Analysis of Environmental Factors Associated with Cyanobacterial Dominance after River Weir Installation

Following the installation of 16 weirs in South Korea’s major rivers through the Four Rivers Project (2010–2012), the water residence time increased significantly. Accordingly, cyanobacterial blooms have occurred frequently, raising concerns regarding water use and the aquatic ecosystem health. This study analyzed the environmental factors associated with cyanobacterial dominance at four weirs on the Nakdong River through field measurements, and parametric and non-parametric data mining methods. The environmental factors related to cyanobacterial dominance were the seven-day cumulative rainfall (APRCP7), seven-day averaged flow (Q7day), water temperature (Temp), stratification strength (ΔT), electrical conductivity (EC), dissolved oxygen (DO), pH, and NO3–N, NH3–N, total nitrogen (TN), total phosphorous (TP), PO4–P, chlorophyll–a, Fe, total organic carbon (TOC), and SiO2 content, along with biological and chemical oxygen demands. The results indicate that site-specific environmental factors contributed to the cyanobacterial dominance for each weir. In general, the physical characteristics of EC, APRCP7, Q7day, Temp, and ΔT were the most important factors influencing cyanobacterial dominance. The EC was strongly associated with cyanobacterial dominance at the weirs because high EC indicated persistent low flow conditions. A minor correlation was obtained between nutrients and cyanobacterial dominance in all but one of the weirs. The results provide valuable information regarding the effective countermeasures against cyanobacterial overgrowth in rivers.

Download Full-text

Molecular Verification of Bloom-forming Aphanizomenon flos-aquae and Their Secondary Metabolites in the Nakdong River

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph15081739 ◽

2018 ◽

Vol 15 (8) ◽

pp. 1739 ◽

Cited By ~ 4

Author(s):

Hae-Kyung Park ◽

Mi-Ae Kwon ◽

Hae-Jin Lee ◽

Jonghee Oh ◽

Su-Heon Lee ◽

...

Keyword(s):

Secondary Metabolites ◽

Water Samples ◽

Its Region ◽

Cyanobacterial Blooms ◽

Specific Primer ◽

Nakdong River ◽

Off Flavors ◽

Primer Sets ◽

The Nakdong River ◽

Harmful Cyanobacterial Blooms

Aphanizomenon spp. have formed harmful cyanobacterial blooms in the Nakdong River during spring, autumn, and now in winter, and the expansion of blooming period and area, associated with the global warming is predicted. The genus Aphanizomenon has been described to produce harmful secondary metabolites such as off-flavors and cyanotoxins. Therefore, the production of harmful secondary metabolites from the Aphanizomenon blooms in the Nakdong River needs to be monitored to minimize the risk to both water quality and public health. Here, we sampled the cyanobacterial blooms in the Nakdong River and isolated ten Aphanizomenon strains, morphologically classified as Aphanizomenon flos-aquae Ralfs ex Bornet et Flahault 1888. Phylogenetic analysis using 16S rRNA and internal transcribed spacer (ITS) region nucleotide sequences confirmed this classification. We further verified the harmful secondary metabolites-producing potential of A. flos-aquae isolates and water samples containing cyanobacterial blooms using PCR with specific primer sets for genes involved in biosynthesis of off-flavor metabolites (geosmin) and toxins (microcystins, saxitoxins and cylindrospermopsins). It was confirmed that these metabolite biosynthesis genes were not identified in all isolates and water samples containing only Aphanizomenon spp. Thus, it is likely that there is a low potential for the production of off-flavor metabolites and cyanotoxins in Aphanizomenon blooms in the Nakdong River.

Download Full-text

Environmental factors associated with toxic cyanobacterial blooms across 20 drinking water reservoirs in a semi-arid region of Brazil

Harmful Algae ◽

10.1016/j.hal.2019.05.006 ◽

2019 ◽

Vol 86 ◽

pp. 128-137 ◽

Cited By ~ 6

Author(s):

Mário U.G. Barros ◽

Alan E. Wilson ◽

João I.R. Leitão ◽

Silvano P. Pereira ◽

Riley P. Buley ◽

...

Keyword(s):

Drinking Water ◽

Environmental Factors ◽

Arid Region ◽

Cyanobacterial Blooms ◽

Water Reservoirs ◽

Factors Associated ◽

Semi Arid Region ◽

Semi Arid

Download Full-text

Environmental factors associated with a toxic bloom of Microcystis aeruginosa

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f99-234 ◽

2000 ◽

Vol 57 (1) ◽

pp. 231-240 ◽

Cited By ~ 164

Author(s):

Jean M Jacoby ◽

Diane C Collier ◽

Eugene B Welch ◽

F Joan Hardy ◽

Michele Crayton

Keyword(s):

Environmental Factors ◽

Microcystis Aeruginosa ◽

Toxin Production ◽

Water Transparency ◽

Cyanobacterial Blooms ◽

Zooplankton Abundance ◽

Factors Associated ◽

Water Column Stability ◽

Microcystin Concentration ◽

Toxic Bloom

Environmental factors associated with the occurrence of toxic cyanobacterial blooms and toxin production were investigated during the summers of 1994 and 1995 in Steilacoom Lake, Washington. A pronounced and prolonged toxic bloom of Microcystis aeruginosa occurred during summer 1994 but not during 1995. Lake characteristics that were associated with the toxic bloom in 1994 were higher total phosphorus, decreased water transparency, high water column stability, high surface water temperature and pH, and decreased lake flushing. Decreased water transparency during 1994 may have been due to significantly lower zooplankton abundance. We hypothesize that this decreased transparency was caused by increased planktivory by higher numbers of coho salmon (Oncorhynchus kisutch) fingerlings during 1994 and (or) inhibition of zooplankton grazing by Microcystis. The success of Microcystis over other cyanobacteria was associated with low nitrogen to phosphorus ratios and low nitrate-nitrogen with sufficient ammonium-nitrogen concentrations. Toxin production (i.e., micrograms of microcystin per gram of plankton biomass) was not constant over the duration of detectable toxicity; hence, no relationship was found between Microcystis abundance and microcystin concentration. However, microcystin concentration was positively correlated with increasing soluble reactive phosphorus concentrations between 1 and 10 µg·L-1, indicating that toxin production may have been limited by phosphorus.

Download Full-text

Bathymetric Changes in the Nakdong River Estuary owing to Discharge from the Nakdong River Barrier and Environmental Factors

Journal of Environmental Science International ◽

10.5322/jesi.2021.30.7.507 ◽

2021 ◽

Vol 30 (7) ◽

pp. 507-517

Author(s):

Ki-cheol Kim ◽

Sung-Bo Kim

Keyword(s):

Environmental Factors ◽

River Estuary ◽

Nakdong River ◽

The Nakdong River ◽

Bathymetric Changes

Download Full-text

Effects of Environmental Factors on Algal Communities in the Nakdong River

Journal of Korean Society on Water Environment ◽

10.15681/kswe.2014.30.5.539 ◽

2014 ◽

Vol 30 (5) ◽

pp. 539-548 ◽

Cited By ~ 4

Author(s):

Jae Jeong Yu ◽

Hae Jin Lee ◽

Kyung-Lak Lee ◽

In Jeong Lee ◽

Gang Young Jung ◽

...

Keyword(s):

Environmental Factors ◽

Nakdong River ◽

Algal Communities ◽

The Nakdong River

Download Full-text

Investigation of the environmental factors associated with the inflow of Sargassum horneri into the Korean Peninsula using GOCI

10.5194/egusphere-egu2020-22278 ◽

2020 ◽

Author(s):

Jihui Kim ◽

Young-je Park

Keyword(s):

Environmental Factors ◽

Korean Peninsula ◽

Field Measurements ◽

Detection Algorithm ◽

Tourism Industry ◽

Sargassum Horneri ◽

Factors Affecting ◽

Factors Associated ◽

Air Pocket ◽

Red Edge Effect

&#160;<ul><li> Sargassum horneri is one of the major components of the floating sargassum that is distributed widely along the coast, including Korea, China and Japan. Sargassum horneri has an air pocket called an &#8216;air sec&#8217; on its body which leads to a floating life, and drifts by ocean currents and winds. Due to these characteristics, blooms of Sargassum horneri have occurred April-June in the East China Sea. If these blooms flow into Jeju Island in South Korea, the blooms can cause enormous damage to fishing activities and the marine tourism industry. In order to minimize the damage caused by these blooms, we have been studied using remote sensing and field measurements. This study investigates environmental factors associated to the inflow of Sargassum horneri into Korean Peninsula. We used floating algae detection algorithm developed by a Geostationary Ocean Color Imager (GOCI). Since GOCI provides data of the seas surrounding the Korea eight times a day (00 to 07 UTC), it is suitable to monitor the blooms. The algorithm was made using the Red-edge effect which has a sharply rising reflectivity at around 700 nm but a low reflectivity in the red area (660-680 nm). And it was considered that the reflectivity of background seawater which varies from place to place is eliminated. Based on the results of the algorithm for detecting floating algae, Sargassum horneri&#8217;s inflow into the Korean Peninsula was analyzed January to June for six years (2014 to 2019). Also, the environment factors affecting to the inflow path were investigated each months and years. </li> </ul>&#160;

Download Full-text