• Analytical Science and Technology
• /
• v.24 no.3
• /
• pp.225-230
• /
• 2011

Anatoxin-a is a cyanobacterial neurotoxin with a high toxicity produced by Anabaena, Aphanizomenon and Oscillatoria. Water bloom, formed by Anabaena has been occurring frequently in Lake Yeongchun. It is need to develop a sensitive method for determination of anatoxin-a to control potential hazard in raw water resources. In this study, we developed a highly sensitive analytical method of anatoxin-a using solid phase extraction (SPE) and high performance liquid chromatography (HPLC) with fluorescence detection. Anatoxin-a was converted into a highly fluorescent derivative using 4-fuoro-7-nitro-2,1,3-benzoxadiazole (NBF-F). The method was evaluated in terms of linearity of calibration curve, recovery and repeatability, and the adequate values were obtained. The method detection limit was $0.034\;{\mu}g/g$ and $0.022\;{\mu}g/L$ for algal and water samples, respectively. The concentrations of anatoxin-a were measured in algal and water samples from Lake Andong, Yeongchun and Daechung and ranged from $0.135\;{\mu}g/g$ to $10.979\;{\mu}g/g$ in algal samples and not detected in water samples.

• Korean Journal of Microbiology
• /
• v.34 no.4
• /
• pp.188-193
• /
• 1998

The authors examined the variations of environmental factors, the distributions of cyanobacteria, heterotrophic bacteria, and microorganisms that inhibit the growth of Anabaena cylindrica according to development and extinction of cyanobacterial bloom at a site in Daechung Dam reservoir. And certified the relationship between each other. Water temperature variated in a typical pattern. pH and concentrations of dissolved oxygen and chlorophylla was high in bloom period, and lowered with the decline of bloom. Phosphorus played as a growth-limiting factor at this study site. Total nitrogen concentration increased during blooming period, which indicated that nitrogen has been fixed by aquatic organisms such as cyanobacteria. Cyanobacteria distributed from June 17, and such cyanobacterial species as Anabaena spp., Aphanizomenon spp., Microcystis spp., Oscillatoria spp. and Phormidium spp. was detected during study period. Anabaena spp. distributed relatively highly distributed from July 23 to September 22, and disappeared completely at September 29. Heterotrophic bacterial and cyanobacterial populations varied inverse-proportionally. There was a relevancy between the variations of Anabaena spp., heterotrophic bacteria, and microorganisms that inhibit the growth of Anabaena cylindrica. Microorganisms that inhibit the growth of Anabaena cylindrica distributed from early growth phase of Anabaena spp. population to immediately after the extinction of Anabaena spp. With the population of Anabaena cylindrica growth-inhibiting microorganisms decreasing, increases of heterotrophic bacterial population followed it. Thease results indicate that microorganisms have a part in the extinction of cyanobacterial bloom, especially at its destroying period.

• Journal of Korean Society on Water Environment
• /
• v.27 no.4
• /
• pp.491-498
• /
• 2011

We investigated the ranges of total cellular microcystins content of cyanobacterial blooms collected in Korean lakes and rivers from 2005 to 2009. The amount and composition of microcystins of Korean cyanobacteria varied depending on the sampling water bodies and dominant cyanobacterial genera. Toxic cyanobacterial cell numbers equivalent to $1{\mu}g$ MCYSTs/L using total cellular microcystin content of Korean cyanobacteria were in the range of 2,348 to 66,980,638 cells/mL. Only four samples among forty nine samples showed less cell numbers than current criterion of Harmful Algae Alert System, 5,000 cells/mL indicating current criterion do not reflect properly the microcystins content of Korean cyanobacteria. Anabaena and Aphanizomenon spp. showed three to six times higher cell numbers equivalent to $1{\mu}g$ MCYSTs/L than Microcystis spp. To propose criteria of Harmful Algae Alert System for Korean toxic cyanobacteria, we calculated about 50% selective geometrical means of cyanobacterial cell numbers equivalent to $1{\mu}g$ MCYSTs/L in order of toxic content. The proposed criteria for Microcystis, Oscillatoria, Anabaena, and Aphanizomenon spp., are 10,000, 20,000, 40,000, and 80,000 cells/mL, respectively.

• Journal of Korean Society on Water Environment
• /
• v.35 no.4
• /
• pp.352-361
• /
• 2019

The purpose of this study is to analyze the characteristics and correlations of the Yeongcheon Lake in order to reduce the occurrence of harmful cyanobacteria. In this study, we investigated the water quality and phytoplankton of the lake from May to November in 2017. Correlation and data mining analyses were performed to analyze the relationship between the two factors. The water temperature was lowest at the point where the Yeongcheon Lake inflow occurs at Imha Lake. It was highest at the point where the outflow occurs to Angye Lake. The pH was also highest at the outflow point, but in the case of DO, it was highest at the midpoint between the inflow and outflow. The main cyanobacteria that emerged during the study period were Oscillatorialimosa, Microcysti saeruginosa and Aphanizomenon flos-aquae. As a result of correlation analysis, the water temperature, inflow, COD loading, TOC loading at the inflow point of the Yeongcheon Lake were the items that were related to the harmful cyanobacteria. The data mining analysis indicated that the TP loading and harmful cyanobacteria in the inflow point of the Yeongcheon Lake were influential on the detrimental cyanobacteria in the Yeongcheon Lake outflow point. When the TP loading was less than 39.0 kg/day at the inflow site, it was expected that the amount of harmful cyanobacteria could be maintained below 10,000 cells/mL.

• Korean Journal of Environmental Biology
• /
• v.36 no.3
• /
• pp.424-437
• /
• 2018

The incidence of freshwater algal bloom has been increasing globally in recent years and poses a major threat to environmental health. Cyanobacteria are the major component of the bloom forming community that must be monitored frequently. Their morphological identities, however, have remained elusive, due to their small size in cells and morphological resemblances among species. We have analyzed molecular diversity and seasonal changes of cyanobacteria in Paldang Reservoir, Korea, using morphological and 16S rRNA pyrosequencing methods. Samples were collected at monthly intervals from the reservoir March-December 2012. In total, 40 phylotypes of cyanobacteria were identified after comparing 49,131 pyrosequence reads. Cyanobacterial genera such as Anabaena, Aphanizomenon, Microcystis and Synechocystis were predominantly present in samples. However, the majority of cyanobacterial sequences (65.9%) identified in this study were of uncultured origins, not detected morphologically. Relative abundance of cyanobacterial sequences was observed as high in August, with no occurrence in March and December. These results suggested that pyrosequencing approach may reveal cyanobacterial diversity undetected morphologically, and may be used as reference for studying and monitoring cyanobacterial communities in aquatic environments.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.10 no.3
• /
• pp.154-163
• /
• 2005

Irregular discharges of freshwater through the water gates of the Keum River Estuarine Weir, Korea, whose construction had been completed in 1998 with its water gates being operated as late as August 1994, drastically modified the estuarine environment. Sharp decrease of salinity along with the altered concentrations of inorganic nutrients are accompanied with the irregular discharges of freshwater into the estuary under the influence of regular semi-diurnal tidal effect. Field sampling was carried out on the time of high tide at 2 fixed stations(St.1 near the Estuarine Weir and St.2 off Kunsan Ferry Station) every other day for 4 months from mid-February 2004 to investigate into the semi-weekly variation of spring phytoplankton community in relation to the freshwater discharges from Keum River Estuarine Weir. CV(coefficient of variation) of salinity measurements was roughly 2 times greater in St.1 than that in St.2, reflecting extreme salinity variation in St.1 Among inorganic nutrients, concentrations of N-nutrients($NO_3^-,\;NO_2^-$ and $NH_4^+$) were clearly higher in St.1, to imply the more drastic changes of the nutrient concentrations in St.1. than St.2 following the freshwater discharges. As a component of phytoplankton community, diatoms were among the top dominants in terms of species richness as well as biomass. Solitary centric diatom, Cyclotella meneghiniana, and chain-forming centric diatom, Skeletonema costatum, dominated over the phytoplankton community in order for S-6 weeks each (Succession Interval I and II), and the latter succeeded to the former from the time of <$10^{\circ}C$ of water temperature. Cyanobacterial species, Aphanizomenon Posaquae and Phormidium sp., which might be transported into the estuary along with the discharged freshwater, occupied high portion of total biomass during Succession Interval III(mid-April to late-May). During this period, freshwater species exclusively dominated over the phytoplankton community except the low concentrations of the co-occurring 2 estuarine diatoms, Cyclotella meneghiniana and Skeletonema costatum. During the 4th Succession Interval when the water temperature was over $18^{\circ}C$, the diatom, Guinardia delicatula, was predominant for a week with the highest dominance of $75\%$ in discrete samples. To summarize, during all the Succession Intervals other than Succession Interval III characterized by the extreme variation of salinity under cooler water temperature than $18^{\circ}C$, the diatoms were the most important dominants for species succession in spring. If the scale and frequency of the freshwater discharge could have been adjusted properly even during the Succession Interval III, the dominant species would quite possibly be replaced by other estuarine diatom species rather than the two freshwater cyanobacteria, Aphanizomenon flosaquae and Phormidium sp.. The scheme of field sampling every other day for the present study was concluded to be the minimal requirement in order to adequately explore the phytoplankton succession in such estuarine environment as in Keum River Estuary: which is stressed by the unpredictable and unavoidable discharges of freshwater under the regular semi-diurnal tide.

• Korean Journal of Environmental Biology
• /
• v.31 no.2
• /
• pp.105-112
• /
• 2013

Environmental parameters and phytoplankton community structure were investigated at four sites of Yeongsan River between April 2010 and December 2011. The standing crops of the phytoplankton ranged from $275cells{\cdot}mL^{-1}$ to $58,600cells{\cdot}mL^{-1}$ with an average of $5,850cells{\cdot}mL^{-1}$. The dominant species were Cyclotella sp., Stephanodiscus sp., Aulacoseira granulata, Scenedesmus quadricauda, Pediastrum biwae, Coelastrum sp., Aphnizomenon sp., and Oscillatoria sp.. The most dominant species was Stephanodiscus sp.. The concentration of chlorophyll-a ranged from $2.3mg{\cdot}m^{-3}$ to $164.2mg{\cdot}m^{-3}$. The phytoplankton community structure of the survey area was influenced by temperature and rainfall.

• Journal of Korean Society on Water Environment
• /
• v.31 no.3
• /
• pp.286-294
• /
• 2015

Temporal and spatial characteristics of cyanobacterial communities at the monitoring stations for Harmful Algal Bloom Alert System (HABAS) in Nakdong River and Lake Dukdong were investigated for two years (2013 to 2014). A total of 30 cyanobacterial species from 14 genera were found at the survey stations. Microcystis sp. showed maximum cell density in the total cyanobacterial community in August, 2014 at ND-2 and in September, 2013 at ND-3 station. Lynbya limnetica and Geitlerinema sp., non-target species for alert criteria showed maximum cell density at ND-1 (August, 2013) and Dam station of Lake Dukdong (September, 2014), respectively. Total cyanobacterial cell density and the relative abundance of four target genera (Microcystis, Anabaena, Aphanizomenon and Oscillatoria spp.) for alert criteria was relatively lower in the mesotrophic Lake Dukdong than at the eutrophic riverine stations of Nakdong River, indicating cyanobacterial density and the RA of target genera is affected by the trophic state of the monitoring stations. Simulating the alert system using phycocyanin concentration as an alert criterion resulted in the longer period of alert issued compared to the period of alert issued using the current criterion of harmful cyanobacterial cell density due to the influence of phycocyanin concentration from non-target cyanobacterial species.

• Journal of Korean Society on Water Environment
• /
• v.30 no.4
• /
• pp.377-385
• /
• 2014

To study the fluctuations and relationship in climate change, environmental factors and cyanobacteria communities, we investigated Chudong station of the Daechung reservoir. The average annual temperature showed the maximum value ($13.9^{\circ}C$) from 1994, showed a gradually increasing pattern from 1969 to 2010 in the Daechung reservoir. The number of days with temperatures over $20^{\circ}C$, minimum temperature of the year and average temperature of the winter season patterns also showed a significant increase. The long-time changed in the annual precipitation were not showed a significant variation. The water temperature record comparatively high value in summer, declined in winter. At all period, the phytoplankton were highest biomass in July 2000, and then, showed comparative higher biomass in the summer months. Cyanobacteria taxa were also showed more than 50%. Emergence of cyanobacteria also appeared in November 2007, were prolonged emergence. The dominant genera of taxa were the dominant sphere (Microcystis spp.) until early 2000. After that, the dominant species were the dominant linear (Aphanizomenon spp., Anabaena spp.). Cyanobacteria were the most correlated with water temperature (r = 0.341, p<0.01) and phosphate concentration (r = 0.355, p<0.01).

• Korean Journal of Environmental Agriculture
• /
• v.34 no.1
• /
• pp.14-20
• /
• 2015

BACKGROUND: Contamination of source water by odorous compounds are one of the problems related to the water quality management, especially in Korea where surface water is used as drinking water. Geosmin (1, 10-trans-dimethyl-trans-9-decalol) and 2-MIB (2-methyl isoborneol : 1,2,7,7-tetramethyl-exo-bicycloheptan-2-ol) are commonly recognized earthy-musty odor compounds produced by algae causing serious problems to the drinking water purification facilities. METHODS AND RESULTS: In this study, spatial and temporal distribution of the odor compounds, geosmin and 2-MIB were investigated along with the development of phytoplankton in the Daechung reservoir from July 2012 to October 2013. CONCLUSION: Concentrations and frequencys of detection of both compounds increased from April to October which were related to cyanobacterial bloom periods. However, concentrations of odor compounds were not related to the number of cyanobacteria. Concentrations of both cyanobacteria and geosmin showed similar trends with depth. Pearson correlation analyses showed that geosmin concentration exhibited significant correlation with the count of Anabaena macrospora and Aphanizomenon flos-aquae. On the other hand, 2-MIB concentration showed a significant correlation with the count of Anabaena smithii.