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Toxicology of a Microcystis ichthyoblabe waterbloom from Lake Oued Mellah (Morocco)

2002; Wiley; Volume: 17; Issue: 1 Linguagem: Inglês

10.1002/tox.10028

1522-7278

Brahim Sabour, Mohammed Loudiki, Brahim Oudra, Vı́tor Vasconcelos, Rosário Martíns, Saïd Oubraim, Brahim Fawzi,

Marine Toxins and Detection Methods

Abstract In the Lake Oued Mellah cyanobacteria waterblooms occur periodically in late spring and summer with Microcystis ichthyoblabe as the main bloom‐forming species. In 1999, a heavy waterbloom of M. ichthyoblabe occurred during May June with a maximal biomass of 298 mg/l. During this period, several bloom samples were collected. The toxicity assessment was done by mouse and brine shrimp ( Artemia ) bioassays. Apart from the sample collected on 15/06/1999, all the other samples were toxic by mouse bioassay. The LD 50 determined by intraperitoneal injection to mice during active cyanobacterial growth and decline phases were 518 and 1924 mgDW/kg respectively. Using Artemia bioassay, the 24hLC 50 varied from 6.0 to 40.6 mg/ml and the 48hLC 50 ranged from 2.8 to 18.2 mg/ml. The separation and identification of microcystin variants was performed by high performance liquid chromatography–photodiode array detection. Eleven toxins were separated and preliminarily identified as microcystin variants as they exhibit a typical UV spectra like the microcystin‐LR standard. The quantification of total microcystins determined by enzyme‐linked immunosorbent assay showed that the contents were varied between 0.1 and 0.76 μg/g DW. © 2002 by Wiley Periodicals, Inc. Environ Toxicol 17: 24–31, 2002