• Korean Journal of Ecology and Environment
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• v.35 no.2 s.98
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• pp.103-110
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• 2002

Seasonal changes of the phytoplankton community was investigated from July 2000 to April 2001 at the river bed lake, Jangjwa Lake in the Imjin River, which appeared to be the most natural condition. A total of phytoplankton were composed of 112 taxa, belonging to 5 divisions,83 species, 10 varieties,1 variety-form, 1 form and 17 unidentified species. Of those, the green algae and the diatoms were present during the investigation periods more frequently then the other taxa. The phytoplantton standing crops varied from $2,943{\times}10^3\;cells/l$ on April 2001 to $5,742{\times}10^3\;cells/l$ on January 2001. The phytoplankton standing crops had a continuous high value over $3,000{\times}10^3\;cells/l$ during the investigated periods and showed the highest value during winter period. The major dominant species were Aulacoseira granulata, Chlamydomonas nivalis v. kobayasii, Dinobryon sertularia, Mougeotia so. and Uroglenopsis americana. Among those, Chlamydomonas nivalis v. kobayasii was a major dominant species during winter period.

• Journal of Korean Society on Water Environment
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• v.24 no.5
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• pp.550-555
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• 2008

This study was conducted to assess the growth characteristics of phytoplankton and to understand seasonal dynamics of phytoplankton in response to limiting nutrients in an agricultural reservoir from November 2002 to December 2003. Marked increase of chl.a concentration observed in July ($99.0{\mu}g/L$) and November ($109.7{\mu}g/L$) after heavy rainfall. TP concentration ranged $48.0{\sim}126.6{\mu}g/L$, and its the temporal variation was similar to that of chl.a concentration. Microcystis spp., dominant phytoplankton species were used for the growth kinetics experiment, except for the season when Aulacoseira spp. (March, April) and Aphanocapsa sp. (May) dominated. In the temperature range between $10{\sim}25^{\circ}C$, the rate of growth increase per $10^{\circ}C$ was almost two folds. The highest maximum growth rate (${\mu}_{max}=1.09day^{-1}$) of phytoplankton observed September, and ${\mu}_{max}$ was lowest ($0.34day^{-1}$) in March when Aulacoseira spp. dominated. The ${\mu}_{max}$ ($0.78{\pm}0.20day^{-1}$) was relatively high in the summer season when water temperature is above $20^{\circ}C$ and cyanobacteria dominated compared to the spring when diatoms dominated ($0.43{\pm}0.08day^{-1}$). The maximum growth rate ($0.55{\pm}0.12day^{-1}$) and the half saturation concentration ($K_s=0.73{\pm}0.15{\mu}M$) of cyanobacteria during winter season (November, December) was higher than those of diatoms. However, the ${\mu}_{max}$ and $K_s$ of cyanobacteria in December was similar to those of diatom, reflecting that diatom cell quota (Mean 48.4 pgP/cell) was greater than cyanobacteria (34.0 pgP/cell) during this time.

• Journal of Korean Society on Water Environment
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• v.27 no.6
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• pp.855-861
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• 2011

Short-term effects of current velocity and turbid water on the benthic diatom community and water quality were examined in artificial channel ($20{\times}200{\times}10cm$) with two different experiments. The first and second experiments were consisted of different current velocities such as 1 L/min., and 1, 3, and 6 L/min., respectively. The concentration of turbid water is prepared with loess and fixed at 10 and 20 times of the turbidity of control inflow (10 NTU, LTW), respectively. At experiment 1 (EXP-1), introduction of turbid water increased dissolved oxygen, electric conductivity, pH and turbidity, but there were no differences between low- (100 NTU, MTW) and high-turbid water (200 NTU, HTW). However, experiment 2 (EXP-2) did not change any environmental parameters except dissolved total and inorganic nitrogen like EXP-1. MTW in EXP-1 strongly stimulated the growth of benthic diatom, while both MTW (150 NTU) and HTW (300 NTU) in EXP-2 did not increase or decrease the diatom abundance. Over the study, the dominant species was four, Aulacoseira ambigua, Cyclotella stelligera, Aulacoseira granulata and Achnanthes minutissima. In EXP-1, two highest species in abundance, A. ambigua and A. granulata were highly grown in MTW, while Achnanthes minutissima high in HTW adversely. These results indicate that the introduction of turbid water can play an important role in the shift of water quality and benthic diatom community in stream ecosystem, especially inflow of soil water in low current velocity.

• Korean Journal of Ecology and Environment
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• v.45 no.1
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• pp.129-138
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• 2012

We investigated an ecological impact of drought simulated by discharge depletion on the water quality and benthic diatom community in the indoor experimental channel. As artificial substrates slide-glass was installed in acrylic channel for 16 days. Channels were supplied continuously with eutrophic lake water with a discharge rate of 6 L $min^{-1}$ in duplication during the colonized period. And then during the discharge depletion period, three discharge rates were provided: NDF (No depletion of flow rate (Control): 6 L $min^{-1}$), LDF (Low depletion of flow rate: 3 L $min^{-1}$) and HDF (High depletion of flow rate: 1 L $min^{-1}$). Environmental factors in the water, such as suspended solid, Chl-$a$ and nutrients concentration, were measured with periphytic algae including AFDM (ash free dry matter), Chl-$a$ concentration and cell density at 1-day intervals. Light intensity increased significantly with discharge depletion (F=229.5, p= 0.000). $NH_4$-N concentration was highest at HDF. Suspended solid in outflowing water decreased at HDF (88%), LDF (97%) and NDF (99%), compared to inflowing water (100 %). Chl-$a$ in substrates increased more than two times at LDF and HDF than NDF (F= 8.399, p=0.001). Also AFDM and benthic diatom density increased significantly at LDF and HDF than NDF (F=9.390, p=0.001; F=6.088, p=0.007). In all experimental groups, $Aulacoseira$ $ambigua$, $Achnanthes$ $minutissima$ and $Aulacoseira$ $granulata$ were dominant species accounting for greater than 10% of benthic diatom density. The most dominant species, $A.$ $ambigua$ was highest at LDF, followed by HDF and NDF (F=8.551, p=0.001). In conclusion, the effect of drought simulated by discharge depletion in an artificial stream ecosystem caused significant changes on water quality and benthic diatom biomass. This result provides a useful data to understand the effect of draught on stream ecosystem in situ.

• Korean Journal of Ecology and Environment
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• v.41 no.2
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• pp.174-187
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• 2008

In an effort to identify structure and function of microbial loop in Paldang reservoir, we monitored environmental and biological factors at Kyungan stream (station K), Paldang dam (station P) and the confluence of North and South Han River (station M) from March to December, 2005. DOC concentration was higher in March to May and November than the others. Nutrient concentration in station K detected relatively higher than that of two stations. Both of phosphate and silicate gradually increased at all stations until September, after then decreased. The highest Chl-$\alpha$ concentration was observed at all stations in April, and November. The carbon biomass of bacteria and HNF were relatively higher in March, May and August than the others, whereas that of the ciliate showed no significant difference in monthly fluctuation. Nevertheless, the significant relationships revealed between ciliate (P<0.001) and HNF (P<0.05) and bacterial density. Tintinnopsis cratera, Didinium sp., Vorticella sp., Paramecium sp. and Strombidium sp. were dominant species in ciliate community. The dominant species of phytoplankton were Stephanodiscus hantzschii and Cyclotella meneghiniana at almost stations in Spring, Summer and Autumn. However, Aulacoseira granulata accounted for >95% of phytoplankton biomass at station P and M in Autumn. The carbon biomass of zooplankton was highest at station P and M in June, and relatively higher biomass observed at all stations in August, October and November. Diaphanosoma brachyurum and Bosmina longirostris were dominant in stations P and M of June and in all stations of October and November, respectively. The maximum growth (A. granulata: $0.17\;d^{-1}$, S. hantzschii: $0.14\;d^{-1}$) and grazing rate (A. granulata: 1.93 preys $d^{-1}$, S. hantzschii: 1.63 preys $d^{-1}$) of Bosmina longirostris revealed in algal preys as Aulacoseira granulata and Stephanodiscus hantzschii. In conclusion, these results suggest that bacteria and phytoplankton can play the most crucial source as prey within microbial food chain in Spring and Summer and grazing food chain in Autumn, respectively.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.18 no.4
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• pp.214-226
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• 2013

To understand the changing patterns in phytoplankton communities, we conducted 12 surveys along the Nakdong River, its estuary, and adjacent coastal areas between January 2011 and October 2012 (during the period of barrage construction and sediment dredging). Monthly precipitation ranged from 0 to 502 mm during the survey period, and salinity ranged between 0.1 psu and 0.3 psu in the Nakdong River, regardless of the depth, indicating no seawater influence, while salinity showed large seasonal fluctuations in the estuarine and coastal station, ranging from 0.1 psu to 34.8 psu. A total of 402 phytoplankton species were identified, 178 species from the river and 331 species from the estuary and coastal areas. Phytoplankton standing crop increased in 2012 compared to that in 2011, and was found to be highest in the river, followed by the estuary and coastal areas. Among the top 20 species in frequency of occurrence and dominance, Stephanodiscus spp., Aulacoseira granulata, and Aulacoseira granulata var. angustissima and Pseudo-nitzschia spp. were important species along the river-estuary-coastal areas. Diatoms were the major taxonomic group inhabiting the Nakdong river-estuary-coastal areas. A comparison of seasonal dominant phytoplankton species revealed a slight decrease over the years, from 13 species in 2011 to 10 species in 2012. However, no significant difference was found in the diversity of phytoplankton species between the two survey years, although lightly greater diversity was observed in the coastal areas than in the river and estuary. Cluster analysis with community composition data revealed that the community structure varied significantly in 2011 depending on the time of survey, while in 2012, it hardly showed any variation and was simpler. An increase in the phytoplankton standing crop, fewer dominant species, and simpler community structure in 2012 compared to those in 2011 are probably due to the rapid environmental changes along the Nakdong River. To investigate these ecological relationships, it is necessary to conduct further studies focusing on integrated analyses of biocenosis, including phytoplankton with respect to the changes in nutrient distribution, variation of freshwater discharge, and effect area of freshwater in the Nakdong estuary and adjacent coastal areas.

• ALGAE
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• v.22 no.2
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• pp.69-85
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• 2007

From six reservoirs in Gyeonggi-do, we have collected the distribution and standing crop of phytoplankton since Nov. 2005 through Sep. 2006. As a result, the phytoplankton appeared totally 340 taxa belong to 7 classes, 15 orders, 5 suborders, 32 families, 4 subfamilies, 84 genera, 283 species, 43 varieties, 9 forms and 5 unidentified species. The standing crop was shown as minimum was 0.3 × 106 cells and maximum was 5,950 × 106. The relation of standing crop with TN, TP and Chl-a showed as positive. Total 12 taxa including 2 taxa of blue-green algae occurred to every seasons at six lakes, and it was thought that they distributed in mesotrophic state. Also, Achnanthes minutissima, Aulacoseira granulata, Eudorina elegans, Gloeocystis ampla, Pandorina morum, Pediastrum simplex var. duodenarium, Scenedesmus ecornis were regarded as the indicators of eutrophic state. From the estimation of LTSI and TSI, it was shown that the rest of lakes except for Idong reservoir of winter were eutrophic states.

• Journal of environmental and Sanitary engineering
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• v.19 no.2
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• pp.51-59
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• 2004

강우가 집중하고 남조류가 대발생하던 시기의 중영양호소인 주암호에서 박테리아, 식물플랑크톤, ANF, HNF, 섬모충플랑크톤, 동물플랑크톤과 환경요인들의 변화에 대해 조사하였다. 조사기간동안 우점종은 Cyclotella meneghinana, Aulacoseira granulata, Cryptomonas tetrapyrenoidsa로서 총현존량의 67% 이상을 차지하였다. 조사기간동안 남조류 대발생의 구성원은 현존량 및 종조성에서 크게 변화 하였다. 여름철 강우에 의한 엽록소 a, 수질 (COD, TP)의 변동이 심하였으며, 특히 C. tetrapyrenoidsa는 HNF, nauplii, rotifer, 섬모충의 변동에 매우 밀접한 관계를 보였다. 포식자인 rotifer는 박테리아, 피코플랑크톤이나 ANF같은 소형플랑크톤의 변동과 높은 관계를 보였다.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2005.05a
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• pp.257-259
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• 2005

서낙동강에서 조사된 식물플랑크톤은 6강 31과 128종류로 녹조류(Chlorophyceae)가 49종류(38.3%), 규조류(Bacillariophyceae)가 44종류(34.4%)였다. 계절별로는 여름에 최고 80종, 겨울에 최소 47종으로 출현하였으나 일반적인 경우와는 상이한 결과였다. 정점별로는 여름에 정점 1에서 63종류로 가장 많은 종수를, 가을과 겨울의 정점 4에서 18종류로 가장 적은 종수로 조사되어 계절별, 정점별 출현종수의 차이는 크게 나타났다. 생태적 주요종은 모두 63종류였고 Actinastrum hantzschii var. fluviatile을 비롯한 33종류가 광분포종, 오수지표종은 Ankistrodesmus falcatus를 비롯하여 28종류, 적조원인종은 Aulacoseira garanulata var. angustissima for. spiralis를 비롯하여 23종류, 우점종으로는 Aphanizomenon flos-aquae를 비롯하여 8종류, 출현빈번종은 Asterionella formosa를 비롯하여 7종이었다. Jaccard's coefficient에 의한 집괴분석을 실시한 결과, 거의 모든 계절에서 서낙동교를 중심으로 서낙동교 상부지역(st. 1 ${\sim}$ st. 3)과 하부지역(st. 4 ${\sim}$ st. 6)으로 구분되거나 또는 담수지역(st. 1 ${\sim}$ st. 4)과 해수의 영향이 미칠 것으로 예상되는 지역(st. 5 ${\sim}$ st. 6)의 두그룹으로 그룹지어졌다.

• ALGAE
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• v.21 no.4
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• pp.377-392
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• 2006

Seventy eight taxa of Bacillariophyceae belonging to 1 species of Aulacoseira, 1 species of Cyclotella, 1 species of Tabellaria, 1species of Diatoma, 1 species of Thallasionema, 1 species of Grammatophora, 1 species of Fragilaria, 8 species of Synedra, 2 species of Achnanthes, 1 species of Cocconeis, 1 species of Diadesmis, 1 species of Diplonies, 2 species of Gyrosigma, 3 species of Pleurosigma, 15 species of Navicula, 4 species of Pinnularia, 3 species of Stauroneis, 1 species of Eunotia, 2 species of Himantidium, 11 species Gomphonema, 5 species of Cymbella, 1 species of Cocconema, 4 species of Amphora, 1 species of Rhopalodia, 5 species of Nitzschia and 1 species of Surirella were reported from different fresh water habitats of Orissa state and its neighbouring regions of India. All the taxa were recorded for the first time from this region.