Effects of cyanobacterial extracts containing anatoxin-a and of pure anatoxin-a on early developmental stages of carp.

This study compares the effects of pure anatoxin-a and cyanobacterial extracts of an anatoxin-a producing strain on early stages of development of carp. Carp eggs were exposed from 2:30 h to 4 days post-fertilization to different ecologically relevant concentrations of anatoxin-a, provided as pure toxin or contained in the cyanobacterial extracts. Data on time to mortality, mortality rate, time to hatching, hatching rate, skeletal malformations rate, and larval standard length were registered until 8 days post-fertilization. At any tested concentration of anatoxin-a, the pure toxin was almost harmless to carp early stages of development, contrarily to cell extracts that were highly toxic. Only an adverse effect on the larval length was found at the highest concentration of pure toxin, while increasing concentrations of cell extracts caused increasing adverse effects in all the analyzed parameters. Anatoxin-a producing cyanobacteria should be regarded as putative modulators of aquatic ecosystems communities.