Phytoplankton community from Lake Taihu, China, has dissimilar responsesto inorganic and organic nutrients
Xiaodong Wang , Boqiang Qin , Guang Gao , Yongping Wang , Xiangming Tang , Timothy Otten
DOI:
Received November 24, 2009,Revised February 25, 2010, Accepted , Available online
Volume 22,2010,Pages 1491-1499
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To evaluate the response of phytoplankton from Lake Taihu to di erent types of nutrients, the phytoplankton responses were
measured after adding inorganic nitrogen (N) and phosphorus (P) or decomposed algal scum (Microcystis spp.) into the lake water.
Both types of nutrients promoted an increase in phytoplankton biomass as determined by chlorophyll a and algal wet weight. The
addition of decomposed algal scum resulted in a significantly greater phytoplankton response than the addition of inorganic N and P
alone. The dissolved inorganic N and P in the inorganic nutrient treatment were found not limit phytoplankton growth. The higher algal
biomass obtained in the treatment with decomposed algal scum indicated the importance of other organic nutrients besides N and P
such as trace elements, as well as the importance of the form of N since the levels of ammonia nitrogen (NH4
+-N) from the decomposed
algal treatment were actually higher than that of the inorganic N and P addition. Microcystis spp. (Cyanobacteria), Scenedesmus spp.
(Chlorophyta) and Synechocystis spp. (Cyanobacteria) were the dominant taxa in the control, inorganic N and P treatment, and the
decomposed algal scum treatment, respectively. Microcystis never bloomed in response to both types of nutrient additions indicating
that the bloom propagation is not solely related to nutrient additions, but may be related to the absence of selective grazing from
zooplankton.
