Bacterial distribution pattern in the surface sediments distinctive among shelf, slope and basin across the western Arctic Ocean

Abstract

The Arctic Ocean is undergoing a rapid change due to global climate change. Knowledge about bacterial community composition will help us to evaluate their ecological role and predict possible community shifts in future. To this end, we collected 11 sediment samples across the western Arctic Ocean from shelf near to the North Pole, spanning three geographical regions: ice-free Chukchi Shelf, more than 90 % ice-covered Canadian Basin and the partial ice-covered slopes between them. The spatial distribution of bacterial community composition was examined by 16S rRNA gene using Illumina high-throughput sequencing in conjunction with sediment geophysicochemical variables and sampling geographical distance. Overall, Proteobacteria, Acidobacteria, Planctomycetes, Actinobacteria, Chloroflexi, Gemmatimonadetes, Bacteroidetes, Verrucomicrobia, Nitrospira and Thermomicrobia were the top ten dominant phyla. The bacterial communities from the same region exhibited similar composition pattern, but distinctive in each region. Statistical analysis (linear discriminant analysis effect size) showed Deltaproteobacteria, Gammaproteobacteria and Alphaproteobacteria were the distinct taxa in Chukchi Shelf, Slopes and Canadian Basin, respectively. Correspondingly, Desulfobacterales, Planctomycetales and Rhodospirillales were determined at order level. Canonical correspondence analysis demonstrated bacterial distribution was significantly correlated with sediment geophysicochemical factors and geographical distance. Furthermore, variance partitioning analysis confirmed that the combination of geophysicochemical factors, including sediment nutrients content, grain size, sampling site water depth and ice coverage, contributed more than geographical distance to the spatial distribution of bacterial communities across the western Arctic Ocean. In general, this study offers a snapshot of bacterial community composition under the background in rapidly changing Arctic Ocean.