The decline process and major pathways of Microcystis bloom in Taihu Lake, China

Abstract

Eutrophication has become a serious concern in many lakes, resulting in cyanobacterial blooms. However, the mechanism and pathways of cyanobacteria decline are less understood. To identify and define the growth and decline of Microcystis blooms in Taihu Lake of China, and to illuminate the destination of surface floating blooms, we investigated the biomass distribution and variations in colony size, morphology, and floating velocity from October 2008 to September 2009. The results showed that the Microcystis bloom declined in response to biomass decrease, colony disaggregation, buoyancy reduction, and increased phytoplankton biodiversity, and these indicative parameters could be applied for recognition of the development phases of the bloom. Three major decline pathways were proposed to describe the bloom decline process, colony disaggregation (Pathway I), colony settlement (Pathway II), and cell lysis in colonies (Pathway III). We proposed a strategy to define the occurrence and decline of Microcystis blooms, to evaluate the survival state under different stress conditions, and to indicate the efficiency of controlling countermeasures against algal blooms.

A niche model to predict Microcystis bloom decline in Chaohu Lake, China

“…Our previous study found a decline in Microcystis blooms occurred between July and August in Meiliang Bay of Lake Taihu, China (Wang et al, 2012). Certain decline processes and mechanisms were determined from this study.…”

“…Environmental factors were not considered as parameters in this niche model, effectively removing human error caused by the time difference between sample collection and data analysis and avoiding the effects of this time-lag on model construction. The Microcystis bloom was observed to decline in autumn (Wang et al, 2012). However, from fi eld data, the exact timing of this decline and the decline rate was unknown.…”

Sediment–water interaction in phosphorus cycling as affected by trophic states in a Chinese shallow lake (Lake Donghu)

“…Excess inputs of nitrogen (N) and phosphorus (P) into lakes often result in eutrophication and affect the phytoplankton community structure (Vollenweider, 1970;Arhonditsis et al, 2003;Wang et al, 2012). As a result of eutrophication, harmful cyanobacterial blooms in water bodies frequently occurred and lead to a decrease in biodiversity (Meijer & Hosper, 1997;Wu et al, 2010) and a miniaturization trend in size distribution of phytoplankton (Ruggiu et al, 1998;Finkel et al, 2009;Ma et al, 2010).…”

A quantitative protocol for rapid analysis of cell density and size distribution of pelagic and benthic Microcystis colonies by FlowCAM

“…Schöne et al (2010) found that the colonies in the water column were smaller than the colonies in the sediments of Quitzdorf Reservoir (Germany). Colony disaggregation was found during the bloom-decline process in Lake Taihu (China) (Wang et al 2012). The colony size of Microcystis also affects its vertical migration (Wang et al 2011), microcystin cell quota (Kurmayer et al 2003;Wang et al 2013a), and grazing resistance (White and Sarnelle 2014).…”