Diversity, activity, and abundance of benthic microbes in the Southeastern Mediterranean Sea

Maxim Rubin-Blum, Guy Sisma-Ventura, Yana Yudkovski, Natalia Belkin, Mor Kanari, Barak Herut, Eyal Rahav

Research output: Contribution to journalArticlepeer-review


Benthic microbes are key organisms in the oligotrophic Southeastern Mediterranean Sea (SEMS), yet their abundance, activity, and diversity in this rapidly changing basin are not fully understood. We investigated the prokaryotic and microfungal communities throughout years 2018-2020 at 27 stations (6-1900 m water depths, down to 20 cm below the sediment surface), in two transects with distinct downslope transport regimes, and along the eutrophic coastline. We estimated microbial abundance with flow cytometry, secondary production as leucine assimilation, and sequenced marker genes (the 16S rRNA and internal transcribed spacer) to assess diversity indices. The highest abundance (0.21 × 108 cells gr-1 sediment) was estimated at slope stations where we assumed substantial transport rates and found an accumulation of organic carbon. Secondary production was the highest nearshore (12 ± 4 ng C gr-1 h-1), and markedly declined offshore (0.5 ± 0.9 ng C gr-1 h-1). Populations of archaea (dominant Nitrososphaeria and Nanoarchaeia) and diverse bacteria were stable over three years, and taxonomic composition was dictated mainly by depth gradients. Saprotrophic and pathotrophic microfungi Ascomycota (70% ± 23%) and Basidiomycota (16% ± 18%) were prevalent, whereas parasitic chytrids were abundant nearshore. Our results highlight the role of downslope transport, which enriched the typical deep-sea communities with anaerobic lineages, in shaping microbial populations near the continental slope.

Original languageEnglish
Article numberfiac009
JournalFEMS Microbiology Ecology
Issue number2
StatePublished - 1 Feb 2022
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2022 The Author(s) 2022.


  • Marine sediment
  • Mediterranean Sea
  • archaea
  • bacteria
  • biomonitoring
  • fungi

ASJC Scopus subject areas

  • Microbiology
  • Ecology
  • Applied Microbiology and Biotechnology


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