Increasing contribution of coccolithophorids to the phytoplankton in the northeastern Black Sea

Abstract

During 2005-2011, 418 phytoplankton samples were collected in Novorossiysk and Tuapse ports and near the resort cities of Anapa and Gelendzhik in the northeastern Black Sea. The maximal values of both abundance and biomass of phytoplankton related to high nutrient concentration, probably due to anthropogenic load, were observed at Novorossiysk (5.82×10⁵cells/l, 1.492g/m³); in other bays values were about three times lower. The annual cycle included two to four phytoplankton abundance peaks. Emiliania huxleyi was the most abundant coccolithophorid (1.15×10⁵cells/l offshore and 2.20×10⁴cells/l in bays and ports). In spring-summer it contributed up to 90% of the phytoplankton abundance offshore. The maximal abundance of E. huxleyi was observed offshore of Gelendzhik (up to 1.32×10⁶cells/l); the minimum was in the coastal zone in the port of Novorossiysk (on average 7.7×10³cells/l). Generally, the species appears to avoid eutrophic waters.

Keywords: Black Sea; Blooms; Coccolithophorids; Emiliania huxleyi; Eutrophication; Phytoplankton.