Tests for the toxicity assessment of cyanobacterial bloom samples

Cyanobacterial (blue-green algal) blooms are one of the common consequences of the increasing eutrophication of surface waters. The production of cyan obacterial toxins and their presence in drinking and recreational waters re presents a growing danger to human and animal health. Due to a lack of toxi n standards and to resource limitations on the wide-scale use of analytical methods (e.g., high-performance liquid chromatography, enzyme-linked immun osorbent assay (ELISA)) in cyanobacterial toxin monitoring, it is necessary to assess and to develop additional methods for their detection and estima tion. Microbiotests using invertebrates offer a possible approach for the i nexpensive and straightforward detection and assessment of cyanobacterial b loom toxicity. Three microbiotests with: Thamnocephalus platyurus, Daphnia magna, and Spirostomum ambiguum were examined with bloom samples containing hepatotoxic microcystin-LR and up to five additional microcystin variants. Two kinds of cyanobacterial bloom sample preparations were tested: crude e xtracts (CE) and purified extracts (PE). The highest toxicity was found whe n CE was used for microbiotests. The sensitivity of microorganisms decrease d from S. ambiguum to T. platyurus and to D. magna. A statistically signifi cant correlation was found between microcystin concentration and T. platyur us biotest, and between mouse bioassay and S. ambiguum results. Addition of Me2SO (1%, v/v) is a possible method to increase the sensitivity of the mi croorganisms for microcystin-LR. (C) 2001 by John Wiley & Sons, Inc.