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Cyanotoxins in inland lakes of the continental United States: Photic Zone Occurrence and potential recreational health risks in the 2007 Survey of the Nation's lakes
Loftin, K., J. Graham, E Hilborn, S. Lehmann, M. Meyer, AND C. Griffith. Cyanotoxins in inland lakes of the continental United States: Photic Zone Occurrence and potential recreational health risks in the 2007 Survey of the Nation's lakes. Eighth Symposium on Harmful Algae in the U.S, Long Beach, CA, November 15 - 19, 2015.
This report describes co-occurrence of cyanobacteria toxins in 2007 National Lake survey samples. The National Lake Survey was a representative survey of water quality among US lakes. Previous reports have described microcystin detections among 32% of samples. This report describes detections of cylindrospermopsin among 4% of samples, and saxitoxin among 8% of samples. The Contaminant Candidate Lists have included microcystins and cylindropermopsin as emerging chemical contaminants in drinking water.
The largest spatial survey of cylindrospermosins, microcystins, and saxitoxins in the United States was conducted as part of the 2007 U.S. Survey of the Nation’s Lakes. Integrated photic zone samples were collected from 1,161 lakes during May-September 2007. Cyanotoxin, cyanobacteria, and chlorophyll concentrations were compared with World Health Organization (WHO) guidance for public health protection. Cylindrospermopsins, microcystins, and saxitoxins were detected by ELISA in 4.0, 32, and 7.7 % of samples with mean concentrations (detections only) of 0.56, 3.0, and 0.061 μg/L, respectively. Co-occurrence of the three cyanotoxin classes was rare (0.32%). Cyanobacteria were present in 98% of samples and dominated total phytoplankton abundance in 76% of samples. Potential anatoxin-, cylindrospermopsin-, microcystin-, and saxitoxin-producing cyanobacteria occurred in 82, 66, 95, and 78% of samples, respectively. Anatoxin-a and nodularin-R were detected in 15 and 3.7% of samples (n=27) that were analyzed by LC/MS/MS. Both Cylindrospermopsis sp. and Nodularia sp. occurred rarely (3.9 and 0.24%). Cylindrospermopsis sp. was not associated with cylindrospermopsin occurrence. Microcystin concentrations exceeded the WHO guidance for moderate and high risk in 0.40 % and 0.72% of samples. In contrast, WHO guidelines based on cyanobacterial abundance and chlorophyll were exceeded in 27 and 44% of samples, respectively. Only 27% of samples were categorized in the same risk category by evaluating concurrence among all three WHO microcystin risk metrics. The lack of parity amongst WHO guidelines was expected given chlorophyll’s lack of specificity to cyanobacteria and not all cyanobacteria produce microcystins.