Cyanobacterial blooms are a global concern because they pose a threat to human and aquatic ecosystem health and cause economic damage. Cyanobacteria can produce toxins potent enough to adversely affect the health of humans, pets, livestock, and wildlife. The USGS is collaborating with the U.S. Environmental Protection Agency (EPA), the National Aeronautical and Space Administration (NASA), and the National Oceanic and Atmospheric Administration (NOAA) on the Cyanobacteria Assessment Network (CyAN) project. The overarching goal of this collaborative effort is to detect and quantify cyanobacterial blooms using satellite data records in order to support the environmental management and public use of lakes and reservoirs throughout the Nation.
Data from ocean color instruments on board multiple satellite platforms including Landsat, Medium Resolution Imaging Spectrometer (MERIS), Aqua, Sentinel-2, and Sentinel-3 are being used to create a protocol for early identification of cyanobacterial blooms in freshwater systems. The protocol will provide early-warning indicators of cyanobacterial bloom development at the local scale while maintaining continuous national coverage. As one input to this study, a surface-water temperature product derived from Landsat data was created and validated across all conterminous U.S. (CONUS) ecoregions – the first to quantify temperature in Landsat-resolvable CONUS lakes and reservoirs. By coupling ocean (water) color and surface temperature, a robust and repeatable method for identifying temporal changes in the spatial extent of cyanobacterial blooms over time was developed and used to quantify the surface area of cyanobacterial blooms at both local and regional scales. Validation of continental-scale methods are ongoing.
Information about potential exposure, such as duration, frequency, and extent of cyanobacterial blooms, is critical for effective management decisions. Quantification of changes in cyanobacterial bloom frequency and extent over time is essential to understanding the effect of longer-term environmental changes on blooms at local, regional, national, and global scales. With additional time series data provided by recently launched and future satellite missions, the methods developed by CyAN can enable long-term trend assessments for the entire Nation using uniform datasets and consistent approaches. This study is part of a larger effort of the USGS Environmental Health Mission Area to provide information that will help resource managers understand how to effectively minimize potential risks to the health of humans and other organisms exposed to cyanotoxins through recreation, drinking water, and other exposure routes.