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Victoria Glenn Christensen, PhD (Former Employee)

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Image: Euglena sanguinea Bloom

Toxin Producing Algae Across U.S. Landscapes—Are They Gaining a Foothold?

There are still many unknowns related to the occurrence and potential range of various types of algae in inland waters. To fill some of these gaps, scientists at the U.S. Geological Survey (USGS) recently published a review and synthesis of toxic algae in inland waters of the conterminous United States.
By
Ecosystems Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology
Toxin Producing Algae Across U.S. Landscapes—Are They Gaining a Foothold?

Toxin Producing Algae Across U.S. Landscapes—Are They Gaining a Foothold?

There are still many unknowns related to the occurrence and potential range of various types of algae in inland waters. To fill some of these gaps, scientists at the U.S. Geological Survey (USGS) recently published a review and synthesis of toxic algae in inland waters of the conterminous United States.
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Close up of a cyanobacteria bloom on Elysian Lake, Minnesota

Review of Cyanobacterial Neurotoxins—Information for Prioritizing Future Science Directions

The current state of knowledge on the modes of action, production, fate, and occurrence of the freshwater cyanobacterial neurotoxins, anatoxin-a and saxitoxin, was reviewed and synthesized to identify gaps and critical research needs to better understand the health effects of algal toxins.
By
Ecosystems Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology
Review of Cyanobacterial Neurotoxins—Information for Prioritizing Future Science Directions

Review of Cyanobacterial Neurotoxins—Information for Prioritizing Future Science Directions

The current state of knowledge on the modes of action, production, fate, and occurrence of the freshwater cyanobacterial neurotoxins, anatoxin-a and saxitoxin, was reviewed and synthesized to identify gaps and critical research needs to better understand the health effects of algal toxins.
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algae

Mixtures of Algal Toxins Present Prior to and After Formation of Visible Algal Blooms—Science to Inform the Timing of Algal Toxin Exposure

Cyanobacteria with toxin-producing potential, genes indicating an ability for toxin synthesis, or cyanotoxins were present before and after formation of a visible algal bloom in Kabetogama Lake, a popular recreation area in Voyageurs National Park that lies along the border of Minnesota and Canada. The temporal patterns observed in this study indicate that sampling only when there is a visible...
By
Ecosystems Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, Upper Midwest Water Science Center
Mixtures of Algal Toxins Present Prior to and After Formation of Visible Algal Blooms—Science to Inform the Timing of Algal Toxin Exposure

Mixtures of Algal Toxins Present Prior to and After Formation of Visible Algal Blooms—Science to Inform the Timing of Algal Toxin Exposure

Cyanobacteria with toxin-producing potential, genes indicating an ability for toxin synthesis, or cyanotoxins were present before and after formation of a visible algal bloom in Kabetogama Lake, a popular recreation area in Voyageurs National Park that lies along the border of Minnesota and Canada. The temporal patterns observed in this study indicate that sampling only when there is a visible...
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Voyageurs National Park

Water Quality in Voyageurs National Park

Voyageurs National Park was established in 1975 to preserve the scenery and remote system of interconnected waterways along a portion of the US-Canada border. The complexity of the waterways increased with the installation of dams in the early 1900s. Subsequently, the International Joint Commission set rules governing dam operation (rule curves) for this system of lakes, with the most recent...
By
Upper Midwest Water Science Center
Water Quality in Voyageurs National Park

Water Quality in Voyageurs National Park

Voyageurs National Park was established in 1975 to preserve the scenery and remote system of interconnected waterways along a portion of the US-Canada border. The complexity of the waterways increased with the installation of dams in the early 1900s. Subsequently, the International Joint Commission set rules governing dam operation (rule curves) for this system of lakes, with the most recent...
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Two scientists collect samples in a tributary of the Minnesota River Basin

Environmental Effects of Agricultural Practices

As agricultural land in the Minnesota River Basin is retired, tile drains are removed or broken and riparian corridors are planted to reduce runoff. Early studies saw decreased sediment and nitrogen and improved biological indicators but no significant changes in phosphorus. This project continues to investigate the linkages between riparian buffer extent, age, and continuity; stream water; and...
By
Upper Midwest Water Science Center
Environmental Effects of Agricultural Practices

Environmental Effects of Agricultural Practices

As agricultural land in the Minnesota River Basin is retired, tile drains are removed or broken and riparian corridors are planted to reduce runoff. Early studies saw decreased sediment and nitrogen and improved biological indicators but no significant changes in phosphorus. This project continues to investigate the linkages between riparian buffer extent, age, and continuity; stream water; and...
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Image: Scientist Taking Water Samples

National Water-Quality Project Sampling Methods

USGS National Water Quality Assessment (NAWQA) studies require analyses of stream and bed-sediment samples for major ions, nutrients, sediments, and organic contaminants that are consistent across time and space. Procedures have been designed specifically to produce information that is comparable among studies in different parts of the Nation.
By
Water Resources Mission Area
National Water-Quality Project Sampling Methods

National Water-Quality Project Sampling Methods

USGS National Water Quality Assessment (NAWQA) studies require analyses of stream and bed-sediment samples for major ions, nutrients, sediments, and organic contaminants that are consistent across time and space. Procedures have been designed specifically to produce information that is comparable among studies in different parts of the Nation.
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Experimental results from intact core incubations of nearshore sediments in Lake Kabetogama, MN (2021, 2022) Experimental results from intact core incubations of nearshore sediments in Lake Kabetogama, MN (2021, 2022)

Lake water level fluctuations are an important factor driving variation in many ecosystem processes. The nearshore sediments that are periodically exposed and re-inundated can develop distinct physical and chemical characteristics, especially in relationship to the organic matter content of the sediments and the particle size distribution. These sediment characteristics in turn can alter...
By
Upper Midwest Environmental Sciences Center

Algal toxins and Mycobacterium avium ssp. paratuberculosis measured in surface-water, quarry-water, and sediment samples collected at Pipestone National Monument, Pipestone, Minnesota, 2018-19 Algal toxins and Mycobacterium avium ssp. paratuberculosis measured in surface-water, quarry-water, and sediment samples collected at Pipestone National Monument, Pipestone, Minnesota, 2018-19

The U.S. Geological Survey, in cooperation with the U.S. National Park Service, conducted a study to determine the presence of algal toxins and Mycobacterium avium ssp. paratuberculosis (MAP) within Pipestone National Monument located in Pipestone County in southwestern Minnesota. Three algal toxins (microcystins, saxitoxin, and anatoxin-a) were analyzed in 12 water-quality samples...
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Upper Midwest Environmental Sciences Center, Upper Midwest Water Science Center

Data and model archive for multiple linear regression models for prediction of weighted cyanotoxin mixture concentrations and microcystin concentrations at three recurring bloom sites in Kabetogama Lake in Minnesota Data and model archive for multiple linear regression models for prediction of weighted cyanotoxin mixture concentrations and microcystin concentrations at three recurring bloom sites in Kabetogama Lake in Minnesota

Multiple linear regression models were developed using data collected in 2016 and 2017 from three recurring bloom sites in Kabetogama Lake in northern Minnesota. These models were developed to predict concentrations of cyanotoxins (anatoxin-a, microcystin, and saxitoxin) that occur within the blooms. Virtual Beach software (version 3.0.6) was used to develop four models: two cyanotoxin...
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Upper Midwest Environmental Sciences Center, Upper Midwest Water Science Center

Chemical and physical data for sediment source fingerprinting of suspended and bottom sediment in the West Fork of Beaver Creek, Minnesota Chemical and physical data for sediment source fingerprinting of suspended and bottom sediment in the West Fork of Beaver Creek, Minnesota

This data release includes physical and chemical data for samples from suspended and bottom sediments of streams in Minnesota. Data were collected in September 2011 and April 2012. These data include total nitrogen and carbon, organic carbon, concentrations for 39 metals, and particle-size analysis. Source samples were grouped into one of three land-use categories: channel (Mid-bank,Low...
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Ohio-Kentucky-Indiana Water Science Center

Rapid assessment test strip data for determining cyanotoxin presence in algal blooms, Kabetogama Lake, northern Minnesota, 2017-2018 Rapid assessment test strip data for determining cyanotoxin presence in algal blooms, Kabetogama Lake, northern Minnesota, 2017-2018

Algal toxins are a growing concern worldwide. Rapid assessment test strips are a newer technology and their accuracy in detecting toxins in different lakes with different phytoplankton and toxins present is unknown. This data release is supported by our testing of toxin test strips. This research took place in Voyageurs National Park in northern Minnesota. The research will indicate...
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Upper Midwest Environmental Sciences Center, Upper Midwest Water Science Center

Phytoplankton enumeration and identification from a recurring algal bloom location in Sullivan Bay, Kabetogama Lake, northern Minnesota, 2016 Phytoplankton enumeration and identification from a recurring algal bloom location in Sullivan Bay, Kabetogama Lake, northern Minnesota, 2016

This data release provides phytoplankton identification, phytoplankton enumeration, chlorophyll concentration, phaeophytin concentration, phycocyanin data, and nutrient quality assurance data from three recurring algal bloom sites in Kabetogama Lake, Voyaguers National Park, Minnesota in 2016 and 2017. The goal of this research is to better understand the drivers of algal bloom toxicity...
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Upper Midwest Environmental Sciences Center, Upper Midwest Water Science Center
Rural setting in North Dakota
White barn in a rural setting
White barn in a rural setting
Rural setting in North Dakota

White barn in a rural setting

White barn in a rural setting

White barn in a rural setting in North Dakota.

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Contaminant Biology, Toxic Substances Hydrology, Environmental Health Program
Rural setting in North Dakota

White barn in a rural setting

White barn in a rural setting

White barn in a rural setting in North Dakota.

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Contaminant Biology, Toxic Substances Hydrology, Environmental Health Program
Well pump
Well pump in a rural setting in North Dakota
Well pump in a rural setting in North Dakota
Well pump

Well pump in a rural setting in North Dakota

Well pump in a rural setting in North Dakota

A well pump in rural North Dakota.

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Contaminant Biology, Toxic Substances Hydrology, Environmental Health Program
Well pump

Well pump in a rural setting in North Dakota

Well pump in a rural setting in North Dakota

A well pump in rural North Dakota.

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Contaminant Biology, Toxic Substances Hydrology, Environmental Health Program
Winnewissa Falls viewing area
Visitors at Winnewissa Falls viewing area, Pipestone National Monument
Visitors at Winnewissa Falls viewing area, Pipestone National Monument
Winnewissa Falls viewing area

Visitors at Winnewissa Falls viewing area, Pipestone National Monument

Visitors at Winnewissa Falls viewing area, Pipestone National Monument

Visitors at Winnewissa Falls in Pipestone National Monument

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Contaminant Biology, Toxic Substances Hydrology, Environmental Health Program
Winnewissa Falls viewing area

Visitors at Winnewissa Falls viewing area, Pipestone National Monument

Visitors at Winnewissa Falls viewing area, Pipestone National Monument

Visitors at Winnewissa Falls in Pipestone National Monument

By
Contaminant Biology, Toxic Substances Hydrology, Environmental Health Program
Filter Total Items: 50

Possible influence of water level management on nutrient flux in nearshore sediments of Kabetogama Lake, Minnesota, USA Possible influence of water level management on nutrient flux in nearshore sediments of Kabetogama Lake, Minnesota, USA

Lake water level fluctuations are an important factor driving variation in many ecosystem processes. The nearshore sediments that are periodically exposed and re-inundated can develop distinct physical and chemical characteristics, especially in relationship to the organic matter content of the sediments and the particle size distribution. These sediment characteristics in turn can alter...
Authors
James H. Larson, Sean Bailey, Ryan P. Maki, Victoria Christensen, Erin A. Stelzer, James C. Smith, Jamie F. LeDuc, Seth McWhorter
By
Ecosystems Mission Area, Upper Midwest Environmental Sciences Center

Interdisciplinary science approach for harmful algal blooms (HABs) and algal toxins—A strategic science vision for the U.S. Geological Survey Interdisciplinary science approach for harmful algal blooms (HABs) and algal toxins—A strategic science vision for the U.S. Geological Survey

Executive SummaryAlgal blooms in water, soils, dusts, and the environment have captured national attention because of concerns associated with exposure to algal toxins for humans and animals. Algal blooms naturally occur in all surface-water types and are important primary producers for aquatic ecosystems. However, excessive algae growth can be associated with many harmful effects...
Authors
Victoria G. Christensen, Christopher J. Crawford, Robert J. Dusek, Michael J. Focazio, Lisa Reynolds Fogarty, Jennifer L. Graham, Celeste A. Journey, Mari E. Lee, James H. Larson, Sarah M. Stackpoole, Viviana Mazzei, Emily Pindilli, Barnett A. Rattner, E. Terrence Slonecker, Kristen B. McSwain, Timothy J. Reilly, Ashley E. Lopez
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Ecosystems Mission Area, Water Resources Mission Area, Environmental Health Program, Toxic Substances Hydrology, Earth Resources Observation and Science (EROS) Center , Kansas Water Science Center, National Wildlife Health Center, New Jersey Water Science Center, New York Water Science Center, South Atlantic Water Science Center (SAWSC), Upper Midwest Water Science Center, Landsat Missions

Toxic algae in inland waters of the conterminous United States—A review and synthesis Toxic algae in inland waters of the conterminous United States—A review and synthesis

Cyanobacteria are the most common toxigenic algae in inland waters. Their toxins can affect the health of aquatic and terrestrial organisms, including humans. Other algal groups, such as haptophytes (e.g., Prymnesium parvum) and euglenoids (e.g., Euglena sanguinea), can also form harmful algal blooms (HABs) whose toxins cause injury to aquatic biota but currently have no known effects on...
Authors
Reynaldo Patiño, Victoria Christensen, Jennifer L. Graham, Jane Rogosch, Barry H. Rosen
By
Water Resources Mission Area, Cooperative Research Units, New York Water Science Center, Upper Midwest Water Science Center

Creek and quarry water quality at Pipestone National Monument and pilot study of pathogen detection methods in waterfall mist at Winnewissa Falls, Pipestone, Minnesota, 2018–19 Creek and quarry water quality at Pipestone National Monument and pilot study of pathogen detection methods in waterfall mist at Winnewissa Falls, Pipestone, Minnesota, 2018–19

Pipestone National Monument is a 301-acre site sacred to many Native American Tribes, providing cultural exhibits and walking trails to Pipestone Creek, Winnewissa Falls, and historical pipestone quarries for numerous visitors each year. However, the Minnesota Pollution Control Agency has determined turbidity and fecal coliform bacteria occur in Pipestone Creek in high enough numbers to...
Authors
Aliesha L. Krall, Kerensa A. King, Victoria G. Christensen, Joel P. Stokdyk, Barbara C. Scudder Eikenberry, S. A. Stevenson
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Water Resources Mission Area, Upper Midwest Environmental Sciences Center, Upper Midwest Water Science Center, Laboratory for Infectious Disease and the Environment

Phytoplankton community interactions and cyanotoxin mixtures in three recurring surface blooms within one lake Phytoplankton community interactions and cyanotoxin mixtures in three recurring surface blooms within one lake

Cyanobacteria can produce numerous secondary metabolites (cyanotoxins) with various toxicities, yet data on cyanotoxins in many lakes are limited. Moreover, little research is available on complex relations among cyanobacteria that produce toxins. Therefore, we studied cyanobacteria and 19 cyanotoxins at three sites with recurring blooms in Kabetogama Lake (USA). Seven of 19 toxins were...
Authors
Victoria Christensen, Hayley T. Olds, Jack E. Norland, Eakalak Khan
By
Ecosystems Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, Upper Midwest Water Science Center

A review of algal toxin exposures on reserved federal lands and among trust species in the United States A review of algal toxin exposures on reserved federal lands and among trust species in the United States

Associated health effects from algal toxin exposure are a growing concern for human and animal health. Algal toxin poisonings may occur from contact with or consumption of water supplies or from ingestion of contaminated animals. The U.S. Federal Government owns or holds in trust about 259 million hectares of land, in addition to the Trust species obligations. We completed the first...
Authors
Zachary Laughrey, Victoria Christensen, Robert J. Dusek, Sarena Senegal, Julia S. Lankton, Tracy Ziegler, Lee C. Jones, Daniel K. Jones, Brianna Williams, Stephanie Gordon, Gerald A. Clyde, Erich B Emery, Keith Loftin
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Ecosystems Mission Area, Water Resources Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, Kansas Water Science Center, National Wildlife Health Center, Upper Midwest Water Science Center

Riparian forest cover modulates phosphorus storage and nitrogen cycling in agricultural stream sediments Riparian forest cover modulates phosphorus storage and nitrogen cycling in agricultural stream sediments

Watershed land cover affects in-stream water quality and sediment nutrient dynamics. The presence of natural land cover in the riparian zone can reduce the negative effects of agricultural land use on water quality; however, literature evaluating the effects of natural riparian land cover on stream sediment nutrient dynamics is scarce. The objective of this study was to assess if stream...
Authors
Rebecca Kreiling, Lynn A. Bartsch, Patrik M. Perner, Enrika Hlavacek, Victoria Christensen
By
Ecosystems Mission Area, Upper Midwest Environmental Sciences Center, Upper Midwest Water Science Center

Freshwater cyanotoxin mixtures in recurring cyanobacterial blooms in Voyageurs National Park Freshwater cyanotoxin mixtures in recurring cyanobacterial blooms in Voyageurs National Park

Algal and cyanobacterial blooms can foul water systems, inhibit recreation, and produce cyanotoxins, which can be toxic to humans, domestic animals, and wildlife. Blooms that recur yearly present a special challenge, in that chronic effects of most cyanotoxins are unknown. To better understand cyanotoxin timing, possible environmental triggers, and inter-relations among taxa and toxins...
Authors
Victoria Christensen
By
Upper Midwest Water Science Center

Mercury and water level management in lakes of northern Minnesota Mercury and water level management in lakes of northern Minnesota

Water level (WL) fluctuations substantially alter the fauna, flora, and microbial community of nearshore aquatic ecosystems. Water level management therefore has the potential to strongly influence a wide variety of ecosystem processes. Many northern temperate lake food webs experience substantial methylmercury contamination, which is partially mediated by the action of sulfate-reducing...
Authors
James H. Larson, Ryan P. Maki, Victoria Christensen, Enrika Hlavacek, Mark B. Sandheinrich, Jaime F. LeDuc, Claire Kissane, Brent C. Knights
By
Ecosystems Mission Area, Upper Midwest Environmental Sciences Center

Cyanotoxin mixture models: Relating environmental variables and toxin co-occurrence to human exposure risk Cyanotoxin mixture models: Relating environmental variables and toxin co-occurrence to human exposure risk

Toxic cyanobacterial blooms, often containing multiple toxins, are a serious public health issue. However, there are no known models that predict a cyanotoxin mixture (anatoxin-a, microcystin, saxitoxin). This paper presents two cyanotoxin mixture models (MIX) and compares them to two microcystin (MC) models from data collected in 2016–2017 from three recurring cyanobacterial bloom...
Authors
Victoria Christensen, Erin A. Stelzer, Barbara C. Scudder Eikenberry, Hayley T. Olds, Jaime F. LeDuc, Ryan P. Maki, Jack E. Norland, Eakalak Khan
By
Ecosystems Mission Area, Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, Ohio-Kentucky-Indiana Water Science Center, Upper Midwest Water Science Center, Ohio Water Microbiology Laboratory

Rapid-assessment test strips: Effectiveness forcyanotoxin monitoring in a northern temperate lake Rapid-assessment test strips: Effectiveness forcyanotoxin monitoring in a northern temperate lake

Precise and rapid methods of determining toxin levels are needed in lakes used for recreation and drinking water to facilitate a quick risk assessment during cyanobacteria blooms. Therefore, we evaluated rapid-assessment test strips, a newer technology for estimating the toxicity of cyanobacterial blooms, in Kabetogama Lake, a popular recreational area of Voyageurs National Park in...
Authors
Jaime F. LeDuc, Victoria Christensen, Ryan P. Maki
By
Contaminant Biology, Environmental Health Program, Toxic Substances Hydrology, Upper Midwest Water Science Center

Land use effects on sediment nutrient processes in a heavily modified watershed using structural equation models Land use effects on sediment nutrient processes in a heavily modified watershed using structural equation models

Contemporary land use can affect sediment nutrient processes in rivers draining heavily modified watersheds; however, studies linking land use to sediment nutrient processes in large river networks are limited. In this study, we developed and evaluated structural equation models (SE models) for denitrification and phosphorus retention capacity to determine direct and indirect linkages...
Authors
Rebecca Kreiling, Martin C. Thoms, Lynn A. Bartsch, James H. Larson, Victoria Christensen
By
Ecosystems Mission Area, Upper Midwest Environmental Sciences Center, Upper Midwest Water Science Center

Algal blooms aren’t always harmful, but when they are, science is here to help

USGS scientists across the nation are working to understand, predict and prevent impacts from harmful algal blooms to people and wildlife.

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Comprehensive water-quality assessment in the Delaware River Basin identifies increasing trends in salinity and decreasing trends in nutrients

A new report focusing on the Delaware River Basin has found a general upward trend in specific conductance, total dissolved solids, chloride, and...

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Common insecticide mixtures cause greater than expected effects in stream ecosystems

A new USGS study clarifies the relation between neonicotinoid mixtures in Coastal California surface waters and the health of the aquatic life in...

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Project Underway to Identify Algal Toxins in US National Park Waterways

Scientists from the U.S. Geological Survey and National Park Service partnered on a first-of-its-kind, nationwide harmful algal bloom, or HAB, field...

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New study predicts levels of algal bloom toxins from readily available measurements

Emerald-green harmful algal blooms have become an all-too-familiar summertime sight in many U.S. lakes and reservoirs. A new study successfully...

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Review of Cyanobacterial Neurotoxins—Information for Prioritizing Future Science Directions

The current state of knowledge on the modes of action, production, fate, and occurrence of the freshwater cyanobacterial neurotoxins, anatoxin-a and...

Read Article

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