• Journal of Ecology and Environment
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• v.38 no.4
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• pp.629-636
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• 2015

The samples were collected at lowland swamps, reservoirs, mountainous wetlands, and sphagnum bogs from 2012 to 2014. The followings were newly recorded in Korea: two species, three varieties, and one form, including six taxa of the genus Cosmarium. The newly recorded Korean species were Cosmarium bioculatum var. hians, C. bireme, C. pseudobiremum, C. nitidulum var. pseudorectangulare, C. trilobulatum f. retusum, and C. trilobulatum var. depressum. The flora of the genus Cosmarium contains 303 taxa in total in Korea. The specimens were cultured and deposited on the algal culture collection of Kyonggi University (ACKU) and National Institute of Botanical Resources (NIBR).

• Journal of Korean Society on Water Environment
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• v.31 no.3
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• pp.328-333
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• 2015

In this study, Mg-Sericite was used as a flocculant to harvest freshwater microalgae, Chlorella. vulgaris. Mg-Sericite separated successfully >95% of the C. vulgaris at the following optimal parameters: Mg/Si mol ratio 1.25 to 1.50, mixing time of 20 min and settling time of 20 min. The harvesting efficiency was pH dependent. The highest harvesting efficiency ($99{\pm}0.3%$) was obtained at Mg/Si mol ratio 1.5 and pH 9 to 11. These results indicated that a biopolymer, Mg-Sericite, can be a promising flocculant due to its high efficiency, low dose requirements, short mixing and settling times. This harvesting method is helpful to lower the production cost of algae for biodiesel.

• Journal of Korean Society on Water Environment
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• v.33 no.1
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• pp.8-14
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• 2017

Microcystis aeruginosa (M. aeruginosa) is a cyanobacterium species that can form harmful algal blooms in freshwater bodies worldwide. The use of pine needle extract (PNE) to control nuisance algae by allelopathic inhibition will be environmentally friendly and promising. PNE removed successfully upto 98% of M. aeruginosa at the following optimal conditions: pH 7, $25^{\circ}C$ of temperature, 100 rpm of mixing rate, 5 min of mixing time. These results was indicated that the amount of 1 g/L PNE was removed 1g dryweight/L of M. aeruginosa. The kinetic data showed substrate inhibition kinetics and maximum growth rate was obtained when the M. aeruginosa was grown in medium containing 0.5 g/L of initial concentration of PNE. Different substrate inhibition models were fitted to the kinetic data and found the Luong model was best. The model predicted kinetic parameters were in agreement with the experimental findings. The natural extract, PNE, can be a promising inhibition due to its high efficiency and low dose requirements.

• Korean Journal of Environmental Biology
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• v.33 no.1
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• pp.1-6
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• 2015

Increased harmful algal blooms by cyanobacteria are threatening public health and limiting human activities related with freshwater ecosystems. Phosphorus (P) has long been suggested as a critical nutrient for cyanobacterial bloom through field research in Canada during the 1970s, proposing a P-based freshwater management guideline. However, recently, nitrogen (N) has also been highlighted as an impacting nutrient on cyanobacterial harmful algal blooms (CyanoHABs). Due to the intensive and frequent observation of Microcystis, this kind of paradigm shift from P limitation to season-dependent N or P limitation has an important implication for a dual nutrient management strategy in eutrophic freshwaters. Through recent international researches, general strategies to control CyanoHABs in lakes and reservoirs are as follows: a dual nutrient (N & P) reduction, wastewater collection and treatment, pre-treatment of influent water in buffer zones, dredging of sediment, reduction of residence time, algal collection, and precipitation and flocculation of cyanobacteria. In addition, sustainable and integrative freshwater algae management should be carried out, based on the ecological aspect, because cyanobacteria are not the target organism to be eradicated, but an essential microbial member in the freshwater ecosystem.

• Korean Journal of Ecology and Environment
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• v.42 no.1
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• pp.115-123
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• 2009

Grazing effects of a freshwater bivalve, Unio douglasiae, on both the phytoplankton communities of cold- and warm eutrophic lakes were examined in aquarium with sediment. The animal U. douglasiae used in the study was collected from the Gunsan (Jeonbuk), acclimatized in laboratory aquaria with washed sand from the mussel collection stream, and starved for $2{\sim}3$ days by the experiment. Grazing experiments were performed with the surface waters collected from Lake Ilgam (Seoul) in the cold period (March 31, 2008), and the warm period (June 19, 2008), respectively. Results clearly showed that the concentration of chlorophyll-a (chl-a) and algal abundance were decreased with the increase of mussel-treated density and treated-time. At the same animal density, U. douglasiae effectively decreased the chl-a of cold-lake water (CW), compared to warm-lake water (WW). Increasing the mussel density, the filtering rate (or algal abundance) of the mussel on the CW gradually decreased, while those of WW did not increase or decrease. Major phytoplankton species Synedra ulna and Stephanodiscus hantzschii, and Scenedesmus ecornis in CW, and those of Tetraedron regulare and Pediastrum simplex in WW, were quickly decreased after the mussel stocking. Interestingly, cyanobacterium Microcystis aeruginosa in WW, not dominant species, were less removed. These results suggest that a freshwater bivalve U. douglasiae have a strategic potential to control dense hibernal diatom or green algae, rather than the cyanobacterial bloom in eutrophic water.

• The Korean Journal of Pesticide Science
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• v.12 no.1
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• pp.50-56
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• 2008

The purpose of the study was to determine the effects of isoprothiolane, diazinon, butachlor, dimethametryn and molinate in Selenastrum capriconurtum, Scenedesmus subspicatus, Chlorella vufgaris and Nitzschia palea during an exposure period of 72 hours. The study was carried out in according with the OECD Guidelines for Testing of Chemicals No 201 Alga, Growth Inhibition Test. The toxicological responses of isoprothiolane to S. capriconutum, S. subspicatus, C. vulgaris and N. palea expressed as in individual $ErC_{50}$ (Median Effective Concentration by growth rate) value, were 5.87, 9.91, $18.55 and 38.79\;mg\;L^{-1}$, respectively. Diazinone to S. capriconutum, S. subspicatus, C. vulgaris and palea expressed as in individual $ErC_{50}$ value, were 10.31, 11.44, >32 and $14.32\;mg\;L^{-1}$, respectively. Butachlor to S. capriconutum, S. subspicatus, C. vulgaris and N. plaea expressed as in individual $ErC_{50}$ value, were 0.002, 0.019, 8.67 and $4.94\;mg\;L^{-1}$, respectively. Dimethamelryn to S. subspicatus, C. vulgaris and N. palea expressed as in individual $ErC_{50}$ value, were 0.0071, 0.011, 0.0065 and $0.009\;mg\;L^{-1}$, respectively. Molinate to S. capriconutum, S. subspicatus, C. vulgaris and N. palea expressed as in individual $ErC_{50}$ value, were 0.44, 1.26, 48.84 and $28.52\;mg\;L^{-1}$, respectively. The sensitivities of five pesticides were different depending on freshwater alga in the order of S. capriconutum > S. subspicatus > C. vulgaris, N. palea. Highly significant correlation (r=0.9677) based on $ErC_{50}$ were found between S. capriconutum and S. subspicatus.

• The Korean Journal of Pesticide Science
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• v.8 no.2
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• pp.117-128
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• 2004

The influence of different feeding rates of three green algae on growth and reproduction in four Korean cladocera, Daphnia sp., Daphnia obtusa, Moina macrocopa, and Simocephalus vetulus was investigated. The growth and reproduction rates of Daphnia sp. fed Chlorella vulgaris cells were significantly increased than those of daphnid fed Senedesmus subspicatus and Selenastrum carpricornutum. The total offsprings of Daphnia sp. fed $25\times10^4$ and $50\times10^4$ cells Chlorella vulgaris for 21days were $124{\pm}2.8$ and $168{\pm}22.1$, respectively. The Daphnia obtusa fed $25\times10^4$ and $50\times10^4$ cells Selenastrum carpricornutum was shown good reproduction rates, $72.2{\pm}7.9$ and $79.6{\pm}22.9$, respectively. The Moina macrocopa fed $25\times10^4$ and $50\times10^4$ cells Senedesmus subspicatus as well as Simocephalus vetulus and $25\times10^4$ and $50\times10^4$ cells Chlorella vulgaris were shown good reproduction rates. All of algae tested were sufficient as a good diet for Korean Cladocerans in this study. However, the preferred alga was Chlorella vulgaris and the optimal feeding concentrations were $2.5\times10^5\sim5\times10^5$ cells/mL, because the alga was shown most stable and generally high production rates in all cladocerans tested.

• Korean Journal of Environmental Biology
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• v.29 no.3
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• pp.212-224
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• 2011

The Yeongsan River estuary, located in the south west coast, was a typical estuary before a dike was constructed in December 1981. After the construction, the water quality and plankton communities are expected to change. We investigated the change of phytoplankton community and environmental properties in the Yeongsan River estuary by comparing the data collected recently with the results reported before and/or shortly after the construction. Concentrations of $NH_4$-N were significantly increased in the freshwater zone. Concentrations of DO at the surface, $NO_2+NO_3$ and $NH_4$-N were increased while the concentrations of $PO_4$ at the surface were decreased in the seawater zone. The number of green algae species was decreased in the freshwater zone. The number of diatom species was decreased while the numbers of green algae and dinoflagellates were increased in the seawater zone. This study can provide information for better management of the Yeongsan River estuary since no comparison study has been documented between the phytoplankton community before and after the construction of the dike in the estuary.

• Journal of Microbiology and Biotechnology
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• v.27 no.6
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• pp.1112-1119
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• 2017

The aim of this study was to develop a potential process for bioethanol production from Hydrodictyon reticulatum (HR), a filamentous freshwater alga, using Saccharomyces cerevisiae (KCTC7017). From the sugar solutions prepared by the four different hydrolysis methods, bioethanol production ranged from 11.0 g/100 g dried material (acid hydrolysis) to 22.3 g/100 g dried material (enzymatic hydrolysis, EH). Bioethanol was fermented from a highly concentrated sugar solution obtained by a decompression-mediated (vacuum) enrichment method (VE). As the results, ethanol was more efficiently produced from HR when sugar solutions were concentrated by VE following EH (EH/VE). Using multiple feeding of the sugar solution prepared by EH/VE from HR, ethanol reached up to a concentration of 54.3 g/l, corresponding to 24.9 g/100 g dried material, which attained the economic level of product concentration (approximately 5%). The results indicate that by using HR, it is feasible to establish a bioethanol production process, which is effective for using microalgae as the raw material for ethanol production.

• Journal of Environmental Science International
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• v.10 no.3
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• pp.225-231
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• 2001

The fish species collected in the Keumho River basin are 42 species 31 genera belonging to 15 Families. This report was investigated for the evaluation of water quality in the Keumho River system which is a tributary of Nakdong River in Korea on september in 1999. The fishes collected were 42 species, 31 genera belonging to 15 Families. The dominant species were 5 species; Zacco platypus, Zacco temmincki, Squalidus chankaensis tsuchigae, Moroco oxycephalus, Squalidus gracilis majimae, and 8 species; Hemibarbus longirostris, Pseudogobio esocinus, Culter brevicauda, Cobitis rotundicaudata, Pseudobagrus fulvidraco, Pungitius sinensis kaibarae, Monopterus albus, Channa argus were rare species. The relationship among the GPI, EC and BOD by the organic pollutants were over 0.9. The group pollution index(GPI) was lowest at St. 1(0.85) and highest at St. 1(0.85) and highest at St. 5(2.33). The water quality of the Keumho river divided into 3 parts; the water of upper reaches in river(St. 1) was 1st class(oligotrophic condition), middle parts(St. 2, 3, 4) were 3rd class($\alpha$-mesosaprobic condition) and lower part(St. 5) was 4th class(Polysaprobic condition) as the source of tap water, respectively. And the tributary which are the Sinryeong Stream(St. 6), the Sincheon(St. 7) and the Donghwa Stream(St. 9) in Keumho river were 2nd class as the source of tap water. The results in this study was represented same patterns as the result by the use of indicator species like as algae and invertebrates for the discrimination of water quality. So, some freshwater fish species can be use applicant for the discrimination of water quality.