Dr. Christensen is a research hydrologist who studies HABs, algal toxins, and cyanobacteria. She is a member of the Environmental Health Program's Algal Toxin Team and serves as the acting Communications Coordinator for the Water Mission Area.
Victoria Christensen studies cyanotoxins, with a focus on the neurotoxins, anatoxin-a and saxitoxin. Cyanotoxins are produced by cyanobacterial harmful alglal blooms (HABs), which are sometimes called blue-green algae. Her master’s research examined the occurrence and fate of dissolved solids, nutrients, atrazine, and bacteria in an agricultural watershed. Her dissertation research focused on cyanotoxin mixtures with an emphasis neurotoxins—looking at the environmental variables like wind and temperature that may trigger cyanobacteria to produce or release toxins. In addition to the study of harmful algae and their toxins, Victoria's interests and project work include real-time water-quality monitoring, effects of land use on water quality, the fate of nutrients in agricultural and reservoir systems. She also has an interest in writing and communicating science topics to broad audiences and is a trainer and USGS Subject Matter Expert on Scientific Project Management.
Education and Certifications
PhD, Environmental and Conservation Science, North Dakota State University
MS, Water Resources Science, Dept. of Engineering, University of Kansas
BS, Geology, University of Kansas
BA, Management, Hamline University
Science and Products
Phytoplankton community interactions and cyanotoxin mixtures in three recurring surface blooms within one lake
A review of algal toxin exposures on reserved federal lands and among trust species in the United States
Riparian forest cover modulates phosphorus storage and nitrogen cycling in agricultural stream sediments
Freshwater cyanotoxin mixtures in recurring cyanobacterial blooms in Voyageurs National Park
Mercury and water level management in lakes of northern Minnesota
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 locations in Ka
Rapid-assessment test strips: Effectiveness forcyanotoxin monitoring in a northern temperate lake
Land use effects on sediment nutrient processes in a heavily modified watershed using structural equation models
Freshwater neurotoxins and concerns for human, animal, and ecosystemhealth: A review of anatoxin-a and saxitoxin
Phytoplankton community and algal toxicity at a recurring bloom in Sullivan Bay, Kabetogama Lake, Minnesota, USA
Kabetogama Lake in Voyageurs National Park, Minnesota, USA suffers from recurring late summer algal blooms that often contain toxin-producing cyanobacteria. Previous research identified the toxin microcystin in blooms, but we wanted to better understand how the algal and cyanobacterial community changed throughout an open water season and how changes in community structure were related to toxin pr
Complex response of sediment phosphorus to land use and management within a river network
Denitrification in the river network of a mixed land use watershed: Unpacking the complexities
Review of Cyanobacterial Neurotoxins—Information for Prioritizing Future Science Directions
Mixtures of Algal Toxins Present Prior to and After Formation of Visible Algal Blooms—Science to Inform the Timing of Algal Toxin Exposure
Environmental Effects of Agricultural Practices
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
Rapid assessment test strip data for determining cyanotoxin presence in algal blooms, Kabetogama Lake, northern Minnesota, 2017-2018
Phytoplankton enumeration and identification from a recurring algal bloom location in Sullivan Bay, Kabetogama Lake, northern Minnesota, 2016
Science and Products
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Filter Total Items: 47
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 detected iA 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 comprehensiveRiparian 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 sediment pFreshwater 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 in bloom coMercury 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 bacteria oCyanotoxin 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 locations in Ka
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 northern MinnesLand 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 between currFreshwater neurotoxins and concerns for human, animal, and ecosystemhealth: A review of anatoxin-a and saxitoxin
Toxic cyanobacteria are a concern worldwide because they can adversely affect humans, animals, and ecosystems. However, neurotoxins produced by freshwater cyanobacteria are understudied relative to microcystin. Thus, the objective of this critical review was to provide a comprehensive examination of the modes of action, production, fate, and occurrence of the freshwater neurotoxins anatoxin-a andPhytoplankton community and algal toxicity at a recurring bloom in Sullivan Bay, Kabetogama Lake, Minnesota, USA
Kabetogama Lake in Voyageurs National Park, Minnesota, USA suffers from recurring late summer algal blooms that often contain toxin-producing cyanobacteria. Previous research identified the toxin microcystin in blooms, but we wanted to better understand how the algal and cyanobacterial community changed throughout an open water season and how changes in community structure were related to toxin pr
Complex response of sediment phosphorus to land use and management within a river network
Rivers affected by anthropogenic nutrient inputs can retain some of the phosphorus (P) load through sediment retention and burial. Determining the influence of land use and management on sediment P concentrations and P retention in fluvial ecosystems is challenging because of different stressors operating at multiple spatial and temporal scales. In this study, we sought to determine how land use aDenitrification in the river network of a mixed land use watershed: Unpacking the complexities
River networks have the potential to permanently remove nitrogen through denitrification. Few studies have measured denitrification rates within an entire river network or assessed how land use affect rates at larger spatial scales. We sampled 108 sites throughout the network of the Fox River watershed, Wisconsin, to determine if land use influence sediment denitrification rates, and to identify z - Science
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.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...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... - Data
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 mixture (MIRapid 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 whether thesePhytoplankton 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 in the lar - Multimedia
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