Contrasting sensitivity among oligotrophic marine microbial communities to priority PAHs.

Ananya Ashok, Susana Agusti

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


Oligotrophic areas represent a large proportion of the oceans, wherein microbial food webs largely determine carbon flux dynamics and biogeochemical cycles. However, little is known regarding the sensitivity of microbial planktonic communities to pollutants in such areas. Organic pollutants such as polycyclic aromatic hydrocarbons (PAH/s) are toxic oil derivatives that occur as complex mixtures and reach marine environments through different sources. Therefore, our study analyzed the PAH tolerance of natural photosynthetic and heterotrophic bacteria and eukaryotes from the oligotrophic Red Sea, which is uniquely susceptible to high oil contamination. Natural communities sampled from the surface layer were exposed to a concentration gradient of a mixture of 16 priority PAHs at in situ conditions for 48 h. The populations of the dominant picocyanobacteria Synechococcus sp., picophytoeukaryotes, and low nucleic acid (LNA) bacteria decreased upon exposure to PAHs in a strong dose-dependent manner. Chlorophyll-a, which was measured as an indicator of the total autotrophic community response, also decreased substantially. High nucleic acid (HNA) bacteria, however, exhibited lower growth inhibition (
Original languageEnglish (US)
Pages (from-to)136490
StatePublished - Oct 3 2022

Bibliographical note

KAUST Repository Item: Exported on 2022-10-13
Acknowledgements: This research was funded by baseline funding to Susana Agusti from the King Abdullah University of Science and Technology (KAUST). We also thank the KAUST Core Laboratories for their participation in the analysis of the PAHs in seawater. Moreover, we thank the members of the Biological Oceanography Lab, namely Daffne Lopez-Sandoval, Gala Gonazalez, Reny Devassy, Chunzi Cai, Afrah Alothman, Sreejith Kottuparambil, and especially, Francisco L. Aparicio-Bernat for the invaluable help extended with the experiments. We also thank the CMOR SeaLABS Facility and the R/V Thuwal crew for their support during the cruise and experiments.

ASJC Scopus subject areas

  • Environmental Chemistry
  • Chemistry(all)


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