Allochthonous Groundwater Microorganisms Affect Coastal Seawater Microbial Abundance, Activity and Diversity

Keren Yanuka-Golub, Natalia Belkin, Nurit Weber, Meor Mayyani, Yehuda Levy, Itay J. Reznik, Maxim Rubin-Blum, Eyal Rahav, Yael Kiro

Research output: Contribution to journalArticlepeer-review


Submarine groundwater discharge (SGD) is a globally important process supplying nutrients and trace elements to the coastal environment, thus playing a pivotal role in sustaining marine primary productivity. Along with nutrients, groundwater also contains allochthonous microbes that are discharged from the terrestrial subsurface into the sea. Currently, little is known about the interactions between groundwater-borne and coastal seawater microbial populations, and groundwater microbes' role upon introduction to coastal seawater populations. Here, we investigated seawater microbial abundance, activity and diversity in a site strongly influenced by SGD. In addition, through laboratory-controlled bottle incubations, we mimicked different mixing scenarios between groundwater and seawater. Our results demonstrate that the addition of 0.1 μm filtered groundwater stimulated heterotrophic activity and increased microbial abundance compared to control coastal seawater, whereas 0.22 μm filtration treatments induced primary productivity and Synechococcus growth. 16S rRNA gene sequencing showed a strong shift from a SAR11-rich community in the control samples to Rhodobacteraceae dominance in the <0.1 μm treatment, in agreement with Rhodobacteraceae enrichment in the SGD field site. These results suggest that microbes delivered by SGD may affect the abundance, activity and diversity of intrinsic microbes in coastal seawater, highlighting the cryptic interplay between groundwater and seawater microbes in coastal environments, which has important implications for carbon cycling.

Original languageEnglish
Article numbere2023JG007610
JournalJournal of Geophysical Research: Biogeosciences
Issue number2
StatePublished - Feb 2024

Bibliographical note

Publisher Copyright:
© 2024. The Authors.


  • autotrophs activity
  • coastal environments
  • heterotrophs activity
  • microbial community
  • submarine groundwater discharge (SGD)
  • subterranean estuary

ASJC Scopus subject areas

  • Forestry
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Atmospheric Science
  • Paleontology


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