Diversity and Selection of Surface Marine Microbiomes in the Atlantic-Influenced Arctic

Abstract

Arctic marine environments are experiencing rapid changes due to the polar amplification of global warming. These changes impact the habitat of the cold-adapted microbial communities, which underpin biogeochemical cycles and marine food webs. We comparatively investigated the differences in prokaryotic and microeukaryotic taxa between summer surface water microbiomes sampled along a latitudinal transect from the ice-free southern Barents Sea and into the sea-ice-covered Nansen Basin to disentangle the dominating community (ecological) selection processes driving phylogenetic diversity. The community structure and richness of each site-specific microbiome were assessed in relation to the physical and biogeochemical conditions of the environment. A strong homogeneous deterministic selection process was inferred across the entire sampling transect via a phylogenetic null modeling approach. The microbial species richness and diversity were not negatively influenced by northward decreasing temperature and salinity. The results also suggest that regional phytoplankton blooms are a major prevalent factor in governing the bacterial community structure. This study supports the consideration that strong homogeneous selection is imposed across these cold-water marine environments uniformly, regardless of geographic assignments within either the Nansen Basin or the Barents Sea.

Microbial community dynamics during a harmful Chrysochromulina leadbeateri bloom in northern Norway

“…Previously reported studies have also shown that members belonging to these orders commonly accompany microalgae in marine environments, except in the case of Teleaulax sp. and C. leadbeateri, which may be due to lack of previous records from events such as the 1991 HAB of northern Norway (Teeling et al, 2016; Ajani et al, 2018; Zhou et al, 2018; Aalto et al, 2022). The bacterial community compositions obtained from Middle-Balsfjord and South-Tromsø stations where distinct and corresponded to the highest observed relative abundance of the focal taxon.…”

“…Amplicon sequencing. Genomic DNA was extracted and downstream amplicon sequences were obtained using the same protocol as described in Aalto et al (2022). All the samples were processed together in accordance with the Earth Microbiome Project protocols (Gilbert et al, 2010) with modifications according to Amaral-Zettler et al (2009).…”

“…Amplicon analysis. The amplicon analyses were performed through the QIIME2 environment and using QIIME2 plugins as previously described (Aalto et al 2022). Briefly, Illumina reads and the corresponding barcode files were imported and demultiplexed using the Earth Microbiome Project paired end flag.…”

“…However, the role of N:P ratio in determining the magnitude, frequency, and duration of HABs has been questioned (Davidson et al, 2012) as more evidence is showing that abiotic conditions are not the only influencing factors of microalgal bloom dynamics. The importance of intra- and interspecific interactions between members of the marine microbiome has become well recognized as a major factor in structuring the temporal and spatial relationships of phytoplankton communities (e.g., Needham and Fuhrman, 2016; Martin-Platero et al, 2018; Aalto et al, 2022). These interactions can be complex and subject to rapid change within a marine microbial ecosystem.…”

“…However, the physical environment is not the only determining factor for the strength and duration of a HAB (Davidson et al, 2012) as more evidence is showing that biological interactions impact microalgal bloom dynamics. The roles and importance of co-blooming members of the marine microbiota is becoming a more recognized factor in structuring the temporal and spatial relationships of phytoplankton communities (e.g., Needham and Fuhrman, 2016; Martin-Platero et al, 2018; Aalto et al, 2022). Therefore, it is important (yet uncommon today) to observe and catalogue the blooming patterns of whole surface water microbiome while studying the ecology of focal taxa involved with HAB events.…”