Heterotrophic Bacterioplankton Growth and Physiological Properties in Red Sea Tropical Shallow Ecosystems With Different Dissolved Organic Matter Sources
Type
ArticleAuthors
Silva, LuisCalleja Cortes, Maria de Lluch
Huete-Stauffer, Tamara M.
Ivetic, Snjezana
Ansari, Mohd Ikram

Viegas, Miguel
Moran, Xose Anxelu G.

KAUST Department
Division of Biological and Environmental Sciences and Engineering, Red Sea Research Center, King Abdullah University of Science and Technology, Thuwal, Saudi ArabiaRed Sea Research Center (RSRC)
Marine Science Program
Biological and Environmental Science and Engineering (BESE) Division
Water Desalination and Reuse Research Center (WDRC)
Field & Lab Research Support
Date
2022-01-03Permanent link to this record
http://hdl.handle.net/10754/674877
Metadata
Show full item recordAbstract
Despite the key role of heterotrophic bacterioplankton in the biogeochemistry of tropical coastal waters, their dynamics have been poorly investigated in relation to the different dissolved organic matter (DOM) pools usually available. In this study we conducted four seasonal incubations of unfiltered and predator-free seawater (Community and Filtered treatment, respectively) at three Red Sea coastal sites characterized by different dominant DOM sources: Seagrass, Mangrove, and Phytoplankton. Bacterial abundance, growth and physiological status were assessed by flow cytometry and community composition by 16S rRNA gene amplicons. The Seagrass site showed the highest initial abundances (6.93 ± 0.30 × 10$^{5}$ cells mL$^{–1}$), coincident with maximum DOC concentrations (>100 μmol C L$^{–1}$), while growth rates peaked at the Mangrove site (1.11 ± 0.09 d$^{–1}$) and were consistently higher in the Filtered treatment. The ratio between the Filtered and Community maximum bacterial abundance (a proxy for top-down control by protistan grazers) showed minimum values at the Seagrass site (1.05 ± 0.05) and maximum at the Phytoplankton site (1.24 ± 0.30), suggesting protistan grazing was higher in open waters, especially in the first half of the year. Since the Mangrove and Seagrass sites shared a similar bacterial diversity, the unexpected lack of bacterial response to predators removal at the latter site should be explained by differences in DOM characteristics. Nitrogen-rich DOM and fluorescent protein-like components were significantly associated with enhanced specific growth rates along the inshore-offshore gradient. Our study confirms the hypotheses that top–down factors control bacterial standing stocks while specific growth rates are bottom-up controlled in representative Red Sea shallow, oligotrophic ecosystems.Citation
Silva, L., Calleja, M. L., Huete-Stauffer, T. M., Ivetic, S., Ansari, M. I., Viegas, M., & Morán, X. A. G. (2022). Heterotrophic Bacterioplankton Growth and Physiological Properties in Red Sea Tropical Shallow Ecosystems With Different Dissolved Organic Matter Sources. Frontiers in Microbiology, 12. doi:10.3389/fmicb.2021.784325Sponsors
We gratefully acknowledge Najwa Al-Otaibi, Eman I. Sabbagh, and Abbrar Labban, who aided us with laboratory and fieldwork. We are also grateful to the Coastal and Marine Resources Core Lab (CMOR) for their diligent fieldwork assistance.Funding This project was supported by King Abdullah University of Science and Technology (KAUST) through the baseline research funding provided to XAGM. This research was undertaken in accordance with the policies and procedures of KAUST. Permissions relevant for KAUST to undertake the research have been obtained from the applicable governmental agencies in the Kingdom of Saudi Arabia.
Publisher
Frontiers Media SAJournal
Frontiers in MicrobiologyAdditional Links
https://www.frontiersin.org/articles/10.3389/fmicb.2021.784325/fullae974a485f413a2113503eed53cd6c53
10.3389/fmicb.2021.784325