Assessing Cyanobacteria Blooms from Space

Sachidananda Mishra1,2, Richard P Stumpf2, Andrew Meredith2,3, Blake A Schaeffer4, Jeremy Werdell5, Keith A Loftin6, Erin Urquhart7 and Bridget Seegers8,9, (1)CSS Inc., Fairfax, United States, (2)National Oceanic and Atmospheric Administration, National Centers for Coastal Ocean Science, Silver Spring, MD, United States, (3)CSS Inc., Under Contract to NCCOS, NOAA, Fairfax, United States, (4)Environmental Protection Agency, NERL Exposure Methods and Measurement Division, Research Triangle Park, NC, United States, (5)NASA Goddard Space Flight Center, Ocean Ecology Laboratory, Greenbelt, MD, United States, (6)USGS Kansas Water Science Center, Lawrence, KS, United States, (7)Oak Ridge Institute of Science and Education, Durham, United States, (8)NASA Goddard Space Flight Center, Ocean Ecology Laboratory, Greenbelt, United States, (9)Universities Space Research Association (USRA), Columbia, CA, United States
Frequent occurrence of cyanobacterial harmful algal blooms (CyanoHABs) has drawn support for more frequent and synoptic observation and assessment of inland-lake water quality. In this study, we present spatiotemporal dynamics of CyanoHABs in Continental United States (CONUS) lakes by using a bloom magnitude metric. We estimated bloom magnitude as the spatiotemporal mean of satellite-derived areal CyanoHAB biomass, which was calculated from Medium Resolution Imaging Spectrometer (MERIS) and Ocean Land Color Imager (OLCI) observations. CyanoHAB magnitudes in all satellite-resolvable CONUS lakes were calculated for the MERIS (2003-2011) and OLCI (2016-present) time series. In total, 2,369 lakes were resolved in MERIS/OLCI data, with the majority of these lakes in Minnesota, Maine, Michigan, Texas, and Florida. About 40% of all the lakes had CyanoHAB magnitude in the high risk category, as per World Health Organization guidelines using only biomass, comparable to the one-third of lakes in the National Lake Assessment with cyanotoxins present. These lakes with CyanoHAB issues were found in all regions of the country. We also complemented this analysis by integrating other published bloom metrics such as the spatial extent and temporal frequency to draw actionable insights about the bloom, which may be usable by water-quality managers to prioritize lake management strategies. The proposed framework may serve as a national-level CyanoHAB screening tool for larger lakes, and would allow for annual evaluation of recreational and drinking water lakes.