Abstract
MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 160:47-56 (1997) - doi:10.3354/meps160047 Evidence for anaerobic bacterial processes in the water column: denitrification and dissimilatory nitrate ammonification in the northwestern Mediterranean Sea Valerie Michotey, Patricia Bonin* Laboratoire d'Océanologie et de Biogéochimie, Centre d'Océanologie de Marseille (OSU), Université de la Méditerranée, CNRS UMR 6535, Campus de Luminy, Case 901, F-13288 Marseille cedex 09, France *Addressee for correspondence. E-mail: pbonin@com.univ-mrs.fr Bacterial anaerobic processes in particles in the water column of the northwestern Mediterranean Sea were investigated. Particles concentrated on a filter were incubated in oxygen-free sterile sea water. Results demonstrated that there is a weak but almost constant expression of bacterial nitrate-dissimilation processes [denitrification and dissimilatory nitrate ammonification (DAP)] associated with particles. Both activities were found from 30 m down to 615 m depth in coastal water off Marseilles, France, in autumn and from 100 to 700 m depth in spring and autumn in coastal water off Nice. In summer when oligotrophic conditions occurred, both activities were just detectable. In the other seasons, denitrification was the main process of nitrate dissimilation, with peak activity in autumn. This activity was associated with both large and small particles. In contrast, nitrate ammonification was associated only with large particles that were located in the upper layer in autumn and spread throughout the water column in spring. Nitrate ammonification · Denitrification · Water column · Mediterranean Sea · Particles Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 160. Publication date: December 15, 1997 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1997 Inter-Research.
Highlights
Particulate macroaggregates are often formed in the upper 50 m of the oceans (Alldredge & Gottschalk 1989).Typical aggregates contain rich communities of bacteria a n d protozoa, at densities 2 to 5 orders of magnitude higher than populations found in the surrounding water (Alldredge et al 1986)
This study was undertaken as part of the Mediterranean Targeted Project (MTP)-EMPS (European Microbiology of Particulate Systems); its purpose was to study the role of suspended particulate matter in microbial activities, and the main question addressed was 'the bacterial communities attached to the aggregates, their composition, their metabolic activities and their role in bio
Reduction of nitrate to dinitrogen through denitrification leads to the production of gaseous products (N2or N 2 0 ) that a r e rapidly lost for the ecosystem, whereas the alternative pathway (DAP) conserves nitrogen in a readily useable form (NH,') a n d may cause nutrient enrichment
Summary
Particulate macroaggregates are often formed in the upper 50 m of the oceans (Alldredge & Gottschalk 1989).Typical aggregates contain rich communities of bacteria a n d protozoa, at densities 2 to 5 orders of magnitude higher than populations found in the surrounding water (Alldredge et al 1986). With regard to the nitrogen cycle, dissimilatory reduction of nitrate by bacteria [comprising denitrification and dissimilatory nitrate ammonification (DAP)] is an important process. Depending on the relative intensity of both pathways, dissimilatory nitrate reduction can act as a source as well as a sink in the cycling of this element. Both corresponding pathways a r e generally described as strictly anaerobic processes, and their simultaneous occurrence has only been demonstrated in sediment (Jargensen & Ssrensen 1988, Gilbert et al 1997) and in a generally oxygenated environment such as the particulate system from the very
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