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
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2024. The Authors.


This work was partly supported by the Israeli National Monitoring Program and by the Ministry of Energy (Grant 3‐11519). We thank the Sustainability and Energy Research Initiative (SAERI) grant, the Helen Kimmel Center for Planetary Science grant and the De Botton center for Marine Sciences grant for their funding supporting this study. This study was supported by the Zuckerman Faculty Scholars program, a research grant from the Center for Scientific Excellence, a research grant from the Raymond Lapon Fund, and the Estate of David Levinson, a research grant from Paul and Tina Gardner, and a research grant from the Center for New Scientists at the Weizmann Institute of Science. We thank H. Michael and I. Halevy for fruitful discussions and suggestions. We also thank D. Gat for her help and advice in bioinformatics analysis.

FundersFunder number
Center for Scientific Excellence
De Botton center for Marine Sciences
Raymond Lapon Fund
Sustainability and Energy Research Initiative
Ministry of Energy3‐11519
Weizmann Institute of Science
Helen Kimmel Center for Planetary Sciences, Weizmann Institute of Science


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


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