Acute effects of an anatoxin-a producing cyanobacterium on juvenile fish—Cyprinus carpio L.

The worldwide increase of eutrophication in fresh water bodies has caused cyanobacterial blooms to be more frequent. Anatoxin-a is a potent neurotoxin known to be produced by several genera of cyanobacteria including Anabaena. In this work, we exposed juvenile carps to freeze-dried cells of a toxic strain of the cyanobacterium Anabaena sp. during a 4-day period. Two different cell density—105 and 107 cell ml−1—were assayed. Lethality and anatoxin-a concentration in the whole fish were determined. In the higher cell density, all fish died between 26 and 29 h after exposure to toxin, whereas in the 105 cell ml−1 density no deaths were observed. Levels of anatoxin-a in the whole fish ranged between 0.031 μg g−1 d.w. at the 105 cell ml−1 concentration and 0.768 μg g−1 d.w. at 107 cell ml−1. Minor uptake of anatoxin-a occurred.