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 algal bloom and sampling only for microcystin may miss some low-level toxin occurrence of which effects are not well understood.
Cyanobacteria and the cyanotoxins they can produce have been associated with adverse health effects including neurological symptoms; gastrointestinal distress; dermatitis; or liver failure in humans, pets, livestock, and wildlife. However, there is a gap in understanding about when toxin exposures are likely to occur in the environment. Resource managers are seeking information about the timing of toxin exposures to safeguard health.
The U.S. Geological Survey’s Toxins and Harmful Algal Blooms Science Team collaborated with the National Park Service to study the temporal variability of the cyanobacterial community composition and occurrence of cyanotoxins at a recurring bloom site in Kabetogama Lake’s Sullivan Bay, a popular recreation area in Voyageurs National Park that lies along the border of Minnesota and Canada. The Lake is in a remote location with less than one percent of the watershed consisting of urban or agricultural land use. This site was chosen because previous water samples collected during visible algal blooms contained several toxin-producing cyanobacteria along with the cyanotoxin microcystin at concentrations exceeding recreational guidelines (20 micrograms per liter, World Health Organization; and 8 micrograms per liter, U.S. Environmental Protection Agency).
Multiple lines of evidence were used to understand the potential and actual toxicity at the site throughout the growing season. Samples were collected 12 times from June through August 2016, beginning from before visible blooms appeared and continuing until large blooms were present in August. Samples were analyzed for cyanobacteria identification, abundance, and biovolume using microscopy. Cyanotoxin concentrations (anatoxin-a, microcystin, and saxitoxin) were analyzed using enzyme-linked immunosorbent assays. Cyanobacteria identification and toxin synthetase genes were identified through gene analysis with quantitative polymerase chain reaction (qPCR). Analyzing the synthetase genes with the qPCR technique helps to differentiate between toxin-producing strains and non-toxin-producing strains of cyanobacteria.
Cyanobacteria with the potential to produce toxins; synthetase genes for anatoxin-a, microcystin, and saxitoxin; and cyanotoxins were detected in lake samples throughout the sampling period prior to and after formation of a visible bloom. Microcystin was detected in 7 of 12 samples (less than 0.3–5.1 micrograms per liter) throughout the sampling period, whereas saxitoxin and anatoxin were detected during August in 3 of 12 samples (less than 0.02–0.8 microgram per liter) and 1 of 11 samples (0.31 microgram per liter), respectively. Microcystin concentrations were detected at relatively lower concentrations during the early season, with peak concentrations in August near the time when the visible bloom appeared. These results indicate that the absence of a visible bloom is not a clear indication of the absence of cyanotoxins. Conversely, the presence of a bloom does not always indicate toxin presence.
The occurrence of microcystin synthetase genes, indicating the potential for microcystin production, peaked 20 days prior to a similar peak in microcystin concentrations, which may be important for distinguishing when a bloom is capable of producing toxins and may serve as an early warning indicator. However, questions still remain about the relation between synthetase gene occurrence and actual toxin concentrations. Understanding this relation is necessary to determine if the genes are reliable predictors of the timing, occurrence, and severity of bloom toxicity.
The results of this study have advanced the understanding of possible human and wildlife exposure scenarios related to multiple algal toxins over time by analyzing samples throughout the growing period using a combination of traditional and molecular tools. The temporal patterns observed in this study indicate that sampling only when there is a visible algal bloom and sampling only for microcystin may miss some low-level toxin occurrence of which effects are not well understood. The results are particularly applicable to understanding cyanobacterial blooms and toxin production in lakes within remote locations, but the techniques and measurements used in the study are applicable to other locations.
The Toxins and Harmful Algal Blooms Science Team’s approach for understanding if exposure to algal toxins results in adverse health effects for humans and wildlife is a sequential process where each step informs the next in the laboratory and in the field. The results of this study will be particularly useful in understanding exposure to algal toxin mixtures at variable concentrations over time, and the toxin data can be used in combination with modeling data to understand when algal blooms contain algal toxins—an important next step to be able to forecast toxins and assess health risk.
This study was supported by the U.S. Geological Survey – National Park Service Partnership and the U.S. Geological Survey Toxics Substances Hydrology and Contaminant Biology Programs.
Below are other science projects associated with this project.
Toxins and Harmful Algal Blooms Science Team
Satellite Data Used to Estimate and Rank Cyanobacterial Bloom Magnitude in Florida and Ohio Lakes—Developing Tools to Protect Human and Wildlife Health from Cyanotoxin Exposure
Understanding Drivers of Cyanotoxin Production in the Lake Okeechobee Waterway
Algal and Other Environmental Toxins — Lawrence, Kansas
Understanding Associations between Mussel Productivity and Cyanotoxins in Lake Erie
New Method Developed to Quantify Spatial Extent of Cyanobacterial Blooms
Satellite Imagery Used to Measure Algal Bloom Frequency—Steps Toward Understanding Exposure Risk
Cyanobacteria from 2016 Lake Okeechobee Harmful Algal Bloom Photo-Documented
Evaluating Linkages Between Algal Toxins and Human Health
- Overview
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 algal bloom and sampling only for microcystin may miss some low-level toxin occurrence of which effects are not well understood.
Sources/Usage: Public Domain.Algal bloom near the Ash River boat dock, a public access point for boating and fishing on Kabetogama Lake. Microcystin has been detected at this location and at nearby Sullivan Bay at concentrations exceeding recreational guidelines. Cyanobacteria and the cyanotoxins they can produce have been associated with adverse health effects including neurological symptoms; gastrointestinal distress; dermatitis; or liver failure in humans, pets, livestock, and wildlife. However, there is a gap in understanding about when toxin exposures are likely to occur in the environment. Resource managers are seeking information about the timing of toxin exposures to safeguard health.
The U.S. Geological Survey’s Toxins and Harmful Algal Blooms Science Team collaborated with the National Park Service to study the temporal variability of the cyanobacterial community composition and occurrence of cyanotoxins at a recurring bloom site in Kabetogama Lake’s Sullivan Bay, a popular recreation area in Voyageurs National Park that lies along the border of Minnesota and Canada. The Lake is in a remote location with less than one percent of the watershed consisting of urban or agricultural land use. This site was chosen because previous water samples collected during visible algal blooms contained several toxin-producing cyanobacteria along with the cyanotoxin microcystin at concentrations exceeding recreational guidelines (20 micrograms per liter, World Health Organization; and 8 micrograms per liter, U.S. Environmental Protection Agency).
Multiple lines of evidence were used to understand the potential and actual toxicity at the site throughout the growing season. Samples were collected 12 times from June through August 2016, beginning from before visible blooms appeared and continuing until large blooms were present in August. Samples were analyzed for cyanobacteria identification, abundance, and biovolume using microscopy. Cyanotoxin concentrations (anatoxin-a, microcystin, and saxitoxin) were analyzed using enzyme-linked immunosorbent assays. Cyanobacteria identification and toxin synthetase genes were identified through gene analysis with quantitative polymerase chain reaction (qPCR). Analyzing the synthetase genes with the qPCR technique helps to differentiate between toxin-producing strains and non-toxin-producing strains of cyanobacteria.
Sources/Usage: Public Domain.An algal bloom near the Ash River Visitor Center at Kabetogama Lake, where visitors enjoy picnics and trails year-round. Cyanobacteria with the potential to produce toxins; synthetase genes for anatoxin-a, microcystin, and saxitoxin; and cyanotoxins were detected in lake samples throughout the sampling period prior to and after formation of a visible bloom. Microcystin was detected in 7 of 12 samples (less than 0.3–5.1 micrograms per liter) throughout the sampling period, whereas saxitoxin and anatoxin were detected during August in 3 of 12 samples (less than 0.02–0.8 microgram per liter) and 1 of 11 samples (0.31 microgram per liter), respectively. Microcystin concentrations were detected at relatively lower concentrations during the early season, with peak concentrations in August near the time when the visible bloom appeared. These results indicate that the absence of a visible bloom is not a clear indication of the absence of cyanotoxins. Conversely, the presence of a bloom does not always indicate toxin presence.
The occurrence of microcystin synthetase genes, indicating the potential for microcystin production, peaked 20 days prior to a similar peak in microcystin concentrations, which may be important for distinguishing when a bloom is capable of producing toxins and may serve as an early warning indicator. However, questions still remain about the relation between synthetase gene occurrence and actual toxin concentrations. Understanding this relation is necessary to determine if the genes are reliable predictors of the timing, occurrence, and severity of bloom toxicity.
The results of this study have advanced the understanding of possible human and wildlife exposure scenarios related to multiple algal toxins over time by analyzing samples throughout the growing period using a combination of traditional and molecular tools. The temporal patterns observed in this study indicate that sampling only when there is a visible algal bloom and sampling only for microcystin may miss some low-level toxin occurrence of which effects are not well understood. The results are particularly applicable to understanding cyanobacterial blooms and toxin production in lakes within remote locations, but the techniques and measurements used in the study are applicable to other locations.
Sources/Usage: Public Domain.The cyanobacteria Gleotrichia shown under a microscope from a water sample collected at Ek Lake Trail, a popular recreational area in Kabetogama Lake where algal blooms frequently occur. Gleotrichia can produce microcystin. The Toxins and Harmful Algal Blooms Science Team’s approach for understanding if exposure to algal toxins results in adverse health effects for humans and wildlife is a sequential process where each step informs the next in the laboratory and in the field. The results of this study will be particularly useful in understanding exposure to algal toxin mixtures at variable concentrations over time, and the toxin data can be used in combination with modeling data to understand when algal blooms contain algal toxins—an important next step to be able to forecast toxins and assess health risk.
This study was supported by the U.S. Geological Survey – National Park Service Partnership and the U.S. Geological Survey Toxics Substances Hydrology and Contaminant Biology Programs.
- Science
Below are other science projects associated with this project.
Toxins and Harmful Algal Blooms Science Team
The team develops advanced methods to study factors driving algal toxin production, how and where wildlife or humans are exposed to toxins, and ecotoxicology. That information is used to develop decision tools to understand if toxin exposure leads to adverse health effects in order to protect human and wildlife health.Satellite Data Used to Estimate and Rank Cyanobacterial Bloom Magnitude in Florida and Ohio Lakes—Developing Tools to Protect Human and Wildlife Health from Cyanotoxin Exposure
Cyanobacterial bloom magnitude during 2003–11 was quantified and ranked in Florida and Ohio lakes with a newly developed modelling tool that allows for the use of multiple satellite data sources and user-defined thresholds. This tool was designed to identify the magnitude of algal blooms, but one metric alone cannot adequately represent the severity of a bloom of interest in terms of toxicity. The...Understanding Drivers of Cyanotoxin Production in the Lake Okeechobee Waterway
The U.S. Geological Survey (USGS) and other researchers combined field and laboratory approaches in two studies to understand the factors that drive cyanobacterial bloom development and associated cyanotoxin production in Lake Okeechobee, the St. Lucie River and Estuary, and the Indian River Lagoon in response to the large-scale Lake Okeechobee cyanobacteria bloom in 2016.Algal and Other Environmental Toxins — Lawrence, Kansas
About the Laboratory The Environmental Health Program collaborates with scientists at the Organic Geochemistry Research Laboratory (OGRL) in Lawrence, Kansas, to develop and employ targeted and non-targeted analytical methods for identification and quantitation of known and understudied algal/cyanobacterial toxins. The laboratory contructed in 2019 is a 2,500 square foot modern laboratory facility...Understanding Associations between Mussel Productivity and Cyanotoxins in Lake Erie
Study findings indicate that cyanobacteria and cyanotoxins were not associated with mussel mortality at the concentrations present in Lake Erie during a recent study (2013-15), but mussel growth was lower at sites with greater microcystin concentrations.New Method Developed to Quantify Spatial Extent of Cyanobacterial Blooms
This study provides a method for quantifying changes in the spatial extent of cyanobacterial blooms at local and regional scales using remotely sensed data to determine if bloom occurrence and size are increasing or decreasing for inland water resources.Satellite Imagery Used to Measure Algal Bloom Frequency—Steps Toward Understanding Exposure Risk
Study explores the utility and limitations of currently available remotely sensed satellite data for identifying the frequency of algal blooms in the Nation's lakes and reservoirs. This information provides a first step toward the goal of understanding exposure risk to protect the health of humans, pets, livestock, and wildlife.Cyanobacteria from 2016 Lake Okeechobee Harmful Algal Bloom Photo-Documented
New report provides photographic documentation and identification of the cyanobacteria present in Lake Okeechobee, the Caloosahatchee River, and St. Lucie Canal during an extensive algal bloom in 2016.Evaluating Linkages Between Algal Toxins and Human Health
The amino acid β-methylamino-L-alanine (BMAA) is produced by cyanobacteria and has been suggested by human health researchers as a causal factor for degenerative neurological diseases such as Amyotrophic Lateral Sclerosis (ALS), Parkinsonism, and dementia. An objective review concluded that this hypothesis is not supported by existing data. - Publications
- News