Nodularin and cylindrospermopsin: a review of their effects on fish

Nodularin (NOD) and cylindrospermopsin (CYN) are hepatotoxic cyanotoxins that are present in numerous ecosystems where bloom episodes occur. In this review, the different effects of both of these cyanotoxins on the different ontogenic stages of various fish species were summarised to clarify the state-of-the-art scientific knowledge on this topic. It is clear that fish that are exposed to NOD and CYN were negatively impacted in every studied ontogenic stage. Indeed, these cyanotoxins can accumulate in various organs of fish, leading to deleterious effects on the physiology. This review highlights the fact that all of the previously published studies on the topic have focused only on the short-term effects of a given cyanotoxin on fish. However, during cyanobacterial blooms, fish can be exposed chronically to a variety of toxic compounds with which the fish interact, leading to stronger effects than those observed with a single toxin tested over a short timeframe. Thus, it is essential to conduct additional studies to better understand the actual toxic effects of cyanobacterial blooms on fish populations over medium- and long-term time scales.