Effects of cyanobacterial toxins, microcystins on freshwater invertebrates

Cyanobacteria, also known as blue-green algae, are prokaryotic, phototrophic microorganisms that may form massive blooms in eutrophic water reservoirs. Some cyanobacterial strains are able to produce secondary metabolites – cyanotoxins that may be hazardous to aquatic and terrestial animals. These compunds can be grouped into: hepatotoxins, neurotoxins, cytotoxins dermatotoxins and irritant toxins. Microcystins are well-known cyclic heptapeptides acting as inhibitors of protein phosphatases type 1 and 2A. These cyanotoxins induce various adverse effects in freshwater invertebrates including biochemical, physiological and behavioral changes. Moreover, accumulation of microcystins in different tissues occurs, therefore transfer of these cyanotoxins through the food chain to animals being at higher trophic levels may be possible. The purpose of this paper is to review the knowledge on the effects of microcystins on three main groups of freshwater invertebrates: zooplankton, higher crustaceans, mollusks and to indicate possible ecotoxicological consequences of this impact on aquatic environment and invertebrate aquacultures.