Both M.
macrocopa and B. thailandensis were able
to reduce levels of chlorophyll a over 80%,
which was more effective than in natural
water bodies where daily grazing by
crustaceans produced reductions of 2–21%
of the chlorophyll (Pyr and Pace, 1992). In
the experiment, the zooplankton was more
efficient, but this was possibly because they
were present in higher densities.