Variation of phytoplankton functional groups modulated by hydraulic controls in Hongze Lake, China

Abstract

Hongze Lake is a large, shallow, polymictic, eutrophic lake in the eastern China. Phytoplankton functional groups in this lake were investigated from March 2011 to February 2013, and a comparison was made between the eastern, western, and northern regions. The lake shows strong fluctuations in water level caused by monsoon rains and regular hydraulic controls. By application of the phytoplankton functional group approach, this study aims to investigate the spatial and temporal dynamics and analyze their influencing factors. Altogether, 18 functional groups of phytoplankton were identified, encompassing 187 species. In order to seek the best variable describing the phytoplankton functional group distribution, 14 of the groups were analyzed in detail using redundancy analysis. Due to the turbid condition of the lake, the dominant functional groups were those tolerant of low light. The predominant functional groups in the annual succession were D (Cyclotella spp. and Synedra acus), T (Planctonema lauterbornii), P (Fragilaria crotonensis), X1 (Chlorella vulgaris and Chlorella pyrenoidosa), C (Cyclotella meneghiniana and Cyclotella ocellata), and Y (Cryptomonas erosa). An opposite relationship between water level and the biomass of predominant groups was observed in the present study. Water level fluctuations, caused by monsoonal climate and artificial drawdown, were significant factors influencing phytoplankton succession in Hongze Lake, since they alter the hydrological conditions and influence light and nutrient availability. The clearly demonstrated factors, which significantly influence phytoplankton dynamics in Hongze Lake, will help government manage the large shallow lakes with frequent water level fluctuations.

People, pollution and pathogens – Global change impacts in mountain freshwater ecosystems

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On the successful use of a simplified model to simulate the succession of toxic cyanobacteria in a hypereutrophic reservoir with a highly fluctuating water level

“…A good prediction of the water level is mandatory for tackling the water crisis and developing efficient emergency plans (Kozhevnikova & Shveikina, 2014). Water level fluctuations, caused by monsoonal climate and artificial drawdown can alter the hydrological conditions and influence light and nutrient availability, influencing phytoplankton succession (Tian et al 2015). The decrease in water level can indirectly affect the physical-chemical and biological characteristics of freshwater bodies, mainly through mixing enhancement (Valdespino-Castillo et al 2014).…”

Phytoplankton Functional Groups Variation and Influencing Factors in a Shallow Temperate Lake

“…In its current form, the PFG approach uses more than 40 categories according to the sensitivities and tolerances of representative taxa, identified by alphanumeric codes (Padisa´k et al, 2009;Salmaso et al, 2014). In the past decade, the PFG approach has provided important information for understanding the dynamics of phytoplankton communities and has been successfully applied in temperate (Huszar et al, 2003;Leita˜o et al, 2003;Tian et al, 2015), subtropical (Becker et al, 2009;Souza et al, 2016;Xiao et al, 2011), and tropical (Costa et al, 2009;Gebrehiwot et al, 2017;Rodrigues et al, 2017) regions.…”