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Generating ecotoxicity information on microcystins and prymnesins: A different approach (2019 SETAC)
Citation:
Lazorchak, J., H. Haring, W. Thoeny, N. Dugan, Hubert Allen, T. Sanan, C. Nietch, AND D. Tettenhorst. Generating ecotoxicity information on microcystins and prymnesins: A different approach (2019 SETAC). 2019 SETAC North America Annual Meeting, Toronto, CANADA, November 03 - 07, 2019.
Impact/Purpose:
This is presentation covers the work we have been doing with pure cultures and surface water samples in order to access the toxicity of toxins to standard EPA test organisms.
Description:
There is a lack of information to estimate safe levels for aquatic life concerning the toxicity of natural toxins produced by cyanobacteria and algae. There is even less ecotoxicity information available for prymnesin, a toxin produced by the estuarine golden algae Prymnesium parvum. Given the uncertainty of standards for bacteria and algal toxins, the cost of using them to conduct acute and chronic toxicity tests and their potential impurities, a new approach is proposed using cultures and ambient samples. In this study we have used laboratory cultures of a toxin producing unicellular Microcystis aeruginosa and P parvum and non-toxin producing filamentous Anabaena flos-aquae. Each culture was centrifuged to remove each species from its culture media, then resuspended in moderately hard water. The toxin culture, M aeruginosa was then frozen/thawed three times at -80 C following procedures used for ELISA analyses. The non-toxin strain was not lysed. Both 48-hour acute tests and 7-day short term chronic tests were conducted with Ceriodaphnia dubia, Neocloeon triangulifer, Hyalella azteca and larval Pimephales promelas on all strains. A similar lysing procedure was also used on lake water samples. Microcystin concentrations in the lysed samples as high as 74 ug/L did not cause any toxicity greater than the lab water controls to any of the 4-test species. A flos-aguae caused mortality greater than the controls to N triangulifer. For chronic tests 80 L of culture Microcystin aeruginosa were grown to achieve a cell density of 2.2625 X 106 cells/ml. No lysed M. aeruginosa treatment levels exhibited any adverse survival effects versus the moderately hard water controls in C. dubia, P. promelas or H. azteca tests. N triangulifer tests did not meet test performance criteria. The only adverse effects noted in these tests were the sub-lethal point estimate endpoints for reproduction inhibition (IC25=30.96% [1.37X106 cells/ml]) in the C. dubia bioassay. August 2017 Lake Harsha sample (total # of cells 300,000 cells/ml) was not acutely toxic to any of the 4-test species. P. parvum acute and chronic tests with the same 4 species. C. dubia and N. triangulifer exhibited LC50s of 493,850 cells/ml and 121,761 cells/ml, respectively. Additional analyses will be provided based on toxin results and results from 2017 and 2019 whole lake sample tests.