• Korean Journal of Microbiology
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• v.27 no.2
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• pp.130-138
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• 1989

Microbiological parameters such as bacterial biovolume and biomass in Soyang Reservoir was statistically analyzed with the physico-chemical enviromental factors. Analysis of correlation and multiple regression showed that temperature affects most of microbiological parameters. Variations of total bacterial number, total bacterial biovolume and saprophyte number were highly correlatd with the concentrations of chlorophyll a and pheophytin a. Bacterial production by the $^{3}H$-thymidine incorporation rate was largely affected by Seston. It suggests that microbiological factors such as bacterial biovolume and bacterial biomass were controled by the concentration of seston and distribution of phytoplankton which acts as carbon and energy source for the bacterial community in the water column of Soyang Reservoir.

• Animal cells and systems
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• v.5 no.2
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• pp.117-126
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• 2001

Occurence, seasonal changes and vertical distribution of the silica-scaled chrysophytes in a small fish-free pond were studied using electron microscopy (EM) and light microscopy (LM) from October 1998 to July 1999. The phytoplankton community was characterized by Chrysophyta and Cryptophyta. Ten species of the silica-scaled chrysophytes of genera Mallomonas, Synura, Chrysosphaerella and Spiniferomonas were identified by EM, and the most abundant species were Mallomonas akrokomos and M. portae-ferreae. The maximum population density of M. akrokomos was observed in December and several peaks appeared periodically at about one to two month intervals, whereas M. portae-ferreae developed the maximum density in March. The diurnal vertical distribution of M. akrokomos exhibited clear downward migration at night and slightly upward migration in the morning. A complex interaction among physico-chemical and biological factors seemed to affect the vertical distribution of M. akrokomos. However, the seasonal changes of M. akrokomos did not show significant corre1ations with the physico-chemical and some biologica1 factors. Although M. akrokomos was evenly distributed throughout the water column during some experimental periods, the diurnal patterns found in the two diurnal cycles showed consistency in that it clearly avoided the surface water during the day. This suggested that M. akrokomos may be a shade plankton with maximum densities below surface layer.

• Ocean and Polar Research
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• v.30 no.3
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• pp.303-312
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• 2008

Despite the impacts of the climate changes on the pelagic ecosystem, few studies have examined the pelagic-benthic coupling in the adjacent East China Sea and Korea Strait. Therefore, the species composition and abundance of the macrobenthic community, as well as the potential food sources of benthic fauna were investigated in the present study using stable isotope analysis (${\delta}^{13}C\;and\;{\delta}^{15}N$) for suspended particulate organic matter (SPOM), sedimentary organic matter (SOM), phytoplankton, and zooplankton. A total of 157 macrobenthic fauna were collected, and the density of the macrobenthic fauna ranged from 4 to 434 ind./0.25 $m^2$, with an average density of 149 ind./0.25 $m^2$. The density of the benthic fauna increased moving from offshore shelf sites to coastal sites adjacent to the Korea Strait. Cluster analysis showed that the macrobenthic communities consisted of three distinct groups: group A in the Korea Strait, group B in the East China Sea, and group C near Ieodo. The dominant species in group A were the amphipods Photis japonica and Ampelisca miharaensis, followed by the polychaete Scolotoma longifolia. Environmental variables, such as the temperature of the seawater and sediment, and oxygen, and chlorophyll a levels, appeared to affect the structure of the community, suggesting the importance of coupling with the pelagic system. The ${\delta}^{13}C$ values of SPOM and zooplankton ranged from -22.97 to -23.5% and -19.92 to -21.86%, respectively, showing a relatively narrow range(<1%) between the two components. The difference between the ${\delta}^{13}C$ values of SOM and pelagic organic matter was also within 1%, suggesting that the SOM originated from the pelagic system, which is an important factor controlling the macrobenthic community.

• Korean Journal of Ecology and Environment
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• v.51 no.4
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• pp.299-310
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• 2018

Odor compounds (geosmin, 2-MIB) have been causing problems in the Bukhan River system, but the causative organisms have not been clearly identified. To evaluate the relationship between dynamics of microbial community and odor compounds, two times monthly monitoring of water quality and microbial community from the three serial lakes (Lake Uiam, Lake Cheongpyeong and Lake Paldang) in the Bukhan River system were conducted from April to October 2017. The odor compounds were analyzed by HS-SPME analysis method using GC/MS. Bacteria communities were identified at the class level by NGS analysis. Actinobacteria and Betaproteobacteria were dominant taxon in bacteria community of three serial lakes. In the case of phytoplankton communities showed that seasonal changes by Bacillariophyceae and Cryptophyceae in spring, Cyanobacteria in summer, and Bacillariophyceae and Cryptophyceae in autumn. Dominant species was Dolichospermum (=Anabaena), Microcystis and Pseudanabaena in Bukhan River system in all study period. At the same time the odors geosmin and 2-MIB were also detected at high concentration. There is a significant positive correlation between proportion of Actinobaceria and 2-MIB concentration (r=0.491, p<0.01). In addition, proportion of cyanobacteria showed a significant correlation of geosmin (r=0.381, p<0.05) and 2-MIB (r=0.386, p<0.05) concentration. In this study, odor compounds in the Bukhan River system are considered to be a direct relationship between with Actinobacteria and cyanobacteria.

• Korean Journal of Ecology and Environment
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• v.37 no.1 s.106
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• pp.1-11
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• 2004

The limnological characteristics of a coastal lagoon were studied in Lake Hyangho, one of a series of brackish lagoons along the eastern coast of Korea. Phytoplankton community structure, physical factors, and chemical factors were surveyed from May 1998 through November 2002 on a two-month interval basis. Temperature, salinity, Secchi disc transparency, TN, TP, organic matter content of sediment, chlorophyll a concentration, dominant phytoplankton species, and phytoplankton cell density were measured. Salinity gradient was formed between the overlying freshwater stream water and the permeated seawater at the bottom. The chemocline was persistent at the depth of 2 ${\sim}$ 5 m that caused discontinuities of salinity, DO, and temperature profiles. The inversion of vertical temperature profiles with higher temperature in deeper layer was observed in early winter. Secchi disc transparency was very low with the range of 0.1 to 1.1m. TP, TN, and Chl. a concentration in the epilimnion was 0.011 ${\sim}$ 0.238 mgP $L^{-l}$, 0.423 ${\sim}$ 2.443 mgN $L^{-l}$, and 0.7 ${\sim}$ 145.2 mg $m^{-3}$, respectively. Sediment was composed of silt and coarse silt. COD, TP, and TN content of dry sediment were 19.7 ${\sim}$ 73.3 mg$O_2\;g^{-1}$, 0.61 ${\sim}$ 1.32 mgP $g^{-l}$ and 0.64 ${\sim}$ 0.88 mgN $g^{-l}$, respectively. Dominant phytoplankton species were chlorophytes (Ankistrodesmus falcatus) and cyanobacteria (Oscillatoria sp. and Merismopedia tennuissima). The total cell density was in the range of 560 ${\sim}$ 35,255 cells $mL^{-l}$.

• Journal of Environmental Science International
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• v.14 no.2
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• pp.177-184
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• 2005

This study was to determine the fluctuation in phytoplankton assemblages with regarding to environmental conditions and nutrients, which were surveyed around Mokpo waters in the southwestern waters, Korea. Sampling was carried out on the Mokpo, Sinan, and Wando coasts from March to November 2003. The maximum sea surface temperature was recorded in August, and it ranged around $25^{\circ}C$ regardless of sampling sites. However, salinity in Mokpo waters showed a great variation, which ranged from 5-30 psu and recoded the minimum of 5 psu in July and the maximum of 30 psu in November. Moreover, in Mokpo waters, the chlorophyll a and SS concentration of the surface layer were also the highest values of $20\;{\mu}g\;l^{-1}\;and\;40\;{\mu}g\;l^{-1}$, respectively than those of Sinan and Wando waters. The concentrations of $NH_4-N,\;NO_2-N,\;NO_3-N,\;and\;PO_4-P$ were also he highest values of $0.018\;{\mu}mol\;^l{-1},\;0.062\;{\mu}mol\;l^{-1},\;1.2\;{\mu}mol\;l^{-1}\;and\;0.078\;{\mu}mol\;l^{-1}$, respectively in Morpo waters than those of Sinan and Wando waters. During the period of this study, the majority of the taxa were diatoms; Thalassiosira rotula, Rhizosolenia setigera, Prorocentrum minimum, Chaetoceros curvisetus, Leptocylindrus danicus, Pseudonitzschia pungens, and Chaetoceros spp. were detected in the dominant species of phytoplankton. The dinoflagellates were relatively abundant during the summer season in Wando waters, which attained an abundance of $10-20\%$. In Mokpo waters, DIN/DIP was the highest value of 700 in March, whereas the lowest was shown in Wando waters. However, DIN/DIP value in summer at Wando waters was extremely reversed, which appeared to be associated with the development of dinoflagellates. On the bais of factor analysis using SYSAT 6.0, nutrient showed somewhat correlation with chlorophyll a. Consequently, the process of discharge of fresh water in Mokpo waters plays an important role in extremely fluctuation in nutrients and conditions. Although Wando waters maintains a lack of nutrients, it should be influenced by different water current and may be associated with a concentration of nutrients.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.14 no.1
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• pp.48-55
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• 2009

Seasonal variations of microalgal biomass and community composition in both the sediment and the seawater were investigated by HPLC pigment analysis in an estuarine muddy sandflat of Gwangyang Bay from January to November 2002. Based on the photosynthetic pigments, fucoxanthin, diadinoxanthin, and diatoxanthin were the most dominant pigments all the year round, indicating that diatoms were the predominant algal groups of both the sediment and the seawater in Gwangyang Bay. The other algal pigments except the diatom-marker pigments showed relatively low concentrations. Microphytobenthic chlorophyll ${\alpha}$ concentrations in the upper layer (0.5 cm) of sediments ranged from 3.44 (March at the middle site of the tidal flat) to 169 (July at the upper site) mg $m^{-2}$, with the annual mean concentrations of $68.4{\pm}45.5,\;21.3{\pm}14.3,\;22.9{\pm}15.6mg\;m^{-2}$ at the upper, middle, and lower tidal sites, respectively. Depth-integrated chlorophyll ${\alpha}$ concentrations in the overlying water column ranged from 1.66 (November) to 11.7 (July) mg $m^{-2}$, with an annual mean of $6.96{\pm}3.04mg\;m^{-2}$. Microphytobenthic biomasses were about 3${\sim}$10 times higher than depth-integrated phytoplankton biomass in the overlying water column. The physical characteristics of this shallow estuarine tidal flat, similarity in taxonomic composition of the phytoplankton and microphytobenthos, and similar seasonal patterns in their biomasses suggest that resuspended microphytobenthos are an important component of phytoplankton biomass in Gwangyang Bay. Therefore, considering the importance of microphytobenthos as possible food source for the estuarine benthic and pelagic consumers, a consistent monitoring work on the behavior of microphytobenthos is needed in the tidal flat ecosystems.

• Korean Journal of Ecology and Environment
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• v.37 no.1 s.106
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• pp.26-35
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• 2004

We investigated the effect of physicochemical environmental factors on the community dynamics of phytoplanktons and bacteria at the Hoeya Dam Reservoir, a drinking water reservoir for Ulsan city. Water samples were collected and analyzed every two to four weeks at three sites along the reservoir from April to October, 2001. During the study period, the Secchi depths were between 0.4 and 3.5 m. At the surface layer of water column, temperature ranged 10.2 ~ $32.0^{\circ}C$, pH 7.3${\sim}$9.6, dissolved oxygen 5.5 ${\sim}$ 12.4 mg $L^{-1}$, $BOD_5$ 0.8 ${\sim}$ 5.0 mg $L^{-1}$, $COD_{Mn}$ 3.7 ${\sim}$ 10.0 mg $L^{-1}$, and Chl-a 8.9 ${\sim}$ 60.9 mg $m^{-3}$. At the bottom layer, temperature varied 7.2 ${\sim}$ $28.9^{\circ}C$, pH 7.1 ${\sim}$ 9.3, dissolved oxygen 0.6 ${\sim}$ 9.7 mg $L^{-1}$, $BOD_5$ 0.8 ${\sim}$ 4.5 mg $L^{-1}$, $COD_{Mn}$ 3.9 ${\sim}$ 10.0 mg $L^{-1}$, and Chl-a 4.3 ${\sim}$ 81.9 mg $m^{-3}$. The numbers of phytoplanktons were 7.4${\pm}10^2{\sim}2.6{\pm}10^5$ cells $mL^{-1}$ at surface and 2.5${\pm}10^2{\sim}2.4{\pm}10^4$ cells $mL^{-1}$ at bottom, and were positively correlated with water temperature and Chl- a concentration. Genus Stephanodiscus and genus Oscillatoria dominated on April and on May, respectively. Cyanobacterial blooms of Aphanizomenon, Microcystis, Anabaena were observed from June to early September, and thereafter Stephanodiscus and Aulacoseiral dominated again. Total microbial counts ranged 1.73${\pm}10^4{\sim}1.68{\pm}10^5$ cells $mL^{-1}$, and were positively correlated with water temperature and phytoplankton counts at surface water. Heterotrophic plate counts (HPCs) ranged 30${\sim}4.1{\pm}10^3$ CFU $mL^{-1}$, and were positively correlated with $BOD_5$ and $NO^3\;^-$-N concentration at bottom water. Unlike the total microbial counts, the numbers of fecal coliforms and fecal streptococci as well as HPCs were higher at the bottom than the surface layer and were highest at the upper a site among the three sampling sites. Since the concentrations of fecal coliforms and streptococci were still high at the bottom of site c, where intake for water treatment plant is located, it appeared that special management of water treatment processes may be needed especially after strong rainfall.

• Korean Journal of Environmental Biology
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• v.28 no.3
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• pp.172-178
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• 2010

The bloom of the genus Stephanodiscus was gradually extinguished after 18 April. Counts of bacterial population were increased as the diatom bloom was disappeared. Numbers of the heterotrophic nanoflagellates and ciliates were also increased during the disappearance of the bloom. The densities of the mesozooplankton, the major predator of the diatoms, started to increase in April. However, their growth was suppressed during the bloom period of the diatoms (from January to March). During the bloom period of the diatoms, the monthly average value of the basic productivity amounted up to 11,765.7 mgC $m^{-2}day^{-1}$, which is relatively high value considering the low temperature and light during that period. The growth rate of phytoplankton in March, when the bloom was beginning to be supressed was 0.007. The growth rate of phytoplankton was negative value in April when the decreasing of the algal density was started.

• Korean Journal of Ecology and Environment
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• v.44 no.4
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• pp.347-357
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• 2011

We examined two reservoirs (Inkyung res. and Joongang res.) and two streams (Kyungan str. and Jecheon str.), all of which were eutrophic, during the 2010 warm season, to evaluate the water quality improvement activity (WQIA) of plant-mineral composite (PMC), which was previously developed to control suspended solids, including cyanobacterial bloom (Kim et al., 2010). We simultaneously measured both solid (S-MCLR) and dissolved microcystin-LR (D-MCLR), before and after PMC treatment, in the Joongang reservoir. Taking water body size and volume into account, we conducted the whole-scale experiment in the Inkyung reservoir, and mesocosm-scale experiments in the other three systems. The WQIAs of PMC were found to be comparatively high in SS (70~81%), TP (75~91%), BOD (65~91%), Chl-a (88~98%), phytoplankton (84~92%) and zooplankton (68~88%), except for the Kyungan stream, which was below 45% in all parameters. After PMC treatment, the concentrations of both SMCLR (47%) and D-MCLR (96%) decreased within two days, suggesting a mitigation possibility of hazardous chemicals such as agrochemicals and endocrine disrupters in the aquatic ecosystem. Our results collectively indicate that PMC is a useful agent to control suspended solids, including nuisance cyanobacterial bloom and their exudates, in an undisturbed water system with a long residence time.