Growth of Toxic Cyanobacteria Dolichospermum flos-aquae (Anabaena flos-aquae) in the Waters of the Boreal Zone

The life cycle of cyanobacteria Dolichospermum flos-aquae causing the blooming of waters of the boreal zone is studied. The mass propagation of the D. flos-aquae in the plankton stage occurs due to their ability to realize high biotic potential, defined by the combination of features developed during evolution, which the other partners of the plankton community lack. These include: adaptation to a certain growth temperature; low demand for nutrients; nitrogen fixation and intracellular accumulation of phosphates; and the ability of trichomes to migrate, allowing them to occupy the optimal parts of the euphotic zone for photosynthesis. It is established that the trichomes of D. flos-aquae consist of heterocysts and vegetative cells of different maturity, generosity, and activity during the planktonic stage, and their ratio changes throughout the life cycle of microorganisms. It is believed that the primary and secondary metabolites released by D. flos-aquae into the medium take part in the regulation of their own population growth, including cell destruction at the final stage of blooming, akinetes formation, and the simultaneous suppression in propagation of community partners. With the dominance of one species, the released toxic metabolites increase in years with an anticyclone type of weather, resulting in the reduction of species diversity and the simplification of the biotic community structure. © 2019, Allerton Press, Inc.