title: Bacterioplankton growth and nutrient use efficiencies under variable organic carbon and inorganic phosphorus ratios.
abstract: We carried out enclosure experiments in an unproductive lake in northern Sweden and studied the effects of enrichment with different dissolved organic carbon (glucose)/inorganic phosphorous (DOC/Pi) ratios on bacterioplankton production (BP), growth efficiency (BGE), nutrient use efficiency (BNUE), growth rate, and specific respiration. We found considerable variation in BP, BGE, and BNUE along the tested DOC/Pi gradient. BGE varied between 0.87 and 0.24, with the highest values at low DOC/Pi ratios. BNUE varied between 40 and 9 g C g P(-1), with high values at high DOC/Pi ratios. More DOC was thus allocated to growth when bacteria tended to be C-limited, and to respiration when bacteria were P-limited. Specific respiration was positively correlated with bacterial growth rate throughout the gradient. It is therefore possible that respiration was used to support growth in P-limited bacteria. The results indicated that BP can be limited by Pi when BNUE is at its maximum, by organic C when BGE is at its maximum, and by dual organic C and Pi limitation when BNUE and BGE have suboptimal values.
authors.affiliation: Department of Ecology and Environmental Science, University of Umeå, SE-901 87 Umeå, Sweden. mats.jansson@emg.umu.se
authors.forename: Mats
authors.initials: M
authors.lastname: Jansson
authors.forename: Ann-Kristin
authors.initials: AK
authors.lastname: Bergström
authors.forename: David
authors.initials: D
authors.lastname: Lymer
authors.forename: Katarina
authors.initials: K
authors.lastname: Vrede
authors.forename: Jan
authors.initials: J
authors.lastname: Karlsson
mesh_terms: D001419:Bacteria / Q000254:growth & development* / Q000378:metabolism; D002244:Carbon / Q000032:analysis* / Q000378:metabolism; D005618:Fresh Water / Q000032:analysis / Q000382:microbiology*; D005947:Glucose / Q000032:analysis / Q000378:metabolism; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism; D010758:Phosphorus / Q000032:analysis* / Q000378:metabolism; D010933:Plankton / Q000254:growth & development* / Q000378:metabolism; D013548:Sweden
chemical_list: D010758:Phosphorus; D002244:Carbon; D005947:Glucose; D009584:Nitrogen