Geospatial variability in the autumn community structure of epipelagic zooplankton in the upper layer of the northern South China Sea

Nano- and pico-eukaryotes play important roles in the diversity and functions of marine ecosystems. Warm, saline, and nutrient-depleted water that originates in the Kuroshio Current seasonally intrudes into the northern South China Sea (NSCS) from autumn to spring. To clarify the mechanisms in shaping the community structure of nano- and pico-eukaryotes as well as impacts of the Kuroshio intrusion on the NSCS ecosystem, genomic DNA and RNA were co-extracted from samples collected at two depths from nine stations, and then the V9 region of 18S rDNA and rRNA was sequenced with high-throughput sequencing. Our results showed that Dinophyceae was the most diverse and abundant nanoeukaryotic group during the study period revealed by both DNA and RNA surveys. In contrast, the relative read abundance of MAST, Pelagophyceae, and Dinophyceae in the size fraction of picoeukaryotes might be largely underestimated by the DNA survey. The RNA survey was the more reliable method to investigate the eukaryotic community structure. Environmental filtering played an important role in shaping the community structure, and the sampling depth became the governing factor of the beta diversity under the environmental setting of stratification during the study period. The spatial variations in the diversity of nanoeukaryotes were subject to the dispersal limitation under the size rule. The effects of the Kuroshio intrusion on the nanoeukaryotic community structure might also be explained by the dispersal limitation. Overall, neutral processes are critical in shaping the community structure of nanoeukaryotes. The relative metabolic activities of nanoeukaryotes were relatively stable in accordance with the high similarity of community structure between sampling sites. The responses of the relative metabolic activities of picoeukaryotes to environmental factors displayed two distinct patterns: positive correlations with salinity and nutrients and negative with temperature for Dinophyceae, MAST, and Pelagophyceae, while reversed patterns for Mamiellophyceae and Radiolaria. Our findings improve the understanding of the nano- and pico-eukaryotic communities in the NSCS and the mechanisms of their assembly.

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Community structure and biodiversity of free-living marine nematodes in the northern South China Sea

Acta Oceanologica Sinica ◽

10.1007/s13131-014-0549-8 ◽

2015 ◽

Vol 34 (6) ◽

pp. 77-85 ◽

Cited By ~ 1

Author(s):

Xiaoshou Liu ◽

Man Xu ◽

Jinghuai Zhang ◽

Dan Liu ◽

Xiao Li

Keyword(s):

Community Structure ◽

South China Sea ◽

South China ◽

Northern South China Sea ◽

Marine Nematodes ◽

Free Living ◽

China Sea

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Thaumarchaeotal Signature Gene Distribution in Sediments of the Northern South China Sea: an Indicator of the Metabolic Intersection of the Marine Carbon, Nitrogen, and Phosphorus Cycles?

Applied and Environmental Microbiology ◽

10.1128/aem.03204-12 ◽

2013 ◽

Vol 79 (7) ◽

pp. 2137-2147 ◽

Cited By ~ 40

Author(s):

Hongyue Dang ◽

Haixia Zhou ◽

Jinying Yang ◽

Huangmin Ge ◽

Nianzhi Jiao ◽

...

Keyword(s):

Community Structure ◽

South China Sea ◽

Pore Water ◽

Marine Sediments ◽

South China ◽

Carbon Fixation ◽

Northern South China Sea ◽

Nitrogen And Phosphorus ◽

China Sea ◽

Lipid Biomarker

ABSTRACTThaumarchaeota are abundant and active in marine waters, where they contribute to aerobic ammonia oxidation and light-independent carbon fixation. The ecological function of thaumarchaeota in marine sediments, however, has rarely been investigated, even though marine sediments constitute the majority of the Earth's surface. Thaumarchaeota in the upper layer of sediments may contribute significantly to the reservoir of nitrogen oxides in ocean waters and thus to productivity, including the assimilation of carbon. We tested this hypothesis in the northern South China Sea (nSCS), a section of a large oligotrophic marginal sea with limited influx of nutrients, including nitrogen, by investigating the diversity, abundance, community structure, and spatial distribution of thaumarchaeotal signatures in surface sediments. Quantitative real-time PCR using primers designed to detect 16S rRNA andamoAgenes in sediment community DNA revealed a significantly higher abundance of pertinent thaumarchaeotal than betaproteobacterial genes. This finding correlates with high levels ofhcdgenes, a signature of thaumarchaeotal autotrophic carbon fixation. Thaumarchaeol, a signature lipid biomarker for thaumarchaeota, constituted the majority of archaeal lipids in marine sediments. Sediment temperature and organic P and silt contents were identified as key environmental factors shaping the community structure and distribution of the monitored thaumarchaeotalamoAgenes. When the pore water PO43−concentration was controlled for via partial-correlation analysis, thaumarchaeotalamoAgene abundance significantly correlated with the sediment pore water NO2−concentration, suggesting that theamoA-bearing thaumarchaeota contribute to nitrite production. Statistical analyses also suggest that thaumarchaeotal metabolism could serve as a pivotal intersection of the carbon, nitrogen, and phosphorus cycles in marine sediments.

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