Key Factors Controlling Primary Production and Cyanobacterial Harmful Algal Blooms (cHABs) in a Continuous Weir System in the Nakdong River, Korea

To identify key factors that control primary production (P.P.) and trigger cyanobacterial harmful algal blooms (cHABs), we investigated spatio-temporal variations in P.P. in a continuous weir system in the Nakdong River once or twice a month from April to October 2018. P.P. was measured through an in-situ incubation experiment using a 13C tracer. Relative proportion of pigment-based phytoplankton composition was calculated by the CHEMTAX program based on pigment analysis using a high-performance liquid chromatography (HPLC). P.P. was higher in spring (1130 ± 1140 mg C m−2 d−1) and summer (1060 ± 814 mg C m−2 d−1) than autumn (180 ± 220 mg C m−2 d−1), and tended to increase downstream. P.P. was negatively related to PO43− (r = −0.41, p < 0.01) due to utilization by phytoplankton during the spring and summer when it was high. The relative proportion of pigment-based cyanobacteria (mainly Microcystis sp.) was positively correlated with water temperature (r = 0.79, p < 0.01) and hydraulic retention time (HRT, r = 0.67, p < 0.01), suggesting that these two factors should affect cHABs in summer. Therefore, to control HRT could be one of the solutions for reducing cHABs in a continuous weir system.

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Long-Term Ecological Research in the Nakdong River: Application of Ecological Informatics to Harmful Algal Blooms

Ecological Informatics ◽

10.1007/978-3-319-59928-1_20 ◽

2017 ◽

pp. 435-453 ◽

Cited By ~ 1

Author(s):

Dong-Gyun Hong ◽

Kwang-Seuk Jeong ◽

Dong-Kyun Kim ◽

Gea-Jae Joo

Keyword(s):

Harmful Algal Blooms ◽

Algal Blooms ◽

Ecological Research ◽

Nakdong River ◽

Long Term Ecological Research ◽

The Nakdong River

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Predicting Cyanobacterial Harmful Algal Blooms (CyanoHABs) in a Regulated River Using a Revised EFDC Model

Water ◽

10.3390/w13040439 ◽

2021 ◽

Vol 13 (4) ◽

pp. 439

Author(s):

Jung Min Ahn ◽

Jungwook Kim ◽

Lan Joo Park ◽

Jihye Jeon ◽

Jaehun Jong ◽

...

Keyword(s):

South Korea ◽

Chlorophyll A ◽

Harmful Algal Blooms ◽

Algal Blooms ◽

Environmental Research ◽

Regulated River ◽

Water Current ◽

Harmful Cyanobacteria ◽

Cyanobacterial Harmful Algal Blooms ◽

The Nakdong River

Cyanobacterial Harmful Algal Blooms (CyanoHABs) produce toxins and odors in public water bodies and drinking water. Current process-based models predict algal blooms by modeling chlorophyll-a concentrations. However, chlorophyll-a concentrations represent all algae and hence, a method for predicting the proportion of harmful cyanobacteria is required. We proposed a technique to predict harmful cyanobacteria concentrations based on the source codes of the Environmental Fluid Dynamics Code from the National Institute of Environmental Research. A graphical user interface was developed to generate information about general water quality and algae which was subsequently used in the model to predict harmful cyanobacteria concentrations. Predictive modeling was performed for the Hapcheon-Changnyeong Weir–Changnyeong-Haman Weir section of the Nakdong River, South Korea, from May to October 2019, the season in which CyanoHABs predominantly occur. To evaluate the success rate of the proposed model, a detailed five-step classification of harmful cyanobacteria levels was proposed. The modeling results demonstrated high prediction accuracy (62%) for harmful cyanobacteria. For the management of CyanoHABs, rather than chlorophyll-a, harmful cyanobacteria should be used as the index, to allow for a direct inference of their cell densities (cells/mL). The proposed method may help improve the existing Harmful Algae Alert System in South Korea.

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CyanoHABs: unavoidable evolutionary ecological consequence for low nutrient-requiring cyanobacteria in eutrophic water

10.1101/2021.11.22.469516 ◽

2021 ◽

Author(s):

Wenduo Cheng ◽

Somin Hwang ◽

Qisen Guo ◽

Haibei Zhang ◽

Leyuan Qian ◽

...

Keyword(s):

Harmful Algal Blooms ◽

Algal Blooms ◽

Nutrient Requirements ◽

Key Factors ◽

Narrow Angle ◽

Eutrophic Water ◽

Evolutionary Radiation ◽

Cyanobacterial Harmful Algal Blooms ◽

Multiple Species ◽

Water Eutrophication

The mechanism of cyanobacterial harmful algal blooms (CyanoHABs) is complicated and confusing. One major reason is they are studied primarily from an ecological perspective and on bloom-forming species only. This narrow angle loses a broader evolutionary and ecological context in which CyanoHABs occur and fails to provide information on relevant components to achieve a wholistic understanding. To derive a comprehensive mechanism of CyanoHABs, we examine CyanoHABs through the overlooked evolutionary and ecological lenses: evolutionary radiation, ecological comparison with co-living algae, and recently identified genomic functional repertoire between blooming and non-blooming species. We found key factors: (1) elaborate diverse functional repertoire and low nutrient requirement in cyanobacteria molded by early adaptive evolution, (2) cyanobacteria having lower nutrient requirements than green algae indeed, (3) there is no directed evolution in biological functions toward water eutrophication in cyanobacteria, (4) the CyanoHAB-associated functional repertoire are more abundant and complete in blooming than non-blooming species. These factors lead us to postulate a preliminary mechanism of CyanoHABs as a synergistic quad: superior functional repertoire, established with long adaptive radiation under nutrient-deficient conditions and not evolved toward eutrophic conditions, enables cyanobacteria to efficiently utilize elevated nutrients under current eutrophic regime for excess growth and CyanoHABs thereof, due to their lower nutrient requirements than co-living algae. This preliminary synthesis without doubt needs further empirical testing, which can be undertaken with more comparative studies of multiple species using integrated systems biology approaches.

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