Determination of the population density of Ophelia bicornis savigny in Lamarck,1818 (Polychaeta:Annelida) in Sinop Peninsula coasts

This study was aimed to determine the population density of Ophelia bicornis in Sinop Peninsula coasts.In this aim, benthic samples were collected between August, 2009 and July, 2010 from the 4 station (Akliman-Stat, Kumkapı, Karakum and DSİ-Kiraztepe) in Sinop Peninsula coasts, monthly.As a result, a total of 1371 individuals of Ophelia bicornis was collected. The maximum individulas in Kumkapı station and minimum in DSİ-Kiraztepe station counted. As for the seasons the maximum density in fall and minimum in winter were determinated.Among the 1371 individuals, the largest length (53.90 mm) in Karakum station and, the shortest length (3.94 mm) were measured in Akliman-Stat station. The highest wet weight with 1.29 g was obtained in Karakum station and the lowest wet weight with 0.0003 g was measured in Akliman-Stat station. Although, eggs of Ophelia bicornis were observed throughout May and October, their maximum densities were established between June and July. The size of eggs were average 0.08±0.02 mm diameter and 0.12±0.02 mm height.In the research area, redoks potential and sediment granulometry analysis in the sediman samples were made. According the particle size analysis; medium sand class in Akliman-Stat and Kumkapı stations, coorse sand class in Karakum station, in DSİ-Kiraztepe station very coarse sand class in winter and spring, medium sand class in summer and fall were dominated.Key Words: Ophelia bicornis, Polychaeta, Annelida, Population density, Sinop Peninsula.