Effect of intensive epilimnetic withdrawal on phytoplankton community in a (sub)tropical deep reservoir

  • Man Zhang Jinan University, China.
  • Qiu-Qi Lin Jinan University, China.
  • Li-Juan Xiao Jinan University, China.
  • Sheng Wang Nanjing University, China.
  • Xin Qian Nanjing University, China.
  • Bo-Ping Han | tbphan@jnu.edu.cn Jinan University, China.

Abstract

Withdrawal is an important process in reservoir hydrodynamics, removing phytoplankton with flushed water. Zooplanktonthe grazers of phytoplankton, having longer generation times, are even more susceptible than phytoplankton to flushing loss. Therefore phytoplankton are affected not only by abiotic conditions linked to hydrodynamics but also by zooplankton due to weakened grazing pressure. During the Asian Games (November 12-27, 2010 in Guangzhou, China), two intensive epilimnetic withdrawals were conducted in Liuxihe, a deep canyon-shaped reservoir. To examine the influence of the intensive epilimnetic withdrawals on the phytoplankton community, a seven-week field observation and a hydrodynamic simulation were carried out. The observation was divided in two stages: stage 1 represented partial surface vertical mixing period, and stage 2 represented intensive epilimnetic withdrawal period. It was found that phytoplankton abundance and biomass declined with water temperature and partial surface vertical mixing in stage 1. However, the intensive epilimnetic withdrawal reversed this decreasing trend and increased phytoplankton biomass and abundance in stage 2. Phytoplankton showed a higher rate of composition change in stage 2. A numerical model (DYRESM-CAEDYM) simulated scenarios with and without epilimnetic withdrawal to test their effects on abiotic factors (water temperature, suspended sediment and soluble reactive phosphorus) for phytoplankton. The results showed no obvious difference in the abiotic factors between the two scenarios during stage 2. We therefore suggested that the abiotic factors in the water column were probably driven by a seasonal pattern, not by epilimnetic withdrawal. It is likely that the intensive epilimnetic withdrawal could remove large crustaceans. The reduced grazing pressure probably explained the increase of phytoplankton biomass and abundance after the withdrawal. Thus, we suggest that reservoir operation should pay more attention to grazing from large crustaceans. It is recommended that, in the management of reservoirs, intensive epilimnetic withdrawal during autumn should be avoided in order to control excessive phytoplankton in the tropics and subtropics.

 

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Author Biographies

Man Zhang, Jinan University
Department of Ecology and Institute of Hydrobiology
Qiu-Qi Lin, Jinan University
Department of Ecology and Institute of Hydrobiology
Li-Juan Xiao, Jinan University
Department of Ecology and Institute of Hydrobiology
Sheng Wang, Nanjing University
State Key Laboratory of Pollution Control and Resources Reuse, School of the Environment
Bo-Ping Han, Jinan University
Department of Ecology and Institute of Hydrobiology
Published
2013-10-02
Section
Original Articles
Keywords:
epilimnetic withdrawal, flushing, zooplankton grazing, phytoplankton, simulation
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How to Cite
1.
Zhang M, Lin Q-Q, Xiao L-J, Wang S, Qian X, Han B-P. Effect of intensive epilimnetic withdrawal on phytoplankton community in a (sub)tropical deep reservoir. jlimnol [Internet]. 2Oct.2013 [cited 31Mar.2020];72(3):e35. Available from: https://www.jlimnol.it/index.php/jlimnol/article/view/jlimnol.2013.e35

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