• 한국환경과학회지
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• 제17권4호
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• pp.439-449
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• 2008

Algicidal bacterium was isolated from sea water during the declining period of Cochlodinium polykrikoides blooms and this bacterium had a significant algicidal activity against C. polykrikoides. In this study, algicidal bacterium was identified on the basis of biochemical and chemotaxonomic characteristics, and analysis of 16S rDNA sequences. The algicidal bacterium showed 98.6% homology with Micrococcus luteus ATCC $381^T$. Therefore, this bacterium was designated Micrococcus luteus SY-13. The optimal culture conditions of the algicidal bacterium was $25^{\circ}C$, initial pH 8.0, and 3.0% NaCl concentration. M. luteus SY-13 is assumed to produce secondary metabolites which have algicidal activity. When 10% culture filtrate of this strain was applied to C. polykrikoides ($1.0\;{\times}\;10^4\;cells/ml$) cultures, over 98% of C, polykrikoides cells were destroyed within 6 hours. The culture filtrate of M. luteus SY-13 exhibited similar algicidal activity after heat-treatment at $121^{\circ}C$ for 15 min. While algicidal activity remained in filtrates with pH adjusted to 8.0, loss of algicidal activity occurred when the pHs of filtrates were adjusted to over 9.0 or heat-treated at $121{\times}180^{\circ}C$ for 1 hour. M. luteus SY-13 showed significant algicidal activities against C. polykrikoides (98.9%) and a wide algicidal range against various harmful algal bloom (HAB) species. However, there was no algicidal effect on diatom and marine livefood organisms except Isocrysis galbana. These results suggest that M. luteus SY-13 could be a candidate for use in the control of HABs.

• 한국전자통신학회논문지
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• 제14권6호
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• pp.1161-1170
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• 2019

본 연구에서는 심층 신경망을 이용하여 Cochlodinium polykrikoides 적조 발생을 예측하는 모델을 제안한다. 적조 발생 예측을 위해 8개의 은닉층을 가진 심층 신경망을 구축하였다. 위성 재분석 자료와 기상수치모델 자료를 이용하여 과거 적조 발생해역의 해양 및 기상인자 총 59개를 추출하여 신경망 모델 학습에 활용하였다. 전체 데이터셋 중 적조 발생 사례는 적조 미발생 사례에 비해 매우 적어 불균형 데이터 문제가 발생하였다. 본 연구에서는 이를 해결하기 위해 과표집화(Over sampling) 기반 데이터 증식(Data augmentation) 기법을 적용하였다. 과거자료를 활용하여 모형의 정확도를 평가한 결과 약 97%의 정확도를 보였다.

• 한국수산과학회지
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• 제29권2호
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• pp.165-173
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• 1996

무각류의 와편모조인 C. polykrikoides에 의한 적조는 맹독성으로 알려져 있으며, 이로 인한 어패류의 폐사로 매년 막대한 손실을 초래하고 있어, 어패류 폐사의 원인 독성분을 규명하고, 유용 조류로서 활용하기 위한 기초 자료를 얻을 목적으로 93년 10월 경남 통영군 욕지도 인근에서 발생한 적조시 채취한 천연 조체를 시료로 수종의 생리활성을 검색하였다. MeOH 추출물의 마우스 치사 독성은 없었으며 (지용성 획분 : 50mg, 수용성 획분 : 10mg), 미량 형광 HPLC 분석에서도 마비성이나 설사성 패류독은 검출되지 않았다. 또한, 5mg/ml의 농도에서는 어독성을 나타나지 않았으며, 항균성도 없었다 (10mg/disc). P-388 종양 세포에 대하여는 지용성 획분이 $180{\mu}g/m1$의 농도에서 $20\%$의 생육 저지활성을 나타내었고, 아미노산 분석에서 2개의 미확인 아미노산이 검출되었다. 용혈활성을 나타내는 성분은 지용성, 수용성 양 획분에 모두 존재하였으며, 지용성 획분중의 성분으로서는 EPA와 DHA가 동정되었고, 이들이 총지방산의 $40.6\%$를 차지하여 고도 불포화 지방산 자원으로서 이용 가능성을 시사하였다.

• 한국양식학회지
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• 제11권3호
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• pp.285-294
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• 1998

When Cochlodinium polykrikoides came into the culture tanks through influent cultivated water during the red tides, hundred thousands of commercial flounders were concomitantly killed and many culturists suffered from a great deal of financial loss in the east coast of Korea. It is charactrized by high sinking rate after sunset and the formatino of clump which results in oxygen deficiency by its respiration at tank bottom under condition. We investigated the efficacy of hydrogen peroxide and chlorine dioxide, known to form radicals, for extermination of red tide organism C. polykrikoides. When C. polykrikoides seawater with a density of 6,000 cells/$m\ell$ was treated with 14, 28 and $42mg/\ell$ of hydrogen peroxide, its survival rate was markedly decreased to 9.8, 0.8 and 0.3% respectively immediately after 6 hours of treatments whereas when it was treated with 1.5, 2.1 and $3.0mg/\ell$ chlorine dioxide, its survival rate showed 87.7, 81.3 and 80.1 and 80.1% respectively at the same treatment time. Hydrogen peroxide was the effective agent since it has scarcely injured the cultured olive flounder when exposed to the tested concentration range of $14~28mg/\ell$ with the extermination of almost3 C. polykrikoides during the experimental period of 5 days and has shown the oxygen increase of approximately $1.23mg/\ell$ 2 hours immediately after the flounder by C. polykrikoides in the land-based culture tank is assumed to be not by the toxicity of itself but by oxygen dificiency from the rapid respiration of dinoflagellate clump sunken to the tank bottom.

• 한국환경과학회지
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• 제9권3호
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• pp.215-221
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• 2000

The relationship between the distribution of sea surface temperature(SST) and dinoflagellate(Cochlodinium polykrikoides) bloom areas were studied. The SST data were derived from the infrared channels of AVHRR(Advanced Very High Resolution Radiometer) sensor on NOAA(National Oceanic and Atmospheric Administration) 12 and 14 satellites during 1995-1998. The initial water temperature at C. polykrikoides bloom was about 21${\circ}C$ at the coastal areas of the South Sea and along the shore of the East Sea of Korea during the summer season of 1995. The northern limit of red tides was coincident with that of 21${\circ}C$ isothermal line in the East Sea. The red tides that initially bloomed at the coast of Pohang on September 21, 1995 moved to the coast of Uljin on September 26, 1995. The skipped appearance of the red tides in the areas between Pohang and Uljin was due to the East Korean Warm Current, which was moving offshore from Pohang to approach to Uljin. The cold water which was formed by tidal front in the western coast of the South Sea and by upwelling water from deep layer in the southeastern coast of the Korean peninsula played a role in blocking the spreading of red tides during summer season in 1997 and 1998. In conclusion, the distribution of red tides appeared to be dependent on the initial water temperature at red tides bloom. The SST at the red tides varied from 21${\circ}C$ to 25${\circ}C$; 21${\circ}C$, 23${\circ}C$, 24 and 24-25${\circ}C$ in 1995, 1996, 1997 and 1998, respectively.

• ALGAE
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• 제21권3호
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• pp.311-316
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• 2006

The effects of light quality and irradiance on the growth of Cochlodinium polykrikoides were investigated in the laboratory. At 25°C and 30 psu the irradiance-growth curve was described as μ = 0.34 (I-9.76)/(I+12.5), (r=0.98). This suggests half-saturation photon flux density (PFD) (Ks) of 32.0 μmol photons m–2 s–1, and a compensation PFD (Ic) of 9.76 μmol photons m–2 s–1. Because the Ic equates to a depth of ca. 15.4 m, these responses suggest that irradiance at the depth around and below the thermocline in Yeosuhae Bay would provide favorable conditions for C. polykrikoides. Photoinhibition did not occur at 300 μmol photons m–2 s–1, which was the maximum irradiance used in this study. Blue (450 nm), yellow (590 nm) and red (650 nm) light had different effects on the growth of C. polykrikoides: it grew well under blue light, but not under yellow light. This implies that C. polykrikoides is more likely to cause an outbreak of red tide in the open sea where blue-green wavelengths predominate, rather than in enclosed water bodies where suspended particles absorb most of the blue wavelengths, and yellow-orange wavelengths predominate.

• Fisheries and Aquatic Sciences
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• 제3권2호
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• pp.111-117
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• 2000

To clarify the ichthyotoxic mechanisms of a harmful dinoflagellate Cochlodinium polykrikoides, hematological responses of the flounder Paralichthys olivaceus and red sea bream Pagrus major exposed to this algal bloom were investigated. The mortality of red sea bream was considerably larger than that of flounder, and the threshold lethal density of C. polykrikoides to the test fish was approximately 3,000 cells/ml. Blood $PO_2$declined in proportion to the increasing density of algal cells. The blood $PO_2$ of moribund fish was about $40-60\% of control test fish. Particularly, the fishes began to be killed when the blood $PO_2$ fell below 30-40 mmHg. However, the blood pH dropped almost 1.0 unit just before fish kill. Hemoglobin and hematocrit levels of fish exposed to C. polykrikoides of 5,000 cells/ml for 24 h and of moribund fish did not show great difference. The concentrations of plasma $Na^+$, $K^+$ and $Cl^-$ were slightly elevated to different magnitudes except $Ca^{2+}$ and plasma osmolality was also increased in Cochlodinium-exposed fish. In the plasma cortisol level, these values of moribund flounder and red sea bream were 4- 5 times higher than those of control fish. These results suggest that the drop of blood $PO_2$ was may be one of the principal causes of fish kill by C. polykrikoides, and the changes of other hematological parameters were secondary responses elicited by the decrease in blood $PO_2$.

• 한국지리정보학회지
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• 제6권3호
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• pp.139-150
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• 2003

한국 연근해역의 중규모 해양 환경변동이 Cochlodinium polykrikoides 적조의 시공간 분포 변동과 밀접한 관련성이 있는 것으로 나타났다. 매년 하계 한국 연안역에서 적조가 최초로 발생한 전남 고흥 나로도 연안의 해양환경 상태는 최근 7년(1995~2001) 동안 열염전선대에 위치하였다. 대규모 적조발생은 7년 동안 매 홀수해(1995, 1997, 1999, 2001)에 나타났는데 동중국해 북부해역에서 표면 수온 및 염분의 큰 변동 또한 격년 주기로 나타났다. 저온 고염(홀수해), 고온 저염(짝수해)의 중규모적 해황 변동에 따라 적조의 공간분포 규모가 크게 변동되는 것으로 추정되었다. 한편, 동해연안으로 유입 확산되는 C. polykrikoides 적조의 분포와 이동상황은 동해남부 연안에서 발생하는 냉수대의 시공간 변동 규모에 따라 다르게 나타났다.

• 한국환경과학회지
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• 제16권7호
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• pp.799-804
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• 2007

Oil spill caused severe effects on the marine fauna and flora due to direct contact of organisms with the oil and even in regions not directly affected by the spill. This study was conducted to understand the effects of the oil spill accidents and the use of dispersant on the red tide of Cochlodinium polykrikoides. Crude oil produced in Kuwait, bunker-C, kerosene and diesel oil, and a chemical dispersant produced in Korea, were added with a series of 10 ppb to 100 ppm in the f/2-Si medium at $20^{\circ}C$ under a photon flux from cool white fluorescent tubes of $100\;mol\;m^{-2}\;s^{-1}$ in a 14: 10 h L:D cycle for the culture of C. polykrikoides. In low concentrations of ${\leq}$ 1 ppm of examined oils no impact on the growth of C. polykrikoides was recorded, while in high concentration of ${\geq}$ 10 ppm, cell density was significantly decreased with the range of 10 to 80% in comparison with the control. The growth of C. polykrikoides after the addition of the dispersant and the mixtures combined with oils and a dispersant of ${\geq}$ 10 ppm appeared to decrease, whereas the growth of C. polykrikoides exposed to ${\leq}$ 100 ppb showed little serious impact. However, almost all the C. polykrikoides cells were died regardless of a dispersant and combined mixtures within a few days after the addition of high concentrations.

• 한국환경과학회지
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• 제16권10호
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• pp.1119-1125
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• 2007

We examined the horizontal distribution of salinity and the concentrations of DIN and DIP after heavy rain-fall events in coastal areas of South Korea from Yeoja Bay to Narodo and from Gwangyang Bay to Geomodo to determine whether fresh water actually flows into areas of Cochlodinium polykrikoides red tides and to observe its effect on the growth of this organism after heavy rainfall. Following heavy rainfall (155 mm) in the Yeosu and Suncheon regions, the average salinity was 21 and 29 psu at Yeoja Bay and in the coastal waters of Narodo, respectively. After 126 mm of rainfall, the values were 19 and 25 psu in the coastal waters of Yeosu and Geomodo, respectively. This may have been caused by an influx of fresh water, after the rainfall event, into the open sea coastal areas around Narodo and Geomodo from the Dong and Seomjin Rivers, which are about 3540 km away. After the rainfall, the concentrations of $NH_4-N,\;NO_2-N$, and $PO_4-P$ were slightly increased; however, the concentration of $NO_3-N$ was greatly increased and diffused throughout the coastal areas of Narodo and Geomodo, which frequently experience C. polykrikoides blooms. The influence of $NH_4-N,\;NO_2-N$, and $PO_4-P$ on the occurrence of C. polykrikoidesred tides in coastal areas around Narodo and Geomodo after heavy rainfall does not appear to be great. Instead, the occurrence C. polykrikoides red tides in the coastal areas of Narodo and Geomodo seems to be facilitated by $NO_3-N$.