• 한국어업기술학회:학술대회논문집
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• 한국어업기술학회 2003년도 춘계 수산관련학회 공동학술대회발표요지집
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• pp.373-374
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• 2003

There were many studies on the effects of red tide dinoflagellates on shellfish populations (Nielsen and Stromgren, 1991; Lesser and Shumway, 1993; Luckenbach et al., 1993; Matsuyama et al., 1997; Li et al., 2001). However, these studies mainly focused on the toxic effects of dinoflagellates oui adults or juveniles. Interactions between dinoflagellates and bivalve larvae have not been understood comprehensively yet. (omitted)

• Fisheries and Aquatic Sciences
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• 제6권2호
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• pp.66-73
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• 2003

To understand the physiology of a suspension-feeding bivalve and its potential impacts on the dynamics of red tides on tidal flats, rates of clearance and ingestion of Glauconome chinensis were measured as a function of algal concentration, when the bivalve was fed on a nontoxic strain of red tide dinoflagellate Prorocentrum minimum, Cochlodinium polykrikoides or Scrippsiella trochoidea. With increasing algal concentration, weight-specific clearance rate increased rapidly at lower concentrations and after reaching the maximum at ca. 0.2 to 1.0 mgC/L, it decreased at higher concentrations. Maximum clearance rate was nearly equal for different algal species and ranged between 2.1 and 2.6 L/g/hr. Weight-specific ingestion rate also increased at lower algal concentrations but saturated at higher concentrations. Maximum ingestion rate was 2 to 10 fold different with different algal species: S. trochoidea (10.1 mgC/g/hr), P. minimum (3.9 mgC/g/hr), and C. polykrikoides (0.99 mgC/g/hr). Nitrogen and protein content showed that S. trochoidea is the best among the tested three red tide dinoflagellates. The maximum filtration capacity, calculated by combining the data on ingestion rate from laboratory experiments and those from the field for the density of the bivalve and the red tide dinoflagellates was 4.7, 1.4, and 25.3 tons/m2/day for P. minimum, C. polykrikoides, and S. trochoidea, respectively. It is hypothesized that the abundant suspension-feeding bivalves in tidal flats can effectively mitigate the outbreak of red tides.

• 한국패류학회지
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• 제19권1호
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• pp.25-32
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• 2003

To know the effects of the red tide and toxic dinoflagellates on survival and growth of larvae of the mussel, Mytilus galloprovincialis, laboratory experiments were conducted by incubating larvae with either unialgal culture of 4 dinoflagellate species (Amphidinium carterae, Prorocentrum triestinum, Gymnodinium impudicum, or Akashiwo sanguinea) or a standard food (Isochrysis galbana) for 10 days. The survival of larvae was higher than 80% when the food was A. carterae, G. impudicum, or A. sanguinea. The lowest survival (20%) was found when the food was P. triestinum. When the food was P. triestinum, the survival of larvae rapidly decreased from 87% at day 4 down to ca. 50% at day 6, and 20% at day 10. This implies that the larval population of M. galloprovincialis can seriously be affected if they are exposed to the red tide water dominated by P. triestinum for more than 4 days. Shell length of larvae either increased or decreased according to the food species. When the food was A. carterae, G. impudicum, or A. sanguinea, shell length of larvae increased. But, it decreased when the food was P. triestinum. Though shell length increased in 3 treatments, the daily increments (0.63 $\mu$ m for A. carterae, 0.46 m for $\mu$ G. impudicum, and 1.10 m for $\mu$ A. sanguinea) were smaller than that of the standard food (3.79 m for $\mu$ I. galbana). Correlation analyses chowed that the change in shell length was not significant when the food was A. carterae or G. impudicum. Therefore, all of 4 dinoflagellates affected the growth of M. galloprovincialis larvae: growth was negative for P. triestinum, nil for A. carterae and G. impudicum, and positive but lower than standard food for A. sanguinea. These imply that the dinoflagellates are less valuable as foods for M. galloprovincialis larvae. So, decreased growth rate of larvae is expected during red tides, which will consequently cause delayed metamorphosis or failure to recruitment to the adult populations. In considering the harmful effects of red tides on the aquatic ecosystem, not only the effects on adult populations of fish and shellfish, but also the effects on larval populations should be included.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2009년도 춘계학술발표논문집
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• pp.839-841
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• 2009

Dinoflagellates are known to cause red tide outbreaks and even to produce toxin. Recently, red tide events have frequently occurred in several embayments of the Korean coast and have brought serious damage to inshore fisheries. Thus, the red tide research activities including the taxonomy as well as distribution of toxic dinoflagellates have received ever increasing attention in Korean waters. Therefore, it is necessary to conduct an extensive taxonomical study on red tide organisms in coastal zone of Korea. The present study is to clarify the fine structures of Prorocentrum spp. and to describe each species with taxonomical notes for plankton monitoring network.

• ALGAE
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• 제32권4호
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• pp.285-308
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• 2017

Cochlodinium polykrikoides red tides have caused great economic losses in the aquaculture industry in many countries. To investigate the roles of metazooplankton in red tide dynamics of C. polykrikoides in the South Sea of Korea, the abundance of metazooplankton was measured at 60 stations over 1- or 2-week intervals from May to November 2014. In addition, the grazing impacts of dominant metazooplankton on red tide species and their potential heterotrophic protistan grazers were estimated by combining field data on the abundance of red tide species, heterotrophic protist grazers, and dominant metazooplankton with data obtained from the literature concerning ingestion rates of the grazers on red tide species and heterotrophic protists. The mean abundance of total metazooplankton at each sampling time during the study was 297-1,119 individuals $m^{-3}$. The abundance of total metazooplankton was significantly positively correlated with that of phototrophic dinoflagellates (p < 0.01), but it was not significantly correlated with water temperature, salinity, and the abundance of diatoms, euglenophytes, cryptophytes, heterotrophic dinoflagellates, tintinnid ciliates, and naked ciliates (p > 0.1). Thus, dinoflagellate red tides may support high abundance of total metazooplankton. Copepods dominated metazooplankton assemblages at all sampling times except from Jul 11 to Aug 6 when cladocerans and hydrozoans dominated. The calculated maximum grazing coefficients attributable to calanoid copepods on C. polykrikoides and Prorocentrum spp. were 0.018 and $0.029d^{-1}$, respectively. Therefore, calanoid copepods may not control populations of C. polykrikoides or Prorocentrum spp. Furthermore, the maximum grazing coefficients attributable to calanoid copepods on the heterotrophic dinoflagellates Polykrikos spp. and Gyrodinium spp., which were grazers on C. polykrikoides and Prorocentrum spp., respectively, were 0.008 and $0.047d^{-1}$, respectively. Therefore, calanoid copepods may not reduce grazing impact by these heterotrophic dinoflagellate grazers on populations of the red tide dinoflagellates.

• 환경생물
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• 제17권3호
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• pp.217-232
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• 1999

본 종설은 우리나라에서 발생하고 있는 적조현상을 정리하여 적조의 정의, 명칭, 년도별 연구상황, 적조발생 원인 및 생물, 독성, 인명 및 수산물의 피해, 피해저감 및 방제기술에 대하여 소개하였다. 우리나라의 초기의 적조는 돌말류에 의해 발생되었으나, 해양오염이 심각한 1970년대 말부터 무독성 와편 모조류에 의해 그리고 1980년대 말에는 유독성 편모조류에 의해 발생되고 있다. 적조발생 규모는 초기에는 국지적이었으나 근래에는 광역화이기 때문에 수산업에 막대한 지장을 초래하고 있다. 따라서 적조에 따른 피해저감 및 방제대책의 연구가 절실히 요구된다.

• 한국양식학회지
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• 제10권4호
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• pp.457-462
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• 1997

1997년 9월 1일과 2일 심한 적조가 발생된 해역의 가두리 양식어장에서 적조원인 생물인 Cochlodinium polykrikoides의 주야 수직이동을 세포수와 Chlorophyll a로 분석한 결과 낮에는 표층에서 4 m까지 농밀층이 분포하고 있었으나 저녁에는 저층 10 m, 15 m층에 주로 분포하였다. 이로 볼 때 황토를 이용한 적조방제는 저녁 18시부터 20시까지, 아침 8시부터 10시까지가 눈에 보이지 않는 위험시기이다. 조사 당시 가두리 주위에 황토를 12시부터 18시까지 연속적으로 뿌려 적조를 방제하였으나 가두리 주위에서 용존산소의 분포는 정상이었다. 이때 수질환경 중 pH는 8.45로 정상치보다 높았으며 영양염 중 암모니아와 인산은 군집유지에 효율적으로 이용되었고, 질산염과 규산염은 정상보다 다소 높은 농도를 나타내었다.

• ALGAE
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• 제32권3호
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• pp.199-222
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• 2017

Occurrence of Cochlodinium polykrikoides red tides have resulted in considerable economic losses in the aquaculture industry in many countries, and thus predicting the process of C. polykrikoides red tides is a critical step toward minimizing those losses. Models predicting red tide dynamics define mortality due to predation as one of the most important parameters. To investigate the roles of heterotrophic protists in red tide dynamics in the South Sea of Korea, the abundances of heterotrophic dinoflagellates (HTDs), tintinnid ciliates (TCs), and naked ciliates (NCs) were measured over one- or two-week intervals from May to Nov 2014. In addition, the grazing impacts of dominant heterotrophic protists on each red tide species were estimated by combining field data on red tide species abundances and dominant heterotrophic protist grazers with data obtained from the literature concerning ingestion rates of the grazers on red tide species. The abundances of HTDs, TCs, and NCs over the course of this study were high during or after red tides, with maximum abundances of 82, 49, and $35cells\;mL^{-1}$, respectively. In general, the dominant heterotrophic protists differed when different species caused red tides. The HTDs Polykrikos spp. and NCs were abundant during or after C. polykrikoides red tides. The mean and maximum calculated grazing coefficients of Polykrikos spp. and NCs on populations of co-occurring C. polykrikoides were $1.63d^{-1}$ and $12.92d^{-1}$, respectively. Moreover, during or after red tides dominated by the phototrophic dinoflagellates Prorocentrum donghaiense, Ceratium furca, and Alexandrium fraterculus, which formed serial red tides prior to the occurrence of C. polykrikoides red tides, the HTDs Gyrodinium spp., Polykrikos spp., and Gyrodinium spp., respectively were abundant. The maximum calculated grazing coefficients attributable to dominant heterotrophic protists on co-occurring P. donghaiense, C. furca, and A. fraterculus were 13.12, 4.13, and $2.00d^{-1}$, respectively. Thus, heterotrophic protists may sometimes have considerable potential grazing impacts on populations of these four red tide species in the study area.

• 한국패류학회지
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• 제28권4호
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• pp.349-359
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• 2012

The purpose of this study is to compare the clearance rate (CR) and intake rate (IR) of juvenile purple clam, Saxidomus purpuratus when feeding on different unialgal diet of red tide dinoflagellates (RTDs), and to know what is the most important cell characteristic of RTDs to cause the differences in feeding parameters. Experiments were performed to measure the CR and IR of juvenile S. purpuratus as a function of algal concentration when food was either the standard food, Isochrysis galbana or one of 9 RTDs. Patterns of CR with increasing algal concentration were similar among different RTDs. The highest $C_{max}$ was observed when S. purpuratus was feeding on A. affine, while the lowest on C. polykrikoides. The patterns of IR with increasing algal concentration were also similar among different RTDs. However, there were great differences in the maximum value of IR ($I_{max}$) among different RTDs. The highest $I_{max}$ was observed when S. purpuratus was feeding on A. carterae, while the lowest on G. catenatum. Some RTDs similar in size showed different $C_{max}$. Other RTDs different in size showed similar $I_{max}$. Life form of each RTD affected significantly the $I_{max}$, which was higher for single-celled RTDs than chain-forming RTDs. There were no significant differences in feeding parameters between toxic and nontoxic RTDs. Moreover, a toxic dinoflagellate, A. carterae recorded the highest $I_{max}$ among RTDs. The most important characteristic of RTD as a factor affecting the feeding rate of S. purpuratus was life form, not size or toxicity of RTD species.

• ALGAE
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• 제32권2호
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• pp.101-130
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• 2017

The ichthyotoxic Cochlodinium polykrikoides red tides have caused great economic losses in the aquaculture industry in the waters of Korea and other countries. Predicting outbreak of C. polykrikoides red tides 1-2 weeks in advance is a critical step in minimizing losses. In the South Sea of Korea, large C. polykrikoides red tide patches have often been recorded offshore and transported to nearshore waters. To explore the processes of offshore C. polykrikoides red tides, temporal variations in 3-dimensional (3-D) distributions of red tide organisms and environmental parameters were investigated by analyzing 4,432 water samples collected from 2-5 depths of 60 stations in the South Sea, Korea 16 times from May to Nov, 2014. In the study area, the vegetative cells of C. polykrikoides were found as early as May 7, but C. polykrikoides red tide patches were observed from Aug 21 until Oct 9. Cochlodinium red tides occurred in both inner and outer stations. Prior to the occurrence of large C. polykrikoides red tides, the phototrophic dinoflagellates Prorocentrum donghaiense (Jun 12 to Jul 11), Ceratium furca (Jul 11 to Aug 21), and Alexandrium fraterculus (Aug 21) formed red tides in sequence, and diatom red tides formed 2-3 times without a certain distinct pattern. The temperature for the optimal growth of these four red tide dinoflagellates is known to be similar. Thus, the sequence of the maximum growth rates of P. donghaiense > C. furca > A. fraterculus > C. polykrikoides may be partially responsible for this sequence of red tides in the inner stations following high nutrients input in the surface waters because of heavy rains. Furthermore, Cochlodinium red tides formed and persisted at the outer stations when $NO_3$ concentrations of the surface waters were < $2{\mu}M$ and thermocline depths were >20 m with the retreat of deep cold waters, and the abundance of the competing red-tide species was relatively low. The sequence of the maximum swimming speeds and thus potential reachable depths of C. polykrikoides > A. fraterculus > C. furca > P. donghaiense may be responsible for the large C. polykrikoides red tides after the small blooms of the other dinoflagellates. Thus, C. polykrikoides is likely to outgrow over the competitors at the outer stations by descending to depths >20 m and taking nutrients up from deep cold waters. Thus, to predict the process of Cochlodinium red tides in the study area, temporal variations in 3-D distributions of red tide organisms and environmental parameters showing major nutrient sources, formation and depth of thermoclines, intrusion and retreat of deep cold waters, and the abundance of competing red tide species should be well understood.