Morphospecies of potentially toxic cyanobacterium Microcystis - A review on colony formation and its global distribution

Abstract

The increased occurrence of toxic blooms of Microcystis is emerging as a global concern due to the health implications and associated water quality issues. Microcystis are single-celled ubiquitous cyanobacteria capable of forming colonies of different morphologies in various eutrophic water bodies, including freshwater, estuaries and marine systems. Their distribution and severity have increased during past decades, contributed by factors like warmer temperatures, climate change, eutrophication and other hydrological changes. They form colonies of varying shapes and sizes depending on the type of species and environmental factors. This cyanobacterial genus consists of more than 50 distinct morphological variants, mainly based on their physical characteristics like cell shape, size, colony arrangement etc. However, their greater morphological variations and phenotypic plasticity often complicate their morphological identification. Studies regarding their morphospecies are thus crucial for improved taxonomic classification, identifying the major bloom-forming species and their ecological impacts. This review has attempted to provide a brief knowledge about some of the common morphospecies of Microcystis, its colony formation and distribution worldwide.