Taxonomical study of phytoplanktonic diatoms in the marine lake (Rogoznica, eastern Adriatic coast)

Godrijan, Jelena; Burić, Zrinka; Kralj, Koraljka; Gligora, Marija; Caput-Mihalić, Katarina; Acs, Eva; Kiss, Keve; Ciglenečki-Jušić, Irena Taxonomical study of phytoplanktonic diatoms in the marine lake (Rogoznica, eastern Adriatic coast). In: Gajović, Srećko, (ed.) Proceedings of the 2nd Croatian Congress on Microscopy with International Participation. Zagreb, Croatian Society for Electron Microscopy, pp. 209-210 .

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Abstract

Phytoplankton in the naturally eutrophicated and periodically anoxic salt Lake Rogoznica was investigated in the period from April 2004 to March 2005. The research provided first data on composition and abundance, as well as temporal and spatial distribution of nanophytoplankton. The lake is karstic and stratified, with regard to temperature, salinity, density, oxygen and hydrogen sulphide concentration. The layer above the halocline (above 6-7 m) is unstable, while the layer below has low oxygen saturation and high sulphur concentration. The nanophytoplankton cell counts were obtained with phase contrast 40 x objective using the inverted microscope Zeiss Axiovert 200. Extreme ecological conditions resulted in low species diversity with high abundance. Nanophytoplankton maximum abundance alternated with microphytoplankton maximum, not following the succession typical for temperate climate conditions. The community was composed of the following recognizable higher taxa: diatoms, dinoflagellates, coccolithophorides, cryptophytes and green flagellates. Pennate diatoms dominated the community in summer and late autumn with maximum abundance in the halocline layer. Centric diatoms were present throughout the year in the whole water column, with maximum development in winter. Under the scanning electron microscope (HITACHI S-2600-N) we were able to distinguish the centric genera such as Thalassiosira, Podosira and Hyalodiscus. Within pennate diatoms we determined Brachysira aponina and Thalassionema nitzschioides.

Item Type:

Conference or workshop item published in conference proceedings (UNSPECIFIED)

Uncontrolled Keywords:

phytoplankton; diatoms; Rogoznica lake; Adriatic sea

Subjects:

NATURAL SCIENCES > Biology
NATURAL SCIENCES > Interdisciplinary Natural Sciences
NATURAL SCIENCES > Interdisciplinary Natural Sciences > Marine Science

Divisions:

Center for Marine Research

Projects: