Weekly field samplings were performed at the Kepez Harbor located at the Dardanelles Strait for temperature, salinity, Secchi disk, dissolved oxygen, chlorophyll-a and nutrient concentrations, zooplankton abundance, and community structure from 26 April 2005 to 25 April 2006. Zooplankton samples were collected Using a plankton net with a mesh size of 1,80 mu m for the mesozooplankton and vertical tows were conducted between 0-5 m 10-15 m, and 15-20 m. Whole water samples were also collected for microzooplankton. All mesozooplankton groups increased in number starting at the end of May through June. Copepoda dominated the surface and mixed layer during the early spring and Acartia clausi was the most Abundant species when compared to the others. Cladocera showed a clear seasonal succession pattern in the study site and were mainly composed of Penilia avirostris, Pleopsis polyphemoides, and Evadne nordmanni. Oikopleura dioica, the only representative of the appendicularians, reached its maximum abundance during mid summer. The zooplankton species composition in the sampling site was diverse and a unique two layer flow regime of the system allowed us to observe both the Mediterranean and the Black Sea influence on the organisms.