• ALGAE
• /
• v.29 no.4
• /
• pp.311-319
• /
• 2014

The biocide sodium hypochlorite (NaOCl) is widely used for controlling algal growth, and this application can be extended to marine environments as well. This study evaluates the biocidal efficiency and cellular toxicity of NaOCl on the harmful dinoflagellate Cochlodinium polykrikoides, with emphasis on pigment production and antioxidant enzyme activity. The test organism showed dose-dependent decrease in growth rate on exposure to NaOCl, and the 72 h $EC_{50}$ was measured to be $0.584mg\;L^{-1}$. NaOCl significantly decreased pigment levels and chlorophyll autofluorescence intensity, indicating possible detrimental effects on the photosystem of C. polykrikoides. Moreover, it significantly increased the activities of antioxidant enzymes, suggesting the production of reactive oxygen species in the cells. These data indicate that NaOCl exerted deleterious effects on the photosynthetic machinery and induced oxidative damage in the dinoflagellate and this biocide could be effectively used for the control of algal blooms.

• ALGAE
• /
• v.27 no.1
• /
• pp.63-70
• /
• 2012

Algae are sensitive to a wide range of pollutants, and are effective bioindicators in ecotoxicity assessments. Here, we evaluated the sub-lethal sensitivity of the marine dinoflagellate Cochlodinium polykrikoides upon exposure to copper (Cu), lead (Pb), bisphenol A (BPA), and Aroclor 1016 (polychlorinated biphenyl, PCB). Toxic effects were assessed by observations of the reduction in cell counts and chlorophyll a levels after exposure to each toxicant. C. polykrikoides displayed dose-dependent, sigmoidal responses when exposed to the tested chemicals. $EC_{50}$-72 h values for Cu, Pb, BPA, and PCB were 12.74, 46.70, 68.15, and $1.07mg\;L^{-1}$, respectively. PCB, which is an endocrine-disrupting chemical, was the most sensitive, proving its toxic effect on the dinoflagellate. This study provides baseline data on the toxic effects of commonly used heavy metals and endocrine-disrupting chemicals to a marine dinoflagellate.

• ALGAE
• /
• v.24 no.2
• /
• pp.105-110
• /
• 2009

The rDNAs of figh-killing dinoflagellates Cochlodinium polykrikoides and Karlodinium veneficum were detected from the East China Sea by species-specific real-time PCR probes. Sequence analysesusing the partial ITS sequences from the real-time PCR products showed identical sequences with C. Polykrikoides and K. veneficum, respectively and low expectation values (E-value) of less than 1e-5 suggesting the presence of these organisms in the East Ching Sea shelf water that flows into the Tsushima Strait and the Yellow Sea.

• Journal of Life Science
• /
• v.13 no.5
• /
• pp.651-657
• /
• 2003

Randomly amplified polymorphic DNA (RAPD) analysis was used to study genetic relationships among C. polykrikoides, G. impudicum and G. catenatum, which possess similar morphological features. Four of 12 primers were selected and 59 amplification products ranged from 0.2 kb to 3.0 kb. The number of polymorphic products in C. polykrikoides, G. impudicum and G. catenatum was 16 (27.1%), 8 (13.5%), and 16 (27.1%), respectively, while 17 were monomorphic. Number of species-specific bounds was 26 (44.0%), 34 (57.6%), 26 (44.0%) in C. polykrikoides, G. impudicum and G. catenatum, respectively. The genetic similarity between C. polykrikoides and G. impudicum/G. catenatum was 0.83, whereas G. impudicum and G. catenatum was 0.78. Our results suggest that C. polykrikoides, G. impudicum and G. catenatum are extremely different on the basis of RAPD analysis, despite similarity based on their morphology. The RAPD technique appears to be efficient in detecting genetic variation in these dinoflagellates.

• Fisheries and Aquatic Sciences
• /
• v.5 no.3
• /
• pp.150-155
• /
• 2002

Marine bacteria producing algicidal substance against Cochlodinium polykrikoides was screened and isolated from seawater. Metabolite of marine bacteria Micrococcus sp. LG-5 showed strong algicidal activity against C. polykrikoides. C. polykrikoides was inhibited above $90\%$ at $5\%$ solution of the metabolite within 24 hrs. Algicidal substance from the metabolite was extracted with ethyl acetate, and then purified by PTLC and reversed-phase HPLC. Algicidal activity of purified compound against C. polykrikoides was above $90\%$ at 3.7, 11.0 and 33.0${\mu}g/mL$ concentration after 12, 9 and 3 hrs, respectively. Ninety percent inhibition of other red tides, Gymnodinium sanguineum and Gyrodinium impudicum was observed when treated with 3.7${\mu}g/mL$ of purified compound within a period of 12 hrs. The microscopic view of red tides treated with purified compound showed the deformations such as cell node cuts and swelling of cells.

• Journal of Environmental Science International
• /
• v.18 no.4
• /
• pp.435-443
• /
• 2009

A bacterial strain SY-97 that showed algicidal activity against Cochlodinium polykrikoides was isolated from coastal water of Uljin (eastern coast of Korea) in August, 2005. The isolated strain was identified as Brachybacterium sp. by morphological and biological tests, and analysis of 16S rDNA sequence. The optimal culture conditions for the growth of strain SY-97 were $30^{\circ}C$, initial pH 7.0, and salinity 2.0%. From the result of cell culture insert experiment, Brachybacterium sp. SY-97 is assumed to produce secondary metabolites which have algicidal activity. When 10% culture filtrate of this strain was applied to C. polykrikoides ($1.2{\times}10^4\;cells/m{\ell}$) cultures, 100% of C. polykrikoides cells was destroyed within 15 hours. The released algicides were heat-tolerant to $100^{\circ}C$ and stable in pH $6.0{\sim}10.0$. These results suggest that Brachybacterium sp. SY-97 is potentially useful for controlling outbreaks of C. polykrikoides.

• Journal of Environmental Science International
• /
• v.17 no.4
• /
• pp.439-449
• /
• 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.

• Journal of Aquaculture
• /
• v.11 no.3
• /
• pp.285-294
• /
• 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.

• ALGAE
• /
• v.21 no.3
• /
• pp.311-316
• /
• 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.

• Journal of Life Science
• /
• v.14 no.4
• /
• pp.589-592
• /
• 2004

The growth response of the fish-killing dinoflagellate Cochlodinium polykrikoides was studied in cultures, using the treatment of Ceratium extracts by a methanol, a water-soluble, and a cell-free medium. The cell-free medium had the most increasing on the growth of C. polykrikoides cultures, enriched with $\geq$ 25% Ceratium, whereas the methanol and water-souble fractions did not affect the growth of C. polykrikoides exposed to even higher concentration. In particular, the cell-free medium also increased the growth of Gyrodinium impudicum and Chaetoceros sp., similar species to C. polykrikoides. In contrast to C. polykrikoides, G. impudicum and Chaetoceros sp., the growth of Alexandrium tamarense was inhibited significantly, and there was no great effect on the growth of Prorocentrum minimum. These results imply that Ceratium extracts may play an important role in the stimulatory effect of C. polykrikoides, and they have to affect the interaction between C. polykrikoides and Ceratium when co-existing.