Abstract: To approach the effects of eutrophication on the phytoplankton in Taihu Lake, water samples were collected from the Meiliang Bay of Taihu Lake, and an experiment of inorganic nutrients enrichment was conducted. Three treatments were installed, i.e., no  addition of nutrients (T₀), adding 10 mg·L^-1 of inorganic nitrogen and 0.5 mg·L^-1 of inorganic phosphorous (T₁), and adding 20 mg·L^-1 of inorganic nitrogen and 1.0 mg·L^-1 of inorganic phosphorous (T₂). In treatment T₀, the phytoplankton chlorophyll a concentration was significantly lower than that in treatments T₁ and T₂, but no significant difference was observed between treatments T₁ and T₂, showing that inorganic N and P enrichment could promote the growth of phytoplankton, but the enrichment level had little effects on the phytoplankton biomass. The periphyton chlorophyll a concentration showed the same pattern as the phytoplankton chlorophyll a concentration. The proliferation of the phytoplankton in treatment T₂ could be limited by other factors rather than nitrogen and phosphorous. In treatments T₁ and T₂, no cyanobacteria blooms happened as expected, showing that the formation of cyanobacteria blooms was not only related to the enough nitrogen and phosphorous supply.

Key words: Arid area, Oasis, Surface runoff, Dynamic change, Analysis