• Korean Journal of Ecology and Environment
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• v.36 no.2 s.103
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• pp.191-199
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• 2003

This study was conducted to investigate a seasonal variation of phytoplankton communities at 6 stations in the Hantan River from November, 2001 to August, 2002. Electric conductivity gradually increased from the upper reaches to the down reaches. DO differed not much from the upper reaches to down reaches, but it decreased at the station where the pollutants inflowed. T-N and T-P concentrations were high at station 4${\sim}$6. Chlorophyll-a concentration gradually increased at the mid and down reaches. It was high in May but decreased in August by the heavy rains. Phytoplankton communities were identified a total 354 taxa composed of 99 genus, 320species, 19 varieties, 3 forma and 12 unidentified species. There were 135 taxa of Chlorophyceae, 134 taxa of Bacillariophyceae, and the other taxa were Euglenophyceae, Cyanophyceae, Xanthophycaea, Chrysophyceae and Dinophyceae. Standing crops ranged from 8,600 to 337,100 cells/mL and it was lower in August than May by the rains. Dominant species included Achnanthes alteragracillima, Achnanthes convergens, Achnanthes minutissima and Cymbella minuta var. silesiaca which were the saproxenous species at the reaches, and were Cyclotella meneghiniana, Chlamydomonas pseudopertyi and Nitzschia which were saprophilous and eutrophic species at the down reaches. The correlation coefficients between phytoplankton standing crops and EC, BOD and T-N, T-P was 0.68, 0.60, 0.60 and 0.70, respectively. All correlation coefficients between Chlorophyceae and EC, BOD and T-P were higher than 0.6. A. convergens were negative correlations with EC and BOD, but N. palea were positive with EC, BOD, T-N and T-P.

• Korean Journal of Ecology and Environment
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• v.49 no.4
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• pp.375-384
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• 2016

Phytoplankton community is one of the important factors for the management of aquatic environment due to generation of varying toxins by harmful algal species. This study was performed to examine the phytoplankton community structure (PCS) in the midstream of Geum River (GR) from January 2014 to December 2015. The water sampling was performed in five stations on 2014, and three stations on 2015. Subsequently, the morphological identification was performed by microscopic observation in laboratory condition. As results, total 265 species were identified and it was comprised of 40.8% of Bacillariophyceae, 9.1% of Cyanophyceae, 44.5% of Chlorophyceae, and the others (4.9%). During the investigation period, total average standing crop of phytoplankton was $12,948cells\;mL^{-1}$, and it was comprised of $7,702cells\;mL^{-1}$ of Bacillariophyceae, $2,821cells\;mL^{-1}$ of Cyanophyceae, $2,121cells\;mL^{-1}$ of Chlorophyceae, and $305cells\;mL^{-1}$ of others. To verify which tributaries of upstream area influence on PCS of midstream of GR, the phytoplankton standing crops of two stations including Mihocheon (MH) and Gapcheon (GC) were examined on 2014, and compared to result of on 2015. The results were shown that the MH station had more similar phytoplankton standing crops with midstream of GR than GC station. The relationship between environmental parameters and phytoplankton dynamics was studied at the investigated station. As results, whereas water temperature and total phosphorus were represented the positive correlation, N/P ratio was remarkably exhibited negative correlation. From the results, it is suggested that the PCS of midstream of GR was more affected by MH station than GC station, and the changes of temperature, phosphorus concentration, and N/P ratio may be important factors on the PCS formation of midstream of GR.

• Korean Journal of Environment and Ecology
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• v.35 no.2
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• pp.115-125
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• 2021

This study surveyed the population ecology of Acheilognathus chankaensis (Pisces: Acheilognathinae) in the vicinity of the Churyeongcheon (Stream) and Seomjingang (River) in Jeonbuk, Korea, from February 2006 to May 2007. The survey found the habits mainly in the slow-flowing waters having sand, mud, and gravel bottoms. Age groups estimated by the standard length-frequency distribution of the population indicated that the one-year-olds were 30-46 mm long, the two-year-olds were 47-58 mm long, the three-year-olds were 59-68 mm long, and the four-year-olds were longer than 69 mm. The gonadosomatic index (GSI) and the ratio of ovipositor length/standard length were the highest in March (♀: 12.9%, ♂: 5.0%) and in April (46.3%), respectively. The ratio of mature egg diameters that were 1.6 mm was highest in May (13.2%). The comprehensive analysis of spawning characteristics showed that the spawning season was from March to June with water temperatures in 11.5-22.5℃, and the sex ratio of female:male was 1:1.13. The fecundity in the ovaries and the number of mature eggs were 318±174.5 (50~583) and 220±139.2 (50~406), respectively. The size of the mature eggs was 2.04±0.110 mm on the long axis and 1.55±0.100 mm on the short axis for the study period. Gut contents of A. chankaensis were mainly phytoplankton such as the genera Fragilaria, Synedra, Navicular, Cymbella (Bacillariophyceae), and Cosmarium (Chlorophyceae).

• Korean Journal of Ecology and Environment
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• v.41 no.4
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• pp.519-529
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• 2008

Recent studies reveal one of the representative endocrine disrupters of nonylphenol affects on the composition of a planktonic community. Since nonylphenol is sometimes discharged into eutrophic waters, we monitored planktonic community composition of a eutrophic pond after receiving nonylphenol when cyanobacterium Microcystis aeruginosa mainly dominated. The experiment was carried out two times using small-scale microcosms in a laboratory. In both two experiments, ciliate abundances significantly decreased when nonylphenol was added. On the seventh day, the ciliate abundances in $10{\mu}g\;L^{-1}$ added treatments decreased by 36.9% in the first experiment and 33.6% in the second, when compared to the control. The response of other planktonic groups was less obvious to nonylphenol addition. In particular, in the first experiment, Chl. b/Chl. $\alpha$ and Chl. c/Chl. $\alpha$ significantly increased with the addition of nonylphenol, while total Chl. $\alpha$ concentration did not change. Indeed, bacillariophyceae and chlorophyceae abundances tended to increase with nonylphenol dosing. From these results, we tentatively hypothesized that nonylphenolloading positively affects on abundances of edible phytoplankton such as Scenedesmus spp. and diatoms by releasing from grazing pressure due to decrease in ciliate abundances. The present study emphasizes that the indirect effect of endocrine disrupters should be paid more attention when freshwater resources are polluted by them.

• ALGAE
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• v.22 no.4
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• pp.261-271
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• 2007

The variations of species compositions, standing crops and seasonal succession of phytoplanktons including Cyanophyceae, Chlorophyceae and Bacillariophyceae were investigated with physico-chemical elements of water to clarify the causes of water bloom according to the water depth in the Lake Unmun. The increased amounts of turbidity, T-N, T-P and SS originated from heavy rain and typhoon in the middle of June provoked to produce phytoplanktons. In July and August, the dominant species was Peridinium sp., while the subdominant species was Microcystis aeruginosa. In October, Aulacoseira distans was dominant and Asterionella formosa was subdominant. During the period of water shortage, the concentrated pollutants caused the decrease of precipitation, the long stagnation time of water body and the mixed pollutants by upwelling as decreasing water temperature could accelerate the water bloom. The preventives to decrease microalgal generation should be controled by the stagnation time of water body by increasing outflow to intercept water bloom such as ulacoseira sp. in October as well as summer.

• ALGAE
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• v.19 no.1
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• pp.15-22
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• 2004

This study investigated the temporal and spatial dynamics of an epilithic algal community in the Hantan River in November 2001, February, May and August 2002. It was identified a total of an epiphlithic 301 taxa which were composed of 275 species, 16 varieties and 10 unidentified species. The standing crops ranged between 598,600-16,525,200 cells $\cdot$ $cm^2$ and showed the temporal and spatial variations, A higher value was found at the lower station than the upper station in winter, but a higher value was found at the upper station than the lower station in summer due to the effects of typhoons. Chlorophyll concentrations ranged between 13.4-304.2 ${\mu}g$ $\cdot$ $cm^2$. Standing crops and chlorophyll showed similar trends in autumn and winter, but temporal dynamics were not apparent in the overgrowth of Lyngbya, Schizothrix and so others in Cyanophyceae in spring and summer. They were composed of species in Chlorophyceae-Bascillariophyceae-Cyanophyceae and no seasonal effect was detected. Low diversity index values probably indicated the effects of environmental stresses (water temperature, flow and current velocity) other than organic pollution. An assessment of organic pollution using epilithic diatoms (DAIpo) showed $\alpha$-oligosaprobic states at the upper- and mid- stations, and $\alpha$-mesosaprobic states at the lower- stations.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.1
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• pp.61-67
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• 2005

The objective of this study was to investigate community structure of attached algae and microbes in sedimentation basin of water and wastewater treatment plants by using respiratory quinone profile. There was an evident difference, in microbial community structure and attached algae species, between inclination plate settler and drainage canal in the sedimentation basin. The algae was composed of species in following order; Chlorophyceae>Bascillariophyceae>Cyanophyceae. The dominant quinone types of attached microorganisms in the wastewater treatment plant were plastoquinone (PQ)-9, vitamin(V)K-1 followed by UQ-8, but those for water treatment plant were VK-1, PQ-9 followed by UQ-8. These results suggests that nutrients, seasons and material of sedimentation basin have notable influence on composition of attached algae and microbial community structure in water and wastewater treatment plants.

• Journal of Microbiology and Biotechnology
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• v.16 no.8
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• pp.1222-1228
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• 2006

Two kinds of Haematococcus pluvialis cells (green vegetative cells cultivated under optimal cell culture conditions and red cyst cells maintained under high light stress conditions to induce astaxanthin production) were used to investigate the protein expression profiles by two-dimensional electrophoresis, image analysis, and peptide mass fingerprinting. The cellular accumulation of astaxanthin was evident after exposure to high light intensity and reached the maximum cellular level after 78 h of high light stress. In a 2-D electrophoresis analysis, 22 proteins were upregulated over 2-fold in the red cyst cells when compared with the green vegetative cells and selected for further analysis by chemically assisted fragmentation (CAF)-MALDI-TOF sequencing to identify the protein functions. Among 22 different spots, several key enzymes specific to the carotenoid pathway, including isopentenyl pyrophosphate isomerase (IPP) and lycopene $\beta$-cyclase, appeared in H. pluvialis after exposure to high light intensity. Therefore, IPP and lycopene $\beta$-cyclase would appear to be involved with carotenoid accumulation in the cytoplasm, as these peptides were preferentially upregulated by high light intensity preceding an increase in carotenoid, and only these forms were detected in the red cyst cells.

• Fisheries and Aquatic Sciences
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• v.11 no.1
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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.

• ALGAE
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• v.17 no.2
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• pp.117-125
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• 2002

Five microalgal species isolated from the Jeju coast and four microalgal stock strains in hatchery were cultured in order to investigate their adapation to extreme changes in environmental factors such as salinity, water temperatue, adn nutrients. In case of salinity variation, Nitzschia sp. of Bacillariophyceae, Isochrysis galbana of Haptophyceae and Tetraselmis gracilis of Prasinophyceae showed optimum growth at the low salinity of 20 and 25 psu. Amphora coffeaeformis and Chetoceros simplex of Bacillariophyceae, and Pavlova lutheri of Haptophyceae adapted well at the relatively high salinities of 30 and 35 psu. However Phaeodactylum tricornutum of Bacillariophyceae and Chlorella sp. of Chlorophyceae showed euryhaline property In case of water temperature variation, most of all the species studied wer inhibited at 10℃. C. simplex, Nitzschia sp., p. tricornutum, Chlorella sp. and T. gracilis grew well at above 20℃. A. coffeaeformis, I. galbana and P. lutheri adapted also at the high temperature of 30℃. Each microalgal strain showed different growth rates and its maximum biomass. Generally microalgal populations from the Jeju coast grow well in relatively high salinity and high water temperature. Their growth were inhibited at low water temperature, but not likely affected at low salinity. This study indicates that the microalgal populations could not be affected by abnormally low salinity phenomena, which have happened occasionally around the west Jeju coast in summer and have led macrobenthic animals to mass mortality.