When
studying allelopathic interactions between macrophytes
and
microalgae it is important to consider the growth phases of
the
microalgae (lag phase, the exponential phase, the stationary
phase,
the declining phase and the death phase) and the effect of
allelochemicals
on each phase (Fogg and Thake, 1987; Mulderij
et
al., 2005a, 2005b). The growth of A. variabilis did not follow
the
usual pattern in Exp. III. Normally, algal cell density would
have
increased. Instead, there was a decrease in the growth of
A.
variabilis in both the control and the macrophyte treatments,
which
did not match the expected ‘lag phase’. The cyanobacteria
started
to grow at day 2 (Fig. 4). Accordingly, comparison between
macrophyte
treatments and control took place after day two.
Bacteria
or phytoplankton in the lake water were unlikely to have
contributed
to the observed effects because lake water was also