Abstract
Climate change has resulted in an accelerated decline of Arctic sea ice since 2001 resulting in primary production increases and prolongation of the ice-free season within the Northwest Passage. The taxonomic and functional microbial community composition of the seawater and sea ice of the Canadian Arctic is not very well known. Bacterial communities from the bottom layer of sea ice cores and surface water from 23 locations around Cornwallis Island, NU, Canada, were extensively screened. The bacterial 16S rRNA gene was sequenced for all samples while shotgun metagenomics was performed on selected samples. Bacterial community composition showed large variation throughout the sampling area both for sea ice and seawater. Seawater and sea ice samples harbored significantly distinct microbial communities, both at different taxonomic levels and at the functional level. A key difference between the two sample types was the dominance of algae in sea ice samples, as visualized by the higher relative abundance of algae and photosynthesis-related genes in the metagenomic datasets and the higher chl a concentrations. The relative abundance of various OTUs and functional genes were significantly correlated with multiple environmental parameters, highlighting many potential environmental drivers and ecological strategies.
Highlights
The objectives of the present survey were to 1) characterize bacterial community structures in seawater and the immediate bottom layer of sea ice cores recovered near Cornwallis Island in the Northwest Passage, and 2) relate the relative abundance of key taxa and functional genes to environmental parameters
A summary of the biochemical characteristics of sea ice and seawater is presented in Table 1, showing significantly higher concentrations of chl a, particulate organic carbon, dissolved organic carbon and nitrogen, bacterial abundances, and nutrient (N and P) concentrations in the sea ice compared to seawater (t-tests, p < 0.05)
We compared seawater and the immediately overlying sea ice at 23 locations around Cornwallis Island in the Canadian high Arctic. It is one of the first studies to simultaneously look at linked seawater and sea ice samples using shotgun metagenomics and 16S rRNA gene sequencing and to relate this genomic data to potential environmental drivers
Summary
The objectives of the present survey were to 1) characterize bacterial community structures in seawater and the immediate bottom layer of sea ice cores (referred to as sea ice) recovered near Cornwallis Island in the Northwest Passage, and 2) relate the relative abundance of key taxa and functional genes to environmental parameters. In order to attain these goals, the 16S rRNA gene was amplified and sequenced from sea ice and seawater samples taken at 23 locations around Cornwallis Island in the Canadian high Arctic, while 16 selected samples (6 sea ice and 10 seawater samples) were subjected to shotgun metagenomic sequencing
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