engleski

The structure and dynamics of microphytoplankton in the marine lake Vlaska (eastern Adriatic)

The marine Lake Vlaska (10 m max. depth) is located in the southwest part of the Neretva River delta. This lake has a highly stratified estuarine character. The intensive hypoxia (5-10 m layer) were noted in summer. Sampling was carried out at monthly intervals from April 1999 to April 2000. A total of 145 microphytoplankton taxa was identified. Diatoms, dinoflagellates and cyanophytes were the most important microphytoplankton constituents of the lake. The Bacillariophyceae gave the highest number of taxa (74), followed by Dinophyta (58), Prymnesiophyceae (8), Chrysophyceae (3), Euglenophyceae (1), Cyanophyceae (1) and Chlorophyceae (1). The seasonal development of microphytoplankton cell numbers exhibited two peaks (in April and in August 1999). The first peak reflected the intensive development of Cyclotella sp. and Chaetoceros curvisetus. The second peak was mostly made up of the species Nitzschia longissima and Chaetoceros vixvisibilis. Diatoms had the largest contribution (50-99%) in microphytoplankton cell numbers throughout the year. The main feature of the microphytoplankton assemblages is the simultaneous dominance of more than one species. The reason for this can be found in the very frequent and rapid changes in the environmental conditions of this dynamic ecosystem.

microphytoplankton; marine lake; eastern Adriatic

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