• ALGAE
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• v.19 no.3
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• pp.227-234
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• 2004

A study on the dynamics of phytoplankton community and the physico-chemical environmental factors was performed biweekly from April 1998 to March 1999 in Youngchun Dam. A total 72 phytoplankton taxa was identified and dominant taxa were blue-green algae and diatoms. The highest value of phytoplankton standing crop (24,826cells·ml$^{-1}$) was observed in September 7, 1998, the blooming period of blue-green algae Phormidium sp., while the lowest (318cells·ml$^{-1}$) was measured in June 18, 1999. The phytoplankton communities were dominated by blue-green algae of Anabaena planktonica, Microcystis aeruginosa and Phormidium sp. during the summer and autumn periods and were dominated by diatoms of Synedra acus and Aulacoseira spp. during the spring and winter periods. Secchi disc transparency, chlorophyll-a, total nitrogen, total phosphorus and silicate concentration were varied in the ranges of 0.4-2.5 m, 2.4-32.2mg·m$^{-1}$, 0.845-2.352mg·l$^{-1}$, 0.005-0.093mg·l$^{-1}$, 0.2-15.7mg·l$^{-1}$, respectively. The trophic status of Youngchun Dam were estimated eutrophic according to Lake Trophic States Index (LTSI).

• Korean Journal of Ecology and Environment
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• v.40 no.1
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• pp.149-154
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• 2007

In the present study, we performed the PCR assay using TOX2P/TOX2M primer targeting a specific region within mcyB gene to identify potential microcystin-producing cyanobacteria. TOX2P/TOX2M primer set was effective in amplifying mcy gene in the field samples containing Microcystis spp. of 1,000 cells per mL. Moreover, the results from the PCR assay agreed with those of the ELISA analysis. Consequently, this study demonstrated that TOX2P/TOX2M primer set can be used as a genetic probe for the early detection of cyanobacterial toxigenicity in Korean water bodies.

• Korean Journal of Environmental Biology
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• v.38 no.2
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• pp.299-307
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• 2020

This study reported on the phytoplankton community and seasonal changes in the Seoul passage section and downstream in the Han River in 2012. Field samples were collected monthly from the upper (Paldang), middle (Cheongdam), and downstream(Seongsan) areas of the Seoul passage section. Water temperature, DO, pH, and conductivity were measured at each station. All environmental factors measured were recorded similarly at the three stations. The water temperature ranged from 2 to 30℃ and the dissolved oxygen ranged from 4.8 to 9.1 mg L^-1, showing typical patterns of temperate regions. The phytoplankton cell concentrations ranged from 990 cells mL^-1 (Paldang, December) to 2.9×10⁴ cells mL^-1 (Seongsan, March), and the chlorophyll-a content showed similar patterns to the cell numbers. The phytoplankton community was comprised of 75 genera and 95 species, including 37 diatoms, 29 Chlorophyta, 11 cyanobacteria, and two dinoflagellates. The number of species that appeared seasonally varied greatly, from nine species (Paldang, May) to 35 species (Cheongdam, December). Diatoms were the most dominant in all stations and seasons, except in summer. In contrast, chlorophytes and cyanobacteria showed sporadic high numbers in the summer and fall seasons. Four diatoms Stephanodiscus hantzschii f. tenuis, S. hantzschii, Fragilaria sp., and Aulacoseira spp., a chlorophyte Actinastrum hantzschii, and a cyanobacterium Microcystis sp. were each present in proportions greater than 10%. This study provides fundamental data from phytoplankton communities and environmental factors in the Han River for understanding water quality for long-term environmental monitoring.

• Korean Journal of Ecology and Environment
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• v.39 no.2 s.116
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• pp.271-283
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• 2006

A systematic water quality survey was conducted in August, 2005 for a drinking water supply reservoir (the Jeolgol reseuoir located in an island), which is at an early stage of impoundment, to investigate the causes of water color deterioration of the reservoir and the clogging of filter beds of a water treatment plant. The reservoir shape was simple and its average depth was 5.5 m, increasing from upreservoir toward the downreservoir end near the dam. Dissolved oxygen (DO) and chloropllyll-a (chi-a) showed a large variation while water temperature had a smaller range. Transparency ranged from 0.6 to 0.9 m (average 0.7 m). The average value of turbidity was 9.3 NTU, ranging from 8.0 ${\sim}$ 12.1 NTU. The transparency and the turbidity appear to be affected by a combination of biological and non-biological factors. The poor transparency was explained by an increase of inorganic colloids and algal bloom in the reservoir. The blockage of the filter bed was attributed to the oversupply of phytoplanktons from the reservoir. The range and the average concentration of chi-a within the reservoir were 31.6 ${\sim}$ 258.9 ${\mu}g\;L^{-1}$, 123.6 ${\mu}g\;L^{-1}$ for the upper layer, and 17.0 ${\sim}$ 37.4 ${\mu}g\;L^{-1}$, 26.5 ${\mu}g\;L^{-1}$ for the bottom layer, respectively. A predominant species contributing the algal bloom was Dinophyceae, Peridinium bipes f. occultatum. The distribution of Peridinium spp. was correlated with chi-a concentrations. The standing crop of phytoplankton was highest in the upreservoir with $8.5\;{\times}\;103\;cells\;mL^{-1}$ and it decreased toward the downresevoir. Synedra of Bacillariophyceae and Microcystis aeruginosa of Cyanophyceae appeared to contribute to the algal bloom, although they are not dominated. It is mostly likely that sloped farmlands located in the watershed of the reservoir caused water quality problems because they may contain a significant amount of the nutrients originated from fertilizers. In addition, the aerators installed in the reservoir and a shortage of the inflowing water may be related to the poor water quality. A long-term monitoring and an integrated management plan for the water quality of the watersheds and the reservoir may be required to improve the water quality of the reservoir.

• Journal of Ecology and Environment
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• v.40 no.1
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• pp.66-74
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• 2016

Background: When developing water quality improvement strategies for eutrophic lakes, questions may arise about the relative importance of point sources and nonpoint sources of phosphorus. For example, there is some skepticism regarding the effectiveness of partial reductions in phosphorus loading; because phosphorus concentrations are too high in hypertrophic lakes, in-lake phosphorus concentrations might still remain within typical range for eutrophic lakes even after the reduction of phosphorus loading. For this study, water quality and the phytoplankton and zooplankton communities were monitored in a hypertrophic reservoir (Lake Wangsong) before and after the reduction of phosphorus loading from a point source (a sewage treatment plant) by the installation of a chemical phosphorus-removal process. Results: Before phosphorus removal, Lake Wangsong was classified as hypertrophic with a median phosphorus concentration of $0.232mg\;L^{-1}$ and a median chlorophyll-a concentration of $112mg\;L^{-1}$. The dominant phytoplankton were filamentous cyanobacteria for the most of the ice-free season. Following the installation of the advanced treatment process, phosphorus concentrations were reduced to $81mg\;L^{-1}$, and the N/P atomic ratio increased from 42 to 102. Chlorophyll-a concentrations decreased to $42{\mu}g\;L^{-1}$, and the duration of cyanobacterial dominance was confined to the summer season. Cyanobacteria in spring and autumn were replaced by diatoms and cryptomonads. Filamentous cyanobacteria in summer were replaced by colony-forming unicellular Microcystis spp. It was remarkable that zooplankton biomass increased despite the decrease in phytoplankton biomass, and especially cladoceran zooplankton which increased drastically. These responses to the reduction of point source P loading to Lake Wangsong imply that reducing the point source P loading can have a big impact even when nonpoint sources account for a large fraction of the total annual phosphorus loading. Conclusions: Our results also show that the phytoplankton community can shift to decreased cyanobacterial dominance and the zooplankton community can shift to higher cladoceran dominance, even when phosphorus concentrations remain within the typical range for eutrophic lakes following the reduction of phosphorus loading.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.12
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• pp.943-952
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• 2013

Algae blooms have soared recently in the lakes across the nation due to eutrophication. Blue-green algae cause unpleasant scene, produce taste and odor problem, and hinder processes in drinking water treatment. Algae toxicity monitoring has been strengthened, because the damages of wild lives and livestocks by algal toxins have been reported. Investigation on the characteristics of cyanobacterial occurrence and concentration distribution of Cyanotoxins in Hoeya reservoir have been conducted. Physical and chemical influences of water environment on cyanobacterial occurrences have also been studied. Movements of four species of Microcystin and five species of Anatoxin-a among Cyanotoxins were observed by LC-MS/MS analysis. Microcystis spp. among the cyanobacteria have mainly dominated in the Hoeya reservoir during the investigating period. The density of cyanobacteria were positively correlated with temperature and pH of water. Highest concentrations of Microcystin-LR and Microcystin-RR were $0.424{\mu}g/L$ and $0.117{\mu}g/L$ at the sampling points. Total concentration of Cyanotoxins in water coming into the water treatment plant was $0.182{\mu}g/L$, and they were not detected in treated water.

• Korean Journal of Environmental Biology
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• v.20 no.1
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• pp.91-99
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• 2002

With physico-chemical environmental factors such as temperature, DO, pH, conductivity and nutrients, size fractionated of phytoplankton standing crops and chlorophyll a concentrations $(>8\mu{m},\;3-8\mu{m},\;<3\mu{m})$ and their relationships were investigated at each station of Kyungan Stream and Togyo Reservoir from April to November in 1997. The two sampling sites showed different nutrient status: Kyungan Stream was eutrophic, while Togyo Reservoir was mesotrophic. Large sizes of phytoplankton and chl. a were higher in Kyungan Stream, opposite to those of Togyo Reservoir; Standing crops of phytoplankton $(>8\mu{m)$ and chl. a $(3-8\mu{m)}$ were high in Kyung-an Stream, while phytoplankton $(3-8\mu{m)}$and chi. a $(<3\mu{m)$ were abundant in Togyo Reservoir. These results imply that phytoplankton community in the highly eutrophicated water mainly comprised the large filamentous and/or colonial algae, such as Microcystis spp. and Aphanizomenon flos-aquae, which easily enriched by nutrients loading.