The influence of selected water quality parameters on the decay rate and exoenzymatic activity of detritus of Nymphaea alba L. floating leaf blades in laboratory experiments.

A chemostat study was conducted to investigate the influence of water quality parameters related to acidification processes on the decomposition of floating leaves of Nymphaea alba L. HCO _inf3 ^sup- and total Al concentration and pH influenced the decay rate. The activity of four cell-wall decaying exoenzymes was measured in the detritus. The activity of two types of pectic enzyme and xylanase was low under acid conditions. Cellulase activity was little affected. The exoenzyme activity seemed to be influenced by the pH of the water within the detritus. Inhibition of pectic enzymes under acid conditions may be an important factor causing the slow decay of macrophyte remains in acid waters.