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| Titel |
Seasonal and size-dependent variations in the phytoplankton growth and microzooplankton grazing in the southern South China Sea under the influence of the East Asian monsoon |
| VerfasserIn |
L. Zhou, Y. Tan, L. Huang, Z. Hu, Z. Ke |
| 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 ; 12, no. 22 ; Nr. 12, no. 22 (2015-11-27), S.6809-6822 |
| Datensatznummer |
250118183
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| Publikation (Nr.) |
 copernicus.org/bg-12-6809-2015.pdf |
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| Zusammenfassung |
| To examine seasonal and size-dependent variations in the
phytoplankton growth and microzooplankton grazing in oligotrophic tropical
waters under the influence of seasonal reversing monsoon, dilution
experiments were conducted during the summer of 2009 (21 May to 9 June) and
winter 2010 (9 to 18 November) in the southern South China Sea (SSCS). The
results showed that environmental variables, phytoplankton biomass,
phytoplankton growth rate (μ), microzooplankton grazing rate (m), and
correlationship (coupling) between the μ and m, rather than the
microzooplankton grazing impact on phytoplankton (m/μ) significantly
varied between the two seasons. Higher relative preference index (RPI) for the larger-sized (> 3 μm) phytoplankton than
pico-phytoplankton (< 3 μm), indicating significant
size-selective grazing by microzooplankton on the larger-sized phytoplankton,
were also observed. The μ and m were significantly correlated with
seawater salinity and temperature, and phytoplankton biomass, which indicated
that salient seasonal variations in the phytoplankton growth and
microzooplankton grazing in the SSCS were closely related to the
environmental variables under the influence of the East Asian monsoon. We
propose that intermittent arrivals of the northeast winter monsoon could lead
to the low μ and m, and the decoupling between the μ and m in
the SSCS, through influencing nutrient supply to the surface water, and
inducing surface seawater salinity decrease. The low m/μ (< 50 %
on average) indicates low remineralization of organic matter mediated by
microzooplankton and mismatch between the μ and m, and thus probably
accounts for part of the high vertical biogenic particle fluxes in the
prevailing periods of the monsoons in the SSCS. The size-selective grazing
suggests that microzooplankton grazing partially contributes to the
pico-phytoplankton dominance in the oligotrophic tropical waters such as that
of the SSCS. |
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