The seasonal succession patterns of species of Cladocera with respect to changes in some environmental and biological parameters were examined in a harbour located at Kepez, Dardanelles from 11 April 2006 to 12 April 2007. For this study, environmental parameters and zooplankton data were analysed for one station and sampling trips were conducted every two weeks. Cladoceran abundance varied widely throughout the sampling period, exceeding similar to 87% of total zooplankton, especially during the warmer seasons. The cladoceran community was mainly composed of Penilia avirostris, Pleopsis polyphemoides, and Evadne nordmanni, the first one occurring from late spring through early fall, and the latter two from early spring to early summer. Salinity and temperature seemed to have little or no effect on the distribution, abundance, and variability of the cladocerans in the system, indicating factors other than non-biological environmental parameters, such as competition with other groups of zooplankton, food availability and/or quality, have the greatest effects on cladoceran species composition.