title: Revisited phytoplanktonic carbon dependency of heterotrophic bacteria in freshwaters, transitional, coastal and oceanic waters.
abstract: Positive relationships between heterotrophic bacteria and particulate phytoplankton production (respectively, BP and PPP) have been reported for several areas, suggesting that material produced by phytoplankton was a major substrate for bacterial growth. Since then, thousands of simultaneous measurements of both PPP and BP have been performed. A review of these data showed that BP may exceed PPP considerably (median ranged between 132% and 484%) in all aquatic systems with the lowest PPP. In oceanic waters, BP did not seem to be temporally synchronized with PPP and the median BP : PPP ratio is 15% with moderate PPP, but the immediate bacterial carbon (C) demand (including bacterial respiration) was greater than the corresponding total primary production (i.e. dissolved and particulate primary production) for >80% of both volumetric and areal datasets. In freshwaters, the strong covariation observed between BP and PPP seemed mainly due to a common response to sudden nutrient inputs into enclosed systems, leading to a similar range of production rates and temporal synchronicities. Indeed, phytoplankton exudates contributed directly to only 32% (median) of BP when C-tracking experiments were performed in freshwaters. Therefore, because direct C dependency of bacteria on phytoplankton is questionable, other C sources might be more significant for bacterial growth.
authors.affiliation: Laboratoire Ecosystèmes lagunaires, ECOLAG, UMR 5119 (CNRS, Université Montpellier 2, IFREMER, IRD), Montpellier and Sète, France. eric.fouilland@univ-montp2.fr
authors.forename: Eric
authors.initials: E
authors.lastname: Fouilland
authors.forename: Behzad
authors.initials: B
authors.lastname: Mostajir
mesh_terms: D001419:Bacteria / Q000254:growth & development*; D002244:Carbon / Q000378:metabolism*; D005618:Fresh Water / Q000382:microbiology; D052836:Heterotrophic Processes; D010839:Phytoplankton / Q000254:growth & development*; D012623:Seawater / Q000382:microbiology
chemical_list: D002244:Carbon