Impact of water level fluctuations on the development of phytoplankton in a large subtropical reservoir: implications for the management of cyanobacteria.

Lake water level fluctuations (WLF) are an important factor driving the selection and seasonal dynamics of phytoplankton and potentially toxigenic cyanobacteria. Nevertheless, the relative importance of environmental drivers connected to WLF may be completely different, depending on the typology and use of waterbodies, latitude and climatic regimes. In this study, we investigated the impact of WLF in a large subtropical reservoir in south-eastern China (Hongfeng Reservoir, Guizhou Province).

[Seasonal stratification and eutrophication characteristics of a deep reservoir, Longtan Reservoir in subtropical area of China].

In order to reveal the seasonal stratification and eutrophication characteristics of the subtropical large deep reservoir--Longtan Reservoir, the spatial and temporal distribution of environmental factors and eutrophic index were investigated during November (dry period) 2012, April (level period) and July (wet period) 2013. The results suggested that: (1) The stratification structure of Longtan Reservoir was meromictic lake, it had a single thermocline structure in the dry season, the surface layer to the 60 m was a mixomolimnion, 60-80 m was a thermocline, deeper more than 80 m was a monimolimnion. It had a double thermocline structure in flow period and wet period, the surface to 10 m was a mixed layer, 10-20 m was a thermocline, 20-40 m was a mixed layer, 40-60 m was a thermocline, deeper more than 60 m was a mixed layer.