Microbial processes in a high-latitude fjord (Kongsfjorden, Svalbard) : II. Ciliates and dinoflagellates

This paper is part of Lena Seuthe's doctoral thesis, which is available in Munin at http://hdl.handle.net/10037/3777 The composition and ecological role of ciliates and dinoflagellates were investigated at one station in Kongsfjorden, Svalbard, during six consecutive field campaigns between Mar...

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Bibliographic Details
Published in:Polar Biology
Main Authors: Seuthe, Lena, Iversen, Kriss Wenche Rokkan, Narcy, Fanny
Format: Article in Journal/Newspaper
Language:English
Published: Springer Verlag 2011
Subjects:
VDP::Mathematics and natural science: 400::Zoology and botany: 480::Marine biology: 497
VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Marinbiologi: 497
Microzooplankton
Mesozooplankton
Phytoplankton
Food web
Carbon cycling
Arctic
Svalbard
Kongsfjord*
Kongsfjorden
Polar Biology
Copepods
Online Access:https://hdl.handle.net/10037/3778
https://doi.org/10.1007/s00300-010-0930-9
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Summary:This paper is part of Lena Seuthe's doctoral thesis, which is available in Munin at http://hdl.handle.net/10037/3777 The composition and ecological role of ciliates and dinoflagellates were investigated at one station in Kongsfjorden, Svalbard, during six consecutive field campaigns between March and December 2006. Total ciliate and dinoflagellate abundance mirrored the seasonal progression of phytoplankton, peaking with 5.8 9 104 cells l-1 in April at an average chlorophyll a concentration of 10 lg l-1. Dinoflagellates were more abundant than ciliates, dominated by small athecates. Among ciliates, aloricate oligotrichs dominated the assemblage. A large fraction ([60%) of ciliates and dinoflagellates contained chloroplasts in spring and summer. The biomass of the purely heterotrophic fraction of the ciliate and dinoflagellate community (protozooplankton) was with 14 lg C l-1 highest in conjunction with the phytoplankton spring bloom in April. Growth experiments revealed similar specific growth rates for heterotrophic ciliates and dinoflagellates (\0–0.8 d-1). Food availability may have controlled the protozooplankton assemblage in winter, while copepods may have exerted a strong control during the post-bloom period. Calculations of the potential grazing rates of the protozooplankton indicated its ability to control or heavily impact the phytoplankton stocks at most times. The results show that ciliates and dinoflagellates were an important component of the pelagic food web in Kongsfjorden and need to be taken into account when discussing the fate of phytoplankton and biogeochemical cycling in Arctic marine ecosystems.

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