title: Phytoplankton-bacterioplankton interactions and carbon fluxes through microbial communities in a microtidal lagoon.
abstract: The strength of the bacteria-phytoplankton coupling and the importance of the microbially mediated carbon fluxes have been investigated in a microtidal lagoon (Lagoon of Venice), with emphasis on the trophic variations, in a within-system perspective. The large trophic heterogeneity of the three stations considered corresponded to an elevated variability of phytoplankton biomass and production (from 0.1 up to 300 microg C L(-1) h(-1)), while bacteria standing stock and production (from 2 to 8 microg C L(-1) h(-1)) appeared, in comparison, to be much more constant. The relationships between bacteria and the phytoplankton community could not be related to the trophic state in a straightforward way; rather, some patterns common to the three stations could be evidenced. In particular, the two communities appeared to be clearly uncoupled, bacterial carbon demand (BCD) always exceeding dissolved primary production (DPP) and, mostly, also total primary production, independent of the station and the season considered. The occurrence of situations in which bacterial production was larger than primary production and the continuous prevalence of BCD over DPP implied that, quite independent of the trophic variability, sources of organic carbon other than phytoplankton production were necessary and available to sustain the bacterial metabolism in the Lagoon of Venice.
authors.affiliation: Istituto di Scienze Marine (ISMAR), Consiglio Nazionale delle Ricerche, Venezia, Italy. alessandra.pugnetti@ismar.cnr.it
authors.forename: Alessandra
authors.initials: A
authors.lastname: Pugnetti
authors.forename: Paola
authors.initials: P
authors.lastname: Del Negro
authors.forename: Michele
authors.initials: M
authors.lastname: Giani
authors.forename: Francesco
authors.initials: F
authors.lastname: Acri
authors.forename: Fabrizio Bernardi
authors.initials: FB
authors.lastname: Aubry
authors.forename: Franco
authors.initials: F
authors.lastname: Bianchi
authors.forename: Daniela
authors.initials: D
authors.lastname: Berto
authors.forename: Annalisa
authors.initials: A
authors.lastname: Valeri
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D018533:Biomass; D002244:Carbon / Q000378:metabolism*; D002734:Chlorophyll / Q000032:analysis; D019015:Geologic Sediments / Q000382:microbiology; D010839:Phytoplankton / Q000378:metabolism*; D011157:Population Dynamics; D054712:Salinity; D012621:Seasons; D012623:Seawater / Q000032:analysis / Q000382:microbiology; D014871:Water Microbiology
chemical_list: D002734:Chlorophyll; D002244:Carbon