• Ocean and Polar Research
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• v.32 no.4
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• pp.411-426
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• 2010

The seasonal variations in the zooplankton community of the southern coastal waters of Korea were investigated seasonally in May, August, November 2005, and February 2006. A total of 74 taxa were sampled, with an average abundance ranging from 2,426~23,793 indiv./$m^3$, among which Noctiluca scintillans predominated. Noctiluca scintillans, Acartia omorii, Acartia erythraea, Paracalanus parvus s. l., Centropages abdominalis, Tortanus forcipatus, and Pseudevadne tergestina were the most abundant species detected. Zooplankton diversity was high around the inner regions during the summer, but it was relatively low in the stations located in the outer regions in the autumn. Non-metric multidimensional scaling (nMDS) revealed significant differences in the structures of the zooplankton community among the three regions. Our results showed that the seasonal variations in zooplankton communities in the southern coastal waters of Korea were attributable to seasonal changes in temperature, salinity, chlorophyll a concentrations, and N. scintillans blooms; additionally, this particularly study area might have been specifically influenced by the appearance of the Tsushima Warm Current.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.4
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• pp.421-428
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• 2017

The spatial distribution and abundance of fish species was estimate near Dok-do, East Sea of Korea by conducting midwater trawl survey with hydroacoustic method. Acoustic and midwater trawl data were collected onboard the R/V Tamgu 21 during 7-8 March 2016. Acoustic data were collected at the frequencies of 38 and 120 kHz and converted to nautical area scattering strength ($m^2/nmile^2$). Species are distributed mainly over an extent of 30-55 m, generally around southwest of Dok-do; the squid Watasenia scintillans was the dominant species found. The length-weight function and target strength of squid and other fishes were used to estimate the W. scintillans stock at 2499.1 tons and other fish at 43.8 tons during the winter season. The hydroacoustic method offers an approach for the determination of the biomass and vertical and spatial distributions of species aggregating near Dok-do, East Sea of Korea.

• Ocean Science Journal
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• v.43 no.1
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• pp.49-59
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• 2008

To examine the population development of the dinoflagellates, Ceratium furca and Ceratium fusus, daily field monitoring was conducted between April and July 2003 in the temperate coastal water of Sagami Bay, Japan. During the study period, the concentrations of C. furca were always lower than those of C. fusus. A sharp increase in the densities of both species was recorded on 5 May showing the maximum cell concentrations (C. furca = $14,800\;cells\;L^{-1}$, C. fusus = $49,600\;cells\;L^{-1}$). In the 7 days prior to the May bloom of the Ceratium species (29 April to 1 May), the highest density of the heterotrophic dinoflagellate Noctiluca scintillans was observed. Additionally, a second bloom of C. fusus occurred on 22 July. Here, two causes of the significant increases in the Ceratium populations during the two blooming periods (first time; 1 to 8 May, second time; 15 to 22 July) are presented. First, an increase in the nutrients of the surface layer regenerated by the breakdown of blooms by N.scintillans could be considered as a major cause of the population increase of the two Ceratium species. Second, a decrease in salinity (to 27 psu) was correlated with the later bloom of C. fusus. These results suggest that the population development of the two Ceratium species requires nutrients regenerated after the reduction of the diatom population by N. scintillans and, for C. fusus, continuous low salinity conditions, compared to other environmental factors during the rainy season.

• The Korean Journal of Mycology
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• v.20 no.2
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• pp.95-108
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• 1992

Sixty five soil specimens were collected from the nineteen leguminous plant roots throughout 9 sites in four Provinces from Augast 12 to November 21, 1991. VA-mycorrhizal spores isolated from the collected soils were identified and classified into four genera 21 species. However, six spores were newly found and described here: Acaulospora elegans, A. undulata, Glomus laminated spores of. macrocarpus var. macrocarpus, Gl. WUMI%3, Gl. scintillans, Scutellospora verrucosa. Species of three spores that belong to 3 genera; Acaulospora sp., Glomus sp., Scutellospora sp. were unidentified.

• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.631-639
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• 2017

The relationship between the environmental factors (water temperature, salinity, chlorophyll-a concentration, Noctiluca scintillans density, Diatoms and Dinoflagellates densities) and the zooplankton community was investigated. Zooplankton were seasonally collected at 11 stations of Gwangyang Bay from November 2015 to July 2016. A mean abundance ranged from 544 to $19,753indiv.\;m^{-3}$. The maximum abundance was observed to be $40,000indiv.\;m^{-3}$ in July and the minimum occurred in November with $412indiv.\;m^{-3}$. The zooplankton consisted of 35 taxa, which is dominated by Paracalanus parvus s. l., Corycaeus spp., Oithona spp., Acartia omorii, A. ohtsukai, Centropages abdominalis, unidentified harpacticoids. The result of the Redundancy Analysis (RDA) conducted between the zooplankton and the environmental factors showed that the spring-autumn, summer and winter are separated. The summer was closely related to temperature and diatom density, while the winter was linked to salinity and N. scintillans density (p<0.05).

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 1995.06a
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• pp.19-41
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• 1995

• Journal of Environmental Science International
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• v.23 no.12
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• pp.2015-2028
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• 2014

We analyzed with HPLC (High Performance Liquid Chromatography) analysis photosynthetic pigments and environmental factors, microscopic observations of the phytoplankton and zooplankton in the seawater every month from February 2009 to November 2010 in Haengam Bay. The level of dissolved inorganic nutrients was the highest between July and September, when freshwater influx was at its peak, whereas chlorophyll a levels were the highest in April and August. Also, phytoplankton pigment concentration increased when dissolved inorganic nutrients are carried into nearshore waters by rainfall runoff. Based on identification of phytoplankton and photosynthetic pigments results, diatoms were mainly dominant while dinoflagellate populations increased at July and August 2009, May 2010. The zooplankton communities are dominated in terms of Noctiluca scintillans. The contribution of Noctiluca scintillans in 2010 accounts for approximately 77.3% of the total zooplankton. Distribution patterns over time of zooplankton in the seasonal distribution of phytoplankton showed a different pattern.

• ALGAE
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• v.22 no.2
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• pp.57-67
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• 2007

We analyzed the nuclear-encoded large subunit ribosomal RNA gene (LSU rDNA) sequences of 19 dinoflagellates occurring in costal waters off Korea and reconstructed a phylogenetic tree containing 74 representative species from 37 distinct genera. Of these, the LSU rDNA sequences of Amylax triacantha (Jörgensen) Sournia, Gonyaulax verior Sournia (= Amylax diacantha Meunier), Gyrodinium fissum (Levander) Kofoid et Swezy, Katodinium glaucum (Lebour) Lebour III, Noctiluca scintillans (Macartney) Kofoid et Swezy, Oxyphysis oxytoxoides Kofoid, and Pyrophacus steinii (Schiller) Wall et Dale are reported for the first time. Our LSU rDNA tree consistently placed Oxyrrhis marina Dujardin and N. scintillans at the most primitive positions, giving rise to a strongly supported monophyletic group of typical dinoflagellate species belonging to the Dinophyceae. The phylogenetic relationships among the typical dinoflagellates, however, were not resolved in the higher taxonomic levels in general. Only genera at terminal branches were usually supported with high confidence. The Dinophysiales, represented by Dinophysis species and O. oxytoxoides, formed a strongly supported monophyletic assemblage. The Gymnodiniales and Peridiniales were recovered as polyphyletic groupings. Members of the Gonyaulacales were consistently grouped together, but lacked statistical support. Within this order, the Ceratiaceae and Goniodomataceae each formed a monophyletic group, but the Gonyaulacaceae was polyphyletic. The phylogenetic relationships of the Gonyaulacaceae were generally congruent with differences in the combinations of the apical pore complex, hypothecal organization and thecal formula.

• Korean Journal of Environmental Biology
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• v.38 no.2
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• pp.231-247
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• 2020

The seasonal variation in the zooplankton community and hydrographic conditions were examined in three regions (inner, central, and outer regions) of Gamak Bay, Korea. Zooplankton samples were collected over a period of 12 months from January to December 2006. The hydrographical parameters of temperature, salinity, chlorophyll-a concentrations, dissolved oxygen, and chemical oxygen demand were measured. The total zooplankton density varied from 411 to 58,485 ind. m^-3, with peaks in early summer. A total of 65 taxa accounted for approximately 86.9% of the annual mean zooplankton density: Noctiluca scintillans (30.9%) Paracalanus parvus s. l.(24.3%), Acartia omorii(11.9 %), Eurytemora pacifica (5.7%), cladocerans (4.1%), cirriped larvae (3.8%), Oithona similis (3.7%), and Pseudevedne tergestina(2.5%). Copepods dominated numerically throughout the year and comprised 54.3% of the total zooplankton. Most of the dominant copepods showed a well-defined seasonal pattern. The density and diversity of zooplankton in Gamak Bay were influenced by the hydrographic environment that was subject to significant spatial and temporal variations. Multivariate statistics showed that seasonal temperature was the most significant predictor of zooplankton taxa, density, and diversity, as well as the density of dominant taxa. Our results suggest that fluctuations in the zooplankton populations, particularly copepods, followed progressive increments in the temperature and COD concentrations.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.11 no.3
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• pp.108-116
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• 2006

To investigate the factors controlling the spring population of Acartia hongi, egg production, hatching time of egg and predation pressure were measured. Egg production was maintained the superior position between winter and spring. Egg production was positively correlated with not only water temperature when water temperature was below $7^{\circ}C$ but also chlorophyll-a concentration when it was from $7^{\circ}C$ to $21^{\circ}C$. A regressive equation of development time$(D_e,\;day)$ of eggs derived from water temperature$(T,\;^{\circ}C)$ was obtained as $D_e=18.9(T-0.4)^{-1.0}$, showing longer development time at water temperature below $5^{\circ}C$. In Cross Correlation Analysis(CCA) to examine the time-lag relationship among abundances of developmental stages of A. hongi, egg production rate calculated by multiplying population egg production rate by hatching time showed more significant correlation with nauplii abundance than population egg production rate. Therefore, it suggests that hatching time is also recognized by a factor controlling formation of population and especially, in winter, high abundance of egg derived from high daily egg production rate and delayed hatch by low water temperature become the origin of initial spring population of nauplii. Egg predation by Noctiluca scintillans, suggesting a negative factor in formation of A. hongi spring population, was observed. During spring, A. hongi eggs were found in $2.9\sim21.1%$ of individuals of N. scintillans. It was deduced that $1.2\sim49.5%$ of the eggs produced by A. hongi was preyed on by N. scintillans. In conclusion, the factors controlling spring population of A. hongi were regarded as high egg production by winter generation, the delayed development time of egg by low temperature, and egg predation of N. scintillans.