The vertical distribution of planktonic ciliates in eight strongly stratifi
ed temperate lakes was studied in summer 1998. Ciliate abundance and biomas
s were highest (mean 39.9 cells ml(-1) and 181.9 mug C l(-1)) in the epi-,
and lowest (mean 8.2 cells ml(-1) and 97.6 mug C l(-1)) in the hypolimnion.
The community of ciliates was dominated by five orders: Oligotrichida, Hap
torida, Prostomatida, Scuticociliatida and Peritrichida. The community comp
osition varied greatly with depth. In the epilimnion, the ciliate numbers w
ere dominated by oligotrichs but small algivorous prostomatids, peritrichs
and haptorids were also numerous. In the metalimnion, these groups were rep
laced by scuticociliates and mixotrophic prostomatids. In the hypolimnion s
pecies known as benthic migrants appeared. We found a positive significant
correlation (p < 0.05) between ciliate numbers and Chl a and bacterial dens
ities. Only in the hypolimnion, the correlation between ciliates numbers an
d Chl a was not significant.