The importance of hydrophysical factors in the functioning of benthic communities was justified by Nowel and Jumars (1984), Statzner et al. (1988), and Biggs (1996), among others. Recent studies (Leonard and Luther 1995, Biggs and Stokseth 1996, Goring and Biggs 1996, Sand-Jensen and Mebus 1996) convincingly show that the near-bed hydraulic habitat controls many biological processes determining growth and losses in benthic communities. Among them, periphyton is one of the most important ecosystem components being the dominant source of energy for higher trophic levels in unshaded streams (Lamberti 1996). So, if we want to understand better the relations between components of benthic ecosystems we need firstly to clarify the interaction between the periphyton and the turbulent stream flow. This problem has been addressed by a number of researchers (Reiter 1989, Goring and Biggs 1996, Nikora et al. 1997, among others). Using laboratory and field experiments these works have shown the complexity of periphyton-flow interactions and demonstrated a necessity for a methodology that could provide a working conceptual model in designing and interpreting future experiments. In this note we suggest such a model and a way for data analysis and interpretation.
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