Effects of wattle extract on
Microcystic aeruginosa
growth and
the simulated mini fresh
water ecosystem
Zhou
Lirong1,2,3, Hou Linglong1,2,3, Hu Yunyan1, Song Jingguo1,2 and Chen Wenqing*1,2,3
1Scu-Hitach
Environment Applied Research Center, Sichuan University, Chengdu - 610 065, China
2College of
Architecture and Environment, Sichuan University, Chengdu
- 610 065, China
3State Key Laboratory
of Hydraulics and Mountain River Engineering, Sichuan
University, Chengdu - 610 065, China
(Received:
January 15, 2009;
Revised received: December
31, 2009; Re-revised received: March 26, 2010; Accepted: March 30, 2010)
Abstract: In recent years, there has been an
apparent increase in the occurrence of harmful algal blooms in fresh waters.
The value of applying the novel wattle extract (Acacia
mimosa) to inhibit algal growth was assessed. Our results showed that the
growth of Microcystis aeruginosa
was successfully repressed by the plant extract and resulted in decreased extracellular microcystin-LR
production. In the experiments, it showed a very effective inhibition in the
stage of exponential growth (the largest decrease in level is 47.3% of the
control) especially in nonsterile conditions, and the
extract can reduce 14.5-24.7% cell density of the control in the stationary
stage. In outdoor experiments, the extract reduced dissolved oxygen and pH, and
selectively cut down cyanobacterial cell density to
one-third of the control after 36 d of treatment. Accordingly, due to
competitive inhibition in interspecies, other nanoalgae
and small-sized aquatic animals declined, while macrozooplankton
increased. Finally, more large algae were eliminated and thereby the water
treated was clarified
and the recovery of the
freshwater ecosystem was promoted. Hence, the present study suggested a new and more effective and
very low ecological risk approach to reduce nuisance blooms cyanobacteria
in eutrophic water.
Key
words: Acacia
mimosa, Algal
bloom control, Fresh water ecosystem, Microcystis aeruginosa, Microcystin, Wattle
extract
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