Dataset Information

Bacterioplankton community shifts associated with epipelagic and mesopelagic waters in the Southern Ocean.

ABSTRACT: The Southern Ocean is among the least explored marine environments on Earth, and still little is known about regional and vertical variability in the diversity of Antarctic marine prokaryotes. In this study, the bacterioplankton community in both epipelagic and mesopelagic waters was assessed at two adjacent stations by high-throughput sequencing and quantitative PCR. Water temperature was significantly higher in the superficial photic zone, while higher salinity and dissolved oxygen were recorded in the deeper water layers. The highest abundance of the bacterioplankton was found at a depth of 75 m, corresponding to the deep chlorophyll maximum layer. Both Alphaproteobacteria and Gammaproteobacteria were the most abundant taxa throughout the water column, while more sequences affiliated to Cyanobacteria and unclassified bacteria were identified from surface and the deepest waters, respectively. Temperature was the most significant environmental variable affecting the bacterial community structure. The bacterial community composition displayed significant differences at the epipelagic layers between two stations, whereas those in the mesopelagic waters were more similar to each other. Our results indicated that the epipelagic bacterioplankton might be dominated by short-term environmental variable conditions, whereas the mesopelagic communities appeared to be structured by longer water-mass residence time and relative stable environmental factors.

SUBMITTER: Yu Z

PROVIDER: S-EPMC4530437 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Bacterioplankton community shifts associated with epipelagic and mesopelagic waters in the Southern Ocean.

Yu Zheng Z Yang Jun J Liu Lemian L Zhang Wenjing W Amalfitano Stefano S

Scientific reports 20150810

The Southern Ocean is among the least explored marine environments on Earth, and still little is known about regional and vertical variability in the diversity of Antarctic marine prokaryotes. In this study, the bacterioplankton community in both epipelagic and mesopelagic waters was assessed at two adjacent stations by high-throughput sequencing and quantitative PCR. Water temperature was significantly higher in the superficial photic zone, while higher salinity and dissolved oxygen were record ...[more]

PMID: 26256889

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Project description:Marine microbial communities are complex and dynamic, and their ecology impacts biogeochemical cycles in pelagic ecosystems. Yet, little is known about the relative activities of different microbial populations within genetically diverse communities. We used rRNA as a proxy for activity to quantify the relative specific activities (rRNA/ribosomal DNA [rDNA or rRNA genes]) of the eubacterial populations and to identify locations or clades for which there are uncouplings between specific activity and abundance. After analyzing 1.6 million sequences from 16S rDNA and rRNA (cDNA) libraries from two euphotic depths from a representative site in the Pacific Ocean, we show that although there is an overall positive relationship between the abundances (rDNAs) and activities (rRNAs) among populations of the bacterial community, for some populations these measures are uncoupled. Different ecological strategies are exemplified by the two numerically dominant clades at this site: the cyanobacterium Prochlorococcus is abundant but disproportionately more active, while the heterotrophic SAR11 is abundant but less active. Other rare populations, such as Alteromonas, have high specific activities in spite of their low abundances, suggesting intense population regulation. More detailed analyses using a complementary quantitative PCR (qPCR)-based approach of measuring relative specific activity for Prochlorococcus populations in the Pacific and Atlantic Oceans also show that specific activity, but not abundance, reflects the key drivers of light and nutrients in this system; our results also suggest substantial top-down regulation (e.g., grazing, viruses, or organismal interactions) or transport (e.g., mixing, immigration, or emigration) of these populations. Thus, we show here that abundance and specific activity can be uncoupled in open ocean systems and that describing both is critical to characterizing microbial communities and predicting marine ecosystem functioning and responses to change.

Dataset Information

Bacterioplankton community shifts associated with epipelagic and mesopelagic waters in the Southern Ocean.

Publications

Bacterioplankton community shifts associated with epipelagic and mesopelagic waters in the Southern Ocean.

Similar Datasets

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