• Ocean and Polar Research
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• v.30 no.3
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• pp.289-301
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• 2008

Community structure of heterotrophic protists and their grazing impact on phytoplankton were studied in Northwest Pacific Ocean during October, 2007. The study area was divided into four regions based on physical properties (temperature and salinity) and chlorophyll-a distribution. They were Region I of North Equatorial Currents, Region II of Kuroshio waters, Region III of shelf mixed water, and Region IV of Tsushima warm current from East China Sea. The distribution of chlorophyll-a concentrations and community structure of heterotrophic protists were significantly affected by physical properties of the water column. The lowest concentration of chlorophyll-a was identified in Region I and II, where pico-sized chlorophyll-a was most dominant (>80% of total chlorophyll-a). Biomass of heterotrophic protists was also low in Region I and II. However, Region III was characterized by low salinity and temperature and high chlorophyll-a concentration, with relatively lower pico-sized chlorophyll-a dominance. The Highest biomass of heterotrophic protists appeared in Region III, along with the relatively less important nanoprotists. In Region I, II and IV, heterotrophic dinoflagellates were dominant among the protists, while ciliates were dominant in Region III. Community structure varied with physical(salinity and temperature) and biological (chlorophyll-a) properties. Biomass of heterotrophic protists correlated well with chlorophyll-a concentration in the study area ($r^2=0.66$, p<0.0001). The potential effect of grazing activity on phytoplankton is relatively high in Region I and II. Our result suggest that biomass and size structure of heterotrophic protists might be significantly influenced by phytoplankton size and concentration.

• Korean Journal of Ecology and Environment
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• v.50 no.1
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• pp.148-156
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• 2017

In this study, we analyzed the relationship between phytoplankton community and physicochemical factors in 12 lakes located in Jeollanam-do based on the data surveyed from March to November 2014. Totally, 297 species of phytoplankton were identified including 98 Bacillariophyceae, 148 Chlorophyceae, 23 Cyanophyceae and 28 other phytoplankton taxa. The standing crops ranged from 124 to $59,148cells\;mL^{-1}$ and showed the highest in August with the increase of Cyanophycean cells. The self-organizing map (SOM) was optimized into $9{\times}6$ grid and was classified into 5 clusters based on the similarity of environmental factors and phytoplankton indices. The SOM results showed that phytoplankton communities had positive relationship with water temperature, SS, DO, BOD, TP and Chl-a, whereas low relationship with pH, TN, $NH_3-N$, $NO_3-N$, $PO_4-P$ and Conductivity. In Pearson's correlation coefficient, relationship between environmental factors and phytoplankton communities showed similar results with SOM.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2000.05a
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• pp.251-254
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• 2000

In this study, we investigated vertical distribution and seasonal changes of phytophlankton community in the Hae-Dong Reservoir from March 1999 to Feburary 2000. This reservoir is relativly small (surface area, 2.7 $km^2$) and is the source of drinking water supply to the eastern part of Pusan City. Samples were collected at 2 sites (1, 3, and 6 m; site 1, in front of the dam; site 2, inlet). The dominant group was Bacillriophyceae at both sites (over 63%), and other groups exhibited seasonal changes (high cyanobacterial density in summer; green algal communities in winter). Chrysophyceae and Dinophyceae were maintained lower level during the study period. Along the water depth, all classess of phytoplankton did not show distintive vertical distribution at both sites except during the blue-green algal bloom in the middle of July and late September. The phytoplankton community dynamics in the Hoe-Dong Reservoir was strongly affected by the hydrological factors such as concentrated precipitation and short retention time.

• Journal of Environmental Impact Assessment
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• v.20 no.3
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• pp.281-297
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• 2011

The specie composition, stranding crops and the dominant species of phytoplankton were studied in three streams, Namdae-stream, Yeongok-stream and Sacheon-stream from May 2008 to February 2009. The water qualities of the three streams which run into estuary were also examined using phytoplankton indicators. As the result, the phytoplankton appeared 94 taxa in Namdae-stream, 79 taxa in Yeongok-stream and 73 taxa in Sacheon-stream, diatoms appeared the most in phytoplankton. Genus Navicula and Cymbella in diatoms appeared to be over 10 taxa in each stream, N. cryptocephala, N. cryptotenella and N. gregaria, the pollution tolerance taxa, appeared more frequent in the downstream. Due to the separation of each substrate by the rapid water velocity in the upstream, Achnanthes minutissima, a known periphyton, was dominant in upstream site at Namdae and Yeongok-stream. Some construction areas and sites of downstream of Namdae-stream, Yeongok-stream and Sacheon-stream were shown to be polluted because pollution tolerance taxa, such as Cyclotella meneghiniana, Nitzschia palea and Oscillatoria limnetica, were dominant. The total of 20 taxa phytoplankton indicators were found, composed of 16 taxa of Water pollution algae including Oscillatoria limosa, 2 taxa of Clean water algae Meridion circulare and Staurastrum puntulatum, 1 taxa of Toxic algae Microcystis aeruginosa and 1 taxa of Taste and odor algae Fragilaria construens. Water pollution indicators were appeared frequently in polluted sites of biological water quality(DAIpo, TDI) and of sites containing high trophic state index(TSI). Therefore, using the phytoplankton indicators can assess water quality through relation of biological water quality and trophic state index.

• Journal of Environmental Science International
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• v.10 no.4
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• pp.259-267
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• 2001

Investigations were carried out to observe the seasonal succession of phytoplankton, and viable counts of bacteria from the mid to lower reaches of Nakdong Fiver. An intensive monitoring was conducted from May to December 1999 biweekly at 6 sites in a main channel and 3 tributaries. Although there are several sites with high nutrient loading from the basin, all of study sites showed mesotrophic states owing to high discharge(June~September). Relatively low algal biomass and CFUs(mean of chi. a, $12.3{\pm}$11.5 $\mu\textrm{g}${\el}l$, CFUs : 1.8${\times}10^7$) were observed during the rainy season. The diatom population was dominant(over 85% of total community) year-long with peaks(Stephanodiscus hantzchii) in the fall and winter. Dominance of blue-green algal groups during the summer was not observed in the summer. Microorganisms peaked in the summer and fall(June~September), affected mainly by the inputs of phytoplankton and nutrients. Biomass of phytoplankton and CFU counts were higher in the Kumho River than other tributaries and main channel.

• ALGAE
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• v.23 no.1
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• pp.31-52
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• 2008

This study analyzes characteristics of phytoplankton communities around Wolseong nuclear power plant by selecting 16 stations from July 2006 to June 2007 and understands the influences on standing crops and chlorophyll a of phytoplankton by passing through the cooling water system. The total species number is 283, among which diatoms is 208 occupying 73.5% of total taxa. The mean of total standing crops is 469,380-3,704,114 cells L-1. It is the highest in April 2007 because blooming of Chaetoceros socialis occurs during this period. The mean standing crops of microplankton and nanoplankton are average 129,666-3,392,640 cells L-1 and 240,943-650,505 cells L-1 respectively, which occupy 54.01% and 46.54% of total standing crops. The mean concentrations of total chlorophyll a is 0.64-5.39 μg L-1. The mean concentrations of chlorophyll a of microplankton, nanoplankton and picoplankton are 1.33 μg L-1, 0.21 μg L-1 and 0.49 μg L-1 respectively. Dominant species around Wolseong neclear power plant during this study are Chaetoceros debilis, Chaetoceros socialis, Leptocylindrus danicus, Pseudo-nitzschia fraudulenta, P. subfraudulenta and Thalassiosira decipiens. Fluctuation rates of standing crops and chlorophyll a concentrations of phytoplankton passing through the cooling water system are 22.80% and 50.48% respectively. Decrease of standing crops and chlorophyll a concentrations of phytoplankton means that community structure of phytoplnakton may change at the discharge areas.

• Journal of Korean Society on Water Environment
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• v.29 no.3
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• pp.428-437
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• 2013

Physico-chemical water quality parameters and the phytoplankton communities from 12 sites in Oship-stream, Songchunstream, and Namdae-stream, located Gyeongsangbukdo Uljin-gun, Yeongdeok-gun, and Pyeonghae-eup respectively, were investigated from April 2009 to February 2010. Oship-stream, which is an open estuary, was easily affected by ocean current compared to that of Songchun-stream and Namdae-stream. OS3 and OS4 conductivity was higher with a season average of 3,397 ${\mu}s/cm$. The streams were mesotrophic to hypertrophic. Biological oxygen demand (BOD) was about 3mg/L, which was level 2 on the water quality ratings, but a concentration of 5mg/L in April 2009 indicated increased pollution due to drought. A total of 118, 117, and 124 phytoplankton taxa were found in Oship-stream, Songchun-stream, and Namdae-stream, respectively. The apparent dominant species in the polluted waters included Cryptomonas ovata, Fragilaria construens var. venter, Oscillatoria limnetica, O. limosa, and Phormidium tenue. All of Oship-stream, SC2 and SC4 of Songchun-stream, and ND3 of Namdae-stream were eutrophic as a result of standing crop analysis. BOD was highly correlated with chlorophyll-a content(r=0.52). Phosphorus concentration and proliferation of phytoplankton were thought to most affect BOD concentration in all three streams.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.1
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• pp.451-455
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• 2012

Physicochemical water conditions and phytoplankton were investigated at Ggot-jee beach in Anmyondo, summer season of 2011. COD were sometimes recorded higher than 5.0mg/l and SS were always over 40mg/l. DO, pH and salinity were stable generally but low salinity was affected by heavy rainfall. In spite of relatively high concentrations of chlorophyll and phytoplankton standing stocks, discolored water phenomena(green or red tide) had not been occurred. A few dinoflagellate species were dominated in June and July, but general diatoms were dominant species of phytoplankton community in August. Escherichia coli concentrations were higher in August(>400CFU/100ml) than in July but it's not the level of hygienic problem.

• Ocean and Polar Research
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• v.27 no.2
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• pp.231-235
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• 2005

The European Iron Fertilization Experiment EIFEX studied the growth and decline of a phytoplankton bloom stimulated by fertilising $10km^2$ in the core of a mesoscale $(80{\times}120km)$ cyclonic eddy south of the Antarctic Polar Front with about 2 times 7 tonnes of iron sulphate. The phytoplankton accumulation induced by iron fertilization did not exceed $3{\mu}g\;chl\;a\;l^{-1}$ despite a draw down of $5{\mu}M$ of nitrate that should have resulted in at least double to triple the amount of phytoplankton biomass assuming regular Redfield-ratios for draw down after phytoplankton growth in the Southern Ocean. During EIFEX the fertilized core of the mesoscale eddy evolved to a hotspot for a variety of small and medium sized mesozooplankton copepods. In contrast to copepods, the biomass of salps (Salpa thompson)) that dominated zooplankton biomass before the onset of our experiment decreased to nearly extinction. Most of the species of the rnosozooplankton community showed extremely hiか feeding rates compared to literature values from Southern Ocean summer communities. At the end of the experiment, massive phytoplankton sedimentation reached the sea floor at about 3800m water depth.

• 한국해양학회지
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• v.28 no.2
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• pp.107-113
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• 1993

Interrelationship between bacterial and phytoplankton variables and associations of this relationship with phytoplankton community structure were studied from July, 1990 to October, 1991 in the estuarine system of Mankyung and dongjin Rivers where estuarine mixing is very active. During the study period only bacterial production and chlorophyll were always significantly correlated (r$^2$>0.36, p<0.02), suggesting that phytoplankton-biomass related process seemed to be related to bacterial production in the estuarine waters. However, bacterial production comprised only a small fraction (on average<2.6) of primary production throughout the study period, suggesting that those parameters were uncoupled. this might be partly due that phytoplankton, food particles for zooplankton, food particles for zooplankton, were mostly composed of large and/or chain-forming diatoms.