Ecological implications of organic carbon dynamics in the traps of aquatic carnivorous Utricularia plants
Abstract
We investigated the composition of organic carbon in the trap fluid, its availability for microbial uptake, the influence of plant nutrient status and trap age on its biodegradability, and the composition of prokaryotic assemblages within the traps of three aquatic Utricularia species. Using ion chromatography and basal respiration rate measurements we confirmed that up to 30% of total dissolved organic C in trap fluid were easily biodegradable compounds (mainly glucose, fructose, lactate).
The proportion of these compounds and their microbial utilisation decreased with increasing mineral nutrient supply and trap age. FISH analyses showed that microbial trap assemblages are dominated by Alpha and Beta Proteobacteria, and that the assemblage composition is affected by changes in the ambient minerals.
Thus, organic carbon dynamics within the traps, involving both the plant and associated microbial assemblages, underlies the acquisition of key nutrients by Utricularia.