Dissolved organic carbon contribution to oxygen respiration in the central Red Sea

Maria de Lluch Calleja Cortes, Najwa Aziz Al-otaibi, Xose Anxelu G. Moran

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

In oligotrophic waters, dissolved organic carbon (DOC) is mostly produced in the surface layers by phytoplankton and remineralized by heterotrophic prokaryotes throughout the water column. DOC surface excess is subducted and exported to deeper layers where a semi-labile fraction is further processed contributing to oxygen consumption. How this cycling of DOC occurs in the Red Sea, one of the warmest oligotrophic marine basins, is virtually unknown. We examined DOC vertical and seasonal variability in a mesopelagic station (ca. 700 m depth) of the central Red Sea performing monthly profile samplings over a two-year period. Together with DOC vertical and seasonal distribution we evaluated the interaction with heterotrophic prokaryotes and contribution to oxygen respiration. DOC values ranged from 41.4 to 95.4 µmol C L-1, with concentrations in the epipelagic (70.0 ± 7.5 µmol C L-1) 40% higher on average than in the mesopelagic (50.7 ± 4.1 µmol C L-1). Subduction of seasonally accumulated semi-labile DOC was estimated to be responsible for ∼20% of the oxygen consumption mostly occurring at the low epipelagic-upper mesopelagic boundary layer. Variability in mesopelagic waters was higher than expected (ca. 20 µmol C L-1) evidencing a more active realm than previously thought, with consequences for carbon sequestration.
Original languageEnglish (US)
JournalScientific Reports
Volume9
Issue number1
DOIs
StatePublished - Mar 18 2019

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