• Journal of Aquaculture
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• v.8 no.1
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• pp.47-58
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• 1995

Field studies on the seasonal succesion of phytoplankton population were carried out at the 25 stations of the breeding ground in Kogum-sudo, Southern coast of Korean peninsula in Feburuary, April, August and October, 1993. Sixty four species belonging to 40 genera were identified. Predominant species were mainly centric diatoms throughout the four seasons, two centric diatoms, Skeletonema costatum and Thalassiosira sp. and a pennate diatom, Thaiassionema nitzschioides in the winter; two pennate diatoms, Thaiassionema nitzschioides and Asterionella kariana, and especially a dinoflagellate, Heterocapsa triquetra (station 10) in the spring, two centric diatoms, S. costatum and Chaetoceros diadema in the summer; and a centric diatom, Rhizosolenia alata and a pennate diatom, Bacillaria paxillifer in the fall. The main red tide organisms in the breeding ground were dinoflagellates, Prorocentrum dentatum, P. minimum, P. triestinum, Ceratium furro, Gymnodinium sanguineum, Noctiluca scintillans, H. triquetra, Scrippsiella trichoidea and a diatom S. costatum in the Kogum Sudo. Seasonal phytoplankton cell numbers were in a wide range between $8.8\times10^3$ cells/l and 1.4\times10^6$ cells/l; The seasonal average cell numbers were $12.2\times10^4\pm5.9\times10^4$ cells/l $(mean\;\pm\;standard\; diviation)$ in the winter, $3.3\times10^4\pm1.4\times10^4$ cells/l in the spring, $48.4X10^4\pm40.0\pm10^4$ cells/l in the summer, and $3.6\times10^4\pm1.9\times10^4$ cells/l in the fall, respectively.

• Korean Journal of Environmental Biology
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• v.17 no.4
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• pp.481-492
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• 1999

The observations on the spatio-temporal distribution and seasonal fluctuations of phytoplankton community were carried out in Deukryang Bay of the Korean Southwestern Sea from June 1992 to April 1993. A total of 75 species of phytoplankton belonged to 47 genera was identified. In Deukryang Bay seasonal succession in dominant species; P. alata, G. flaccida, S. costatum, L. danicus and N. longissima in summer, St. palmeriana, Ch. curvisetus and B. paxillifera in autunm, S. costatum, Ch. curvisetus, E. zodiacus and Pn. pungens in winter, and As. glacialis, As. kariana, N. pelagica, Th. nitzschioides and S. costatum in spring, were very marked, that is to say, the communities structure of phytoplankton in Deukryang Bay appeared to be various species composition and it was occupied with diatoms all the year round. Phytoplankton standing crops fluctuated with an annual mean of $1.4{\times}10^5 cells/1 between the lowest value of 2.6{\times}10^3 cells/1 in July and the highest value of 1.0{\times}10^6 cells/1$ by S. costatum in January. Densities of the phytoplankton cell number by the samples of Deukryang Bay ranged from $2.6{\times}10^3cells/1 to 1.2{\times}10^5 cells/1 with the mean value of 3.6{\times}10^4cells/1 in summer, from 6.0{\times}10^3cells/1 to 2.6{\times}10^5 cells/1 with mean of 1.5{\times}10^5 cells/1 in autumn, from 1.3{\times}10^4cells/1 to 1.0{\times}10^6 cells/1 with mean 3.5{times}10^5 cells/1 in winter, and from 4.8{\times}10^3cells/1 to 6.0{\times}10^5 cells/1 with mean of 1.6{\times}10^5 cells/1$ in autumn. That is to say, phytoplankton standing crops was large in low temperature seasons, on the other hand small in high temperature seasons. Chlorophyll $\alpha$ concentration fluctuated between 0.l9 $\mu$g/l and 12.3 $\mu$g/l in March. in Deukryang Bay seasonal flucturation in chi-$\alpha$ concentration was not marked. Especially, chl-$\alpha$ concentration in the water around Deukryang Island located in the middle part of Deukryang Bay showed patchy distributions with a very high concentration. And chl-$\alpha$ concentration was high during a year. Therefore, phytoplankton production in Deukryang Bay could be very high year-round.

• Journal of the Korean Society for Marine Environment & Energy
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• v.13 no.3
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• pp.151-164
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• 2010

Field observations on the seasonal variations of environmental factors and phytoplankton community were carried out four times at 30 stations in the narrow strait between Yeosu and Dolsan Island of the Korean South Sea from September 2005 to May 2006. The ranges of water temperature, salinity and extinction coefficient in the surface waters were 5.6~26.3, 25.36~33.92 psu and 0.13~2.13, respectively. The water temperature measured higher at Gamak Bay in summer and spring. It measured higher at Yeosuhae Bay in autumn and winter. Salinity showed uniformity of distributions in almost all areas, except for an area near a sewage disposal outlet. Extinction coefficient indicated that the turbidity of Gamak Bay and the area near the sewage disposal outlet were higher than that of the Yeosuhae Bay. In the phytoplankton community were identified a total of 99 species belonging to 51 genera. The species composition showed itself to be various in summer and autumn, but poor in winter and spring with a high ratio of centric diatoms all the year round. Seasonal succession of dominant species were Skeletonema costatum and Chaetoceros curvisetus in summer, Eucampia zodiacus in autumn and winter, and Chaetoceros affinis and Thalassionema nitzschioides inspring. Standing crops of phytoplankton and Chlorophyll $\alpha$ concentration were greatly higher at Gamak Bay in summer with ranges of $0.2{\times}10^4\;cells\;L^{-1}$ to $296{\times}10^4\;L^{-1}$, and $1.94\;L^{-1}$ to $22.12\;L^{-1}$, respectively. From the results of principal component analysis (PCA), the northern part of Dolsan Island was divided into two or three regions from the characteristics of marine environment and phytoplankton community.

• Korean Journal of Ecology and Environment
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• v.47 no.4
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• pp.247-257
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• 2014

The construction of eight large weirs in the Nakdong River, Korea, caused a decrease in the water flow velocity and several physical changes to the water environment. Here, changes in phyto- and zooplankton communities and water quality in the areas near the eight weirs were investigated from 2011 to 2013, and relationships between phytoplankton abundances and environmental factors were analyzed. Special emphasis was given to the succession patterns in algal abundance based on temperature fluctuations. At the eight weirs, 24 dominant species were found. The most abundant phytoplankton species was Stephanodiscus sp. (39.4% of dominant frequency). Cyanobacteria of the genus Microcystis dominated during the summer, with an dominant frequency of 8.5% and cell abundance ratio of 36.6%. Significant correlations were observed between temperature and abundance of eight of the main dominant species; seven species showed positive correlations with temperature. Stephanodiscus sp., however, showed a negative correlation with temperature (r=-0.26, p<0.01). In addition, this species showed a significant negative correlation with the dominant algal species-Aulacoseira granulata and Aphanizomenon flos-aquae, with the zooplankton Copepoda and with Cladocera. On the contrary, seven other dominant species of algae showed significant positive correlations with zooplankton. Thus, we showed that the seasonal succession of plankton communities in the Nakdong River was related to the water temperature changes.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.24 no.1
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• pp.92-105
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• 2019

Spatial and temporal characteristics of phytoplankton communities around the coastal waters of Jeju Island were investigated with environmental factors such as water temperature, salinity, and dissolved oxygen. Monthly samples were collected at 0 and 30 m depths of 10 stations from March 2015 to February 2016. During the survey period, water temperature ranged in 13.7~25.9 and $13.6{\sim}20.8^{\circ}C$ at 0 and 30 m, salinity in 31.51~34.47 and 33.03~34.47 psu at 0 and 30 m, and dissolved oxygen in 6.12~8.10 and $5.73{\sim}7.88mg\;L^{-1}$ at 0 and 30 m, respectively. Chlorophyll-a ranged in 0.28~2.48 and $0.44{\sim}1.01{\mu}g\;L^{-1}$ at 0 and 30 m, respectively. Phytoplankton abundance fluctuated in the range of $5,300{\sim}639,900cells\;L^{-1}$ during the year, showing the lowest in February at all stations, and the highest in July at the northern and western sea as well as in August at the southern and eastern sea of Jeju Island. A total of 362 species were occurred including 181 spp. of Bacillariophyta, 147 spp. of Dinophyta and 34 spp. of other phytoflagellates. Dominant species with occupancy rate over 20 percent of phytoplankton abundance showed apparent seasonal succession such as Paralia sulcata and Skeletonema costatum in spring and autumn, 6 spp. of genus Chaetoceros in summer, and 2 spp. of genus Chaetoceros and Thalassionema frauenfeldii in winter. Monthly abundance in the northern and western sea fluctuated with similar tendency, and the southern and eastern sea also showed similar pattern of monthly abundance variation. Species composition and dominant species succession mentioned above were quite different from previous studies, so some physical changes such as water temperature, salinity and current pattern might cause the changes of phytoplankton assemblages around Jeju Island.

• Journal of Ecology and Environment
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• v.37 no.3
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• pp.113-122
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• 2014

The purpose of this study is to compare soil $CO_2$ efflux between burned and unburned sites dominated by Pinus densiflora forest in the Samcheok area where a big forest fire broke out along the east coast in 2000 and to measure soil $CO_2$ efflux and environmental factors between March 2011 and February 2012. Soil $CO_2$ efflux was measured with LI-6400 once a month; the soil temperature at 10 cm depth, air temperature, and soil moisture contents were measured in continuum. Soil $CO_2$ efflux showed the maximum value in August 2011 as 417.8 mg $CO_2m^{-2}h^{-1}$ (at burned site) and 1175.1 mg $CO_2m^{-2}h^{-1}$ (at unburned site), while it showed the minimum value as 41.4 mg $CO_2m^{-2}h^{-1}$ (at burned site) in December 2011 and 42.7 mg $CO_2m^{-2}h^{-1}$ (at unburned site) in February 2012. The result showed the high correlation between soil $CO_2$ efflux and the seasonal changes in temperature. More specifically, soil temperature showed higher correlation with soil $CO_2$ efflux in the burned site ($R^2$ = 0.932, P < 0.001) and the unburned site ($R^2$ = 0.942, P < 0.001) than the air temperature in the burned site ($R^2$ = 0.668, P < 0.01) and the unburned site ($R^2$ = 0.729, P < 0.001). $Q_{10}$ values showed higher sensitivity in the unburned site (4.572) than in the burned site (2.408). The total soil $CO_2$ efflux was obtained with the exponential function between soil $CO_2$ efflux and soil temperature during the research period, and it showed 2.5 times higher in the unburned site (35.59 t $CO_2ha^{-2}yr^{-1}$, 1 t = $10^3$ kg) than in the burned site (14.69 t $CO_2ha^{-2}yr^{-1}$).

• Korean journal of applied entomology
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• v.15 no.3 s.28
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• pp.111-126
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• 1976

Regional differences in economic importance of the four species of rice leafhoppers, viz., Laodelphax striatellus, Nephotettix cincticeps, Nilaparvata Iugens and Sogatella furcifera, were analyzed and discussed based on population surveys conducted in Suweon and in southern and south-western coastal areas. The economic importance of L. striatellus and N. cincticeps, which are found throughout the year in Korea, seems to be less in middle regions. This is believed due to effective natural control through severe winter climate, cultural practices in rice and barley growing, and natural enemies such as spiders. However, the economic importance of these two species is significantly greater in southern regions with a less severe winter climate, and where cultural practices in rice and barley favour synchronization between the life cycles of insects and the seasonal succession of host plants. with regard to N. lugens and S. furcifera, which cannot overwinter in Korea, initial populations are the result of long distance migration across the East China Sea. Weather elements related to their migration result in more abundant immigrants of these two species in southern than in middle regions. Thus, different policies are needed for the integrated control of rice leafhoppers in middle and southern Korea.

• The Korean Journal of Petroleum Geology
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• v.11 no.1 s.12
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• pp.18-26
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• 2005

An occurrence of inclined heterolithic stratification (IHS) is described from a tidal point bar in a 40-m-deep distributary of the macrotidai, Han River delta, Korea. The channel bank demonstrates a convex-upward profile with intermittent presence or wave-formed scarps and terraces near the low-water level. The vertical succession of IHS is approximately 25 m thick and dips into the channel with angles reaching up to $14^{\circ}C$. The IHS overlies 15 m of trough cross-bedded sand deposited in the channel bottom. Even though the channel as a whole is ebb dominated, the preserved cross bedding is predominantly flood directed because the mutually evasive nature of the ebb and flood currents causes the point bar surface to be flood dominated. The IHS itself consists of inter-stratified fine sand, sandy silt, and silt with an fining-upward textural trend. Seasonal discharge variations of the Han River are not obvious in the deposits, because tile large size, distal location, and energetic tidal environment of the studied channel reduces the impart of river-stage fluctuations.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.441-453
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• 2017

This paper described the spatio-temporal distributions in the phytoplankton community, such as species composition, standing crops, and dominant species, from July 2012 to April 2013 in the Coastal Waters of Central South Sea (CWoCSS) of Korea. A total of 87 species of phytoplankton belonging to 52 genera were identified. In particular, diatoms and phytoflagellates comprised more than 62.1% and 37.9% of the total species, respectively. The phytoplankton cell density fluctuated with an annual mean of $7.9{\times}10^4cells{\cdot}L^{-1}$ between the lowest value of $1.0{\times}10^3cells{\cdot}L^{-1}$ in spring and the highest value of $4.5{\times}10^5cells{\cdot}L^{-1}$ in winter. The seasonal succession of the dominant species were Chaetoceros curvisetus, Ch. debilis in summer, Eucampia zodiacus in autumn, E. zodiacus, Thalassiosira curviseriata in winter and Skeletonema costatum -ls (like species), Leptocylindrus danicus in spring. According to principal component analysis, the phytoplankton community of the CWoCSS was characterized by the mixing rate between the freshwater inflow from Somjin River and the seawater of the South Sea, Korea.

• Journal of Environmental Science International
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• v.19 no.11
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• pp.1407-1421
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• 2010

This study was carried out to elucidate the relation between water quality and structure of the aquatic ecosystem in the agriculture reservoir Otae-ji from January to December in 2009. The proportion of forest was 46.98%, which means that non-point sources are major contributor of water pollution in this area. The annual mean COD(Chemical Oxygen Demand) in Otae-ji was $3.6mgL^{-1}$, indicating, level II of environmental standards and the trophic state was mesotrophic. Although total phosporus concentration in the reservoir was high in August due to large inflow of nutrients from outside the reservoir during monsoon season, there was no break out of significant algal bloom in the summer. The seasonal succession of phytoplankton showed that the dinophyta dominated in the the spring, chlorophyta in the summer, chrysophyta and chlorophyta in the autumn and chrysophyta in the winter. In case of zooplankton, rotifers dominated in the most seasons, but cladoceran(Bosmina longirostris) dominated in June and copepod(Nauplii) in August. The macrophyte plants showed diverse species compositon consisted of 3 varieties, 24 species, 23 genera, 15 families and 14 orders. The macroinvertebrates also showed various FFG(Functional Feeding Groups) such as GC(Gathering-Collector), P(Predator), SH(Shedder), FC(Filter-Collector) and PP(Plant-Piercer). Ecosystem stability analysis using aquatic insects was classified as Group I, which has high resilience and resistance indices. A total of 14 species of fish was collected but exotic species such as Lepomis macrochirus and Micropterus salmoides were not found in Otae-ji. In conclusion, the preservation of healthy food wed in the reservoir ecosystem is closely related to water quality management as well as effective prevention of algal bloom by helping good material circulation in aquatic ecosystems.