5. Conclusions
Our results indicate that both macrophytes C. australis and P.
crispus
are allelopathically active, however, their allelopathic activity
differs and they are target-specific. The two target species tested
here
responded differently, suggesting that allelopathic outcomes
are
influenced by the species present within a system. Chara australis
and P. crispus could potentially be used as biological control
agents
to control algal blooms in freshwater systems dominated by
A.
variabilis and perhaps other cyanobacteria. Further investigation
of
the allelopathic effect of C. australis and P. crispus at the study lake
is
needed
because the dominant microalgal species present in the
lake
differed from those available to us for experimentation. Our
initial
results suggest that further study is warranted. The chemical
composition of the allelochemicals of C. australis and P. crispus
also
need to be determined. Investigating the life histories of the
macrophyte
species could also help in determining their potential
as
biological agents for the control of nuisance algal blooms.