title: Capture of algae promotes growth and propagation in aquatic Utricularia.
abstract: OBJECTIVE
  Some carnivorous plants trap not only small animals but also algae and pollen grains. However, it remains unclear if these trapped particles are useless bycatch or whether they provide nutrients for the plant. The present study examines this question in Utricularia, which forms the largest and most widely spread genus of carnivorous plants, and which captures prey by means of sophisticated suction traps.
  
  
  METHODS
  Utricularia plants of three different species (U. australis, U. vulgaris and U. minor) were collected in eight different water bodies including peat bogs, lakes and artificial ponds in three regions of Austria. The prey spectrum of each population was analysed qualitatively and quantitatively, and correlated with data on growth and propagation, C/N ratio and δ(15)N.
  
  
  RESULTS
  More than 50 % of the prey of the Utricularia populations investigated consisted of algae and pollen, and U. vulgaris in particular was found to capture large amounts of gymnosperm pollen. The capture of algae and pollen grains was strongly correlated with most growth parameters, including weight, length, budding and elongation of internodes. The C/N ratio, however, was less well correlated. Other prey, such as moss leaflets, fungal hyphae and mineral particles, were negatively correlated with most growth parameters. δ(15)N was positively correlated with prey capture, but in situations where algae were the main prey objects it was found that the standard formula for calculation of prey-derived N was no longer applicable.
  
  
  CONCLUSIONS
  The mass capture of immotile particles confirms the ecological importance of autonomous firing of the traps. Although the C/N ratio was little influenced by algae, they clearly provide other nutrients, possibly including phosphorus and trace elements. By contrast, mosses, fungi and mineral particles appear to be useless bycatch. Correlations with chemical parameters indicate that Utricularia benefits from nutrient-rich waters by uptake of inorganic nutrients from the water, by the production of more traps per unit of shoot length, and by the capture of more prey particles per trap, as nutrient-rich waters harbour more prey organisms.
authors.affiliation: University of Vienna, Core Facility Cell Imaging and Ultrastructure Research, Althanstrasse 14, A-1090 Vienna, Austria, Gregor Mendel Institute for Molecular Plant Biology, Lab Management, Dr. Bohr Gasse 3, A-1030 Vienna, Austria and University of Vienna, Department of Microbiology and Ecosystem Research Silver - Stable Isotope Lab, Althanstrasse 14, A-1090 Vienna, Austria marianne.peroutka@univie.ac.at.
authors.forename: Marianne
authors.initials: M
authors.lastname: Koller-Peroutka
authors.affiliation: University of Vienna, Core Facility Cell Imaging and Ultrastructure Research, Althanstrasse 14, A-1090 Vienna, Austria, Gregor Mendel Institute for Molecular Plant Biology, Lab Management, Dr. Bohr Gasse 3, A-1030 Vienna, Austria and University of Vienna, Department of Microbiology and Ecosystem Research Silver - Stable Isotope Lab, Althanstrasse 14, A-1090 Vienna, Austria.
authors.forename: Thomas
authors.initials: T
authors.lastname: Lendl
authors.affiliation: University of Vienna, Core Facility Cell Imaging and Ultrastructure Research, Althanstrasse 14, A-1090 Vienna, Austria, Gregor Mendel Institute for Molecular Plant Biology, Lab Management, Dr. Bohr Gasse 3, A-1030 Vienna, Austria and University of Vienna, Department of Microbiology and Ecosystem Research Silver - Stable Isotope Lab, Althanstrasse 14, A-1090 Vienna, Austria.
authors.forename: Margarete
authors.initials: M
authors.lastname: Watzka
authors.affiliation: University of Vienna, Core Facility Cell Imaging and Ultrastructure Research, Althanstrasse 14, A-1090 Vienna, Austria, Gregor Mendel Institute for Molecular Plant Biology, Lab Management, Dr. Bohr Gasse 3, A-1030 Vienna, Austria and University of Vienna, Department of Microbiology and Ecosystem Research Silver - Stable Isotope Lab, Althanstrasse 14, A-1090 Vienna, Austria.
authors.forename: Wolfram
authors.initials: W
authors.lastname: Adlassnig
mesh_terms: D001317:Austria; D019669:Embryophyta / Q000502:physiology; D020387:Food Chain; D005618:Fresh Water / Q000737:chemistry; D019684:Magnoliopsida / Q000254:growth & development / Q000502:physiology*; D009587:Nitrogen Isotopes / Q000032:analysis; D018521:Plant Physiological Phenomena; D012098:Reproduction; D013045:Species Specificity
chemical_list: D009587:Nitrogen Isotopes
keywords: Algae; U. minor; U. vulgaris.; Utricularia australis; aquatic plant; bladderwort; carnivorous plant; nutrient uptake; prey spectrum; suction trap; δ15N