engleski

Diatoms in the extreme euxinic environment (Rogoznica Lake, eastern Adriatic coast)

Marine lake system, Rogoznica Lake is a small, karstic, naturally eutrophic and euxinic marine environment. Abundance and temporal distribution of phytoplankton was investigated in relation to environmental conditions in the period from 1998. - 2013. The 36 determined diatoms contributed to 90% to the total phytoplankton abundance. The diatom composition is characterized by low species diversity and high single species abundance (up to 107 cells L-1). There were, in average, 2.6 diatom species per sample (maximum 14 diatom species per sample) reflecting extreme environmental conditions. Dominant diatoms Thalassionema nitzschioides, Cyclotella choctawhatcheeana, Dactyliosolen fragilissimus and Chaetoceros curvisetus repeatedly occurred alternating in domination in the lake during the whole research period. Some diatoms were dominant only in limited period like Cyclotella choctawhatcheeana (evident since 2001), and Pseudo-nitzschia spp. (evident in the period 2002 to 2009). It appears that interplay of environmental conditions such as variability in thermohaline and redox conditions, nutrient and reduced sulphur concentration influence the phytoplankton development and abundance in the lake.

Diatoms ; phytoplankton ; marine lake ; extreme environmental conditions

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