The species diversity and dominant species proportions of the macrozoobenthos (invertebrates living on the river bottom) is an indicator of water quality, and of the quantity and quality of habitat structures in a water body. All in all, more than 500 macrozoobenthos species were detected in the Rhine between the Alps and the North Sea. Above all molluscs (Mollusca), oligochaeta, crustaceans, insects, freshwater spunges and bryozoa make up the aspect.
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