Effect of nutrient level on phytoplankton community structurein di erent water bodies
Wei Zhu , Lei Wan , Lianfang Zhao
DOI:
Received February 11, 2009,Revised July 28, 2009, Accepted , Available online
Volume 22,2010,Pages 32-39
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Increasing levels of pollution within water bodies can cause eutrophication and an associated rapid growth in and reproduction of
phytoplankton. Although most frequently occurring in bodies of water such as lakes and dams, in recent years an increasing number of
river systems in China have su ered serious algal blooms. The community structure of phytoplankton may di er, however, dependent on
the hydrodynamic conditions and nutrient levels within the water body. The field investigation results obtained from a stagnant river in
Suzhou City and Taihu Lake, China, showed that in water with higher concentrations of nitrogen and phosphorus, Chlorophyta became
the predominant species and in water with lower concentrations of nitrogen and phosphorus, Cyanobacteria became the predominant
species. Growth experiments with competitive species, Microcystis aeruginosa K¨utz and Scenedesmus quadricauda (Turp.), were
conducted at three di erent nutrient levels. The biomass of algae in pure and mixed cultures was measured under conditions of
di erent N/P ratios at oligotrophic, eutrophic and hypertrophic nutrient levels. The results indicated that the most suitable state for
the growth and reproduction of M. aeruginosa and S. quadricauda were eutrophic conditions in both pure and mixed cultures. Under
competition, however, the lower medium nutrient levels favoured M. aeruginosa, while the higher medium nutrient levels better suited
S. quadricauda. Under similar hydrodynamic conditions, the community structure of phytoplankton in the water body was determined
by the dominant species in competition for nutrients.
