• Proceedings of the Korean Environmental Sciences Society Conference
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• 2004.05a
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• pp.249-251
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• 2004

감천항 3개 지점에서 조사된 식물플랑크톤은 3강 46속 98종류였는데 Bacillario-phyceae가 34속 76종류(77.6%), Dinophyceae 9속 17종류(17.3%, Chrysophycese 3속 5종류(5.1%)였다. 항 내에서 출현한 종은 모두 85종류로 항 외에서 출현한 94종류보다 적은 종이 출현하였고 규조류는 항 내에서, 와편모조류는 항 외에서 많이 출현하는 경향을 보였다. 계절별로는 가을에 62종류로 가장 많이 출현하였고 겨울에 45종류로 가장 적게 출현하였다. 지점별 현존량은 1,434(Feb. 2003; st. 3)~최고 17,708 cell/ml(Aug. 2003; st. 1)의 범위였고 여름철에 규조류(특히, Pseudonitzschia pungens와 Chaetoceros curvisetus 등)의 현존량이 많았다. 그리고 Pseudonitzschia pungens는 여름에 항 내에서 8,133 cell/ml로 가장 높은 현존량을 보였고 항 외에서도 4,000 cell/ml 이상 높은 현존량을 보였다, 본 조사기산 동안 출현한 주요종은 1,000 cell/ml 이상 출현한 우점종으로, Chaetoceros curvisetus, Chaetoceros debilis, Pseudonitzschia pungens, Skeletonema costatum, Stephanopyxis turris 등 5종, 출현빈번종은 Chaetoceros curvisetus, Chaetoceros lorenzianus, Skeletonema costatum, Thalassiosira hyalina 등 4종, 4계절 모두 출현한 종은 Chaetoceros didymus var. anhlica 외 13종이었으며 적조원인종도 Ceratium furca 외 13종으로 조사되어 항 내의 주기적인 조사가 필요할 것으로 판단되었다. 군집분석으로 우점도지수는 최저 0.205~최고 0.616였고 종다양성지수는 최저 0.213~최고 0.597로 나타났다.

• Journal of Food Hygiene and Safety
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• v.39 no.5
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• pp.390-397
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• 2024

Domoic acid group toxins are a class of marine biotoxins associated with amnesic shellfish poisoning (ASP). These toxins are primarily synthesized by Pseudonitzschia spp., diatoms which proliferate in coastal waters and accumulate in bivalve mollusks, potentially causing toxicity upon consumption. In Korea, Pseudonitzschia spp. blooms are predominantly observed in spring and fall. Regulatory standards for domoic acid group toxins in marine products are being developed and enforced to address the issue of ASP. The World Health Organization (WHO) and the European Food Safety Authority (EFSA) are actively proposing and managing safety thresholds to mitigate human exposure. This review provides a comprehensive overview of the physicochemical properties of domoic acid toxins, analytical methods for their detection, documented cases of human exposure, and current domestic and international regulatory frameworks. This study establishes a robust foundation for systematic monitoring and effective safety management of domoic acid group toxins.

• The Korean Journal of Malacology
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• v.15 no.2
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• pp.105-113
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• 1999

This study was measured environmental factors of flat oyster habitats and biomass of flat oyster to improve the productivity of flat oyster. Water temperature and salinity of the flat oyster habitat ranged from 5.5 to 27.4$^{\circ}C$ and from 31.2 to 33.4 , respectively. Average concentrations of DO, COD, DIN and PO$\_$4/$\^$3/ -P were 7.11 mg/l, 4.55 $\mu\textrm{g}$-at./l and 0.36 $\mu\textrm{g}$-at./l respectively. Surface sediments at the sampling area were composed of coarse sand, sandy silt and silty sand. Average level of IL, COD and AVS in the surface sediments were 2.6%, 13.70 mg/g dry and 0.33 mg/g dry respectively. In each sampling station, total standing crops of phytoplankton showed peaks twice in February and August. Dominant species of phytoplankton occurred in Haechang Bay throughout the year were Skeletonema costatum, Paralia sulcata, Eucampia zodiacus, Chaetoceros curvicetus, C. affinis, C. debilis, C. decipiens, Asterionella glacialis, Pseudonitzschia longissima, Pseudonitzschia seriata, Ceratium furca and C. fusus. Ten species of the bivalves were collected at the flat oyster habitat. Most of bivalves were the eutrophic species Ostrea denselamellosa, Crassostrea gigas, Ruditapes philippinarum, Scaphraca subcrenata, Scapharca broughtonii, Atrina pectinata, Fulvia mutica, Mytilus edulis, Protothaca jedoensis and Megacardita ferruginosa. The mean density of them was 21 inds./㎡ (479.14 g/㎡), while that of the flat oyster was at 0.25 inds./㎡ (231.25 g/㎡).

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.65.3-66
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• 2003

Bacillariolide III was isolated from the culture medium of the marine diatom, Pseudonitzschia multi series, a causative organism of amnesic shellfish poisoning by Shimizu et al. This extracellular metabolite features bicyclic system of hydroxycyclopentane and (Z)-pentenoic acid-bearing lactone ring. Bacillariolide I is known to possess significant inhibitory activity against phospholipase A$_2$, but the biological function of bacillariolide III is still under investigation. The unique structural feature as well as the promising biological activity led us to the total synthesis of bacillariolide III. (omitted)

• Ocean and Polar Research
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• v.23 no.3
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• pp.245-253
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• 2001

To investigate the community structures and the their seasonal variation of phytoplankton and zooplankton, a study was conducted at 6 selected stations during the period from April 1999 to October 2000 in the marine ranching ground off Tongyeong. One hundred ninety species of phytoplankton were identified, including 146 diatoms, 38 dinoflagellates, 4 silicoflagellates and 2 euglenophytes. Phytoplankton standing crops varied extensively by months and stations, ranging from $3.0{\times}10^4\;cells/l\;to\;1.0{\times}10^6\;cells/l.$. The dominant species varied from the vertical distribution as well as seasonal changes. In April and July 1999, Skeletonema costatum and Ceratium fusus were predominant in both the surface and the bottom water columns. Leptocylindrus danicus was the dominant species in April and June 2000, and Thalassiosira spp. were also predominant in bottom waters in June 2000. Pseudonitzschia pungens and Chaetoceros spp. were the dominant species at both surface and near bottom waters in August and October 2000, respectively. Zooplankton abundance was comparatively high in April and July in 1999, and April, June, and October in 2000, but extremely low in November 1999. The density of dominant zooplankton was higher in 2000 than in 1999. Copepods were the most predominant group except for July 1999 when the bivalve larvae showed extremely high abundance. Acartia omorii and Oithona similis were the dominant or subdominant copepod species mainly in April 2000, and June/July, while O. davisae and O. plumifera had peaks in August and October 2000. Corycaeus affinis and Paracalanus sp. also showed higher peaks in April and June (or July), even though they occurred in all sampling time. Centropages abdominalis occurred abundantly only in April 1999. Oikopleura dioica, a gelatinous zooplankton, was another important zooplankton, showing high density in all samples except in July 1999.

• Korean Journal of Environmental Biology
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• v.21 no.2
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• pp.132-141
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• 2003

We carried out a study on thermohaline structure and phytoplankton com munity in the East China Sea during early summer in 2005. As a result of marine environment and phytoplankton community, three characteristics of water type were identified. The former was characterized by the dominant species with diatoms, Chaetoceros lacinious, Ch. decipiens, Guninardia flaccida, Paralia sulcata, Pseudonitzschia pungens and Pseudosolenia calcar-avis in Chinese coastal waters, the secondary was done by lower water temperature, salinity and the dominant species with dinoflagellates, Prorocentrum donghaiense and Ceratium fusus, in over-all areas and the latter was done by the dominant species with coastal species of diatoms, Skeletonema costafum and Nitzschia longissima and silicoflagellate, Dictyocha speculum var. octopers in the transfer areas of Chinese continental coastal waters. Phytoplankton community in the surface layer identified a total of 66 species belonging to 36 genera. Dominant species was Prorocentrum donghaiense, Chaetoceros lacinious, Skeletonema costatum. Standing crops of phytoplankton in the surface layer flue tuated between $1.5 \times 10^4$cells $L^{-1}$ and $3.5\times 10^{5}$ cells $L^{-1}$. And the highest value appeared in the Changjiang estuaries with high dominance by diatoms and lowest one occurred in the southwestern area of Jeju Island with high dominance by dinoflagellates. Red tides with dinoflagellate, Prororcentrum donghaiense appeared in the frontal areas with mazimum cell density, $3.4\times 10^5$ cells $L^{-1}$. And outbreak environments was low water temperature under $20^{\circ}C$, and low salinity under 31.55 psu. The vertical distribution of red tide organisms went to about 30m depth from surface.

• Journal of Environmental Science International
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• v.28 no.11
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• pp.1005-1017
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• 2019

Environmental factors and changes in phytoplankton community structure before (August 5, 2017), during (August 18 and 25) and after (August 30 and September 15) freshwater input were analyzed to investigate the effects of freshwater input from Ganwol and Bunam lakes located in the upper part of Cheonsu Bay. Due to the large amount of freshwater input in the Cheonsu Bay, the surface salinity of the bay decreased by more than 8 psu, and the thermocline existing in the bay during August weakened. In addition, hypoxic phenomena occurred temporarily in the bay as the low oxygen water mass from the freshwater lakes flowed into the bay, and chemical oxygen demand, nutrients, and N/P increased with freshwater inflow. The density of phytoplankton during the freshwater inflow increased owing to their input from the freshwater lakes. Diatom species (Eucampia zodiacus) dominated the phytoplankton community in the bay before freshwater input; nanoflagellates, chlorophyta, cyanobacteria, and diatoms (Pseudonitzschia delicatissima, Chateocceros spp.) entered during freshwater input; and after freshwater inflow ended, diatoms (Chateocceros spp.) again became predominant indicating a return to previous conditions. The amount of phytoplankton standing crops increased sharply due to the inflow of freshwater species into the bay on the second day of discharge compared to before freshwater input; pre-discharge conditions were restored at most stations except at some sites close to the Bunam Lake three days after discharge. Therefore, the large amount of freshwater flowing into the bay affects not only the geochemical circulation in the bay but also the phytoplankton community structure. In particular, the high concentration of nutrients in the freshwater lake affect the marine ecosystem of the bay during August.

• 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.5 no.1
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• pp.27-36
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• 2000

We investigated the phytoplankton community from June to September 1997 in the waters off Kohung, Korea where red tides dominated by harmful dinoflagellates had occurred from August to September or October since 1995. We took water samples five times from 5 depths at 6 or less stations in this study period. The most dominant harmful dinoflagellate during the red tide which had outbroken on August 24, 1997 was Gyrodinium impudicum, not Cochlodinium polykrikoides. On August 21 just before the harmful red tide occurred the abundance of G. impudicum at the inner bay station, 90cells $ml^{-1}$, was higher than that at the outer bay station. However, on August 27 just after the red tide had outbroken, the abundance of G. impudicum at the inner bay station did not increase, whereas that at the outer bay increased rapidly and reached to the maximum of 30,000 cells $ml^{-1}$. Instead, diatoms such as Skeleltonema costatum, Chaetoceros pseudocurvisetus, Pseudonitzschia pungens rapidly increased at the inner bay station where fresh water from lands has reached. The high abundance of diatoms might have inhibited the growth of red tide dinoflagellates at this station. The transport of already formed red tide patches from offshore areas, aggregation of scattered cells driven by physical forces, and/or competition between diatom and dinoflagellates might be responsible for this appearance of dense red tide patches at the outer bay station.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.41 no.2
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• pp.129-139
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• 2005

We investigated the characteristics of the thermohaline structure and phytoplankton community from the southwestern areas of Jeju to the nothern areas of Taiwan in the Ease China Sea, in June 2004. According to the analysis of a T-S diagram, three characteristic of water masses were identified. We classified them into the mixed water mass by the Chiness continental coastal waters and Yellow Sea cold water (Region A), Chinese continental coastal waters (Region B) and Taiwan warm current (Region C). Region A was characterized by low temperature, low salinity, high density and high Chl-a concentration. Region B was characterized by high temperature, low salinity, low density and high Chl-a and Region C was characterized high temperature, high salinity, low density and low Chl-a concentration. The phytoplankton community identified a total of 56 species belonging to 31 genera. The dominant species was mainly dinoflagellates, Gymnodinium breve, Scrippsiella trochoidea, Ceratium fusus, Prororcentrum triestinum, centric diatoms, Chaetoceros lorenzianus, Leptocylindrus danicus, Proboscia alata, Skeletonema costatum and pennate diatoms, Pseudonitzschia pungens, Cylidrotheca closterium. Standing crops of phytoplakton fluctuated between $0.1{\times}10^2$ cells/L and $5.7{\times}10^4$ cells/L by dominance of dinoflagellates. In the phytoplankton community, the Region A was characterized by the various species composition in 39 species, the dominint species with di-atomes, Pn. pungen, Ch. lorenzianus and standing crops from 6.9 cells/$m\ell$ to 56.6 cells/$m\ell$, Region B by the various species composition in 37 species, the dominant species with dinoflagellates, G.breve, S. trochoidea and standing crops from 4.6 cells/$m\ell$ to 26.7 cells/$m\ell$, and the Region C by low species number with 28 species, the dominant species with one dinoflagellate, S.trochoidea and one diatom, L.danicus and very low standing crops from 0.1 cells/$m\ell$ to 5.7 cells/$m\ell$. Phytoplankton productivity in the East China Sea was controlled by Chinese continental coastal waters which include a high concentrations of nutrients.