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  • Frontiers Media SA  (2)
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  • Frontiers Media SA  (2)
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  • 1
    Online Resource
    Online Resource
    Data_Sheet_8.PDF
    Frontiers Media SA ; 2022
    In:  Frontiers in Marine Science Vol. 9 ( 2022-3-28)
    Details
    In: Frontiers in Marine Science, Frontiers Media SA, Vol. 9 ( 2022-3-28)
    Abstract: Stratigraphic cluster analysis using aquatic palynomorphs preserved in the core sediments revealed a rapid eutrophication due to anthropogenic activities from the mid 1960s in Beppu Bay, East Kyushu, Japan. These assemblages were divided into three major units: BP-I, BP-II and BP-III, and also only dinoflagellate cyst assemblages were divided into the following four units in Beppu Bay: BP-A, BP-B, BP-C, and BP-D. Unit boundaries based on aquatic palynomorphs and dinoflagellate cysts were different except in the upper part, BP-III and BP-D, both of which clearly indicated anthropogenic eutrophication in both sea water and bottom sediments. On the other hand, in dinoflagellate cyst assemblages, Unit BP-A was characterized by stable occurrence of Spiniferites bulloideus and Spiniferites hyperacanthus, Lingulodinium machaerophorum of Gonyaulacales, and reduction of heterotrophic Peridinioid Brigantedinium spp. In Unit BP-C there was a clear decrease of L. machaerophorum. Unit BP-B was characterized by decreases of S. bulloideus , S. hyperacanthus , and L. machaerophorum , and little increase of Spniferites bentori. Unit BP-C was characterized by an increase in S. bulloideus and heterotrophic Peridinioid Echinidinium spp. Unit BP-D was subdivided into Subunit BP-D1 where dinoflagellate cysts showed a marked increase in S. bulloideus accompanied by the appearance of L. machaerophorum and Tuberculodinium vancampoae , and Subunit PB-D2 where there was a decrease of total dinoflagellate cysts. From the dinoflagellate cyst assemblages, the marine environment of the period of BP-A Unit was suggested to be warm and stable. However, L. machaerophorum started to decrease in BP-B. The clear decrease of L. machaerophorum suggest that the marine environment became cooler than that of Unit BP-A. Significant increases of S. bulloideus, S. hypearcanthus, L. machaerophorum, T. vancampoae, Brigantedinium spp., and Polykrikos kofoidii were characteristic of Unit BP-D. The increase in total dinoflagellate cyst density and the increase of the ratio of heterotrophic dinoflagellate cysts in Subunit BP-D1 are manifestations of the Oslo fjord Signal and Heterotroph Signal, respectively. In addition, the decrease in microforaminiferal lining that continued from Unit BP-C to Unit BP-D might indicate deterioration of the bottom sediment environment.
    Type of Medium: Online Resource
    ISSN: 2296-7745
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    DOI: 10.3389/fmars.2022.843824
    DOI: 10.3389/fmars.2022.843824.s001
    DOI: 10.3389/fmars.2022.843824.s002
    DOI: 10.3389/fmars.2022.843824.s003
    DOI: 10.3389/fmars.2022.843824.s004
    DOI: 10.3389/fmars.2022.843824.s005
    DOI: 10.3389/fmars.2022.843824.s006
    DOI: 10.3389/fmars.2022.843824.s007
    DOI: 10.3389/fmars.2022.843824.s008
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
    detail.hit.zdb_id: 2757748-X
    Location Call Number Limitation Availability
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    Online Resource
  • 2
    Online Resource
    Online Resource
    Life Cycle Strategies of the Centric Diatoms in a Shallow Embayment Revealed by the Plankton Emergence Trap/Chamber (PET Chamber) Experiments
    Frontiers Media SA ; 2022
    In:  Frontiers in Marine Science Vol. 9 ( 2022-7-18)
    Details
    In: Frontiers in Marine Science, Frontiers Media SA, Vol. 9 ( 2022-7-18)
    Abstract: In situ emergence of the centric diatoms from the surface sediment, along with the occurrence of the vegetative cells in the water column, were monitored monthly in a shallow embayment, Ago Bay, of central Japan, where light penetrated to the seafloor. The in situ emergence flux (cells m -2 day -1 ) was measured by experiments using a ‘plankton emergence trap/chamber (PET chamber)’. During the study period from July 2006 to May 2008, germinating and rejuvenating cells of centric diatoms were successfully collected by the PET chamber. Furthermore, vegetative cells forming long-chain colonies, including the species which have not been known to form resting stage cells, were also found, indicating that these cells already inhabited the surface sediment prior to the start of the PET chamber experiments. The vegetative cells could be cells that grew after germination/rejuvenation and/or cells deposited from the upper layer in the water column. When comparing emergence flux in the PET chamber and the integrated abundance of the vegetative cells in the water column for the diatoms frequently observed, significant positive relationships were found for some diatom taxa. However, even for these taxa that showed a clear relationship, the magnitude of the vegetative population in the water column did not necessarily correlate with that of the emergence flux. These observations indicate that the magnitude of the vegetative population was not regulated directly by the emergence flux. The magnitude of the vegetative population could be dependent on the vegetative growth itself. This implies that the presence of vegetative cells in the water column is important at the time when environmental conditions become suitable for vegetative growth. In this context, the presence of various types of cells, such as germinating, rejuvenating, and vegetative cells, in the sediment is essential as seeds waiting for recruitment into the water column. Consequently, the seafloor in Ago Bay may act as a ‘refuge and nursery’ for centric diatoms. Based on the above, we demonstrated various patterns of life cycle strategies of the diatoms in a shallow coastal water/embayment.
    Type of Medium: Online Resource
    ISSN: 2296-7745
    URL: Article
    DOI: 10.3389/fmars.2022.889633
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
    detail.hit.zdb_id: 2757748-X
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
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