title: Virus production and lysate recycling in different sub-basins of the northern Baltic Sea.
abstract: In the Gulf of Bothnia, northern Baltic Sea, a large freshwater inflow creates north-southerly gradients in physico-chemical and biological factors across the two sub-basins, the Bothnian Bay (BB) and the Bothnian Sea. In particular, the sub-basins differ in nutrient limitation (nitrogen vs. phosphorus; P). Since viruses are rich in P, and virus production is commonly connected with bacterial abundance and growth, we hypothesized that the role of viral lysis differs between the sub-basins. Thus, we examined virus production and the potential importance of lysate recycling in surface waters along a transect in the Gulf of Bothnia. Surprisingly, virus production and total P were negatively correlated. In the BB, virus production rates were double those elsewhere in the system, although bacterial abundance and production were the lowest. In the BB, virus-mediated cell lysates could account for 70-180% and 100-250% of the bacterial carbon and P demand, respectively, while only 4-15% and 8-21% at the other stations. Low concentrations of dissolved DNA (D-DNA) with a high proportion of encapsulated DNA (viruses) in the BB suggested rapid turnover and high uptake of free DNA. The correlation of D-DNA and total P indicates that D-DNA is a particularly important nutrient source in the P-limited BB. Our study demonstrates large and counterintuitive differences in virus-mediated recycling of carbon and nutrients in two basins of the Gulf of Bothnia, which differ in microbial community composition and nutrient limitation.
authors.affiliation: Department of Natural Sciences, Linneaus University, SE-39182 Kalmar, Sweden. Karin.Holmfeldt@lnu.se
authors.forename: Karin
authors.initials: K
authors.lastname: Holmfeldt
authors.forename: Josefin
authors.initials: J
authors.lastname: Titelman
authors.forename: Lasse
authors.initials: L
authors.lastname: Riemann
mesh_terms: D001419:Bacteria / Q000378:metabolism / Q000821:virology; D002244:Carbon / Q000378:metabolism*; D004279:DNA, Viral / Q000302:isolation & purification; D017753:Ecosystem; D016014:Linear Models; D009584:Nitrogen / Q000378:metabolism; D009792:Oceans and Seas; D010758:Phosphorus / Q000378:metabolism*; D012623:Seawater / Q000737:chemistry / Q000821:virology*; D013548:Sweden; D013696:Temperature; D014780:Viruses / Q000254:growth & development / Q000378:metabolism*
chemical_list: D004279:DNA, Viral; D010758:Phosphorus; D002244:Carbon; D009584:Nitrogen
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