O<sub>2</sub> and CO<sub>2</sub> Responses of the Synaptic Period to Under-Ice Phytoplankton Bloom in the Eutrophic Razdolnaya River Estuary of Amur Bay, the Sea of Japan
Hydrological conditions are an important factor for aquatic ecosystems. Their contribution to stimulating phytoplankton bloom in eutrophic estuaries is not quite clear. We present the results of an outbreak of a phytoplankton bloom event observed in the eutrophic Razdolnaya R. estuary in 2022 from J...
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MDPI AG
2022-11-01
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| Series: | Journal of Marine Science and Engineering |
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| Online Access: | https://www.mdpi.com/2077-1312/10/12/1798 |
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| author | Pavel Semkin Pavel Tishchenko Galina Pavlova Yuri Barabanshchikov Petr Tishchenko Maria Shvetsova Elena Shkirnikova Yulia Fedorets |
| author_facet | Pavel Semkin Pavel Tishchenko Galina Pavlova Yuri Barabanshchikov Petr Tishchenko Maria Shvetsova Elena Shkirnikova Yulia Fedorets |
| author_sort | Pavel Semkin |
| collection | DOAJ |
| description | Hydrological conditions are an important factor for aquatic ecosystems. Their contribution to stimulating phytoplankton bloom in eutrophic estuaries is not quite clear. We present the results of an outbreak of a phytoplankton bloom event observed in the eutrophic Razdolnaya R. estuary in 2022 from January 22 to February 23, when the estuary was covered by ice. The bloom spreads over 21 km from the river mouth bar to upstream in the near-bottom layer below the halocline. The Chl-a concentration in the bloom area increased from 15 to 100 μg/L, and the dissolved oxygen concentration from 350 to 567 μmol/kg at a rate of 11 μmol/(kg day) over the study period, while the CO<sub>2</sub> partial pressure was reduced to 108 µatm in the most oxygen-supersaturated waters. The <i>Thalassiosira nordenskioeldii</i> Cleve sea diatom was the dominant phytoplankton species in the bloom area. The opposite trend was observed near the boundary of the saline water wedge penetration over 29 km from the river mouth bar to upstream where the dissolved oxygen concentration decreased from 140 to 53 μmol/kg over a month, and partial pressure of CO<sub>2</sub> reached 4454 μatm. We also present the results obtained in February 2016 before and after a snowfall, when the ability of PAR to penetrate through the ice was impeded by a layer of snow. After the snowfall, photosynthesis in the under-ice water stopped and the oxygen concentration decreased to almost zero due to the microbiological destruction of the phytoplankton biomass. As such, the main effect of phytoplankton bloom is the formation of superoxia/hypoxia (depending on the light conditions), during the period of maximum ice thickness and minimum river discharge. Thus, this study demonstrates that the eutrophication in the future could lead to unstable ecosystems and large synoptic variations of dissolved oxygen and CO<sub>2</sub> partial pressure of the estuaries. |
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| institution | Directory Open Access Journal |
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| language | English |
| last_indexed | 2024-03-09T16:15:22Z |
| publishDate | 2022-11-01 |
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| spelling | doaj.art-ece7edd255be4ea697e3d614d360c7702023-11-24T15:54:30ZengMDPI AGJournal of Marine Science and Engineering2077-13122022-11-011012179810.3390/jmse10121798O<sub>2</sub> and CO<sub>2</sub> Responses of the Synaptic Period to Under-Ice Phytoplankton Bloom in the Eutrophic Razdolnaya River Estuary of Amur Bay, the Sea of JapanPavel Semkin0Pavel Tishchenko1Galina Pavlova2Yuri Barabanshchikov3Petr Tishchenko4Maria Shvetsova5Elena Shkirnikova6Yulia Fedorets7Il’ichev Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences, 690041 Vladivostok, RussiaIl’ichev Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences, 690041 Vladivostok, RussiaIl’ichev Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences, 690041 Vladivostok, RussiaIl’ichev Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences, 690041 Vladivostok, RussiaIl’ichev Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences, 690041 Vladivostok, RussiaIl’ichev Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences, 690041 Vladivostok, RussiaIl’ichev Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences, 690041 Vladivostok, RussiaIl’ichev Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences, 690041 Vladivostok, RussiaHydrological conditions are an important factor for aquatic ecosystems. Their contribution to stimulating phytoplankton bloom in eutrophic estuaries is not quite clear. We present the results of an outbreak of a phytoplankton bloom event observed in the eutrophic Razdolnaya R. estuary in 2022 from January 22 to February 23, when the estuary was covered by ice. The bloom spreads over 21 km from the river mouth bar to upstream in the near-bottom layer below the halocline. The Chl-a concentration in the bloom area increased from 15 to 100 μg/L, and the dissolved oxygen concentration from 350 to 567 μmol/kg at a rate of 11 μmol/(kg day) over the study period, while the CO<sub>2</sub> partial pressure was reduced to 108 µatm in the most oxygen-supersaturated waters. The <i>Thalassiosira nordenskioeldii</i> Cleve sea diatom was the dominant phytoplankton species in the bloom area. The opposite trend was observed near the boundary of the saline water wedge penetration over 29 km from the river mouth bar to upstream where the dissolved oxygen concentration decreased from 140 to 53 μmol/kg over a month, and partial pressure of CO<sub>2</sub> reached 4454 μatm. We also present the results obtained in February 2016 before and after a snowfall, when the ability of PAR to penetrate through the ice was impeded by a layer of snow. After the snowfall, photosynthesis in the under-ice water stopped and the oxygen concentration decreased to almost zero due to the microbiological destruction of the phytoplankton biomass. As such, the main effect of phytoplankton bloom is the formation of superoxia/hypoxia (depending on the light conditions), during the period of maximum ice thickness and minimum river discharge. Thus, this study demonstrates that the eutrophication in the future could lead to unstable ecosystems and large synoptic variations of dissolved oxygen and CO<sub>2</sub> partial pressure of the estuaries.https://www.mdpi.com/2077-1312/10/12/1798salt-wedge estuaryphytoplankton bloomsdissolved oxygen supersaturationhypoxiapartial pressure CO<sub>2</sub>ice-covered period |
| spellingShingle | Pavel Semkin Pavel Tishchenko Galina Pavlova Yuri Barabanshchikov Petr Tishchenko Maria Shvetsova Elena Shkirnikova Yulia Fedorets O<sub>2</sub> and CO<sub>2</sub> Responses of the Synaptic Period to Under-Ice Phytoplankton Bloom in the Eutrophic Razdolnaya River Estuary of Amur Bay, the Sea of Japan Journal of Marine Science and Engineering salt-wedge estuary phytoplankton blooms dissolved oxygen supersaturation hypoxia partial pressure CO<sub>2</sub> ice-covered period |
| title | O<sub>2</sub> and CO<sub>2</sub> Responses of the Synaptic Period to Under-Ice Phytoplankton Bloom in the Eutrophic Razdolnaya River Estuary of Amur Bay, the Sea of Japan |
| title_full | O<sub>2</sub> and CO<sub>2</sub> Responses of the Synaptic Period to Under-Ice Phytoplankton Bloom in the Eutrophic Razdolnaya River Estuary of Amur Bay, the Sea of Japan |
| title_fullStr | O<sub>2</sub> and CO<sub>2</sub> Responses of the Synaptic Period to Under-Ice Phytoplankton Bloom in the Eutrophic Razdolnaya River Estuary of Amur Bay, the Sea of Japan |
| title_full_unstemmed | O<sub>2</sub> and CO<sub>2</sub> Responses of the Synaptic Period to Under-Ice Phytoplankton Bloom in the Eutrophic Razdolnaya River Estuary of Amur Bay, the Sea of Japan |
| title_short | O<sub>2</sub> and CO<sub>2</sub> Responses of the Synaptic Period to Under-Ice Phytoplankton Bloom in the Eutrophic Razdolnaya River Estuary of Amur Bay, the Sea of Japan |
| title_sort | o sub 2 sub and co sub 2 sub responses of the synaptic period to under ice phytoplankton bloom in the eutrophic razdolnaya river estuary of amur bay the sea of japan |
| topic | salt-wedge estuary phytoplankton blooms dissolved oxygen supersaturation hypoxia partial pressure CO<sub>2</sub> ice-covered period |
| url | https://www.mdpi.com/2077-1312/10/12/1798 |
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