Potential role of oxygen and inorganic nutrients on microbial carbon turnover in the Baltic Sea.

Maßmig, Marie, Piontek, Judith, Le Moigne, Frederic A. C. , Cisternas-Novoa, Carolina and Engel, Anja (2019) Potential role of oxygen and inorganic nutrients on microbial carbon turnover in the Baltic Sea. Open Access Aquatic Microbial Ecology, 83 . pp. 95-108. DOI 10.3354/ame01902.

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Oxygen (O2) deficiency and nutrient concentrations in marine systems are impacting organisms from microbes to higher trophic levels. In coastal and enclosed seas, O2 deficiency is often related to eutrophication and high degradation rates of organic matter. To investigate the impact of O2 concentration on bacterial growth and the turnover of organic matter, we conducted multifactorial batch experiments with natural microbial communities of the central Baltic Sea. Water was collected from suboxic (<5 µmol L -1) depths in the Gotland Basin during June 2015. Samples were kept for four days under fully oxygenated and low O2 conditions (mean: 34 µmol L-1 O2), with or without nutrient (ammonium, phosphate, nitrate) and labile carbon (glucose) amendments. We measured bacterial abundance, bacterial heterotrophic production, extracellular enzyme rates (leucine-aminopeptidase) and changes in dissolved and particulate organic carbon concentrations. Our results show that the bacterial turnover of organic matter was limited by nutrients under both oxic and low O2 conditions. In nutrient and glucose replete treatments, low O2 concentrations significantly reduced the net uptake of dissolved organic carbon and lead to higher accumulation of more labile dissolved organic matter. Our results therewith suggest that the combined effects of eutrophication and deoxygenation on heterotrophic bacterial activity may potentially favor the accumulation of dissolved organic carbon in the Baltic Sea.

Document Type: Article
Keywords: Oxygen; Heterotrophic bacteria; Baltic Sea; Organic matter; Bacterial heterotrophic production; Extracellular enzymes; Leucine-aminopeptidase
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > SFB 754
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-BI Biological Oceanography
OceanRep > SFB 754 > B9
Refereed: Yes
Open Access Journal?: No
Publisher: Inter Research
Projects: SFB754, Future Ocean
Date Deposited: 06 Jun 2019 10:51
Last Modified: 31 Jan 2022 09:16
URI: https://oceanrep.geomar.de/id/eprint/46872

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