Controlling factors of spring–summer phytoplankton succession in Lake Taihu (Meiliang Bay, China)

Abstract

The spring-summer successions of phytoplankton and crustacean zooplankton were examined weekly in Meiliang Bay of the subtropical Lake Taihu in 2004 and 2005. During the study period, the ecosystem of Meiliang Bay was characterized by (i) clearly declined nitrogen compounds (nitrate, TN, and ammonium) and slowly increased phosphorus compounds (TP and SRP), (ii) increased total phytoplankton density and rapid replacement of chlorophyta (mainly Ulothrix) by cyanobacteria (mainly Microcystis), and (iii) rapid replacement of large-sized crustaceans (Daphnia and Moina) by csmall-sized ones (Bosmina, Limnoithona, and Ceriodaphnia). Results from the CCA and correlation analysis indicate that the spring-summer phytoplankton succession was primarily controlled by abiotic factors. Cyanobacteria were mainly promoted by increased temperature and decreased concentrations of nitrogen compounds. The pure contribution of crustacean was low for the variation of phytoplankton suggesting a weak top-down control by crustacean zooplankton in the subtropical Lake Taihu.

Dynamics of the water bloom-forming Microcystis and its relationship with physicochemical factors in Lake Xuanwu (China)

“…were present in all of the samples and were able to be detected even at very low cell abundances during low temperature periods using the qPCR method, indicating that Microcystis can overwinter in the water column even during low temperatures of 4-5°C for lakes of the middle and lower reaches of the Yangtze River. Chen et al (2003) and Ke et al (2008) found that temperature played an important role in changes within the phytoplankton community during the spring-summer succession period in Lake Taihu. Based on their laboratory and field studies, Robarts and Zohary (1987) showed that the temperature optima for the growth rate of Microcystis was 25°C or greater, and growth of Microcystis will be severely limited by temperatures below 15°C.…”

“…Therefore, understanding the dynamics of Microcystis and MC-producing Microcystis in these lakes is of great importance. Among these shallow lakes, the larger ones such as Lake Taihu and Caohu have been studied extensively (Chen et al 2003;Ke et al 2008). In addition, not only large shallow lakes but also small urban lakes located at many populated cities in Eastern and Central China have been found to be eutrophic or hypertrophic and have experienced water blooms (Fan et al 2005).…”

Modelling ecosystem structure and trophic interactions in a typical cyanobacterial bloom-dominated shallow Lake Dianchi, China

“…Negative impacts of bloom formation and collapse are well known on aquatic ecosystems, including high turbidity and shading the light needed by aquatic plants (Berger, 1989), changing physico-chemical factors (elevated pH and reduced CO 2 ), and producing toxins called microcystins (MCs) that affect the habitats of other biological communities (Kann and Smith, 1999;Hessen et al, 2005). Therefore, some studies have focused on different levels of aquatic organisms along with life cycle of Microcystis (Ke et al, 2008) and even the involved dynamics of the 'microbial loop' (Sommaruga, 1995) to postulate the possible relationship between cyanobacteria and community structure of bacteria and flagellates (Xing et al, 2007;Wilhelm et al, 2011). However, predicting the overall effects of blooms on ecosystem seems difficult.…”

Phytoplankton variation and its relationship with the environment in Xiangxi Bay in spring after damming of the Three-Gorges, China

“…In general, temperature was thought to be the most important factor influencing the phytoplankton succession (Abrantes et al 2006;Ke et al 2008). However, our results showed that heavy rainfalls were the most important factors for the changes of phytoplankton community in spring in Xiangxi Bay.…”