Impact of the cyanobacteria toxin, microcystin-lr on behaviour of zebrafish, danio rerio

Quantitative behaviour of zebrafish, Danio rerio, was recorded to assess and predict long-term sublethal effects of the cyanobacteria toxin microcystin-LR (MCYST-LR; nominal concentrations of 0.5, 5, 15 and 50 μg litre−1) by using the automated BehavioQuant®. The exposure to MCYST-LR caused dose–effect related changes in spontaneous locomotor activity. Whereas the two lower exposure concentrations (0.5 and 5 μg litre−1) caused an increase in daytime motility, elevated exposures led to significantly decreased motilities. The highest exposure (50 μg litre−1) also reduced the spawning activity and success. In contrast to daytime activities, night-time swimming activity was significantly greater at the higher MCYST-LR exposures. The chronobiological analysis indicated a phase shift of maximum swimming activities and a lowered reaction on trigger points like feeding, at dusk and dawn. Furthermore, the results indicate some adverse consequences in reproduction success and in the spatial and temporal fit of the fish into its habitat.