• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.2
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• pp.93-102
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• 2001

Biomass and species composition of phytoplankton and zooplankton along the salinity gradients in the Seomjin River estuary were investigated in March, July, September and November, 1999. The locations of sampling sites were set based on the surface salinity during each cruise rather than geographic locations. A total of 96 phytoplankton species were identified with 60 diatom species in the study area. The species number of green algae was relatively high in low salinity region while the number of dinoflagellates increased in high salinity areas. Monthly mean of phytoplankton biomass ranged from 183 cells/ml to 833 cells/ml. There was a diatom bloom of Skeletonema costatum in November at the 5-15 psu salinity region and sharp decrease of biomass in very low salinity region occurred in March. During the rainy season in July with the salinity less than 8.1 psu, the green algae dominated in most of the study areas. Chroomonas spp. were highly dominant in March and September and the biomass increased towards the high salinity regions. A total of 83 zooplankton taxa were identified with 72 marine and 11 freshwater taxa. Major group of marine form was copepods with34 taxonomic groups. Most freshwater taxa were aquatic insects. Threshold salinities of freshwater zooplankton appearance were 8.1 psu in July, 4.7 psu in September, and 0.2 psu in November. The number of taxa appeared and abundances of zooplanktons were minimal in the middle of salinity gradients in this estuary.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.1
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• pp.42-51
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• 2016

We investigated the distribution of dissolved nutrients, phytoplankton community structure and utilization of nitrogen compounds by dominant species in the southwestern part of East Sea in September, 2014. Dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) were lower in the surface layer, and concentrations were increased with depth. Dissolved organic nitrogen (DON) and dissolved organic phosphorus were the opposite of dissolved inorganic nutrients. Although DIN DIP ratio in all of the water masses was higher than Redfield ratio (16), DIN : DIP ratio in mixed layer was about 2, indicating that inorganic nitrogen is the limiting factor for the growth of phytoplankton. In particular, DON proportion in dissolved total nitrogen was about 88 % in the mixed layer where inorganic nitrogen is limiting factor. The dominant species Chaeotceros debilis and Prorocentrum minimum were able to grow using DIN as well as DON such as urea and amino acids. Therefore, DON utilization of phytoplankton may play a role as a survival strategy in the DIN-limited conditions of East Sea.

• Korean Journal of Environmental Biology
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• v.18 no.1
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• pp.1-20
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• 2000

There are increasing evidences of climate change in the Antarctic and Arctic Oceans, especially elevated temperature due to the continuous burning of the fossil fuels and ultraviolet B(UV-B) flux within the ozone hole. Light-dependent, temperature-sensitive, and fast-growing organisms respond to these physical and biogeochemical changes. Polar marine phytoplankton, which are pioneer endemic species and important carbon contributors in the polar waters, are therefore highly suitable biological indicators of such changes. By virtue of light requirement, the primary producers are exposed to extreme seasonal fluctuations in temperature, photosynthetically active radiation, and UV radiation. Local environmental warming and increased UV-B radiation during ozone depletion may have profound effects on the primary producers that are primary carbon producers in the polar water. Small changes in climate temperature and solar radiation may have profound effects on the activity threshold of the polar phytoplanktion. To demonstrate biological response to the environmental changes, standardized representative natural and biological parameters are needed so that replicate samples (including controls) can be taken over extended periods of time. In this paper, we review general characteristics of polar phytoplankton, their environment, environmental changes in the polar waters, the effects on the environmental changes to the polar phytoplankton, and the importance of the polar phytoplankton to understand the global environmental changes. [Biological indicators, Global environmental change, Polar phytoplankton, UV].

• 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.

• Korean Journal of Environmental Biology
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• v.32 no.1
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• pp.75-87
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• 2014

This study describes about the spatio-temporal distributions in phytoplankton community such as species composition, standing crop and dominant species from May 2006 to February 2007 in the Jangsu bay and the northwestern parts of Gamak bay. Based on the principal component analysis (PCA) of the environmental factors as well as biological parameters, the bio-oceanographical characteristics were analysed. A total of 83 species of phytoplankton belonging to 47 genera were identified. Whereas diatoms and dinoflagellates occupied more than 65% and 30% of total species, respectively. The annual dominant species were Chaetoceros affinis, Paralia sulcata and Bacillaria paxillifera in spring, Chaetoceros didymus, Ch. affinis and Octactis octonaria in summer, Skeletonema costatum-like species and B. paxillifera in autumn. Moreover phytoplankton cell density was ranged between 3.1 $cells{\cdot}mL^{-1}$ in spring and 521.0 $cells{\cdot}mL^{-1}$ in winter. It fluctuated with an annual mean of 76.0 $cells{\cdot}mL^{-1}$ between the lowest value of 7.6 $cells{\cdot}mL^{-1}$ in spring and the highest value of 220.2 $cells{\cdot}mL^{-1}$ by Skeletonema costatum-like species in winter. Briefly, the phytoplankton cell density in the mixing seasons was higher in comparison with the other seasons. According to the PCA, the biological oceanographic characteristics of the Jangsu bay was affected by the introduction of outside seawater particularly in temperature increasing seasons, and the other seasons, it may be described the light intensity, and mix between inner and outer bay sea waters.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.22 no.3
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• pp.77-87
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• 2017

Picophytoplankton, an important primary producer especially at the oligotrophic region, is known to contribute a significant portion of the total phytoplankton biomass in the East Sea of Korea. During autumn in the southwestern East Sea, frequent upwellings and oligotrophic conditions occur and annual variation of primary productivity is known to be significant. Moreover sea surface temperature (SST) of the East Sea is steeply increasing compared to global average increase, so various changes in marine ecosystem related with increase of SST are reported. Taking such circumstances into consideration, we measured the contribution from picophytoplankton fraction to total phytoplankton composition by size fraction of phytoplankton biomass during the autumn seasons from 2011, 2013 and 2015 and examined the variation of the phytoplankton composition. As a result of size fraction analyses, we found that the variation of contribution from picophytoplankton(<$3{\mu}m$) to total community of phytoplankton was high and the average fractions of picophytoplankton were measured as 38% (2011), 59% (2013), 7% (2015), respectively. The difference between measured SST and annual mean SST (${\Delta}T$) was highest ($+1.6^{\circ}C$) in autumn of 2013 and lowest ($-0.9^{\circ}C$) in autumn of 2015. The close positive correlation between ${\Delta}SST$ and fraction of picophytoplankton was confirmed($R^2$ > 0.9). The increase in SST at the southern East Sea was confirmed as one of the main environmental factors in the increase in the increase of the contribution from picophytoplankton. Monitoring of changes in the community structure of primary producers and the influences of the environmental factors including SST in the East Sea is necessary to understand the interactions of ecosystem of the East Sea and the climate change in the near future.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.13 no.4
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• pp.333-341
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• 2008

Three embankments are located in the Chunggye Bay, each named as Changpo, Bokkil and Kuil and environmental changes are expected due to freshwater input. To investigate this phenomenon, three sample sites in front of each embankment gate were selected in Nov. 2006(autumn), Feb. 2007(winter), May. 2007(spring) and Aug. 2007(summer). At every point of embankment spot, large cells(micro-size, >$20\;{\mu}m$) of phytoplankton were turned out to be a major cause of algal bloom in Feb. 2007 and nano-size($2-20\;{\mu}m$) phytoplankton became dominant during rainy season. In rainy season, each point of embankment showed low salinity and transparency with higher ammonium and phosphorus concentrations than dry season. However, the number of phytoplankton has decreased and it is expected that freshwater influx has more influence on high turbidity and radical decrease of salinity than nutrient. According to the results of this study, therefore, nutrient could have more influence on growth of phytoplankton in dry season, but high turbidity and radical changes of salinity have more influence in rainy season.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.16 no.1
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• pp.27-38
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• 2011

The distributions of phytoplankton assemblages and environmental factors in Jinhae Bay and their relationships were investigated to estimate the potential limiting nutrient for phytoplankton growth and community structure. In situ algal bioassay experiments were also conducted to assess the species-specific characteristics in phytoplankton responses under different nutrient conditions (control, N(+) and P(+) treatment). During the study periods, bacillariophyceae and cryptophyceae occupied more than 90% of total phytoplankton assemblages. Phytoplankton standing crops in the inner part of Masan Bay were higher than that of Jinhae Bay. The DIN:DIP ratio, pH and transparency showed the significant positive correlation with phytoplankton biomass. According to cluster and multidimensiolnal scaling (MDS) analysis based on phytoplankton community data from each station, the bay was divided into three groups. The first group included stations from the south-western part of Jinhae bay where cryptophyta species were dominated. The second group was distinguished from inner stations in Masan Bay. These stations showed low transpancy and high DIN:DIP ratio. The other cluster included the stations from the eastern part and central part of Jinhae Bay, which was characterized by the high DSi:DIP ratio and dominant of diatom species. Phosphorous (P) was limited in Masan Bay due to significantly increases in the phytoplankton abundances. Based on stoichiometric limitation and algal bio-assay in Jinhae Bay, nitrogen (N) was a major limiting factor for phytoplankton production. However, silicate (Si) was not considered as limiting factor, since Si/DIN and Si/P ratio and absolute concentration of nutrient did not create any potential stoichiometric limitation in the bay. This implies that high Si availability in winter season contributes favorably to the maintenances of diatom species.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.4328-4334
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• 2015

We determined a method to determine marine planktonic organism viability using Evan's blue, Aniline blue, and 5-choromethyfluorescein diacetate (CMFDA). The Evan's blue and Aniline blue methods produced bright blue light for dead phytoplankton and zooplankton and were the best dyes to detect dead cells. The staining efficiency of Evan's blue and Aniline blue were ${\geq}90%$ of the original field sample. However, it was difficult to test the efficiency of a ship's ballast water treatment system because detection of living cells. In contrast, the CMFDA method, which is based on measuring cell esterase activity using a fluorimetric stain, was the best dye to detect live cells of almost all phytoplankton species, and staining efficiency was 70%. The CMFDA method is similar to the fluorescein diacetate (FDA) staining method. Therefore, we estimated viability of phytoplankton species using a double-staining method by combining CMFDA and FDA to determine optimum staining efficiency. As a result, the frequency of dying cells based on the double-staining method was 95%, which was significantly higher than that of single CMDFA staining. Our results suggest that a CMDFA + FDA assay is more effective to determine survival of marine plankton and that this method was applicable to investigate the efficacy of a ship's ballast water treatment system.

• Ocean and Polar Research
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• v.29 no.3
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• pp.273-282
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• 2007

For an efficient management and utilization of marine biodiversity information, we made an attempt to develop the Korea Marine Biodiversity Information System (KoMBIS), building a species name inventory of Korea marine organisms. The inventory includes 17 organism groups: phytoplankton, zooplankton, algae and halophyte, sponges, cnidarians, rotifers, nematodes, bryozoans, brachiopods, molluscs, echiurans, annelids, arthropods, echinoderms, urochordates and fish. The species names were collected from 37 different references and reviewed for validity by taxonomists, which resulted in 9,798 valid names in addition to 1,845 synonyms. The Korea marine species inventory is the first one of this kind, for previous Korean species name inventories were mostly composed of terrestrial and freshwater organisms. KoMBIS, the information system developed, contains not only the species name but also information on morphological and ecological characteristics such as distribution, DNA barcode, and references. This system is convenient for the inputting of new data and servicing users through the internet, so that management and utilization of the biodiversity information is more efficient. Linking the DNA barcode data with species information provides an objective measure for identification of a species, which accommodates the recommendation of Consortium for the Barcode of Life, and makes the Korea marine biodiversity information compatible with international databases. Considering the frequent exchange of marine organisms internationally via ballast water and such issues as climate change, this information system will be useful in many areas of marine biodiversity.