Allelopathy and its effect on growth of phytoplankton
and macrophytes
Virtually various in situ and ex-situ experiments
conducted to confirm allelopathy in AMs have shown its
suppressing performance on phytoplankton growth. It is
quite possible that allelochemicals may produce more
than one effect on the cellular processes responsible to
reduce phytoplankton growth. However, the details of the
biochemical mechanism through which a particular
allelochemical exerts a toxic effect on growth are not well
known. The existing evidences suggest that the
mechanism of growth inhibition of allelochemicals from
macroalgae and macrophytes is dependent on the nature
of the chemical elicited and genotype and diverse in type.
For instance, the mechanism of growth inhibition of the
green macro alga Ulva lactuca on harmful algal bloom
species via allelopathy is achieved through cell lysing and
decreasing cell density (Jin et al., 2005) (Figure 2).
However, some macrophytes release allelochemicals
which induce high rate of photosynthesis that might draw
down CO
and in turn increases pH level. Subsequently,
this would have influence on processes involved in
2