Effects of environmental variation and spatial distance on bacteria, archaea and viruses in sub-polar and arctic waters

Abstract

We investigated the influence of environmental parameters and spatial distance on bacterial, archaeal and viral community composition from 13 sites along a 3200-km long voyage from Halifax to Kugluktuk (Canada) through the Labrador Sea, Baffin Bay and the Arctic Archipelago. Variation partitioning was used to disentangle the effects of environmental parameters, spatial distance and spatially correlated environmental parameters on prokaryotic and viral communities. Viral and prokaryotic community composition were related in the Labrador Sea, but were independent of each other in Baffin Bay and the Arctic Archipelago. In oceans, the dominant dispersal mechanism for prokaryotes and viruses is the movement of water masses, thus, dispersal for both groups is passive and similar. Nevertheless, spatial distance explained 7-19% of the variation in viral community composition in the Arctic Archipelago, but was not a significant predictor of bacterial or archaeal community composition in either sampling area, suggesting a decoupling of the processes regulating community composition within these taxonomic groups. According to the metacommunity theory, patterns in bacterial and archaeal community composition suggest a role for species sorting, while patterns of virus community composition are consistent with species sorting in the Labrador Sea and suggest a potential role of mass effects in the Arctic Archipelago. Given that, a specific prokaryotic taxon may be infected by multiple viruses with high reproductive potential, our results suggest that viral community composition was subject to a high turnover relative to prokaryotic community composition in the Arctic Archipelago.

Figure 1

Location of sampling stations. The figure shows the sampling locations in the Labrador Sea (LS1–LS3), Baffin Bay (BB1–BB5) and the Arctic Archipelago (AA1–AA5). The area shown in the main map is marked by the rectangle in the inset.

Figure 2

Variation partitioning of bacterial, archaeal and viral community composition. The figure depicts the fractions (%) of variation in bacterial, archaeal and viral community composition that are explained by environmental parameters (temperature, salinity, prokaryotic and viral abundance, relative abundance of Bacteria), spatial distance, spatially correlated environmental parameters or remain unexplained for the Labrador Sea, Baffin Bay, the Arctic Archipelago and the entire sampling region in the form of Venn diagrams. The outer circles represent 100% of variation and the surface areas for each fraction correspond to their size given by the numbers. Statistically insignificant values are shown in gray and the circles are not shaded (see Supplementary Tables S5–S10).

Figure 3

Relationships between viral and prokaryotic community composition. The figure shows the partial Mantel statistics (r_PM) calculated between viral community composition (primers OPA-13 and CRA-22) and bacterial as well as archaeal community composition corrected for (a) environmental parameters (temperature, salinity, prokaryotic and viral abundance, relative abundance of Bacteria) and (b) spatial distance. Statistically significant results are marked with ‘*', statistically insignificant results are grayed out (Bonferroni-corrected: P⩽0.0125; Supplementary Tables S3–S4).