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Cyanotoxin occurrence in large rivers of the United States

January 29, 2020

Cyanotoxins occur in rivers worldwide but are understudied in lotic ecosystems relative to lakes and reservoirs. Eleven large river sites located throughout the United States were sampled during June–September 2017 to determine the occurrence of cyanobacteria with known cyanotoxin-producing strains, cyanotoxin synthetase genes, and cyanotoxins. Chlorophyll-a concentrations spanned the range from oligotrophic to eutrophic (0.5–64.4 µg L-1). Cyanobacteria were present in the algal communities of all rivers (82% of samples, n=50), but did not dominate the phytoplankton (0 to 52% of total abundance; mean=8.8%). Pseudanabaena and Planktothrix occurred most often and many (64%) of the cyanobacterial genera identified (n=25) have known cyanotoxin-producing strains. Cyanotoxin synthetase genes occurred in all but one river. The mcyE and sxtA genes were most common, present in 73% of rivers and 44% and 40% of samples, respectively. The cyrA gene was less common (22% of samples) but occurred in 64% of rivers. The anaC gene was detected in one river (4% of samples). Anatoxin-a and microcystins were detected at low levels (0.10–0.38 µg L-1) in two midcontinent rivers. Cylindrospermopsins and saxitoxins were not detected. Cyanobacteria, cyanotoxin synthetase genes, and cyanotoxins were present at low concentrations throughout this subset of US rivers. Eutrophic rivers located in the midcontinent region of the US had the highest algal biomass, abundance of cyanotoxin synthetase genes, and cyanotoxin occurrence.

Publication Year 2020
Title Cyanotoxin occurrence in large rivers of the United States
DOI 10.1080/20442041.2019.1700749
Authors Jennifer L. Graham, Neil Dubrovsky, Guy Foster, Lindsey R. King, Keith Loftin, Barry Rosen, Erin Stelzer
Publication Type Article
Publication Subtype Journal Article
Series Title Inland Waters
Index ID 70208179
Record Source USGS Publications Warehouse
USGS Organization New York Water Science Center