• Proceedings of the Korean Society of Fisheries Technology Conference
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• 1997.06a
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• pp.352-353
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• 1997

• Fisheries and Aquatic Sciences
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• v.2 no.1
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• pp.58-65
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• 1999

Fibrocapsa japonica (Raphidophyceae) is regarded as a harmful algal bloom organism in Japanese waters, where it has been linked to fish kills. Fibrocapsa is a common species in New Zealand coastal waters, particularly in the Hauraki Gulf, where it has regularly bloomed in the spring under E1 Nino climate conditions for the past six years. The New Zealand isolate had 1.4 times more total polyunsaturated acids than the Japanese isolate under the same growth conditions, suggesting that eicosapentaenoic acid in particular coold be used as a discriminating chemotaxonomic marker. The molecular probes tested showed no differential binding of the raphidophytes to lectins, but oligonucleotide probes targeted F. japonica ribosomal RNA bound specifically to both isolates. Neither strain was toxic in mouse or neuroblastoma bioassays. There is no evidence that the New Zealand F. japonica isolates investigated to date produce ichthyotoxins.

• Korean Journal of Environmental Biology
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• v.32 no.2
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• pp.129-137
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• 2014

In order to understand the Heterosigma akashiwo (Raphidophyceae) bloom, we investigated the cell division pattern of its strains under various physicochemical conditions from three different origin. Among the three tested strains, HYM06HA and NFHTS-AK-1, are belong to South Korea and CCMP452 strain was from USA. Interestingly among three strains, HYM06HA was established from the cyst in Korea. Our study results showed that these three strains were indistinguishable under various salinity and iron (Fe) conditions. All strains were survived at 10 to 40 psu and the growth patterns under different iron (Fe) concentrations were observed to be similar. The growth patterns under different N:P ratios and selenium (Se) concentrations led to classification of strains into Korean and USA strain. Briefly these results indicated that the growth pattern from different strains of H. akashiwo could be dominant using their salinity tolerance. Furthermore nutritional enhancer seemed to be different based on geographical origin.

• ALGAE
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• v.22 no.3
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• pp.235-240
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• 2007

The red tide-causing flagellate Chattonella anticfua can cause mass fish kills by their clogging in fish gills. Thisstudy examined the nutrient requirements of C. antiqua isolated from Korea. C. anticfua displayed maximum growthat the day five, followed by a decrease in cell density. Nitrate and nitrite were the preferred nitrogen sources, alonewith adenosine diphosphate for phosphorus compounds. In medium that contained ammonium, a significantdecrease in cell density was observed. Half-saturation constants, Ks, calculated from the maximum growth ratewere 4.94 U|M for NC>3 and 0.79 flM for P04. The growth of C. antiqua was not within the function of the N:P ratio (RU= 0.29). With an N:P ratio as low as 10, the increase in cell density was apparent, with a higher division rate. At lev-els above 50 fiM of NaNOg or 8 ;uM of NaHUPCU, the growth rates were somewhat decreased. Phosphate was thelimiting factor for C. antiqua growth since the starvation of phosphate had brought about a rapid decrease in celldensity in semi-continuous culture. Studies about the temporal modification of the efficiency of nitrate or phosphateuptake may be necessary to explain the bloom dynamics of C. antiaua.

• ALGAE
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• v.22 no.2
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• pp.95-106
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• 2007

Blooms of Chattonella species are normally during summer in inland seas with high nutrients from the land and inflowing water. These blooms cause mass fish kills worldwide. We isolated a Chattonella strain from the south coast of Korea and identified it as C. antiqua. It is known that the morphological changes of phytoplankton correspond to the diurnal vertical migrations that follow an intrinsic biological clock and a nutrient acquisition mechanism during the day and night. In electron micrographs, C. antiqua clearly showed a radial distribution of lipid bodies in subcellular regions and plastids composed in which thylakoid layers were perpendicular to the surface. A single pyrenoid was present in each plastid and it was found at the end of the plastid towards the center of the cell. Throughout the day, plastids of C. antiqua cells appeared as an expanded net-like recticulum. During the night, however, the plastids changed their shape and contracted toward the cell periphery. The electron density of pyrenoids was increased in cells harvested during the night.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.7
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• pp.967-972
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• 2018

The genus Chattonella belonging to the class raphidophyceae, is a harmful algal bloom species. Recently, its occurrence has been increasing and expanding along the Korean coast. Species identification of the genus Chattonella only by morphological observation is difficult due to the lack of rigid cell walls. In this study, the morphological characteristics and genetic affinity of Chattonella sp. isolated from Deungnyang Bay in 2017 were examined. We carried out single-cell isolation from field samples then sequenced three different areas using the single-cell PCR method: 1) parts of ribosomal operon, the large subunit (LSU) of the rDNA, 2) the chloroplast-encoded subunit psaA of Photosystem I, and 3) rbcL encoding the large subunit of the Rubisco gene. The cells were morphologically very similar to the general genus Chattonella ($74.0{\pm}10.1{\mu}m$ in length, $33.1{\pm}3.6{\mu}m$ in width). The three partial gene sequences were insufficient to justify distinction at the species rank. However, they clustered at 99-100 % sequence similarity with C. marina, C. marina var. antiqua and C. marina var. ovata.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.6
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• pp.674-682
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• 2009

Recently, the occurrence of harmful algae blooms from the Chattonella group has been increasing and expanding in the southern and western seas of Korea. We investigated the relationship between growth kinetics and nutrients in the harmful algae Chattonella marina and Chattonella ovata of the South Sea, Korea. As a result; high concentrations of ammonium ($30\;{\mu}M$ and above) was not effective to the growth of C. ovata, while C. marina displayed good growth at concentration of $100\;{\mu}M$. The half-saturation constant ($K_s$) of C. marina for ammonium ($2.51\;{\mu}M$), nitrate ($5.36\;{\mu}M$) and phosphate ($0.75\;{\mu}M$) was higher than C. ovata (1.85, 4.01, and $0.61\;{\mu}M$, respectively). This indicates that C. ovata can achieve higher cell densities than C. marina under lower nutrient conditions. These $K_s$ values were comparatively higher than those of diatoms and other flagellates previously reported. Therefore, our results indicate that the growth of C. marina and C. ovata is less adapted to lower nutrient environments than other competition species, such as Skeletonema costatum and Cochlodinium polykrikoides.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.6
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• pp.487-494
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• 2006

The effects of water temperature, salinity and irradiance on the growth of harmful algae Chattonella marina isolated from Gamak Bay in South Sea, Korea were investigated. C. marina was able to grow in temperatures of $15-30^{\circ}C$ and salinities of 10-35 psu. Maximum specific growth rate (0.64/day) was observed with combination of $25^{\circ}C$ and 25 psu. Optimal growth (${\ge}70%$ of maximum specific growth rate) was obtained with all salinities of the above $20^{\circ}C$. This result indicated that C. marina is a stenothermal of the high water temperature and euryhaline organism. C. marina was did not grow at irradiance ${\le} 10{\mu}mol$ photons/($m^2\;s$). Photoinhibition did not occur at $300{\mu}mol$ photons/($m^2\;s$), which was the maximum irradiance used in this study. The irradiance-growth curve was described as ${\mu}=0.78(I-11.4)/(I+34.1)$ at $25^{\circ}C$ and 25 psu. The half-saturation photon flux density (PFD) ($K_s$) was $56.9{\mu}mol$ photons/($m^2\;s$) and compensation PFD ($I_c$) was $11.4{\mu}mol$ photons/($m^2\;s$). The result of the present study indicate that C. marina has advantage physiological characteristic to the interspecific competition at the embayment and costal areas of South and West Sea, Korea in summer.

• Journal of the Korean Society of Marine Environment & Safety
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• v.12 no.2 s.25
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• pp.81-87
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• 2006

Algal growth potential(AGP) assay using Heterosigma akashiwo was conducted in Pukman Bay. The effects of nutrients and microorganisms on the growth of H. akashiwo were specifically evaluated by the algal bioassay method. The different types of growth response of H. akashiwo to the addition of nutrients, and the co-incubation with microorganisms were clearly observed. Before H. akashiwo red tide occurrence, the growth of H. akashiwo was significantly stimulated by addition of nitrate of $50{\mu}M$ with phosphate of $5{\mu}M$. The addition of single phosphate had no clear effect on the growth of H. akashiwo. And the co-incubation with microorganisms had no clear effect on the growth of H. akashiwo. This result indicates that nitrate potentially limited the growth of H. akashiwo before red tide occurrence. However, during a bloom of H. akashiwo, the growth was significantly stimulated by addition of either nitrate of $50{\mu}M$ or phosphate of $5{\mu}M$. The addition of trace metals and vitamin $B_{12}$ had no clear effect on the growth of H. akashiwo in the period. This result indicates that both nitrate and phosphate potentially limited the growth of H. akashiwo during the bloom. On the other hand, during the termination period of H. akashiwo bloom, the growth of H. akashiwo was slightly stimulated by addition of phosphate and nitrate. But the growth of H. akashiwo was significantly enervated by the co-incubation with microorganisms. This result indicates that microorganisms potentially limited the growth of H. akashiwo in the period of bloom termination.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.23 no.6
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• pp.468-474
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• 1990

Eight species, 6 Dinophyceae and 2 Raphidophyceae, caused a bloom in the southeastern coastal waters mainly in Chinhae Bay in Korea from March to September since 1982. Scrippsiella trochoidea and Heterocapsa triquetra bloomed in March then ensued a vernal species Heterosigma akashiwo. And Cochlodinium sp. and Alexandrium affine were occurred as causative organism in fall next to the estival dinoflagellates Gyrodinium instriatum and Pheopolykrikos hartmannii. Among them, spatio-temporal similarity of outbreak was significant in Heterosigma akashiwo since 1983, and a bit apparent for Cochlodinium sp.. The density was in the level from $10^3\;to\;10^5\;cells/ml$ and was dependent on the cell size rather than environmental characteristics.