@article{EigemannHiltSalkaetal.2013,
  author    = {Eigemann, Falk and Hilt, Sabine and Salka, Ivette and Grossart, Hans-Peter},
  title     = {Bacterial community composition associated with freshwater algae species specificity vs. dependency on environmental conditions and source community},
  series = {FEMS microbiology ecology},
  volume    = {83},
  journal   = {FEMS microbiology ecology},
  number    = {3},
  publisher = {Wiley-Blackwell},
  address   = {Hoboken},
  issn      = {0168-6496},
  doi       = {10.1111/1574-6941.12022},
  pages     = {650 -- 663},
  year      = {2013},
  abstract  = {We studied bacterial associations with the green alga Desmodesmus armatus and the diatom Stephanodiscus minutulus under changing environmental conditions and bacterial source communities, to evaluate whether bacteriaalgae associations are species-specific or more generalized and determined by external factors. Axenic and xenic algae were incubated in situ with and without allelopathically active macrophytes, and in the laboratory with sterile and nonsterile lake water and an allelochemical, tannic acid (TA). Bacterial community composition (BCC) of algae-associated bacteria was analyzed by denaturing gradient gel electrophoresis (DGGE), nonmetric multidimensional scaling, cluster analyses, and sequencing of DGGE bands. BCC of xenic algal cultures of both species were not significantly affected by changes in their environment or bacterial source community, except in the case of TA additions. Species-specific interactions therefore appear to overrule the effects of environmental conditions and source communities. The BCC of xenic and axenic D.armatus cultures subjected to in situ bacterial colonization, however, had lower similarities (ca.55\%), indicating that bacterial precolonization is a strong factor for bacteriaalgae associations irrespective of environmental conditions and source community. Our findings emphasize the ecological importance of species-specific bacteriaalgae associations with important repercussions for other processes, such as the remineralization of nutrients, and organic matter dynamics.},
  language  = {en}
}
@article{KleebergHupferGustetal.2013,
  author    = {Kleeberg, Andreas and Hupfer, Michael and Gust, Giselher and Salka, Ivette and Pohlmann, Kirsten and Grossart, Hans-Peter},
  title     = {Intermittent riverine resuspension effects on phosphorus transformations and heterotrophic bacteria},
  series = {Limnology and oceanography},
  volume    = {58},
  journal   = {Limnology and oceanography},
  number    = {2},
  publisher = {Wiley},
  address   = {Waco},
  issn      = {0024-3590},
  doi       = {10.4319/lo.2013.58.2.0635},
  pages     = {635 -- 652},
  year      = {2013},
  abstract  = {Intermittent riverine resuspension (IRR), a common phenomenon, was applied to investigate its effects on sedimentary resources availability and bacteria in the water column. This lab experiment used organic-rich lowland river sediment in a newly designed erosion chamber, the Benthic Water Column Simulator, generating well-defined ratios of shear velocity u* to turbulence intensity. Eight consecutive resuspension events, 1-8, were initiated at u* = 1.1 cm s(-1). Sedimentary and phosphorus entrainment decreased from 20.4 g m(-2) h(-1) and 111.6 mg m(-2) h(-1) at event 1 to 1.31 g m(-2) h(-1) and 18.7 mg m(-2) h(-1) at event 8, suggesting an exhaustion of particulate and dissolved sediment constituents. Entrainment of particle-associated (PA) bacteria (132.7 x 10(9)-251.1 x 10(9) cells m(-2) h(-1)) was strongly correlated to that of particles. Free-living (FL) bacteria (-27.6 x 10(9)-36.4 x 10(9) cells m(-2) h(-1)) were fractionally entrained. Numbers of PA bacteria remained low after each event, whereas those of FL bacteria strongly increased 5-15 h after an event because of growth due to increased availability of dissolved organic carbon and inorganic nutrients following each event. FL bacteria community structure also changed during IRR. The systematic changes over consecutive IRR cycles show a strong effect in all considered parameters that elude the typical single-event, steady-state experiments. IRR should thus be considered in two respects: experimental protocols on riverine water quality should be revised. In ecosystem modeling, IRR should be considered to better predict extent and effect of resuspension. Only IRR adequately reflects the natural interplay between hydrodynamics and organisms in rivers.},
  language  = {en}
}