Determine the amount of blue - green algae anatoxin-a in water ecosystems Guilan

Summer blue- green algae (Cyanophyta) bloom playing a significant role in fish mortality in fish farms. In order to determine the dominant blue-green algae toxicity eight species of cyanophyts in fish farms were isolated and cultured. Then toxin levels anatoxin-a was measured by gas chromatography with mass spectrometry (GC-MS) detection. The results showed that toxin levels in Aphanizomenon flos- aquae with 19. 91 μg /kg more than the other Species studied and the lowest in Oscillatoria sp. with 1. 53 μg/ kg was estimated. Generally high blooms of cyanophyts، particularly two species of Aphanizomenon flos- aquae and Anabaena flos-aquae can lead to mortality in fish farms.