Heterotrophic bacterioplankton responses in coral- and algae-dominated Red Sea reefs show they might benefit from future regime shift

Luis Silva, Maria de Lluch Calleja Cortes, Snjezana Ivetic, Tamara Huete-Stauffer, Florian Roth, Susana Carvalho, Xose Anxelu G. Moran

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

In coral reefs, dissolved organic matter (DOM) cycling is a critical process for sustaining ecosystem functioning. However, global and local stressors have caused persistent shifts from coral- to algae-dominated benthic communities. The influence of such phase shifts on DOM nature and its utilization by heterotrophic bacterioplankton remains poorly studied. Every second month for one year, we retrieved seawater samples enriched in DOM produced by coral- and algae-dominated benthic communities in a central Red Sea reef during a full annual cycle. Seawater incubations were conducted in the laboratory under in situ temperature and light conditions by inoculating enriched DOM samples with bacterial assemblages collected in the surrounding waters. Dissolved organic carbon (DOC) concentrations were higher in the warmer months (May–September) in both communities, resulting in higher specific growth rates and bacterial growth efficiencies (BGE). However, these high summer values were significantly enhanced in algal-DOM relative to coral-DOM, suggesting the potential for bacterioplankton biomass increase in reefs with algae replacing healthy coral cover under warmer conditions. The potential exacerbation of heterotrophic bacterial activity in the ongoing widespread regime shift from coral- to algae-dominated communities may have detrimental consequences for the overall health of tropical coral reefs.
Original languageEnglish (US)
Pages (from-to)141628
JournalScience of The Total Environment
DOIs
StatePublished - Aug 16 2020

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: We gratefully acknowledge Miguel Viegas, João Curdia and Rodrigo Villalobos who aided us with laboratory and fieldwork and KAUST 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 X.A.G. Morán, S. Carvalho was financially supported by Saudi Aramco / KAUST Center for Marine Environmental Observations. 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.

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