Review of Cyanobacterial Neurotoxins—Information for Prioritizing Future Science Directions Completed
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.
Toxins produced by cyanobacteria in freshwater systems can adversely affect wildlife, domestic animals, and human health. Cyanotoxins are classified into three main groups based on the organ system they can affect: dermatoxins (skin), hepatotoxins (liver), and neurotoxins (nervous system). The most frequently studied freshwater cyanotoxins are the microcystins, which are hepatotoxins; however, the neurotoxins anatoxin-a and saxitoxin also have been linked to acute animal poisonings and are understudied in freshwater environments.
To fill this knowledge gap, the U.S. Geological Survey (USGS), along with academic partners, completed a review of laboratory and field studies worldwide that examines the modes of action, production, fate, and occurrence of the freshwater neurotoxins anatoxin-a and saxitoxin. Their research identified 41 anatoxin-a producing species and 15 saxitoxin-producing species of freshwater cyanobacteria. Studies were reviewed that detected anatoxin-a and saxitoxin on every continent except Antarctica.
The review collates information from numerous publications into one comprehensive resource. This resource provides information on gaps in knowledge, including understanding why these neurotoxins are produced, what happens to them once they are released into the environment, their primary and secondary exposure routes, how their presence changes on time scales ranging from hours to years, and sublethal health effects on individual organisms and populations.
This review provides information to help scientists prioritize future research on anatoxin-a, saxitoxin, and other cyanotoxins to address health concerns related to toxin exposures. USGS research on algal toxins is continuing through the Toxins and Harmful Algal Blooms Science Team.
The Environmental Health Program (Contaminants Biology and Toxic Substances Hydrology) of the U.S. Geological Survey Ecosystems Mission Area supported this study.
Below are other related science topics
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
Mixtures of Algal Toxins Present Prior to and After Formation of Visible Algal Blooms—Science to Inform the Timing of Algal Toxin Exposure
Understanding Drivers of Cyanotoxin Production in the Lake Okeechobee Waterway
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
Freshwater neurotoxins and concerns for human, animal, and ecosystemhealth: A review of anatoxin-a and saxitoxin
- Overview
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.
Toxins produced by cyanobacteria in freshwater systems can adversely affect wildlife, domestic animals, and human health. Cyanotoxins are classified into three main groups based on the organ system they can affect: dermatoxins (skin), hepatotoxins (liver), and neurotoxins (nervous system). The most frequently studied freshwater cyanotoxins are the microcystins, which are hepatotoxins; however, the neurotoxins anatoxin-a and saxitoxin also have been linked to acute animal poisonings and are understudied in freshwater environments.
To fill this knowledge gap, the U.S. Geological Survey (USGS), along with academic partners, completed a review of laboratory and field studies worldwide that examines the modes of action, production, fate, and occurrence of the freshwater neurotoxins anatoxin-a and saxitoxin. Their research identified 41 anatoxin-a producing species and 15 saxitoxin-producing species of freshwater cyanobacteria. Studies were reviewed that detected anatoxin-a and saxitoxin on every continent except Antarctica.
The review collates information from numerous publications into one comprehensive resource. This resource provides information on gaps in knowledge, including understanding why these neurotoxins are produced, what happens to them once they are released into the environment, their primary and secondary exposure routes, how their presence changes on time scales ranging from hours to years, and sublethal health effects on individual organisms and populations.
This review provides information to help scientists prioritize future research on anatoxin-a, saxitoxin, and other cyanotoxins to address health concerns related to toxin exposures. USGS research on algal toxins is continuing through the Toxins and Harmful Algal Blooms Science Team.
The Environmental Health Program (Contaminants Biology and Toxic Substances Hydrology) of the U.S. Geological Survey Ecosystems Mission Area supported this study.
- Science
Below are other related science topics
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...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...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.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. - Publications
Freshwater 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 andAuthorsVictoria Christensen, Eakalak Khan