• Korean Journal of Ecology and Environment
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• v.38 no.2 s.112
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• pp.181-187
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• 2005

For 4 years (2000 ${\sim}$ 2003), annual fluctuations of standing crops of cyanobacteria and physicochemical factors were examined at five sites from Bridge of Seungsoo to Bridge of Seungsan in the lower part of Han River. The cyanobacterial abundance (ND to 4,167 cells $mL^{-1}$) was strongly decreased during the heavy rains in every year. During the similar periods in 2003, cyanobacteria hardly observed, and comprised below of 10 percentage of total phytoplankton. In the period of little cyanobacteria, some green algae and diatom dominated the phytoplankton community, while the concentration of chlorophyll a has not largely change. These results indicate that heavy frequent precipitation strongly limited the growth of cyanobacteria, and lead an algal succession by the appearance of new algal groups.

• Korean Journal of Ecology and Environment
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• v.34 no.2 s.94
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• pp.98-105
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• 2001

Two-monthold silver carps were cultured with seven algal species and zooplankton (Moina macrocopa) in the laboratory. The carps were reared in 10 L translucent cylindrical aquaria with algae and zooplankton for 8 days. The Moina effectively fed almost cultured algae: perfectly removed Cryptomonas (NIES-282) within 60 min. Both algal diets Cryptomonas and Fragilaria (NIES-391) significantly increased the Moina population ($r^2$>0.93, p<0.005), while Microcystis (MIES-90) and Oscillatoria (NIES-204) reduced the zooplankton ($r^2$=0.97, p<001). Fish removed about 50% of all algae for 52 hrs, even 60% of Microcystis still remained: all algae reduced ca. 5${\sim}$12% of initial weight. Furthermore, a continuous supply of algae with same density resulted in the death of fish, e.g. 11 days in cyanobacteria Microcystis. Therefore, the growth limitation of silver carp by algae indicates that zooplankton is of direct dietary contributor in planktivores feeding behavior.

• Korean Journal of Ecology and Environment
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• v.34 no.2 s.94
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• pp.90-97
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• 2001

The seasonal changes in phytoplankton standing crops, species composition, dominant species, species diversity and physico-chemical characteristics in Woopo and Mokpo swamps were studied from January to December, 1998. Phytoplankton of a total 353 taxa were identified, the composition of phytoplankton community was characetrized by green algae and diatoms and quantity composition of standing crops was dominated by green alga Oscillatoria sp. was especially prominent. The standing crops varied from 108 cells/ml and 118 cells/ml to 19,178 cells and 38,393 cells/ml in Woopo and Mokpo swamps, respectively. The maximum algal density was observed in November, Micractinium pusillum and Oscillatoria sp. usually contributed 83.2% to total cell numbers in Woopo swamp. However, the maximum density occurred in May when Oscillatoria sp. formed bloom in Mokpo swamp. The low species diversity of the phytoplankton coincided with maximum standing crops of the filamentous blue-green alga Oscillatoria sp. and green alga Micractinium pusillum in May and November.

• Korean Journal of Ecology and Environment
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• v.34 no.2 s.94
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• pp.81-89
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• 2001

In order to know relationships between green euglenoids and environmental factors, the species composition and density were assessed for 12 months together with environmental variables in the Jeonjucheon urban drainage, Korea. Nitrate was a high of 3.22 mg/1 in June and phosphate concentration was over 0.71 mg/l in the winter. The euglenoids totaled 5 genera and 71 species throughout the year, increasing in the early summer (35 to 42 texa) and decreasing in the winter (below 20 taxa). The number of green euglenoids positively correlated with surface water temperature. the total density of the green euglenoids showed a typical bimodal pattern, being maximal in the winter (5,394 cells/ml in June). The winter peak was a result of active growths of Euglena caudata, E. geniculata and E. viridis, however, each of which positively correlated with the phosphate. The early summer peak was attributed to Euglena deses, Lepocinclis ovum, and Phacus trypanon, each of which positively correlated with the ammonium and nitrate. The complete bimodal spectrum of species number and density of green euglenoids provides a sensitive image in detecting the changes of environmental variables in polluted waters such as Jeonjucheon.

• Korean Journal of Ecology and Environment
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• v.34 no.2 s.94
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• pp.133-139
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• 2001

For elucidating the effective management for nutrients removal by the phytoplankton growing at the effluents of night soil and sewage treatment plant, the dilution rates, physical operation conditions and duration of culture were defined. For nutrients removal from effluent of night soil treatment plant, lower the dilution was better, and Scenedesmus sp. was dominant. For removal from the effluent of sewage treatMent plant, the proper operation conditions were 50% of dilution rate, stirring and 2 days culturing. With these conditions, the removal rate of TKN was 88%, DIP$70{\sim}80%$ and the chlorophyll concentration reached at $1,300\;mg/m^3$ chlorophyll a concentration. the variation of chlorophyll a was highly corrrlated with ammonia ($r^2\;=\;0.96$) and DIP ($r^2\;=\;0.92$).

• Korean Journal of Ecology and Environment
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• v.38 no.2 s.112
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• pp.207-216
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• 2005

Spawning behaviors of Squalidus gracilis majimae (Cyprinidae) were observed in the laboratory whose environmental factors such as light (D/L = 16 : 8), temperature ($20\;{\sim}\;24\;＾{\circ}C$), and dissolved oxygen (>8 mg $L^{-1}$) were quite regularly controlled. The behavioral patterns were categorized into three stages ofpre-spawning, spawning, and Post-spawning behaviors. In Particular, the pre-spawning stage was specified by 11 specific behavioral patterns of aggressive mating behaviors. During the spawning stage, the male and female performed four distinct spawning behaviors including sexual temptation, stimulation, egg spawning, and the separation, and randomly laid about 200 ${\sim}$ 300 eggs on the bottom substrates through the night. After finishing spawning, two adults separated toward their refuges and showed 3 types of post-spawning behaviors such as the resting, occasional eggs protecting, and the egg eating. The fish was identified as a partial-parental care species after the spawning.

• Korean Journal of Ecology and Environment
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• v.33 no.3 s.91
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• pp.206-212
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• 2000

Since some cyanobacterial isolates under selective culturing conditions are lacking of characteristic specialized cells or showing altered morphology, the morpho-taxonomic criteria are not accurate enough to discriminate between species. Instead of morphological parameters, a method based on the single or the combination of repetitive oligonucleotides in a single PCR, repetitive oligonucleotides-primed PCR (ROP-PCR), was applied to generate DNA profiles for members of the cyanobacterial genera Anabaena and Oscillatoria, both of which are responsible for causing poisonous blooms in various freshwater systems. ROP-PCR performed on 10 isolates of the cyanobacteria with ERIC and REP sequences from gram-negative bacteria, STRR1A and LTRR sequences derived from cyanobacterial genome, and eukaryotic repetitive sequences, led to the identification of distinct genotypes, and provided specific and repeatable DNA fingerprints for cyanobacterial isolates. Grouping analysis of cyanobacterial isolates showed a signifiant difference depending on the primer used in PCR.

• Korean Journal of Ecology and Environment
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• v.33 no.2 s.90
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• pp.80-108
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• 2000

This paper deals with floristic and taxonomic accounts of 47 taxa of the genus Trachelomonas collected from 58 waters in Korea. Of these, 19 taxa are added to the Korean Trachelomonas flora, and 4 taxa, T. curta var. reticulata, T. koreana, T. planctonica var. papillosa, and T. spina are newly recorded in the world flora of the euglenoids. Detailed description and illustrations are given for each species. Since 23 taxa are previously reported in the Korean freshwaters, a total of 70 taxa are listed up in the Korean Trachelomonas flora. Trachelomonas species are abundant and diverse in old or stagnant swamps or ponds, where is enriched with organic matters and nutrient salts. T. bacillifera, T. hispida, and T. volvocina formed water blooming in the natural swamps or fishery ponds in spring and summer.

• Korean Journal of Ecology and Environment
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• v.33 no.3 s.91
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• pp.304-310
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• 2000

Enclosure experiments to reduce the growth of Cyanophyceae were carried out using plants in Kyongan stream. Wet plants put into the enclosure at a rate of 2.5 g wet wt/l and at that time, the average concentration of chlorophyll a was ranged from 30 to $50\;{\mu}g/l$. The dominant species was Microcystis aeruginosa. Ginkgo, big cone pine and pine needles significantly inhibited the growth of Microcystis from the early days to the stages of log-Phase. Waterchestnut was the most inhibitory to the growth of Microcystis. Pine needles inhibited in 85% of the algal growth: ginkgo in 80%; big cone pine in 75%; waterchestnut in 78%; wildrice in 59%; and iris in 30%. At the treatment with 0.25 g dried plants/l, algae was declined at a rate of 90% by waterchestnut: 53% by pine needles. Phenolic compounds were purifled from decomposing big cone pine and waterchestnut.

• Korean Journal of Ecology and Environment
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• v.33 no.3 s.91
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• pp.274-281
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• 2000

The dynamic of fish community was investigated in the Wonju stream from March 1998 to February 1999. The collected species during the surveyed period were 24 species belonging to eight families. Eight species (33%) of them were endemic species of Korea. According to relative abundance in the studied areas, Moroco oxycephalus (30.7%), Zacco platypus (29.6%), Carassius auratus (10%), Pseudogobio esocinus (9.4%) and Rhinogobius brunneus (3.6%) dominated. Hemibarbus longirostris, Pungtungia herzi, Squalidus japonicus coreanus, Zacco temmincki, Cobitis rotundicaudata, Silurus asotus, Silurus microdorsalis and Micropterus salmoides were rare to the areas, which occupied less than 0.1% in relative abundance. Dominant species was M. oxycephalus (Kumda-ri, Kwanseol-dong, Hanggu-dong, heongyang-ri), Z. platypus (Gaeun-dong) and C. auratus (Jusan-ri). It was revealed by the analysis of community that St. 3 was the most diverse among all study stations. Coreoleuciscus splendidus and Coreopera herzi have been assumed vanished in the Wonju stream. The species occurring in suddenly decreasing trend were Microphysogobio yaluensis, Liobagrus andersoni, Cottus poecilopus and R. brunneus. The species occurring in representative increasing trend were Cyprinus carpio, C. auratus, P. esocinus, M. oxycephalus, and Z. platypus.