• Korean Journal of Ecology and Environment
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• v.34 no.4 s.96
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• pp.292-297
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• 2001

As a part of study on the microalgal dynamics in a small pond in Hongsung, Chungnam, we found a massive bloom of chlorococcalean green alga, Dictyosphaerium pulchellum during the year-round survey from January 2000 to January 2001. D. pulchellum occurred at a low frequency throughout the year. However, D. pulchellum began to increase from 12 March, showed a peak of blooming with 59,200 colonies $mL^{-1}$ in 2 April, and abruptly decreased in 16 April. Colonies were 8-celled and 16-celled at early stage of blooming, 32-celled or 64-celled at the midst of blooming, and most of colonies consisted of 64 cells at the end of blooming. Colonies of D. pulchellum were healthy at the early stage of blooming, but most of colonies were infected with some parasites at the end of blooming. The infected cells bleached out with decomposing chloroplast and pyrenoids. The infection with parasites, together with irradiance and nutrient limitations, appears to stop D. pulchllum bloom. This is the first report on the occurrence of blooming of a green algal genus Dictyosphaerium and its infection with parasite in Korea.

• Environmental Engineering Research
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• v.19 no.3
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• pp.223-228
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• 2014

We investigated seasonal algae variability and its influence on water quality in an agricultural reservoir. We observed that maximal total phosphorus (TP) loads were 1,715 kg from farmland in September, which changed the ecosystem in the reservoir. At this time, Dictyosphaerium pulchellum as green algae dominated. Aulacoseira ambigua as diatom became the most dominant from November 2010 to May 2011. The diatom was sensitive to water temperature. Microcystis spp. and Oscillatoria spp. as cyanobacteria were dominant during summer and fall, and sank down to the sediment during winter and spring. Increasing water temperature during summer causes anaerobic conditions in the sediment, leading to regrowth of cyanobacteria. With regard to the ratio of total nitrogen (TN) to TP, green algae and cyanobacteria were dominant at TN:TP ratios less than 20-30. Diatoms were dominant at TN:TP ratios greater than 30-40. Statistical analysis indicated that diatom growth was dependent on water temperature and TN concentration. TP concentration and water temperature were the key factors for the growth of cyanobacteria and green algae. From these results of this study, the management of land-use was an important parameter for improving water quality in the agricultural reservoir.

• Korean Journal of Environmental Biology
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• v.18 no.1
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• pp.95-104
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• 2000

In order to elucidate chatracteristics of water quality and seasonal dynamics of phytoplankton community in Kyungpo lake, the weekly variation of algal population and 11 environmental factors were investigated from March 1998 to February 1999. A total 121 species of phytoplankton belonged to 57 genera, 4 genera 7 species of the Euglenophyceae, 1 genera 2 species of the Chrysophyceae, 2 genera 3 species of the Cryptophyceae, 1 genera 1 species of the Dinophyceae, 6 genera 9 species of the Cyanophyceae, 28 genera 78 species of the Bacillario-phyceae and 15 genera 21 species of the Chlorophyceae, was identified. Cryptomonas sp., Chamydomonas sp., Nitzschia frustulum, Oscillatoria sp., Lyngbya sp, and Dictyosphaerium pulchellum occurred successively as dominant phytoplankton species from March 1998 to February 1999. Density of phytoplankton cell number showed the peak in early April when Chlamydomoas sp. was dominated. The diversity index of phytoplankton community showed low values in the dominating period of Cryptomonas sp. and Chlamydomonas sp. The concentration of chlorophyll a fluctuated between 1.09 and 107.7$\mu\textrm{g}$ㆍ1$^{-1}$. Water temperature, salinity, DO, conduc tivity and SS were ranged 0.5-27.8$^{\circ}C$, 2.8-25.2 ppt, 4.62-19.21 mgO$_2$ㆍ1$^{-1}$, 5.33-34.76 mS/cm and 0.017-0.184 mgㆍ1$^{-1}$, respectively. Annual means of Secchi disc transparency was 36cm and thai of pH value was 8.5. The concentrations of PO$_4$-P was ranged 0.0012-0.077 mgㆍ1$^{-1}$ , and showed high value from August to October. The concentrations of NO$_2$-N, NO$_3$-N and NH$_4$-N was ranged 0.0011-0.1 mgㆍ1$^{-1}$, 0.074-3.33mgㆍ1$^{-1}$ and 0.0024-0.259 mgㆍ1$^{-1}$, respectively. Among environmental factors, water temperature was negatively correlated with DO, salinity and conductivity, DO was positively correlated with salinity and conductivity. Chlorophyll a, one of the indicies of eutropication in lake, was negatively correlated with NH$_4$-N. The cell density of Cryptomonas sp., which was the most dominant species in this lake, was negatively correlated with transparency. [Kyoungpo lake, Phytoplankton, Cryptomonas sp. , Chlamydomonas sp., Seasonal variation].

• Korean Journal of Environmental Agriculture
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• v.26 no.1
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• pp.7-16
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• 2007

The objective of this research was to review the correlation between microalgae and agricultural water quality. Although microalgae has been considered as an essential factor for control1ing of water ecosystem, little attention has been paid for evaluating of microalgae as an important factor for water quality management. But it can be use to make us know the water pollution state at saprobic system, LTSI (Lake Tropic State Index), DAIpo (Diatom Assemblage Index to Organic Pollution), and AGP (Algal growth potential). In saprobic system, it is used microalgae such as Actinastrum hantzschii var. fluviatile, Asterionella gracillima, Coelastrum microporum, Synedra acus, Dictyosphaerium pulchellum, Micractinium pusillum, Cyclotella meneghiniana, Microcystis aeruginosa, Scenedesmus quadricauda, and Nitzschia palea for assessment water quality. In addition, they have ecologically significant characteristics such as dominant species, cosmopolitan species, redtide causative species etc. Also, microalgae such as Botryococcus braunii, B. sp., Chlorella vulgaris, C. sp., Phormidium sp., Scenedesmus quadricauda, Selenastrum capricornutum, Spirulina maxima, and S. platensis have an effect on improvement of water quality.

• ALGAE
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• v.18 no.4
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• pp.273-280
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• 2003

The physico-chemical characteristics and seasonal variations of phytoplankton community were investigated in the Paksil and Jungyang marshes. Water and phytoplankton samples for analyses were collected monthly from April 2002 to March 2003. A total of 421 taxa of phytoplankton belonging to eight classes identified. The number of taxa was highest in Bacillariophyceae, followed by Chlorophyceae, Euglenophyceae, Cyanophyceae, Chrysophyceae, Dinophyceae, Xanthophyceae and Cryptophyceae. The standing crops ranged from 1.25 ${\times}$ $10^6$ to 5.85 ${\times}$ $10^6$ cells ${\cdot}l^{-1}$ in Paksil marsh and 0.25 to 9.63 ${\times}$ $10^6$ cells ${\cdot}l^{-1}$ in Jungyang marsh. The highest algal density at Paksil marsh was recorded in October during the high development of Chlorococcales while the lowest value occured in July. In the Jungyang marsh, the maximum algal density was recorded in October when Cryptomonas sp. and Mallomonas sp. accounted for 64% to total cell numbers and the lowest cell density was observed in January due to the decrease of Chlorophyceae. The dominant species were represented by Euglena proxima, Trachelomonas oblonga, Trachelomonas volvocina of Euglenophyceae, Dictyosphaerium pulchellum, Monoraphidium griffithii, Oocystis parva of Chlorophyceae, Dinobryon sertularia, Kephyrion rubri-claustri of Chrysophyceae, Achnanthes minutissima of Bacillariophyceae and Cryptomonas sp. of Cryptophyceae in the Paksil and Jungyang marshes. Phytoplankton diversity(H’) and dominance index varied rather irregularly throughout the sampling period but they were significantly correlated. The highest diversity(H’Paksil = 3.68, H’Jungyang = 3.63) coincided with the lowest values of dominance(DPaksil = 0.05, DJungyang = 0.05)

• Journal of Wetlands Research
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• v.20 no.4
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• pp.363-369
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• 2018

One of the recent environmental problems is climate change due to the increase of atmospheric $CO_2$, which causes ecological changes and various environmental problems. Therefore, various studies are being carried out to reduce $CO_2$ in the world in order to solve various environmental problems caused by increase of $CO_2$. The $CO_2$ reduction using microalgae is an environmentally friendly method by using photosynthesis reaction of microalgae. However, most studies using single species. There is no study on the $CO_2$ fixing efficiency of microalgae in natural rivers. Therefore, this study was to identify the microalgae in the Sum river and to analyze the growth characteristics of microalgae in the river to obtain optimal culture conditions. And the changes of biomass and chlorophyll-a of microalgae were analyzed according to $CO_2$ concentration and injection rate. The purpose of this study was to investigate the fixing efficiency of carbon dioxide in microalgae in natural rivers. Six kinds of dominant species were observed as a result of the identification of microalgae in Sum river(Ankistrodesmus falcatus, Scenedesmus intermedius, Selenodictyum sp., Xanthidium apiculatum var. laeve, Cosmarium pseudoquinarium, Dictyosphaerium pulchellum). All of these species were green algae. Biomass and chlorophyll-a increased with the increase of $CO_2$ concentration and biomass and chlorophyll-a increased faster flow rate at the same $CO_2$ concentration. Also, the quantity of $CO_2$ fixation on the microalgae tended to be higher when the flow rate of injected gas was faster. This study can be referred as being significant in the micro-algae in river. In addition, the optimal conditions for $CO_2$ fixation of microalgae in rivers and the quantification of the quantity of $CO_2$ fixation from microalgae in rivers can be used as basic data for future policy of $CO_2$ reduction.