• Korean Journal of Ecology and Environment
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• v.46 no.2
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• pp.301-309
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• 2013

Between May and August 2012, a massive cyanobacterial bloom with Anabaena has been occurred throughout the North Han River. Sampling was conducted at one station on each lake, L. Uham, L. Cheongpyung, and L. Paldang, where occurred a dense bloom, in 13 July. According to the microscopic examination, the blooms was dominated by one specific filamentous cyanobacterium Anabaena and other phytoplankton. Morphologically, previous literature proven that this Anabaena species is A. crassa (Lemmermann) Komark.-Legn. & Cronberg. However, identification of species in a mixed population is complicated due to limited morphological differences. Therefore, with live sample including trichome, akinete and heterocyst, the sequences of 16S rRNA gene of Anabaena isolates were cloned and analyzed, and three 16S rRNA gene sequences of 1188~1520 bp in length were obtained. It was shown from the homologous analysis results that the obtained 16S rRNA sequences were highly homologous to the relevant sequences of A. crassa in GenBank. The 16S rRNA sequences of 63 species were retrieved from GenBank, and the phylogenetic tree was constructed by using these sequences.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.11 no.4
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• pp.158-164
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• 2006

Yongdam Lake is the fifth largest artificial lake in Korea newly formed by the first impounding the Yongdam Multi-purpose Dam on December, 2002. Yongdam Lake, with her total water storage of 820 million M/T, is located at the roof-top region of the streams flowing into the just-constructed new Saemankeum Lake. Seasonal succession of phytoplakton in Yongdam Lake might affect cyanobacterial blooms in Saemankeum Lake by inoculating seasonal dominants. During 2002-2003 when the first impounding after the construction of Yongdam Multi-purpose Dam was still undergoing, summer cyanobacterial blooms by Anabaena, Microcystis, and Aphanizomenon were observed. Among these three, filamentous Anabaena is well known to have its species with $N_2-fixing$ ability and special cells such as heterocysts and akinetes as well as the vegetative cells. We established a clonal culture of Anabaena spiroides v. crasse (KNU-YD0310) from the live water samples collected at the bloom site of Yongdam Lake. The N- and P-nutrient requirement of the KNU-YD0310 was explored by the experimental cultivation of the laboratory strain. Ratio of heterocysts to vegetative cells increased as N-deficiency extended with its maximum at $N_2-fixing$ condition. The strain KNU-YD0310 exhibited considerable growth under N-limiting conditions while its growth was proportional to the initial phosphate-P concentration under P-deficient conditions. Under P-limiting conditions akinete density increased, which could be interpreted as an adaptation strategy to survive severe environment by transforming into resting stage. The above eco-physiological characteristics of Anabaena spiroides v. crassa might be useful as an ecological criterion in controlling cyanobacterial blooms at Shaemankeum Lake in near future.

• Journal of Ecology and Environment
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• v.36 no.4
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• pp.293-302
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• 2013

The present study summarizes the occurrence, distribution and autecology of 12 taxa of the class Cyanophyceae collected from several swamps, reservoir and highland wetlands in South Korea from 2009 to 2012. A new species, Anabaena koreana sp. nov. and 11 taxa of blue-green algae newly recorded are described and illustrated. Anabaena koreana is similar to A. oumiana, A. spiroides and A. crassa in that the trichomes form regular coils. However, A. koreana is distinguished from these three species by the morphological characteristics of the vegetative cell, heterocyst, and akinet shape and size. This study considers 12 blue-green algal species, including a new species, Anabaena koreana sp. nov. and 11 species that are recorded for the first time in the Korean freshwater algal flora. Among them, the genus Nostochopsis Wood ex Bornet et Flahault 1886 had not previously been recorded in Korea.

• Korean Journal of Ecology and Environment
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• v.47 no.4
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• pp.342-349
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• 2014

This study was conducted to identify the bloom-forming Anabaena strains with two phenotypes (straight-type and coil-type) isolated from North Han River (Sambong-ri Joam-myun) using 16S rDNA sequence. The odor material producing potential was also examined using the geosmin-synthesizing gene cluster. Despite of striking morphological difference of the two stains, resembling A. circinalis and A. crassa species, the phylogenetic analysis using 16S rDNA identified the both strains as a single species of A. circinalis with high genetic similarity (98%~100%). Also, two Anabaena strains showed to possess the geosmin-synthesizing gene cluster, indicating that they are capable of producing the odor substance. This study is the first report that provides the direct evidence of geosmin production in the gene level by A. circinalis in Korea, and provides important basic information to identify the source alga of geosmin increase and its management in North Han River.

• Korean Journal of Ecology and Environment
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• v.47 no.4
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• pp.350-357
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• 2014

Harmful Algal Bloom Alert System (HABAS) for drinking water supply is require to fast and accurate count as system monitoring of cyanobacterium occurrence and inducing a response action. We measured correlation between colony size and cell number including genus Anabaena, Aphanizomenon, Microcystis, Oscillatoria which are targeted at HABAS, deducted from standard formula, and suggested calculation method from colony size to the number of cell. We collected cyanobacteria samples at Han River (Paldang reservoir), Nakdong River (Dalseong weir, Changnyeonghaman weir) and Geum River (Gobok reservoir) from August to October, 2013. Also, we studied correlation between colony size and cell number, and calculated regression equation. As a result of correlation of harmful cyanobacteria by genus, Anabaena spp. and Aphanizomenon spp. having trichome showed high correlation coefficients more than 0.93 and Microcystis spp. having colony showed correlation coefficient of 0.76. As a result of correlation of harmful cyanobacteria by species, Anabaena crassa, Aphanizomenon flos-aquae, A. issatschenkoi, Oscillatoria curviceps, O. mougeotii having trichome showed high correlation coefficients from 0.89 to 0.96, and Microcystis aeruginosa, M. wessenbergii, M. viridis having colony showed correlation coefficients from 0.76 to 0.88. Compared with other genus Microcystis relatively showed low correlation because even species and colony size are the same, cell density and cell size are different from Microcystis strains. In this study, using calculated regression might be fast and simple method of cell counting. From now on, we need to secure additional samples, and make a decision to study about other species.

• Journal of Korean Society on Water Environment
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• v.35 no.1
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• pp.28-34
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• 2019

This study analyzed the occurrence pattern of Dolichospermum (= Anabaena) in the Bukhan river from March 2012 to December 2014 in order to identify the genotypes of Dolichospermum. Furthermore, 16S rRNA were analyzed to identify the genotypes of Dolichospermum that occurred in 2015 which were then compared to the reference sequence deposited at NCBI. During this period, the occurrence of Dolichospermum was highly correlated to water temperature. In the year 2012 and 2013, Dolichospermum appeared in Lake Cheongpyeong (CP), Sambong (SB), and Lake Paldang (P2) between July and August. However, in 2014, it appeared in SB and P2, but not in CP. This reduction in appearance was attributed to the decreased inflow to Lake Uiam as a result of low rainfall in 2014 as compared to 2012. In July 2015, the Dolichospermum 16S rRNA genotype was confirmed in five locations; Lake Cheongpyeong (CP), Seojong (SJ), Songchon Sewage Treatment Plant (SC), Joan (P4), and Lake Paldang (PD). Anabaena crassa of spiral clone, A. planctonica of linear clone, and A. circinalis of spiral clone exhibited high genetic similarity with the reference sequence. The 16r RNA genotype showed approximately 3 % sequence variation between the locations and were more similar to each other in locations that were closer.

• Korean Journal of Environmental Biology
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• v.17 no.4
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• pp.529-541
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• 1999

In order to elucidate characteristics of water quality, investigation of monthly dynamics of environmental factors and algal populations at major four stations of the mid and lower part in Taechong Reservoir was performed from June 1998 to June 1999. Water temperature, DO and pH were ranged 5.3~27.7$^{\circ}C$, 6.2~13.8 mgO$_2$/1 and 6.4~9.5, respectively. Those were varying as the season changes. Among inorganic nitrogen nutrients, NH$_4$was ranged from 5.5% to 7.2% of NO$_3$and NO$_3$was almost same through the seasons except summer in which it was low. SRP and SRSi were increased in summer when the blue-green algae became dominant. Those were decreased as the cell density of diatom increased when the water temperature dropped. Therefore SRSi was considered to be another important nutrient factor contributing to the increment of biomass of freshwater algae as well as SRP. Average chi-$\alpha$ concentration ranged from s to 12 $\mu$g/1 and in the lower part or the reservoir, the lowest was found. Moreover, there were remarkable increment in summer when TN/TP ratio were decreasing from relationships between TN/TP ratio and chi-$\alpha$ concentration. Annual mean ratio of TN/TP ratio was relatively high as the value was 110, which was relatively high, and it showed that P is the dominant factor in the algal growth. The dynamics of phytoplankton were simply dominated by a few species seasonally. In summer, blue -green algae such as Anabaena, Microcystis and Oscillatoria were dominant and algal bloom of blue -green began from early summer, sustained to late autumn. The average standing crops of A. spiroides v. crassa, M. aeruginosa and O. limosa were ranged 0.3~2.0$\times$10$^4$cells/ml, 6.4$\times$10$^2$~1.0$\times$10$^4$cells/ml and 4.6$\times$10$^3$~1.6$\times$10$^4$cells/ml, respectively. In winter, diatom Stephanodiscus was considered to be an important species whose average standing crops of Stephunodiscus was 4.9$\times$10$^2$cells/ml from November to April of the next year and the highest was 1.3$\times$10$^3$cells/ml in January.

• ALGAE
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• v.18 no.2
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• pp.145-156
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• 2003

Seasonal investigations were conducted to determine the major aquatic environmental factors and the variation of phytoplankton in Pyeongtaek Reservoir in March, June, September, and December 2000. Heavy rainfall mainly occurs from late June to mid-September, and water quality of reservoir was high in the influent zone of stream and riverine zone of reservoir. The biomass of phytoplankton was related to aquatic environmental factors. In particular, its value increased where nutrient concentration was high. Likewise, the increase of turbidity was found to have anthropogenic effects on the varying quantity of phytoplankton. The phytoplankton composition in quantitative survey identified into 43 genera and 71 species. Species numbers of Bacillariophyceae, Cyanophyceae, and Chlorophyceae accounted for 17%, 15%, and 49%, respectively, with the remainder constituting less than 3-7%. The distribution of such phyla also significantly varied according to seasons, accounting for 25%, 37%, 61%, and 14% in March, June, September, and December, respectively. Bacillariophyceae and Chlorophyceae were observed throughout the year, while Cyanophyceae proliferated in June and September. Euglenophyceae and Dinophyceae were prevalent in March and September, while Cryptophyceae occurred in March and December. The succession trend of phytoplankton showed the maximum cell density was followed by Bacillariophyceae (6.8$\times$$10^3$ cells ${\cdot}$ml)$\rightarrow$ Chlorophyceae (3.7$\times$$10^3$ cells ${\cdot}$ml)$\rightarrow$Cyanophyceae (1.3$\times$$10^4$ cells ${\cdot}$ml)$\rightarrow$Cryptophyceae (1.2$\times$$10^3$ cells ${\cdot}$ml). The cell density was the highest in the upstream. Dominant species were composed of Aulacoseira ambigua, Stephanodiscus hantzschii f. tenuis of Bacillariophyceae, Anabaena spiroides var. crassa, Microcystis aeruginosa, Oscillatoria amphibia of Cyanophyceae, Actinastrum hantzschii var. fluviatile, Pediastrum duplex var. reticulatum of Chlorophyceae, Euglena gracilis, Trachelomonas spp. of Euglenophyceae, and Chroomonas spp., Cryptomonas spp. of Cryptophyceae. As a results, seasonal variation of phytoplankton in Pyeongtaek Reservoir was evident in spite of inflow the high concentration of nutrients from watershed streams, because hydrological control and anthropogenic disturbance in reservoir were found to have major effects on the retention time of water.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.15 no.1
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• pp.1-25
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• 1982

Limnological study on the physico-chemical properties and biological characteristics of the Lake Ok-Jeong was made from May 1980 to August 1981. For the planktonic organisms in the lake, species composition, seasonal change and diurnal vertical distribution based on the monthly plankton samples were investigated in conjunction with the physico-chemical properties of the body of water in the lake. Analysis of temperature revealed that there were three distinctive periods in terms of vertical mixing of the water column. During the winter season (November-March) the vertical column was completely mixed, and no temperature gradient was observed. In February temperature of the whole column from the surface to the bottom was $3.5^{\circ}C$, which was the minimum value. With seasonal warming in spring, surface water forms thermoclines at the depth of 0-10 m from April to June. In summer (July-October) the surface mixing layer was deepened to form a strong thermocline at the depth of 15-25 m. At this time surface water reached up to $28.2^{\circ}C$ in August, accompanied by a significant increase in the temperature of bottom layer. Maximum bottom temperature was $r5^{\circ}C$ which occurred in September, thus showing that this lake keeps a significant turbulence Aehgh the hypolimnial layer. As autumn cooling proceeded summer stratification was destroyed from the end of October resulting in vertical mixing. In surface layer seasonal changes of pH were within the range from 6.8 in January to 9.0 in guutuost. Thighest value observed in August was mainly due to the photosynthetic activity of the phytoplankton. In the surface layer DO was always saturated throughout the year. Particularly in winter (January-April) the surface water was oversaturated (Max. 15.2 ppm in March). Vertical variation of DO was not remarkable, and bottom water was fairly well oxygenated. Transparency was closely related to the phytoplankton bloom. The highest value (4.6 m) was recorded in February when the primary production was low. During summer transparency decreased hand the lowest value (0.9 m) was recorded in August. It is mainly due to the dense blooming of gnabaena spiroides var. crassa in the surface layer. A. The amount of inorganic matters (Ca, Mg, Fe) reveals that Lake Ok-Jeong is classified as a soft-water lake. The amount of Cl, $NO_3-N$ and COD in 1981 was slightly higher than those in 1980. Heavy metals (Zn, Cu, Pb, Cd and Hg) were not detectable throughout the study period. During the study period 107 species of planktonic organisms representing 72 genera were identified. They include 12 species of Cyanophyta, 19 species of Bacillariophyta, 23 species of Chlorophyta, 14 species of Protozoa, 29 species of Rotifera, 4 species of Cladocera and 6 species of Copepoda. Bimodal blooming of phytoplankton was observed. A large blooming ($1,504\times10^3\;cells/l$ in October) was observed from July to October; a small blooming was present ($236\times10^3\;cells/l$ in February) from January to April. The dominant phytoplankton species include Melosira granulata, Anabaena spiroides, Asterionella gracillima and Microcystis aeruginota, which were classified into three seasonal groups : summer group, winter group and the whole year group. The sumner group includes Melosira granulate and Anabaena spiroides ; the winter group includes Asterionella gracillima and Synedra acus, S. ulna: the whole year group includes Microtystis aeruginosa and Ankistrodesmus falcatus. It is noted that M. granulate tends to aggregate in the bottom layer from January to August. The dominant zooplankters were Thermocpclops taihokuensis, Difflugia corona, Bosmina longirostris, Bosminopsis deitersi, Keratelle quadrata and Asplanchna priodonta. A single peak of zooplankton growth was observed and maximum zooplankton occurrence was present in July. Diurnal vertical migration was revealed by Microcystis aeruginosa, M. incerta, Anabaena spiroides, Melosira granulata, and Bosmina longirostris. Of these, M. granulata descends to the bottom and forms aggregation after sunset. B. longirostris shows fairly typical nocturnal migration. They ascends to the surface after sunset and disperse in the whole water column during night. Foully one species of fish representing 31 genera were collected. Of these 13 species including Pseudoperilnmpus uyekii and Coreoleuciscus splendidus were indigenous species of Korean inland waters. The indicator species of water quality determination include Microcystis aeruginosa, Melosira granulata, Asterionelta gracillima, Brachionus calyciflorus, Filinia longiseta, Conochiloides natans, Asplanchna priodonta, Difflugia corona, Eudorina elegans, Ceratium hirundinella, Bosmina longirostris, Bosminopsis deitersi, Heliodiaptomus kikuchii and Thermocyclops taihokuensis. These species have been known the indicator groups which are commonly found in the eutrophic lakes. Based on these planktonic indicators Lake Ok-Jeong can be classified into an eutrophic lake.