title: An annual survey of bacterial production, respiration and ectoenzyme activity in coastal NW Mediterranean waters: temperature and resource controls.
abstract: We simultaneously measured bacterial production (BP), bacterial respiration (BR), alkaline phosphatase activity (phos) and ectoaminopeptidase activity (prot) in relation to biogeochemical parameters, nutritive resources and in situ temperature over a 1-year survey at the long-term observatory the SOLEMIO station (Marseille bay, NW Mediterranean Sea). Despite its proximity to the coast, oligotrophic conditions prevailed at this station (yearly mean of Chl a = 0.43 μg dm(-3), NO3 = 0.55 μmol dm(-3) and PO4 = 0.04 μmol dm(-3)). Episodic meteorological events (dominant winds, inputs from the Rhone River) induced rapid oscillations (within 15 days) in temperature and sometimes salinity that resulted in rapid changes in phytoplankton succession and a high variability in C/P ratios within the particulate and dissolved organic matter. Throughout the year, BP ranged from 0.01 to 0.82 μg C dm-(3) h-(1) and bacterial growth efficiency varied from 1 to 39%, with higher values in summer. Enrichment experiments showed that BP was limited most of the year by phosphorus availability (except in winter). A significant positive correlation was found between in situ temperature, BP, BR and phos. Finally, we found that temperature and phosphate availability were the main factors driving heterotrophic bacterial activity and thus play a fundamental role in carbon fluxes within the marine ecosystem.
authors.affiliation: Mediterranean Institute of Oceanography (MIO) UMR 7294, Aix-Marseille Université, Université de Toulon, IRD, CNRS, Marseille, France, benj.cea@gmail.com.
authors.forename: B
authors.initials: B
authors.lastname: Céa
authors.forename: D
authors.initials: D
authors.lastname: Lefèvre
authors.forename: L
authors.initials: L
authors.lastname: Chirurgien
authors.forename: P
authors.initials: P
authors.lastname: Raimbault
authors.forename: N
authors.initials: N
authors.lastname: Garcia
authors.forename: B
authors.initials: B
authors.lastname: Charrière
authors.forename: G
authors.initials: G
authors.lastname: Grégori
authors.forename: J F
authors.initials: JF
authors.lastname: Ghiglione
authors.forename: A
authors.initials: A
authors.lastname: Barani
authors.forename: M
authors.initials: M
authors.lastname: Lafont
authors.forename: F
authors.initials: F
authors.lastname: Van Wambeke
mesh_terms: D000469:Alkaline Phosphatase / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry; D000458:Cyanobacteria / Q000254:growth & development / Q000378:metabolism*; D017753:Ecosystem; D052836:Heterotrophic Processes; D008522:Mediterranean Sea; D010101:Oxygen Consumption; D010758:Phosphorus; D045483:Rivers; D054712:Salinity; D012621:Seasons; D012623:Seawater / Q000382:microbiology*; D013696:Temperature; D014871:Water Microbiology
chemical_list: D001426:Bacterial Proteins; D010758:Phosphorus; D000469:Alkaline Phosphatase