On the other hand, feeding experiments so far gave
no evidence for any growth support by algae. In the
terrestrialU . uliginosa, both a pured iet of Euglena and
Euglena intermixed with Acariña even depressed plant
growth (Jobson et al. 2000.). Thus, algae even seem to
be an additional stress factor wherever they form a
significant percentage of prey. It should be considered
that the highest percentage of algae was found next to
the limit of Utricularia's ecological range. In extreme
soft water, where more than 80% algae could be
expected (Fig. 2), Utricularia was not found.
Furthermore, our observations offer no clear
explanation for the mechanism to capture algae.
Running feeding experiments excluding all mechanical
movements will show if the trap is only
extremely sensitive, or if we have to reconsider the
trapping mechanism of Utricularia.