Structure and seasonal trophodynamics of picophytoplankton in sevastopol bay and adjacent waters (the Black Sea)

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• 作者：V. S. Mukhanov ; O. A. Rylkova ; T. Ya. Churilova ; E. G. Sakhon…
• 关键词：picophytoplankton ; Synechococcus ; picoeukaryotes ; specific growth rate ; daily production ; grazing mortality ; biomass turnover ; Black Sea
• 刊名：Microbiology
• 出版年：2016
• 出版时间：September 2016
• 年：2016
• 卷：85
• 期：5
• 页码：553-561
• 全文大小：878 KB
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Life Sciences
  Microbiology
  Medical Microbiology
  Russian Library of Science
  
• 出版者：MAIK Nauka/Interperiodica distributed exclusively by Springer Science+Business Media LLC.
• ISSN：1608-3237
• 卷排序：85

文摘

Abundance and seasonal trophodynamics (specific growth rate, daily production, and grazing mortality) of the major picophytoplankton components, Synechococcus cyanobacteria (Syn) and picoeukaryotes (Pico-E), were studied at three stations in Sevastopol Bay and adjacent coastal waters (the Black Sea) in 2014 by flow cytometry and the dilution method. Pico-E abundance was shown to increase along the nutrient and pollution gradient from the coastal waters outside the bay (annual average of 7.3 ± 5.4 × 103 cells mL–1) to the eastern corner of the bay (28.7 ± 11.4 × 103 cells mL–1), while no relation was found between the water pollution status and Syn abundance (9.9 ± 8.7 × 103 cells mL–1; at all the stations, n = 27). Matter flows through the communities (daily production for Syn and Pico-E 0–16.6 and 0–19.3 µg C L–1 day–1, respectively; grazing mortality for Syn and PicoE 0–3.6 and 0–21.2 µg C L–1 day–1, respectively) were comparable to or even exceeded their biomass stocks (>0.05–6.8 and 0.9–26.5 µg C L–1 for Syn and PicoE, respectively), indicating high biomass turnover rates. The highest flow-to-stock ratio (up to 6 for Syn) and a significant imbalance between daily production (P) and grazing mortality (G) were observed in the most polluted and eutrophic waters of the bay in spring (Pico-E: P/G < 1) and late summer (Syn: P/G > 1). Black River inflow to the bay was hypothesized to be among the mechanisms maintaining this pronounced and long-term imbalance in the open system without any negative consequences for the picophytoplankton assemblages.