Journal of Oceanology and Limnology   2022, Vol. 40 issue(5): 1693-1695     PDF
Institute of Oceanology, Chinese Academy of Sciences

Article Information

LI Renhui, SHI Xiaoli, GAN Nanqin, ZHANG Junyi, CHEN Xuechu
Cyanobacterial blooms in China: ecology, toxicity, and treatment
Journal of Oceanology and Limnology, 40(5): 1693-1695

Article History

Received Jul. 6, 2022
accepted in principle Aug. 13, 2022
Cyanobacterial blooms in China: ecology, toxicity, and treatment
Renhui LI1, Xiaoli SHI2, Nanqin GAN3, Junyi ZHANG4, Xuechu CHEN5     
1 National and Local Joint Engineering Research Center of Ecological Treatment Technology for Urban Water Pollution, Wenzhou University, Wenzhou 325035, China;
2 State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China;
3 State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China;
4 Wuxi Environmental Monitoring Center, Wuxi 214121, China;
5 School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, China

Cyanobacterial blooms are one of the major threats to the health of aquatic ecosystems, and are increasing globally due to the synergistic effects of human activities and global climate change. The 7th National Cyanobacteria Bloom Forum was successfully held in May 28–30, 2021 in Guiyang, Guizhou Province, China. The forum established a platform for exchanging views on the concerns of cyanobacterial blooms from Chinese researchers, lake managers, and treatment engineers. This special issue, "Cyanobacterial blooms in China: ecology, toxicity, and treatment" in Journal of Oceanography and Limnology, presents a collection of 14 papers on the physiological features and the influence on their concurrent aquatic biology of different cyanobacterial groups.

Microcystis blooms are pervasive in temperate and tropical freshwater bodies throughout the world. We have six papers focused on Microcystis related to the detection, the function of bound extracellular polymeric substances (bEPS), the effect on submerged macrophyte and the reed wetland, as well as the control strategy in the littoral area for emergency purposes. It is an essential task to conduct correct identificaiton of Microcystis species in ecological studies and water bloom control. Zu et al. (2022) established an immunological method to identify Microcystis, and they used Microcystis aeruginosa PCC7806 lysates as coated antigens for screening specific Microcystis nanobodies based on the human domain antibody display library. The bEPS play an important role in the proliferation of Microcystis. Wang et al. (2022) found that at certain light intensities, M. aeruginosa grow quickly than M. flos-aquae along with the increase of negative charges, bEPS contents, growth, and tryptophan-like substance contents. Another study related to EPS in Microcystis performed by Duan et al. (2022), identified key physiological traits and chemical components of EPS for colony formation in Microcystis. Their results further presented that the major physiological strategies for Microcystis to produce excess EPS enhancing colony formation, as increasing number for both photosynthetic reaction center and light-harvesting antenna in the PSII and reducing the growth rate.

Microcystis biomass can be largely accumulated to form heavy scums in large eutrophic lakes, posing a potential risk to public health. Gao et al. (2022) explored how decomposed Microcystis-dominant cyanobacterial blooms affect submerged macrophytes by exposing Myriophyllum spicatum to the cell extracts from microcystin (MC)- and non-MC-producing Microcystis strains in a laboratory experiment. Both Microcystis cell extracts exerted obvious damages to plant biomass, photosynthesis, primary and secondary metabolism measures, and resistance of plant antioxidant systems, as MC-producing Microcystis has stronger effects due to the presence of MCs. Meanwhile, planktonic bacterial communities have the potential to use and degrade substances derived from Microcystis cell extracts, which may be beneficial for M. spicatum to alleviate damages from Microcystis. Ma et al. (2022a) investigated the concentration of chlorophyll a and nutrients in reed-covered littoral zones and unvegetated littoral zones of Chaohu Lake, and revealed that reed wetlands in the littoral zone of large eutrophic lake could trap and accumulate algal biomass. To alleviate ecological disasters in littoral zones, Liu et al. (2022) compared three flocculants for heavy Microcystis bloom mitigation and subsequent environmental impacts. Polyaluminum chloride (PAC) was shown to be an efficient flocculant through rapid reduce of cyanobacterial blooms at chlorophyll-a concentrations over 1 500 μg/L within 15 min. Furthermore, the high accumulation of nutrients in sediments after the settling of cyanobacteria can cause high internal phosphorus and total organic carbon of the sediments, which can threaten lake restoration achieved by planting submerged macrophytes.

Raphidiopsis raciborskii is becoming a cosmopolitan species in freshwater systems around the world and attract interest due to its invasion, expansion, and toxicity. We have three papers dealing with R. raciborskii. Wu et al. (2022) presented an overview of R. raciborskii's global distribution and adaptation strategy and demonstrated that the expansion of its geographical distribution could be linked to its genome, toxicity, and ecophysiology. Shi et al. (2022a) reported R. raciborskii to cope with P deficiency at coordinated and complex cellular and physiological responses, reflecting the multi-faceted machinery of R. raciborski dealing with environmental P fluctuations. Ma et al. (2022b) performed bialgal cultures at different initial ratios of biomasses of R. raciborskii and microcystins (MCs)-producing or non-MCs-producing M. aeruginosa strains, and revealed that R. raciborskii in the co-cultures stimulated the growth of both MCs-producing and non-MCs-producing M. aeruginosa strains, comparing to M. aeruginosa monoculture. Such a result indicated M. aeruginosa to outcompete R. raciborskii and gradually become into dominant species even at a lower initial concentration.

Aphanizomenon is a common filamentous and bloom-forming cyanobacterial group. Wen et al. (2022) used the co-culture experiment at different ratios of initial biomass, to confirm that temperature as the dominating factor in the succession of A. flos-aquae and M. aeruginosa. A. flos-aquae was shown at a specific higher growth rate even the coexistence of the both species at 15 ℃, however the growth of A. flos-aquae at 25 ℃ was inhibited by the biomass of M. aeruginosa.

Eutrophication and climate warming have intensified the global expansion of Cylindrospermopsis spp. and Chrysosporum spp., two potential producers of Cylindrospermopsin (CYN). Yin et al. (2022) explored the effect of CYN on the structure and function of the bacterioplankton community based on high-throughput sequencing. High concentrations of CYN (40 μg/L) caused a significant decrease in microbial abundance and functional groups. Actinobacteria had the strongest tolerance to CYN. High CYN concentrations were shown to reduce the correlation among different bacterioplankton groups, and inhibit the abundances of some bacterial taxa functioning in the process of denitrification and carbon transfer in the microbial food web. Dissolved organic phosphorus could be used by cyanobacteria via alkaline phosphatase. Wan et al. (2022) review the current knowledge of extracellular phosphatase excreted by cyanobacteria, highlighting the development of detection method and its ecological roles in regulating phosphorus cycling in freshwater systems, which is based on reports for around 100 species of cyanobacteria.

Shi et al. (2022b) investigated the dynamics of the abundance and diversity of aerobic anoxygenic phototrophic bacteria (AAPB) based on pufM gene in Taihu Lake. The ratios of AAPB to total bacteria varied from 3.4% to 11.5% and peaked in winter in both sites. AAPB abundance was positively correlated with dissolved organic carbon (DOC) concentration. AAPB community compositions showed a difference between warm seasons and cold seasons.

Zheng et al. (2022) investigated the phytoplankton communities both in a semi-closed lake and a closed lake in the Oujiang River mouth in Zhejiang Province, to explore the effect of tides-induced water exchange on aquatic ecosystem. In the closed lake, cyanobacteria were the dominant species. However, in the semi-closed lake, the diversification of the dominant species was greater, and some species of diatoms and green algae became dominant. Water exchange driven by local tidal movement was shown to increase salinity and decrease transparency of water, consequently shaping the phytoplankton community structures and reducing the occurrence of cyanobacterial blooms in the semi-closed lake.

We thank editors of Journal of Oceanology and Limnology for giving us the opportunity to edit this special issue and supervise the whole editorial process, and we also thank all reviewers that have thoroughly reviewed these manuscripts. We hope that this collection of papers will be of interest for a broad scientific audience and will bring about new ideas and new research programs from a wide range of water bodies.

Duan Z P, Tan X, Zeng Q F. 2022. Key physiological traits and chemical properties of extracellular polymeric substances determining colony formation in a cyanobacterium. Journal of Oceanology and Limnology, 40(5): 1720-1731.
Gao Y N, Yang H, Gao X F, et al. 2022. Ecological damage of submerged macrophyte Myriophyllum spicatum by cell extracts from microcystin (MC)-and non-MC-producing cyanobacteria, Microcystis. Journal of Oceanology and Limnology, 40(5): 1732-1749.
Liu K X, Jiang L, Yang J S, et al. 2022. Comparison of three flocculants for heavy cyanobacterial bloom mitigation and subsequent environmental impact. Journal of Oceanology and Limnology, 40(5): 1764-1773.
Ma S Z, Wu Y, Chen S W, et al. 2022a. The impact of the accumulation of algal blooms on reed wetlands in the littoral zones of Chaohu Lake. Journal of Oceanology and Limnology, 40(5): 1750-1763.
Ma Z L, Zhang X Q, Li R H, et al. 2022b. Competitiveness of alga Microcystis aeruginosa co-cultivated with cyanobacterium Raphidiopsis raciborskii confirms its dominating position. Journal of Oceanology and Limnology, 40(5): 1804-1818.
Shi J Q, He S H, Zhao L, et al. 2022a. Physiological and molecular responses of invasive cyanobacterium Raphidiopsis raciborskii to ambient phosphorus deficiency. Journal of Oceanology and Limnology, 40(5): 1792-1803.
Shi L M, Cai Y F, Shi X L, et al. 2022b. Community structure of aerobic anoxygenic phototrophic bacteria in algaeand macrophyte-dominated areas in Taihu Lake, China. Journal of Oceanology and Limnology, 40(5): 1855-1867.
Wan L L, Song C L, Zhou Y Y, et al. 2022. Cyanobacterial extracellular alkaline phosphatase: detection and ecological function. Journal of Oceanology and Limnology, 40(5): 1840-1854.
Wang X Z, Han X Y, Ge H M. 2022. Effect of light intensity on bound EPS characteristics of two Microcystis morphospecies: the role of bEPS in the proliferation of Microcystis. Journal of Oceanology and Limnology, 40(5): 1706-1719.
Wen Q Z, Xiao P, Li H, et al. 2022. Succession of Aphanizomenon flos-aquae and Microcystis aeruginosa in direct co-culture experiments at different temperatures and biomasses. Journal of Oceanology and Limnology, 40(5): 1819-1828.
Wu Z X, Yang S Q, Shi J Q. 2022. Overview of the distribution and adaptation of a bloomforming cyanobacterium Raphidiopsis raciborskii: integrating genomics, toxicity, and ecophysiology. Journal of Oceanology and Limnology, 40(5): 1774-1791.
Yin S C, Huang R H, Jeppesen E, et al. 2022. The effect of cylindrospermopsin on the bacterioplankton community: a microcosm experiment on water from Dishui Lake, Shanghai, China. Journal of Oceanology and Limnology, 40(5): 1829-1839.
Zheng W X, Li R H, Qin W L, et al. 2022. Tidal water exchanges can shape the phytoplankton community structure and reduce the risk of harmful cyanobacterial blooms in a semi-closed lake. Journal of Oceanology and Limnology, 40(5): 1868-1880.
Zu Y, Miao W J, Luo Y, et al. 2022. Screening of nanobody against Microcystis from a human phage display nanobody library. Journal of Oceanology and Limnology, 40(5): 1696-1705.