Silkin, V.; Pautova, L.; Podymov, O.; Chasovnikov, V.; Lifanchuk, A.; Fedorov, A.; Kluchantseva, A. Phytoplankton Dynamics and Biogeochemistry of the Black Sea. J. Mar. Sci. Eng.2023, 11, 1196.
Silkin, V.; Pautova, L.; Podymov, O.; Chasovnikov, V.; Lifanchuk, A.; Fedorov, A.; Kluchantseva, A. Phytoplankton Dynamics and Biogeochemistry of the Black Sea. J. Mar. Sci. Eng. 2023, 11, 1196.
Silkin, V.; Pautova, L.; Podymov, O.; Chasovnikov, V.; Lifanchuk, A.; Fedorov, A.; Kluchantseva, A. Phytoplankton Dynamics and Biogeochemistry of the Black Sea. J. Mar. Sci. Eng.2023, 11, 1196.
Silkin, V.; Pautova, L.; Podymov, O.; Chasovnikov, V.; Lifanchuk, A.; Fedorov, A.; Kluchantseva, A. Phytoplankton Dynamics and Biogeochemistry of the Black Sea. J. Mar. Sci. Eng. 2023, 11, 1196.
Abstract
Biogeochemistry of waters is an essential regulator of phytoplankton dynamics, determining the level of species bloom and the change of dominants. The paper investigated the seasonal dynamics of phytoplankton and the nutrient concentration and their ratios in the NE Black Sea in 2017-2021. Two taxonomic groups, diatoms, and coccolithophores, determine seasonal dynamics and significantly contribute to the total phytoplankton biomass. Coccolithophores annually, except in 2020, formed bloom in early June. Large diatoms in summer annually, except in 2019, dominated with biomass exceeding 1000 mg m-3. During the bloom of these taxonomic groups, their contribution to the total phytoplankton biomass exceeded 90%. Each group has characteristic biogeochemical niches in the nitrogen and phosphorus concentrations coordinates. The regulation of the biogeochemistry of water is the position of the seasonal thermocline. With a high-lying and sharp gradient thermocline (the average for five years is 6.87 m), low nitrogen concentrations and a nitrogen-to-phosphorus ratio below the Redfield ratio are created in the upper mixed layer. These conditions are optimal for the dominance of coccolithophores. When the thermocline is deepened (the average for five years is 17.96 m), the phosphorus concentration decreases significantly and the ratio of nitrogen to phosphorus is significantly higher than the Redfield ratio, and these conditions lead to the dominance of large diatoms. The results of experimental studies with nitrogen and phosphorus additives in the natural phytoplankton population confirm the above statements. The addition of phosphorus leads to an increased role of coccolithophores in the total phytoplankton biomass, the addition of nitrogen alone contributes to the growth of large diatoms, and the combined addition of phosphorus and nitrogen in a ratio close to the Redfield ratio leads to the dominance of small diatoms.
Keywords
phytoplankton; Black Sea; biogeochemistry; species composition; diatoms; coccolithophores
Subject
Environmental and Earth Sciences, Oceanography
Copyright:
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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