For a natural lake, there are usually two stable states, a clean state and a turbid state. However, there exists an alternative state, which is unstable and can shift to either a clean or a turbid state depending on varied environmental factors. In this paper, we report a lake undergoing a pattern of seasonal shifting. We found that Lake Xingyun appeared clean in winter with low level of nutrients, low Chlorophyll a (Chl-a) and high secchi depth (SD). However, during summer, the lake turned into turbid with higher level of nutrients and Chl-a, but lower SD. In close response to environmental changes, phytoplankton population of the lake also adopted a pattern of seasonal shift. The order of the seasonal appearances of the dominant populations was as follows: Cyanophyta and Cryptophyta in spring, Microcystis in summer, Melosira in autumn, and Chlorophyta in winter. Our data clearly indicate that Lake Xingyun stayed in clean state in winter but became turbid in summer, and 0.07-0.135mg/L can be considered as the total phosphorus (TP) threshold concentration for Lake Xingyun's alternation between those two states. We also found that both TP and water temperature were the major factors influencing the phytoplankton biomass and its succession. In addition, wind also played a significant role in promoting the dominance of Chlorophyta in winter. In conclusion, Lake Xingyun, represents an alternative state lake with a certain nutrient level, can undergo a seasonal regime shift. Temperature change is the primary force that drives Lake Xingyun to shift its regime state.
英文摘要:
For a natural lake, there are usually two stable states, a clean state and a turbid state. However, there exists an alternative state, which is unstable and can shift to either a clean or a turbid state depending on varied environmental factors. In this paper, we report a lake undergoing a pattern of seasonal shifting. We found that Lake Xingyun appeared clean in winter with low level of nutrients, low Chlorophyll a (Chl-a) and high secchi depth (SD). However, during summer, the lake turned into turbid with higher level of nutrients and Chl-a, but lower SD. In close response to environmental changes, phytoplankton population of the lake also adopted a pattern of seasonal shift. The order of the seasonal appearances of the dominant populations was as follows: Cyanophyta and Cryptophyta in spring, Microcystis in summer, Melosira in autumn, and Chlorophyta in winter. Our data clearly indicate that Lake Xingyun stayed in clean state in winter but became turbid in summer, and 0.07-0.135mg/L can be considered as the total phosphorus (TP) threshold concentration for Lake Xingyun's alternation between those two states. We also found that both TP and water temperature were the major factors influencing the phytoplankton biomass and its succession. In addition, wind also played a significant role in promoting the dominance of Chlorophyta in winter. In conclusion, Lake Xingyun, represents an alternative state lake with a certain nutrient level, can undergo a seasonal regime shift. Temperature change is the primary force that drives Lake Xingyun to shift its regime state.
1.Chinese Acad Sci, Inst Hydrobiol, Wuhan 430072, Hubei Province, Peoples R China 2.Yangtze Valley Water Environm Monitoring Ctr, Wuhan 430010, Peoples R China
Recommended Citation:
Wang, Yingcai; Wang, Zhicong; Wu, Weiju; Hu, Mingming; Wang, Zhen; Xu, Aihua; Li, Genbao; Liu, Yongding.SEASONAL REGIME SHIFT OF AN ALTERNATIVE-STATE LAKE XINGYUN, CHINA,FRESENIUS ENVIRONMENTAL BULLETIN,2010,19(8):1474-1485
