In this study, we present some data on the quantitative
role of algae in the prey spectrum of Utricularia. So
far, it is not clear if the algae contribute to the nutrition
of the plant. Plant-derived prey is well known from
other carnivorous plant species: In Pinguicula lusitanica
(Lentibulariaceae), flowering is enhanced by
feeding with pollen grains (Harder and Zemlin 1968).
Due to isotope measurements, Nepenthes ampullaria
(Nepenthaceae) depends more on dead leafs collected
by the pitcher traps than on animal prey (Moran et al.
2003). Rainforest species of Drosera (Droseraceae)
have been suggested to utilise nutrients from canopy
leaching (Lavarack 1979). Gordon and Pacheco
(2007) speculate that Utricularia may gain maximum
benefit from a balanced diet consisting of algae and
animals. Since algae are the dominant prey organisms
of Utricularia in the softest and most oligotrophic
water bodies, it can be expected that algae-derived
nutrients significantly contribute to the plant's survival
on these sites.