Seasonal abundance and vertical distribution of Protozoa (flagellates, ciliates), and bacteria in Lake Kinneret, Israel

The seasonal and vertical abundances of ciliates and flagellates are described over a 2 yr period in Lake Kinneret, Israel, a warm rneso-eutroph~c monomictic lake.Ciliate numbers ranged from 3 to 47 cells ml-l.At the thermocline and oxycline region, the h~ghest cillate numbers were observed in autumn, with Coleps hirtus as the dominant speclea.Maximum heterotrophic nanoflagellate abundance (1300 cells ml") was found in the epilimnion In winter-spnng, minimum numbers (66 cells ml-') occurred in autumn.Bacteria ranged from 1 0 h o 3 10' cells ml-l with h ~g h e s t numbers at the decline of the Peridinium yatunense bloom and the lowest during ivlnter.Protozoa, especially ciliates, appeared to be important food sources for metazooplankton.Top-down control is a n important factor determining the structure of the microbial loop in Lake Kinneret.