Enzyme production in the traps of aquatic <Emphasis Type="Italic">Utricularia</Emphasis> species

We studied the influence of habitat and increased mineral phosphorus and nitrogen loading on the extracellular activity of five selected hydrolases and pH in the trap fluid of the aquatic carnivorous plants, Utricularia vulgaris, U. australis, and U. foliosa (Lentibulariaceae). Enzyme activities in the trap fluid were determined using fluorometry. Phosphatase exhibited the highest activities in the traps of the European species as well as field-grown tropical U. foliosa. Trap enzyme production appeared to be uninfluenced by elevated dissolved mineral N or P concentrations both in the trap and ambient environment and thus, it seems to be constitutive. Enzyme activity in the trap fluid was determined by species and environmental conditions and varied significantly among sites within a single species. Trap fluid pH was between 4.2–5.1 in U. vulgaris and U. australis but between 5.7–7.3 in U. foliosa and seems to be regulated by the traps.