D. Petrova, D. Gerdzhikov, G. Kostadinova
Abstract. The genus Chaetoceros Ehrenberg of class Bacillariophyceae is widespread and abundant in species in the Black Sea phytoplankton. The aim of the article was to study its distribution in water and to analyzed its contemporary involvement in the formation of qualitative and quantitative composition of phytoplankton, the season dynamics of genus during the hydro-biological year and its role in the ecology of the Bulgarian Black Sea coastal water area for the period 2008 – 2010. It was found out that the highest species diversity, abundance and biomass of the genus were in the autumn and spring – a bimodal pattern of annual growth. 20 species and forms were registered of the genus Chaetoceros. They formed up to 1/3 of the taxonomic composition of Diatoms and 1/10 of all phytoplankton species. “Blooms” of representatives of the genus Chaetoceros in the researched period were not registered.