• 한국수산과학회지
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• 제23권6호
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• pp.468-474
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• 1990

휴안포자를 형성하는 과편모조류중 우리나라 남해동부와 동해남부의 연안수역 특히 진해만에서 1982년 이래 3월부터 9월에 걸쳐 적조를 일으킨 종은 8종이었으며 이들은 6종의 과편모조류와 2종의 녹색편모조류로 구성되었다. 계절별로는 이른 봄철에 Scrippsiella trochoidea와 Heterocapsa triquetra종이, 늦봄에 Heterosigma akashiwo가 그리고 여름철에는 Gyrodinium instriatum과 Pheopolykrikos hartmannii가 적조를 일으켰다. 한편 Cochlodinium sp.와 Alexandrium affine는 늦여름부터 가을철에 적조를 일으켰다. 이중 Heterosigma akashiwo는 매년 같은 곳에서 같은 시기에 발생하는 경향을 뚜렷히 나타냈으며 Cochlodinium sp.에서도 이와 같은 특성을 발견할 수 있었다. 한편 적조발생시의 밀도는 $10^3\~10^5\;cells/ml$ 수준이었으며, 밀도변화는 환경특성 보다는 오히려 세포의 크기에 따라 변화하고 있었다.

• 한국환경과학회지
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• 제25권7호
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• pp.937-950
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• 2016

Algal blooming in 4 major rivers introduces substantial impacts to water front activity. Concentrations of algae are increasing at major points along the Geum River. Ecosystem food webs can be affected by algal blooming because blue-green algae release toxic materials. Even though there have been many studies on blue-green algae, its causality to environmental factors has not been completely determined yet. This study analyzed the exclusive correlation between various hydrometeorological, water quality, and hydrologic variables and the cell number of cyanobacteria to understand causality of blue-green algae in the Geum River. A prewhitening process was introduced to remove the autocorrelation structure and periodicity, which is useful to evaluate the effective relationship between two time series.

• 환경생물
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• 제37권3호
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• pp.268-277
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• 2019

Severe damages will result in human society, when several different critical natural phenomena coincide. One example relates to the resting cysts of Alexandrium species (dinoflagellates that cause paralytic shellfish poisoning), which are preserved in surface sediments throughout Osaka Bay, Japan. These cysts have been found to accumulate particularly densely in shallow areas in the inner parts of Osaka Bay, where a tsunami caused by an earthquake could occur any time. Damage by a tsunami could cause a change of the coastal ecosystems at Osaka Bay including the resuspension of surface sediments containing resting Alexandrium tamarense cysts and the subsequent redistribution of the cysts in newly deposited sediment. Under certain environmental conditions, these cysts could germinate and form dense blooms, leading to paralytic shellfish poisoning. Such a scenario could also affect other coastal areas, including the southern coast of the Korean Peninsula.

• 한국농공학회논문집
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• 제52권5호
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• pp.47-52
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• 2010

The purpose of this study is to investigate characteristics of total phosphorus (TP) and phosphate phosphorous ($PO_4$-P) concentrations in ponded water and redox potential (Eh) in paddy soil during the growing season. The TP and $PO_4$-P concentrations showed twice peak values after basal dressing and tillering fertilization. The ratio of $PO_4$-P to TP showed low values (0.07~0.18), indicating that most of phosphorus is particlulate. The $PO_4$-P concentrations significantly decreased with dissolved oxygen (DO) concentrations. The Eh showed high values (179~636 mV) under non-ponded aerobic condition, but low values (74~112 mV) under ponded anaerobic condition The TP and $PO_4$-P concentrations in ponded water increased shortly after tillering fertilization even if phosphorus was not applied. This may be due to the release of dissolved phosphorus from the bottom sediment and its associated algal and water flea blooms under anaerobic condition. Therefore, proper water management should be needed shortly after tillering fertilization.

• Fisheries and Aquatic Sciences
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• 제2권2호
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• pp.172-175
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• 1999

Relative DNA contents in some harmful algae were measured using DAPI staining and image analysis system. This method was useful to identify some morphologically similar species and isolates from harmful algal blooms (HABs). In exponential phase, Prorocentrum micans had higher relative DNA content (RD) of $1.83\pm0.52$ than any other isolates, followed by Cochlodinium polykrikoides $(1.10\pm0.46)$ Alexandrium tamarense $(0.93\pm0.32)$ Gyrodinium impudicum $(0.56\pm0.17)$, Scrippsiella trochoidea $(0.41\pm0.26)$ and P. minimum$(0.05\pm0.01)$. When they were fixed with Lugol's solution, it was difficult to d,iscern C. polykrikoides from G. impudicum under the light microscope, but the DNA contents were quite different in two species. C. polykrikoides contained about twice as much RD as G. impudicum under the same culture conditions and exponential phase. DAPI­stained DNA feature in C. polykrikodes showed concentrated in the peripheral part of the cell, but in G. impudicum showed a compact structure in the central part. Although A. tamarense and S. trochoidea were morphologically similar under the light microscope, nuclear DNA content of A. tamarense was twice as much as that of S. trochoidea.

• Fisheries and Aquatic Sciences
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• 제11권1호
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• pp.15-22
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• 2008

Excessive growth of phytoplankton is a common and severe problem in intensively farmed pangasiid catfish (Pangasius hypophthalmus) culture ponds. It can lead to cyanobacterial blooms, reduced fish growth, bad-tasting fish flesh, and lower market demand. To investigate how to manage undesirable phytoplankton growth, we evaluated three stocking strategies in nine rural fishponds (0.020-0.022 ha) owned by various farmers: a pangasiid catfish mono culture (treatment 1, $T_1$), and pangasiid catfish-silver carp (Hypophthalmichthys molitrix) polycultures at two stocking ratios of 1:1 (treatment 2, $T_2$) and 2:1 (treatment 3, $T_3$). The total density of all ponds was approximately 30,000 fishes/ha. Monoculture ($T_1$) resulted in significantly higher (p < 0.05) nutrient levels (nitrate and phosphate) in ponds than did polyculture ($T_2$ and $T_3$). Nutrient loads increased with culture time, resulting in increased growth of phytoplankton, including Cyanophyceae (9 genera), Chlorophyceae (15 genera), Bacillariophyceae (8 genera), and Euglenophyceae (3 genera). The introduction of silver carp as a co-species helped to regulate phytoplankton growth and to improve the water quality of pangasiid catfish culture ponds.

• Journal of Microbiology and Biotechnology
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• 제22권9호
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• pp.1208-1213
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• 2012

Microcystis aeruginosa is a cyanobacterium that can form harmful algal blooms (HABs) producing toxic secondary metabolites. We provide here draft genome information of four strains of this freshwater cyanobacterium that was obtained by the Next Generation Sequencing approach to provide a better understanding of molecular mechanisms at the physiological and ecological levels. After gene assembly, genes of each strain were identified and annotated, and a genome database and G-browser of M. aeruginosa were subsequently constructed. Such genome information resources will enable us to obtain useful information for molecular ecological studies with a better understanding of modulating mechanisms of environmental factors associated with blooming.

• Environmental Engineering Research
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• 제14권4호
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• pp.220-225
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• 2009

The water quality in eutrophic lakes is affected by serious problems, such as abnormal increasing of Cyanobacteria. The purpose of this study was to investigate the possibility of a modified flotation system using a hybrid technique formed by chemical compounds and an electrostatic bridge. Therefore, experiments using the hybrid technique were performed to measure the zeta potential value on the phytoplankton surface and the removal efficiencies of phytoplankton, ammonia nitrogen, nitrate nitrogen and phosphoric acid. The results were as follows: Firstly, the zeta potential of M.aeruginosa was observed to approach charge neutralization due to adhesion of magnesium hydroxide precipitate on the phytoplankton surface in the pH range 10.5 to 11. Secondly, the concentration of chlorophyll-a decreased from about 150 to 20${\mu}g$g/L, with a maximum removal efficiency of 84% due to coagulation with pH values higher than 10. Thirdly, the N$H_4$-N concentration was observed to decrease from 0.62 to 0.54mg-N/L (13%), and the P$O_4$-P concentration, which is a limiting factor to the formation of algae blooms, decreased from 0.27 to 0.02mg-P/L (92%). These findings suggest that the modified flotation system can be applied for the purification of the raw water of numerous lakes containing high phytoplankton populations and elevated pH.

• 한국통신학회논문지
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• 제36권11B호
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• pp.1339-1345
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• 2011

적조란 유해조류 대 번식으로 바다물의 색깔이 변하는 자연현상이다. 적조의 피해가 증가함에 따라서 적조에 대한 많은 연구가 이루어지고 있다. 그러나 자동으로 적조류를 분류하는 연구는 미흡한 실정이다. 적조류는 영상 객체를 일치 할 수 있는 기준 중심 특정이 없기 때문에 인식이 어렵다. 이 때문에 기존이 연구들은 단순히 몇 종류의 적조류 만을 분류에 이용하고 있다. 본 논문은 주성분분석과 영상 객체의 원형율을 이용한 새로운 적조류 인식 방법을 제안한다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.360-363
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• 2006

The red tide related with Cochlodinium Polykrikoides bloom has been frequently occurred around the South Sea of Korea and caused the economic loss in the coastal breeding grounds. The outbreak scale was usually change by physical, biological and environmental condition at each years. Relatively large-scale red tide occurred in 1995, 1997, 1999, 2001, 2002 and 2003 through spatial scale, duration and maximum density. Compared the scale of red tide with physical condition around the South Sea, the lower coastal temperature on August around the South Sea corresponded with the large scale red tide. By serial oceanographic investigations on August in the South Sea and estimated wide area temperature information by satellite, SSTA around the South Sea and wide area was negative when the outbreak of red tide was large scale. From the results of temperature difference between surface and 30m layers, the occurrence of enormous red tide has a tendency when the temperature gradient around the seasonal thermocline was weakened. Larger Kuroshio volume transport in the upstream was also corresponded with the large scale red tide.