Aging of Utricularia traps and variability of microorganisms associated with that microhabitat

Various authors have described algae in aquatic Utricularia traps as commensals, as stress factors or as prey. This study examined the diversity and abundance of organisms (prey, algae, protozoa and bacteria) in the traps of aquatic Utricularia reflexa in relation to prey occurrence and trap age. The number of organisms increased with the trap age. In both young and old traps, phytoplankton dominated of all organisms found. In young traps, Scenedesmus spp. and Characiopsis sp. were the most abundant algae, while Scenedesmus spp. and the palmelloidal form of Euglena spp. dominated in the old traps. Most of the algal species found stayed alive in the trap environment. The number of living algae and ciliates inside the traps increased with the increasing trap age, too. As the number of Paramecium bursaria inside traps consistently increased with the trap age and number of bacteria, which serve as a food for them, ciliates can be regarded as commensals, but not as prey for the plant. The predominant organisms in the traps were those that can be considered either commensals or intruders, exceeding captured macroscopic prey.