of...
Learn More
Scientists aboard research vessel conduct water-quality mapping in support of wastewater-derived nutrients project

Biogeochemistry Group

The Biogeochemistry (BGC) Group uses an interdisciplinary approach to address surface water quality issues and food web dynamics throughout California, particularly in the Sacramento-San Joaquin Delta and San Francisco Bay.
By
California Water Science Center
Biogeochemistry Group

Biogeochemistry Group

The Biogeochemistry (BGC) Group uses an interdisciplinary approach to address surface water quality issues and food web dynamics throughout California, particularly in the Sacramento-San Joaquin Delta and San Francisco Bay.
Learn More
Map showing current San Francisco Bay-Delta water quality sampling station locations.

Sampling Locations for the Water Quality of San Francisco Bay Project

Since 1969, the Water Quality of San Francisco Bay Research and Monitoring Project has conducted water-column sampling along the deep channel of the San Francisco Bay-Delta system. Learn more about when and where we collect data.
By
Water Resources Mission Area, California Water Science Center
Sampling Locations for the Water Quality of San Francisco Bay Project

Sampling Locations for the Water Quality of San Francisco Bay Project

Since 1969, the Water Quality of San Francisco Bay Research and Monitoring Project has conducted water-column sampling along the deep channel of the San Francisco Bay-Delta system. Learn more about when and where we collect data.
Learn More
Scientist sample for clams aboard the R/V Polaris in North San Francisco Bay.

Sampling Methods for the Water Quality of San Francisco Bay Project

The Water Quality of San Francisco Bay Research and Monitoring Project measures changes in water quality along the deep channel of the San Francisco Bay-Delta system using submersible sensors and discrete water samples. Learn more about how we collect and measure water-quality data.
By
Water Resources Mission Area, California Water Science Center
Sampling Methods for the Water Quality of San Francisco Bay Project

Sampling Methods for the Water Quality of San Francisco Bay Project

The Water Quality of San Francisco Bay Research and Monitoring Project measures changes in water quality along the deep channel of the San Francisco Bay-Delta system using submersible sensors and discrete water samples. Learn more about how we collect and measure water-quality data.
Learn More
R/V David H. Peterson at the Redwood City dock.

Research Vessel David H. Peterson

The Research Vessel David H. Peterson begain service with the U.S. Geological Survey in 2015. Named after a founder of the Water Quality of San Francisco Bay Research and Monitoring Project, this vessel is a high-tech scientific platform for estuarine research. Learn more about how the R/V David H. Peterson makes our research possible.
By
Water Resources Mission Area, California Water Science Center
Research Vessel David H. Peterson

Research Vessel David H. Peterson

The Research Vessel David H. Peterson begain service with the U.S. Geological Survey in 2015. Named after a founder of the Water Quality of San Francisco Bay Research and Monitoring Project, this vessel is a high-tech scientific platform for estuarine research. Learn more about how the R/V David H. Peterson makes our research possible.
Learn More
Filter Total Items: 26

Phytoplankton Species Composition and Abundance in the Sacramento-San Joaquin River Delta: Microscopic Enumeration of USGS Samples, beginning in 2016 (ver. 2.0, December 2025) Phytoplankton Species Composition and Abundance in the Sacramento-San Joaquin River Delta: Microscopic Enumeration of USGS Samples, beginning in 2016 (ver. 2.0, December 2025)

This dataset contains multiple types of data characterizing phytoplankton in the Sacramento-San Joaquin Delta (California, USA). 1) Bright field microscopy was used to identify and enumerate phytoplankton community composition; 2) Epifluorescent microscopy was used to enumerate picophytoplankton (phytoplankton cells less than 2 microns in diameter) and, 3) a categorical visual index...
By
California Water Science Center

Cyanotoxins in the California Sacramento-San Joaquin Delta: Whole Water Cyanotoxin Samples Cyanotoxins in the California Sacramento-San Joaquin Delta: Whole Water Cyanotoxin Samples

This dataset is comprised of cyanotoxin concentrations from whole water cyanotoxin samples collected at water quality stations in the Sacramento-San Joaquin Delta, beginning in 2020. Cyanotoxin congeners were measured from whole water cyanotoxin samples within the cyanotoxin classes: microcystins, anatoxins, cylindrospermopsins, saxitoxins, anabaenopeptins, and nodularin. Concentrations...
By
California Water Science Center

Water quality and nutrient data from San Joaquin River and Stockton Waterfront, April and August 2024 Water quality and nutrient data from San Joaquin River and Stockton Waterfront, April and August 2024

This dataset records diel changes to water quality parameters, nutrients, and phytoplankton biomass in the south-eastern region of the Sacramento-San Joaquin Delta. Sampling occurred in August 2024 in the Stockton Waterfront (City of Stockton, San Joaquin County, California, USA) and San Joaquin River. Data was collected from approximately 6am to 9pm Pacific Standard Time on August 6, 13...
By
California Water Science Center

Assessing spatial variability of nutrients, phytoplankton, and related water quality constituents in the California Sacramento-San Joaquin Delta at the landscape scale: 2023 High resolution mapping surveys Assessing spatial variability of nutrients, phytoplankton, and related water quality constituents in the California Sacramento-San Joaquin Delta at the landscape scale: 2023 High resolution mapping surveys

Broad-area, high-resolution, boat-based water quality mapping surveys of the Sacramento-San Joaquin Delta and Suisun Bay (Delta) of California, USA were conducted under different environmental/flow conditions in May, July, and October of 2023. The spatial and temporal variability of nutrients, phytoplankton, and related water quality parameters were assessed. This dataset includes...
By
California Water Science Center

Cyanotoxins in the California Sacramento-San Joaquin Delta: Fixed Station Solid Phase Adsorption Toxin Tracking (SPATT) samplers Cyanotoxins in the California Sacramento-San Joaquin Delta: Fixed Station Solid Phase Adsorption Toxin Tracking (SPATT) samplers

This dataset is comprised of cyanotoxin concentrations in extracts from solid phase adsorption toxin tracking (SPATT) samplers deployed at fixed sampling stations in the Sacramento-San Joaquin Delta, beginning in 2020. SPATT samplers are a form of passive sampler constructed of adsorbent resin beads that concentrate cyanotoxins over time. Cyanotoxin congeners were measured from SPATT...
By
California Water Science Center

Above-water hyperspectral field spectroscopy measurements at Franks Tract in the Sacramento-San Joaquin Delta, California Above-water hyperspectral field spectroscopy measurements at Franks Tract in the Sacramento-San Joaquin Delta, California

Hand-held hyperspectral spectroscopy data were collected in 2022 in Franks Tract, a flooded area located in the central Sacramento-San Joaquin Delta of California. The data were collected from a boat and co-located within pixels from the Ocean Land Color Imaging (OLCI) sensor on the Sentinel-3A and 3-B satellites. Data from 16 sites within 7 OLCI pixels were collected on three days: July...
By
California Water Science Center
Filter Total Items: 111

Assessing environmental drivers and protist community dynamics that shaped the historic August 2022 Heterosigma akashiwo bloom in San Francisco Bay, California Assessing environmental drivers and protist community dynamics that shaped the historic August 2022 Heterosigma akashiwo bloom in San Francisco Bay, California

San Francisco Bay, California, typically has chlorophyll a (chl-a) concentrations below 10 µg L−1, despite nutrient loadings exceeding those in many estuaries with recurring harmful algal blooms (HABs). However, in August 2022 there was a Heterosigma akashiwo (raphidophyte) bloom with chl-a concentrations exceeding 450 µg L−1, resulting in widespread hypoxia and fish die-off. We used...
Authors
Schuyler Crain Nardelli, Keith Bouma-Gregson, David Senn, Daniel Killam, Ariella Chelsky, Erica S. Kress, Emily T. Richardson, Timothy Otten, Tamara E. C. Kraus, Brian A. Bergamaschi
By
California Water Science Center

An integrated sensor network and data driven approach to satellite remote sensing of dissolved organic matter An integrated sensor network and data driven approach to satellite remote sensing of dissolved organic matter

Traditional remote sensing retrieval models for water quality have historically relied on limited, localized data sets due to the prohibitive costs of extensive field campaigns and logistical challenges of collecting match-up data with satellite overpasses. As a result, these models often lack generalizability across seasons, tides, and sites. Furthermore, small field data sets limit the...
Authors
Dulcinea Marie Avouris, Erin L Hestir, Jacob Fleck, Jeffrey A. Hansen, Brian A. Bergamaschi
By
California Water Science Center

Identifying conditions associated with outliers produced by three different chlorophyll fluorometers: A comparison of instrumentation and development of correction formulae Identifying conditions associated with outliers produced by three different chlorophyll fluorometers: A comparison of instrumentation and development of correction formulae

Measurements of chlorophyll concentration reported by fluorometers (fChl) are used in environmental research and monitoring, as inputs to models, and in the interpretation of remote sensing data. Researchers and managers benefit from understanding how to interpret and ensure the accuracy of fChl data collected by in situ fluorometers. Although fChl values produced by different...
Authors
Emily T. Richardson, Tamara E. C. Kraus, Crystal Lee Sturgeon, Katy O’Donnell, Brian A. Bergamaschi
By
California Water Science Center

Estimating biogeochemical rates using a computationally efficient Lagrangian approach Estimating biogeochemical rates using a computationally efficient Lagrangian approach

Nutrient concentrations in many estuaries have increased over the past century due to increases in wastewater discharge and increased agricultural intensity, contributing to multiple environmental problems. Numerous biogeochemical and physical processes in estuaries influence nutrient concentrations during transport, resulting in complex spatial and temporal variability and challenges...
Authors
Edward Gross, Rusty Holleman, Wim Kimmerer, Tamara E. C. Kraus, Brian A. Bergamaschi, Scott Burdick-Yahya, David Senn
By
California Water Science Center

Assessing spatial variability of nutrients, phytoplankton, and related water-quality constituents in the California Sacramento–San Joaquin Delta at the landscape scale—2018 high resolution mapping surveys Assessing spatial variability of nutrients, phytoplankton, and related water-quality constituents in the California Sacramento–San Joaquin Delta at the landscape scale—2018 high resolution mapping surveys

Executive Summary This study examined the abundance and distribution of nutrients and phytoplankton in the tidal aquatic environments of the Sacramento–San Joaquin Delta (Delta) and Suisun Bay, comprising three spatial surveys conducted in May, July, and October of 2018 that used continuous underway high frequency sampling and measurements onboard a high-speed boat to characterize...
Authors
Brian A. Bergamaschi, Tamara E. C. Kraus, Bryan D. Downing, Elizabeth B. Stumpner, Katy O’Donnell, Jeffrey A. Hansen, Jeniffer Soto Perez, Emily T. Richardson, Angela M. Hansen, Alan Gelber
By
Water Resources Mission Area, California Water Science Center

Evaluation and refinement of chlorophyll-a algorithms for high-biomass blooms in San Francisco Bay (USA) Evaluation and refinement of chlorophyll-a algorithms for high-biomass blooms in San Francisco Bay (USA)

A massive bloom of the raphidophyte Heterosigma akashiwo occurred in summer 2022 in San Francisco Bay, causing widespread ecological impacts including events of low dissolved oxygen and mass fish kills. The rapidly evolving bloom required equally rapid management response, leading to the use of near-real-time image analysis of chlorophyll from the Ocean and Land Colour Instrument (OLCI)...
Authors
Raphael M. Kudela, David B. Senn, Emily T. Richardson, Keith Bouma-Gregson, Brian A. Bergamaschi, Lawrence Sim
By
Water Resources Mission Area, California Water Science Center

Non-USGS Publications**

Bergamaschi, B.A. and Hedges, J.I. (1995) A Multichambered Apparatus for HF Solvolysis Experiments - Reaction of Cellulose HF Solvolysis Products with Acetic-Acid and Acetic-Anhydride. Carbohydrate Research 267, 115-126. https://doi.org/10.1016/0008-6215(94)00279-O
Hedges, J.I., Bergamaschi, B.A. and Benner, R. (1994) Comparative Analyses of DOC and DON in Natural Water - Erratum (Vol 41, Pg 121, 1989). Marine Chemistry 46, 407-408. https://doi.org/10.1016/0304-4203(94)90035-3
Hedges, J.I., Bergamaschi, B.A. and Benner, R. (1993) Comparative Analyses of DOC and DON in Natural Water. Marine Chemistry 41, 121-134. https://doi.org/10.1016/0304-4203(93)90110-A
Hopkinson, C., Cifuentes, L., Burdige, D., Fitzwater, S., Hansell, D., Henrichs, S., Kahler, P., Koike, I., Walsh, T. and Bergamaschi, B. (1993) Measurement of Dissolved Organic Carbon and Nitrogen in Natural Waters - DON Subgroup Report. Marine Chemistry 41, 23-36. https://doi.org/10.1016/0304-4203(93)90103-U
Hedges, J.I. and Bergamaschi, B.A. (1992) Seawater Carbon Measurement. Nature 359, 202-202. https://doi.org/DOI 10.1038/359202a0

**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.

San Francisco Bay-Delta Water Quality, Nutrient, and Phytoplankton Mapping, 2018-2020-2021-2022-2023-2024 Comparison San Francisco Bay-Delta Water Quality, Nutrient, and Phytoplankton Mapping, 2018-2020-2021-2022-2023-2024 Comparison

San Francisco Bay-Delta Water Quality, Nutrient, and Phytoplankton Mapping, 2018-2020-2021-2022-2023-2024 Comparison
By
California Water Science Center

Bay- Delta Water Quality, Nutrient and Phytoplankton Mapping | US Geological Survey Bay- Delta Water Quality, Nutrient and Phytoplankton Mapping | US Geological Survey

Data visualization tool created for California's Bay-Delta Regional Monitoring Program. This web applicaton visualizes nutrients and phytoplankton spatially and temporally.
By
California Water Science Center
Heterosigma akashiwo in San Fracisco Bay

Heterosigma akashiwo in San Fracisco Bay

A new study by several scientists examines the environmental conditions that fueled a massive algal bloom in the San Francisco Bay. By analyzing water...

Read Article
CAWSC Biogeochemistry Group Expands its Monitoring of Water Quality in the Delta

CAWSC Biogeochemistry Group Expands its Monitoring of Water Quality in the Delta

The USGS California Water Science Center’s Biogeochemistry Group continues to address surface water quality issues and food web dynamics throughout...

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Scientists Assess Sediment Nutrient Storage and Release in California's Sacramento-San Joaquin Delta

Scientists Assess Sediment Nutrient Storage and Release in California's Sacramento-San Joaquin Delta

California Water Science Center scientists have begun the first comprehensive assessment of sediment nutrient inventories and fluxes in the Sacramento...

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