An in situ experiment was carried out to examine the effects of large filtering zooplankton——Daphnia pulex's on phytoplankton community strcuture in a shallow entrophic lake on the campus of Jinan University. Ceratium hirundinella and Pediastrum simplex are dominant and blooming-forming phytoplankton species in this lake. Daphnia pulex were cultured in the laboratory to reach the body-size of 20 mm, then was transfered into the transparent bottles (4.5 L). Four gradients are set:0 ind(A), 10 ind(B), 20 ind(C) and 30 ind(D), with three replications for each concentration gradient. The bottles were tied together and were floated at a depth of 50cm below the surface water in the pond. After 12 days of the experiment, the phytoplankton abundance and composition in the experimental bottles were significantly different among three treatments. The densities of Ceratium hirundinella and Meclosira granulate declined significantly with the increase of the density of D. pulex in those treatments. The densities of Cyclotella and Scenedesmus in the treatment D were very low, but in the treatments B and C, where the predation from D. pulex were low or moderate, phytoplankton abundance were even higher than in the control treatment A; the density of Chloropyhta showed no clear decrease in all the treatments. The results indicated that the impact of the large zooplankton D. pulex on phytoplankton communities is not only closely related to its own population density, but also closely related to phytoplankton species. It can suppress the population abundance of C. hirundinella by a mechanistic damage; For small phytoplankton species, D. pulex can stimulate the their growth by promoting the nutrients cycle when the predation pressure from D. pulex was low or moderate.
望甜, 肖利娟, 韩博平*. 大型枝角类蚤状溞对小型热带湖泊浮游植物群落影响的研究[J]. , 2007, 26(2): 103-106.
WANG Tian, XIAO Li-juan, HAN Bo-ping. Effects of large filtering zooplankton—Daphnia pulex on phytoplankton communities in a small tropical Lake. , 2007, 26(2): 103-106.
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