The current state of zooplankton in Petrozavodsk Bay of Lake Onego and its response to climate change have been considered using data collected during multidisciplinary sur­veys in 2010-2017. Five seasonal phases of the annual cycle are described relying on mo­dern and archival zooplankton data. The condition of zooplankton under ice has been studied in detail for the first time. The species composition and the dominant complex, as well as the structure and quantitative characteristics were analyzed taking annual cyclicity into consideration. The dominant, subdominant species and indicators species of phe- nological phases were determined. It was shown that the zooplankton species composi­tion and dominants complex have not changed since the second half of the past century. Total summer (August) zooplankton abundance during the surveys was below average, but within the limits of long-term among-year variation. Rapid development of rotifers and early onset of the summer development phase (before long-term average dates) was the response to shifts in the timing of vernal hydrological phenomena. In the past few de­cades, changes have also occurred in the ratio of warm-water and cold-water species.