Abstract
The benthic bacterial community in Antarctic continental shelf ecosystems are not well-documented. We collected 13 surface sediments from the Ross Sea, a biological hotspot in high-latitude maritime Antarctica undergoing rapid climate change and possible microflora shift, and aimed to study the diversity, structure and assembly mechanism of benthic bacterial community using both culture-dependent and -independent approaches. High-throughput sequencing of 16S rRNA gene amplicons revealed 370 OTUs distributed in 21 phyla and 284 genera. The bacterial community was dominated by Bacteroidetes, Gamma- and Alphaproteobacteria, and constituted by a compact, conserved and positively-correlated group of anaerobes and other competitive aerobic chemoheterotrophs. Null-model test based on βNTI and RCBray indicated that stochastic processes, including dispersal limitation and undominated fractions, were the main forces driving community assembly. On the other hand, environmental factors, mainly temperature, organic matter and chlorophyll, were significantly correlated with bacterial richness, diversity and community structure. Moreover, metabolic and physiological features of the prokaryotic taxa were mapped to evaluate the adaptive mechanisms and functional composition of the benthic bacterial community. Our study is helpful to understand the structural and functional aspects, as well as the ecological and biogeochemical role of the benthic bacterial community in the Ross Sea.
Highlights
Marine sediments represent the largest reservoir of organic carbon and support abundant and diverse benthic bacterial communities (Kallmeyer et al, 2012), which play fundamental roles in food web structure, energy flow and global biogeochemical cycle (Sunagawa et al, 2015)
Carr et al revealed that Bacteroidetes, Gamma- and Alphaproteobacteria dominated the bacteria assemblages in a sediment column collected from offshore area adjacent to the French station Dumont d’Urville (66◦40′ S, 140◦1′ E) (Carr et al, 2015)
Learman et al revealed that the benthic microbial communities of Western Antarctica were dominated by Gamma, Delta, Alphaproteobacteria, Bacteroidetes, Verrucomicrobia, Planctomycetes, and Actinobacteria (Learman et al, 2016)
Summary
Marine sediments represent the largest reservoir of organic carbon and support abundant and diverse benthic bacterial communities (Kallmeyer et al, 2012), which play fundamental roles in food web structure, energy flow and global biogeochemical cycle (Sunagawa et al, 2015). Learman et al revealed that the benthic microbial communities of Western Antarctica (including three stations in the Ross Sea) were dominated by Gamma, Delta-, Alphaproteobacteria, Bacteroidetes, Verrucomicrobia, Planctomycetes, and Actinobacteria (Learman et al, 2016). In this context, more comprehensive studies of benthic bacterial communities focusing on a typical and integrated continental shelf area in high-latitude Antarctica are still requisite to understand the processes and functions of benthic ecosystem (Sunagawa et al, 2015)
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