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| Titel |
The role of mixotrophic protists in the biological carbon pump |
| VerfasserIn |
A. Mitra, K. J. Flynn, J. M. Burkholder, T. Berge, A. Calbet, J. A. Raven, E. Granéli, P. M. Glibert, P. J. Hansen, D. K. Stoecker, F. Thingstad, U. Tillmann, S. Våge, S. Wilken, M. V. Zubkov |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 4 ; Nr. 11, no. 4 (2014-02-20), S.995-1005 |
| Datensatznummer |
250117237
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| Publikation (Nr.) |
 copernicus.org/bg-11-995-2014.pdf |
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| Zusammenfassung |
| The traditional view of the planktonic food web describes consumption of
inorganic nutrients by photoautotrophic phytoplankton, which in turn
supports zooplankton and ultimately higher trophic levels. Pathways centred
on bacteria provide mechanisms for nutrient recycling. This structure lies
at the foundation of most models used to explore biogeochemical cycling,
functioning of the biological pump, and the impact of climate change on
these processes. We suggest an alternative new paradigm, which sees the bulk
of the base of this food web supported by protist plankton
communities that are mixotrophic – combining phototrophy
and phagotrophy within a single cell. The photoautotrophic eukaryotic
plankton and their heterotrophic microzooplankton grazers dominate only
during the developmental phases of ecosystems (e.g. spring bloom in
temperate systems). With their flexible nutrition, mixotrophic protists
dominate in more-mature systems (e.g. temperate summer, established
eutrophic systems and oligotrophic systems); the more-stable water columns
suggested under climate change may also be expected to favour these
mixotrophs. We explore how such a predominantly mixotrophic structure
affects microbial trophic dynamics and the biological pump. The
mixotroph-dominated structure differs fundamentally in its flow of energy
and nutrients, with a shortened and potentially more efficient chain from
nutrient regeneration to primary production. Furthermore, mixotrophy enables
a direct conduit for the support of primary production from bacterial
production. We show how the exclusion of an explicit mixotrophic component
in studies of the pelagic microbial communities leads to a failure to
capture the true dynamics of the carbon flow. In order to prevent a
misinterpretation of the full implications of climate change upon
biogeochemical cycling and the functioning of the biological pump, we
recommend inclusion of multi-nutrient mixotroph models within ecosystem
studies. |
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