Defensive Reactions of Stream Ecosystems in the Early Stages of Pollution. Ecological Importance and Possibilities of Ecosystem-Adequate Restoration Methods

Defensive reactions of rhithron and epipotamon against low and early organic pollution are described. Hitherto two reactions could be found in streams: transformation of the epilithic energy flow to intensify microbial decomposition, and the mass production of Cladophora for elimination of biomass, nutrients, heavy metals and other noxious agents. The Cladophora production reaction leads to a centralization of the ecosystem, but functions incompletely. This can be compensated by an ecosystem-adequate restoration method. Similarly the “whiting” (i.e. biogenic decalcification) during in pelagials Cladophora mass production happens at the expense of the benthic communities and may be called “dysoecism”.