Bacterial community structure along the subtidal sandy sediment belt of a high Arctic fjord (Kongsfjorden, Svalbard Islands)

• Published in: The Science of the total environment 2018-04, Vol.619-620, p.203-211
• Main Authors: Conte, Antonella, Papale, Maria, Amalfitano, Stefano, Mikkonen, Anu, Rizzo, Carmen, De Domenico, Emilio, Michaud, Luigi, Lo Giudice, Angelina
• Format: Article
• Language: English
• Subjects: Coastal sands; Glacial inputs; Ion PGM sequencing; Microbial community composition; Prokaryotic abundance
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2017.11.077

Open fjords are subject to contrasting environmental conditions, owing to meltwater glacial inputs, terrestrial runoff, and marine water mass exchanges, which are exacerbated by anthropogenic and climate perturbations. Following a slope-dependent water circulation, the subtidal sandy sediment belt regulates the convergent transport of nutrients downward the fjord depths, and the effective entrapment of suspended particles and microorganisms. In this study, we aimed at testing how glacial and seawater inputs may influence the bacterial community structure of subtidal sand deposits in the Kongsfjorden. Through total and viable cell counting and an amplicon sequencing approach, we found relevant differences in bacterial community structure along the glacio-marine sampling transect. Viable and high nucleic acid content (HNA) cells represented an important fraction of the total community, generally decreasing toward the glacier front. Besides the predominance of Alpha- and Gammaproteobacteria, Bacteroidetes, Firmicutes and Parcubacteria, the bacterial community structure was likely affected by the glacial activity in the inner fjord, with the occurrence of distinctive phylotypes belonging to Gemmatimonadates, Nitrospirae, Acidobacteria, and Chloroflexi. Overall, our outcomes highlighted that exploring the bacterial community distribution and structure can provide new insights into the active role of sand deposits in coastal cold environments. [Display omitted] •Subtidal sands tackle, filter and regulate the transport of glacial inputs in fjords.•Sand deposits may house abundant and metabolically active microbial communities.•The bacterial community structure changed markedly along a glacio-marine gradient.•Melting ice and terrestrial runoff were main factors driving bacterial diversity.•Coastal sands can play a role in biogeochemistry and ecology of cold environments.