engleski

Sediment microbial communities throughout seagrass meadow decline

Background: Seagrasses influence surface sediments forming a specific environment for diverse, abundant, and active microbial communities. Although a major decline in seagrass meadows has been reported in the Mediterranean Sea, little is known about how the sediment microbial communities underlying these meadows respond to such an event. Objectives: The aim of this study was to characterize the sediment community composition of a declining Cymodocea nodosa meadow and assess the temporal dynamics of the community during the seagrass decline. Methods: Samples of surface sediments from a declining C. nodosa meadow were collected at monthly intervals from July 2017 to October 2018. In addition, samples were also collected from an adjacent non-vegetated sediment. Bacterial and archaeal community structure was determined using Illumina MiSeq sequencing of the V4 region of the 16S rRNA gene. Results: Microbial communities were primarily stratified with sediment depth and secondly by area sampled. A clear dominance of bacterial over archaeal sequences was noted. Most archaeal sequences were classified as Nanoarchaeota, Thermoplasmatota, Crenarchaeota, and Asgardarchaeota, while the bacterial community consisted primarily of Desulfobacterota, Gammaproteobacteria, Bacteroidota, and Chloroflexi. Although C. nodosa reached a point where almost no leaves were present, a high stability of the sediment community composition was observed throughout the study period. Overall, it appears that the decline of the C. nodosa meadow had no or little effect on the temporal variation of the sediment microbial communities.

seagrass meadow decline ; sediment ; Cymodocea nodosa ; microbial communities

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