engleski

Phytoplankton composition in relation to physico-chemical drivers in the Bay of Kotor, SE Adriatic Sea

The Bay of Kotor is a deeply indented bay located in the south-eastern coast of the Adriatic Sea. Information on planktonic communities in the area is sparse and knowledge about phytoplankton taxonomic composition and distribution of size classes which influences energy transfer through the food web is lacking. Therefore, the objective of the present study was to investigate the phytoplankton composition and biomass as well as the physical- and chemical environment. Samples were collected seasonally at three locations during 2008/2009. The phytoplankton composition was investigated by means of flow cytometry and various light- and electron microscopic techniques. High influx of freshwater from numerous streams and submarine springs resulted in a strong vertical thermohaline gradient throughout the year influencing the chemical and biological properties of the water column. The picophytoplankton was dominated in all seasons by phycoerythrin-rich cyanobacteria of the Synechococcus type. The nanophytoplankton was dominated by autotrophic/mixotrophic flagellates in the upper part of the water column and the coccolithophores in the lower part with Emiliania huxleyi and Helicosphaera carteri as prevalent among ten identified species. Among diatoms Skeletonema marinoi was the most prominent in spring (maximum abundance 2.9 x 10^7 cells L^-1). The diatom genus Pseudo-nitzschia was present throughout the year with three identified potentially toxin producing species: P. cuspidata, P. calliantha and P. fraudulenta. During summer the harmful dinoflagellate Prorocentrum minimum was also recorded in high abundances (4.0 x 10^4 cells L^-1). The results point at the importance of enhanced research effort with the focus on environmental factors driving potentially harmful algae blooms in the area.

Kotor Bay ; phytoplankton ; Pseudo-nitzschia ; coccolitophores

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