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Generating ecotoxicity information on microcystins and prymnesins: A different approach
Citation:
Lazorchak, Jim, P. Wernsing, N. Dugan, Joel Allen, AND C. Nietch. Generating ecotoxicity information on microcystins and prymnesins: A different approach. 2017 SETAC North America Annual Meeting, Minneapolis, MN, November 12 - 16, 2017.
Impact/Purpose:
This presentation will present results of how to test algal toxins by using lysed cells from pure cultures of microcystis and P parvum to generate standard ecotoxicology endpoints
Description:
There is a lack of information for estimating safe levels for aquatic life concerning the toxicity of natural toxins produced by cyanobacteria and algae. There are a number of reviews that have indicated that the toxicity of microcystins to daphnia and zebrafish is not as great as it is to humans and mammals. Current literature indicates the LC50s for Microcystin LR range from 1 – 21 mg/L. There is even less ecotoxicity information available for prymnesin which is produced from the estuarine golden algae Prymnesium parvum that has invaded freshwater systems in the U.S., even though there have been numerous fish kills recorded in inland Texas lakes and blooms in freshwater systems in 10 other states. Given the uncertainty of standards for bacteria and algal toxins, their cost of using them to conduct acute and chronic toxicity tests and their potential impurities, a new approach is proposed using pure cultures and ambient bloom samples. Herrera, Echeverri and Ferrao-Filho (2015) conducted acute and chronic toxicity tests on several different cladoceran species using lyophilized phytoplankton samples collected from hyrdroelectric/drinking water reservoirs in Brazil. They found that reservoir samples with higher microcystin contents were the most toxic ones and that different cladocerans had different sensitivities to microcystin. In this study we have taken a similar approach but we used laboratory cultures of toxic Microcystis aeruginosa and P parvum. Each culture was centrifuged to remove each species at its peak production of toxin, then resuspended in moderately hard water followed by a freeze/thaw step 3 times at -80 C similar to procedures used for ELISA methods. Initial chemistry results of the M aeruginosa cultures indicate that a 100-x diluted sample had 3.8 ug/L MC-LR, 1.1 ug/L D-Asp3-MC-LR, and 1 ug/L MC-LA or a total microcystin concentration of 600 ug/L. Ceriodaphnia dubia, Daphnia magna, Hyalella azteca and larval Pimephales promelas were exposed to a similar extract. A similar procedure was also used on lake water samples collected during peak bloom condition. The exposure method and comparison of results of the lab culture and lake samples will be presented.
