A rapid bioassay for detecting saxitoxins using a Daphnia acute toxicity test

• Published in: Environmental pollution (1987) Vol. 158; no. 6; pp. 2084 - 2093
• Main Authors: Ferrão-Filho, Aloysio da S., Soares, Maria Carolina S., de Magalhães, Valéria Freitas, Azevedo, Sandra M.F.O.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.06.2010; Elsevier Science Ltd; Elsevier
• Subjects: acute toxicity; Animal, plant and microbial ecology; Animals; Applied ecology; Bioassay; bioassays; Biological and medical sciences; Biological Assay; Biomass; Cladocerans; Crustacea; Cyanobacteria; Cyanobacteria - chemistry; Cyanobacteria - growth & development; Cylindrospermopsis; Cylindrospermopsis raciborskii; Daphnia; Daphnia - drug effects; Daphnia - physiology; Daphnia pulex; Density; Ecotoxicology, biological effects of pollution; Fresh Water - analysis; Fresh Water - microbiology; Freshwater; Fundamental and applied biological sciences. Psychology; General aspects; Invertebrates; Lakes; mice; Moina micrura; neurotoxins; Paralysis; phytoplankton; Raw; Regression Analysis; Reproducibility of Results; Reservoirs; Saxitoxin - analysis; Saxitoxins; Swimming; Swimming - physiology; Toxicity; toxicity testing; Toxicity Tests, Acute; Water Microbiology; Water Pollutants, Chemical - analysis; Daphnia; Cylindrospermopsis; Cladocerans; Cyanobacteria; Saxitoxins; Bioassay; Acute; Cladocera; Toxicity test; Crustacea; Pollution; Arthropoda; Bacteria; Environment; Invertebrata; Branchiopoda
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2010.03.007

Bioassays using Daphnia pulex and Moina micrura were designed to detect cyanobacterial neurotoxins in raw water samples. Phytoplankton and cyanotoxins from seston were analyzed during 15 months in a eutrophic reservoir. Effective time to immobilize 50% of the exposed individuals (ET 50) was adopted as the endpoint. Paralysis of swimming movements was observed between ∼0.5–3 h of exposure to lake water containing toxic cyanobacteria, followed by an almost complete recovery of the swimming activity within 24 h after being placed in control water. The same effects were observed in bioassays with a saxitoxin-producer strain of Cylindrospermopsis raciborskii isolated from the reservoir. Regression analysis showed significant relationships between ET 50 vs. cell density, biomass and saxitoxins content, suggesting that the paralysis of Daphnia in lake water samples was caused by saxitoxins found in C. raciborskii. Daphnia bioassay was found to be a sensitive method for detecting fast-acting neurotoxins in natural samples, with important advantages over mouse bioassays. A new Daphnia bioassay, as an alternative to the mouse bioassay, is able to detect effects of fast-acting, potent neurotoxins in raw water.