Diatom and dinoflagellate cyst distribution in surface sediments of the Chukchi Sea in relation to the upper water masses

Maria S. Obrezkova, Vera Pospelova, Aleksandr N. Kolesnik

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Abstract

Diatom and dinoflagellate cyst analyses were performed on 22 surface sediment samples from the Chukchi Sea to document their geographical distributions in one of the most understudied sections of the Arctic Ocean and to examine the influence of upper water masses on these two major groups of phytoplankton. Total concentrations vary from 0.9 to 5.9 × 106 valves g−1 for diatoms and from 0.8 to 12.5 × 103 cysts g−1 for organic-walled dinoflagellate cysts, with the highest values for both groups observed in the southern part of the Chukchi Sea and away from the Bering Strait. Well-preserved microfossils were recovered, with a total of 35 and 88 taxa of dinoflagellate cysts and diatoms, respectively. The most abundant diatoms are Paralia sulcata, Thalassiosira antarctica, Thalassiosira nordenskioeldii, and resting spores of Chaetoceros spp., whereas cysts of phototrophic Alexandrium spp., Operculodinium centrocarpum sensu Wall and Dale (1966), and heterotrophic Islandinium minutum and Brigantedinium spp. were most common in the dinoflagellate cyst assemblages. Cysts of HAB-causing Alexandrium spp. were found in most of the samples, with the highest abundances in Herald Canyon where they contribute ∼56.6% to the cyst assemblage. As expected, cysts produced by heterotrophic dinoflagellates were more abundant where sedimentary diatom concentrations were the highest. Statistical analysis identified three major diatom and dinoflagellate cyst clusters: 1. Sites influenced by the Alaska Coastal Current in the eastern part of the Chukchi Sea are characterized by high abundances of P. sulcata and O. centrocarpum sensu Wall and Dale (1966); 2. The western part and Herald Canyon in the northern part of the Chukchi Sea are distinguished by diatoms Chaetoceros spp., T. antarctica and dinoflagellate cysts of Alexandrium spp. and affected by the Siberian Coastal Current and Bering Shelf Water; and 3. Assemblages in the southern part of the Chukchi Sea are recognized by noticeable abundances of T. nordenskioeldii and cryophilic diatom taxa, and dinoflagellate cysts I. minutum, as well as by overall lower percentages of cysts of Pentapharsodinium dalei and Brigantedinium spp. This work revealed the potential applicability of the combined use of diatoms and dinoflagellate cysts for reconstructions of past dynamic water mass changes in the Chukchi Sea.

Original languageEnglish (US)
Article number102184
JournalMarine Micropaleontology
Volume178
DOIs
StatePublished - Jan 2023

Bibliographical note

Funding Information:
The authors are very grateful to Prof. A.S. Astakhov and Dr. A.A. Bosin for providing sediment samples for this study. Special thanks to L.V. Osipova for processing samples and preparing diatom slides, as well as to Drs. I.B. Tsoy, N.K. Vagina, T.V. Morozova, and J. Ren for their scientific input. We thank D. Bina, the Copernicus Online Data Access team, the National Oceanographic and Atmospheric Administration (NOAA), the National Aeronautics and Space Administration (NASA), and the State of Alaska Open data Geoportal website for providing data on water quality parameters in the region. We are grateful to the associate editor Dr. X. Crosta and three anonymous reviewers for their detailed and constructive comments that helped to improve this manuscript. This work was funded by the Russian Science Foundation (project 21-17-00081 ) and research cruises through POI FEB RAS (project 121021700342-9 ). Funding for this study was partially provided by the Natural Science and Engineering Research Council of Canada (NSERC) to V.P. (discovery grant RGPIN/6388-2015 ).

Funding Information:
The authors are very grateful to Prof. A.S. Astakhov and Dr. A.A. Bosin for providing sediment samples for this study. Special thanks to L.V. Osipova for processing samples and preparing diatom slides, as well as to Drs. I.B. Tsoy, N.K. Vagina, T.V. Morozova, and J. Ren for their scientific input. We thank D. Bina, the Copernicus Online Data Access team, the National Oceanographic and Atmospheric Administration (NOAA), the National Aeronautics and Space Administration (NASA), and the State of Alaska Open data Geoportal website for providing data on water quality parameters in the region. We are grateful to the associate editor Dr. X. Crosta and three anonymous reviewers for their detailed and constructive comments that helped to improve this manuscript. This work was funded by the Russian Science Foundation (project 21-17-00081) and research cruises through POI FEB RAS (project 121021700342-9). Funding for this study was partially provided by the Natural Science and Engineering Research Council of Canada (NSERC) to V.P. (discovery grant RGPIN/6388-2015).

Publisher Copyright:
© 2022 Elsevier B.V.

Keywords

  • Alexandrium
  • Arctic Ocean
  • Coastal waters
  • Diatoms
  • Dinocysts
  • Phytoplankton
  • Productivity
  • Sediment

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