Daily vertical migration of zooplankton: Karanlik Harbour, Dardanelles strait as an exemplary

This study was seasonally conducted between February 2011 and October 2011 at Karanlik Liman located at the Dardanelles Strait. During the study period, 44 species which belong to 23 family and 24 genus, were determined. According to the results from the selected station in Dardanelles Strait which has a two-layer flow regime, the dominant species were; Copepod nauplii, Oithona sp. (Baird, 1843), Oithona similis (Claus, 1866), Oithona nana (Giesbrecht, 1893), Microsetella norvegica (Boeck, 1865) from the copepods and Penilia avirostris (Dana, 1849) from the cladocerans. The abundance of zooplankton species were observed mostly in fall (28), respectively in summer (26), in spring (22) and in winter (22). When the vertical distribution of species were investigated, migration of Paracalanus sp. (Boeck,1865) during new moon in winter sampling and full moon in spring, Oncaea sp. (Philippi, 1843) during full moon in fall sampling, Oithona plumifera (Baird, 1843) during new moon in fall sampling, Microsetella norvegica (Boeck, 1865) during new moon in winter and full moon in fall sampling and Oithona nana (Giesbrecht, 1893) during new moon in winter sampling were observed. It was determined that temperature, salinity, weather condition, light, predators, diet of species and thermocline layer were effective on the vertical distribution of species.Keywords: Physico-chemical variables, zooplankton groups, vertical migration, the Dardanelles, Karanlık Harbour