Direct Effects on Organisms and Niche Differentiation

  • Christian E. W. Steinberg


Various general properties of HS are involved in biological processes of surface waters:
  • protonation/deprotonation: influences the acid-base status of freshwaters (Chap. 3)

  • light absorption: acts as UV shield, light absorption limits the depth of the euphotic zone with strong thermal gradients during summer stratification (Chaps. 4, 5)

  • particle formation: detritus formation, involvement in the detritus food chain, in some cases as direct trophic energy or carbon source

  • complexation/binding: metals and nutrients (Chap. 6), xenobiotics (Chap. 7)

  • photomineralization and both direct and indirect photolysis: release of substrates for microbial heterotrophy, release of carbon dioxide, release of reactive oxygen species (ROS, which are potentially toxic to organisms), photodegradation of potential toxins (Chap. 5)

  • surface-active effects: potentially strongly stimulating at low concentrations, and inhibitory at higher concentrations. Inhibitory effects of FA on microorganisms and plant roots are possible, with a tenside-like effect on membranes and the linked increased permeability to apolar essential materials (Visser 1985). However, since the effect is strongest under weakly acidic conditions (Vigneault et al. 2000), an additional hydrophobic mechanism may also apply as postulated by Petersen (1991) (Chap. 8)


Methylene Blue Humic Substance Malachite Green Niche Differentiation Kind Permission 
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© Springer-Verlag Berlin Heidelberg 2003

Authors and Affiliations

  • Christian E. W. Steinberg
    • 1
  1. 1.Leibniz-Institut für Gewässerökologie und BinnenfischereiHumboldt-Universität zu BerlinBerlinGermany

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