Weekly dynamics of phytoplankton functional groups under high water level fluctuations in a subtropical reservoir-bay

Abstract

In reservoirs, water level fluctuations strongly influence phytoplankton development. However, studies on the response of phytoplankton in the reservoir-bay to water level fluctuations are very scarce, especially in the highly dynamic reservoir system, for instance, the Three Gorges Reservoir (TGR) on the Yangtze River in China. Therefore, we carried out weekly monitoring in a typical tributary bay-Xiangxi Bay of the TGR from March 2008 to March 2009 analyze the dynamics of phytoplankton functional groups, as well as their response to the water level fluctuations and other environmental conditions. The phytoplankton functional groups G (short, nutrient-rich water columns with high light and without nutrient deficiency), M (dielly mixed layers of small eutrophic, low latitude with high insolation and without flushing and low total light) and Lo (summer epilimnia in mesotrophic lakes with segregated nutrients and without prolonged or deep mixing) were the most important in biomass, mainly represented by Pandorina morum and Eudorina elegans, Microcystis aeruginosa, Peridiniopsis niei and Ceratium hirundinella, respectively. The dominant functional groups had close relationships with the water level fluctuations, light and nutrient, etc. Principal components analysis and redundancy analysis indicated that phytoplankton functional groups in Xiangxi Bay were restricted by the mixing regime and other abiotic variables under the influences of the mixing regime. In Xiangxi Bay, the water level fluctuation showed significant correlations with many physicochemical variables, including the mixing depth (r = 0.97, p \ 0.001) and the relative water column stability (r = -0.80, p \ 0.001). The study implied that water level fluctuations had complex influence on environmental changes and selecting for phytoplankton functional groups in a highly dynamic reservoir-bay. The important characteristics of the dominant phytoplankton functional groups in Xiangxi Bay were also discussed.

Longitudinal Differences of Phytoplankton Community during a Period of Small Water Level Fluctuations in a Subtropical Reservoir Bay (Xiangxi Bay, Three Gorges Reservoir, China)

“…In the previous studies, high values of WT, pH and Z eu /Z mix were detected when Microcystis aeruginosa dominated in Xiangxi Bay, indicating its good adaptability to the water column stratification conditions in summer influenced by weak water level fluctuations (WANG et al, 2010a). Large-scale climatic conditions and the local weather pattern set the physic-chemical conditions which determine the cyanobacterial response (BORMANS et al, 2005).…”

Trophic state categorisation and assessment of water quality in Manjirenji Dam, Zimbabwe, a shallow reservoir with designated multi-purpose water uses

“…The incessant water waves and Langmuir circulations that we observed may also aid the horizontal redistribution of suspended minerals in shallow lakes such as Manjirenji (Hildebrand, 2004). Implications of physicochemical dissimilarities for biotic communities in shallow lakes derive from the almost uniform horizontal distribution of major drivers of productivity such as phosphorus, nitrates and sulphates, as these tend to determine dominant communities (Wang et al, 2011). An increase in the brackishness of the water as well as turbidity, as observed in the study, affects light penetration, which in turn poses a limitation on primary productivity (Fee et al 1996); thus chlorophyll a levels were almost uniform and not significantly different around the lake.…”

The phytoplankton functional group concept provides a reliable basis forecological status estimation in the Çaygören Reservoir (Turkey)

“…Padisak et al (2009) modified the original functional classification system by reviewing numerous studies dealing with the FG concept and described typical misplacements by authors. It then was applied in numerous studies (Becker et al, 2010;Devercelli, 2010;Piirsoo et al, 2010;Wang et al, 2011;Wu et al, 2011;Xiao et al, 2011;Abonyi et al, 2012Abonyi et al, , 2014Hu and Xiao, 2012;Stanković et al, 2012;Scomparin et al, 2013).…”