engleski

Dynamics of sediment microbial communities in a declining Cymodocea nodosa meadow

Seagrass meadow sediments contain diverse and abundant microbial communities. Although the diversity of these microorganisms has been described little is known about their response to a meadow decline. Next-generation amplicon sequencing of the V4 16S rRNA region was performed to determine the diversity and dynamics of bacterial and archaeal microbial communities inhabiting sediments of a declining Cymodocea nodosa meadow. Sampling was performed in surface sediments from Saline Bay located at the eastern coast of the northern Adriatic Sea (45°7’5 ̋ N, 13°37’20 ̋ E) from July 2017 to October 2018 at monthly intervals. For comparison, samples from a nearby non-vegetated sediment were also analyzed. Communities differed primarily by sediment depth and secondly by the presence or absence of seagrass vegetation. Although C. nodosa declined to a point where almost no leaves were present no notable temporal community changes were observed. Taxonomic analysis showed the dominance of bacterial sequences over archaeal. The most abundant detected archaeal taxa were Nanoarchaeota, Thermoplasmatota, Crenarchaeota and Asgardarchaeota, while Bacteria were mainly comprised of Desulfobacterota, Proteobacteria, Bacteroidota and Chloroflexi. Our results indicate that changing environmental conditions caused by a decline of a seagrass meadow did not have a strong effect on the microbial community composition. The lack of compositional change suggests a response by altering community activity as a mechanism of adaptation to changing conditions.

seagrass meadow sediments ; 16S rRNA ; cymodocea nodosa

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