Seasonal dynamics of akinetes of Anabaena flos-aquae in the bottom sediments and water column of a small Siberian reservoir

Seasonal dynamics of akinetes of Anabaena flos-aquae (Lyngb.) Breb. was studied in the sediments and the water column in profundal and littoral zones of a small Siberian reservoir. It was hypothesized that even in a shallow mixed reservoir cyanobacterial bloom initiates in the littoral zone and only then distributes throughout the water body. Two types of akinetes have been recognized: one type ensures vegetative reproduction, and the other, survival during adverse growth conditions. Seasonal dynamics of abundance of akinetes and vegetative cells was quite the same in water column in the littoral and profundal zones. However, there were differences in the seasonal dynamics of abundance of akinetes in the bottom sediments of these two areas: in the central zone the abundance increased throughout the vegetation period, whereas in the littoral zone the abundance decreased after settling of akinetes. During winter, the abundance of akinetes decreased in the sediments in both profundal and littoral zones. The explanation to this fact has not been found yet.