• 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.

• Journal of Aquaculture
• /
• v.4 no.1
• /
• pp.13-18
• /
• 1991

In order to obtain basic biological data for effective seed production of the red sea bream, Pargus major, the influence of water temperature on egg development was investigated. The time of egg development was shorter with higher water temperature. The relationships between the water temperature($T\;:\;^{\circ}C$) and the required time(t : hour) from egg to each developmental stage were given as follows : 8-cell 1/t=0.0618T-0.5877(r=0.9899) Morula : 1/t=0.0284T-0.2556(r=0.9948) Kupffer's : 1/t=0.0076T-0.0829(r=0.9902) vesicle Hatching : 1/t=0.0031T-0.0350(r=0.9985) Biological minimium temperature for the egg development was estimated to be $10.2^{\circ}C$ in average.

• Journal of Aquaculture
• /
• v.3 no.1
• /
• pp.1-11
• /
• 1990

To induce an early spawning, the adult red sea bream, Pagrus major, were exposed to predesignated condition of photoperiod and water temperature during February 21 to June 30, 1988. Spawning began from April 20, a month earlier than that in the natural condition, when the photoperiod and water temperature were controlled at 14L: l0D and $17.0^{\circ}C$, respectively, and the spawning continued until June 15, 1988. There were no particular differences between fish under the controlled condition and those in natural condition in terms of the fertilization rate, surface floating rate, the number of oil glouble and the hatching rate.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.44 no.5
• /
• pp.524-532
• /
• 2011

The intertidal benthic macroalgal floras of 19 uninhabited islands were investigated in the Goheung area, South Sea, Korea, in June 2008. Seaweed community structures on the rocky shores of four (Naemaemuldo, Ceoldo, Araedombaeseom, and Jinjioedo) of the 19 islands were also examined. Eighty macroalgal species were identified, including 13 green, 19 brown, and 48 red algae. The maximum number of species was found at Naemaemuldo, with 35 species, and the minimum was at Aredombaeseom, with 21 species. Seaweed biomass ranged from 21.39-76.22 g dry wt/$m^2$, with a maximum at Naemaemuldo, and minimum at Jinjioedo. Sargassum thunbergii was a representative species, distributed widely in the intertidal zone of the four islands. Subdominant seaweeds were Corallina pilulifera and Ulva pertusa at Naemaemuldo and Jinjioedo, respectively. Also, Ishige okamurae was dominant at Ceoldo and Araedombaeseom. Six functional seaweed forms were found at each study site, except for Araedombaeseom, which had four functional groups. On the rocky shores of the four sites, a coarsely-branched form was the most dominant functional group ranging from 44.44-61.90% in species number and 72.42-91. 09% in biomass. In conclusion, among the four study sites, the shore of Naemaemuldo Island had the best ecological status, with the highest number of species, and greatest biomass (mainly brown and red algae) and functional form diversity of seaweeds. Furthermore, on the rocky shore of Naemaemuldo, coarsely branched- and joint calcareous-form seaweeds, which grow in clean and undisturbed environmental conditions, were the representative functional forms.

• Ocean Science Journal
• /
• v.42 no.2
• /
• pp.103-116
• /
• 2007

Seasonal changes of tide signal(s), temperature, salinity and current were studied during the years 2004-2005 in the northernmost Gulf of Aqaba, which is under developmental activities, to obtain scientific bases for best management and sustainability. Spectrum analysis revealed permanent signals of tide measurements during all seasons, which represented semidiurnal and diurnal barotropic tides. The other signal periods of 8.13, 6.10-6.32, 4.16 and 1.02-1.05 h were not detected in all seasons, which were related to shallow water compound and overtides of principle solar and lunar constituent and to seiches generated in the Red Sea and the Gulf of Aqaba. Spatial and temporal distribution of temperature, salinity and density showed significant differences between months in the coastal and offshore region and no significant differences among the coastal sites, between the surface and bottom waters and between coastal and offshore waters. Therefore, the temporal and spatial variation of water properties in the northernmost Gulf of Aqaba behave similarly compared to other parts. The coastal current below 12 m depth was weak $(3-6\;cms^{-1})$ and fluctuated from east-northeastward to west-southwestward (parallel to the shoreline), which may be related to the effect of bottom topography and/or current density due to differential cooling between eastern and western parts in the study area, and wind-induced upwelling and downwelling in the eastern and western side, respectively. The prevailing northerly winds and stratification conditions during summer were the main causes of the southward current at 6 and 12 m depths with average speed of 28 and $12cms^{-1}$ respectively.

• Horticultural Science & Technology
• /
• v.17 no.6
• /
• pp.768-769
• /
• 1999

Experiments were conducted to find out the optimum condition for in vitro proliferation using shoot tip of Gypsophila paniculata. Formation and fresh weight of adventitious shoots were promoted by shoot culture with $0.2mg{\cdot}L^{-1}$ BA and $0.2mg{\cdot}L^{-1}$ NAA in 'Bristol Fairy', while were promoted with $0.2mg{\cdot}L^{-1}$ BA and $0.1mg{\cdot}L^{-1}$ NAA in 'Red Sea'. Vitrification was suppressed by using $7{\times}13cm $ $(diameter{\times}height)$ vessel. Aeration treatment on cap and agar concentration did not affect vitrification, but promoted the elongation of adventitious shoots. Formation of adventitious shoot was inhibited by increasing agar concentration in the medium.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.56 no.2
• /
• pp.212-220
• /
• 2023

Over the past 50 years, red sea bream Pagrus major has been selectively bred for more than 10 generations to improve its growth rate. However, the effect of genetic factors on growth under low- or non-fish meal diet is still unclear. Here, we analyzed 251 individuals randomly mating 21 females (dam) and 16 males (sire) to determine the difference in growth between non-fish meal (i.e., treatment group) and fish meal-based diet (i.e., control group), if any. The kinship coefficient between each group of individuals and their parents was estimated by the KING (Kinship-based Inference for GWASs) software package. The presumed parents of 74 individuals in the treatment group and 57 individuals in the control group could be effectively identified. Notably, one specific female was consistently related to high- rather than low-growth individuals in both groups. In addition, more than one parent in each group was related to either high- or low-growth individuals. Parents of both high-growth individuals in the treatment group and low-growth individuals in the control group were also identified. Although further study is required on various growth factors, this study suggests the possibility of selective breeding under non-fish meal diet.

• Journal of fish pathology
• /
• v.36 no.2
• /
• pp.229-238
• /
• 2023

In this study, the correlation between clinical changes and RSIV genome copy number was investigated to determine the quantitative criteria for the characteristics of RSIV infection. The rock bream (Oplegnathus fasciatus) was intraperitoneally injected with three different doses (1.0×10¹, 1.0×10³ and 1.0×10⁵ viral genome copies/fish) as low, medium, and high doses, respectively. The clinical signs (spleen enlargement, death) observation and real-time PCR were conducted at 5, 10 and 14 days post-injection. During the experiment, spleen index as a quantitative indicator for spleen enlargement was continuously increased in the medium- (up to 2.26) and high-dose (up to 4.99) challenge groups, respectively. Notably, when the spleen index was over 1.5, 2.0, 2.5 and 3.0, a positive correlation was revealed with average viral genome copy numbers of 2.51, 3.37, 4.97 and 5.43×10⁷ viral genome copies/mg, respectively. Moreover, the threshold of spleen index over 1.5 was 1.0×10⁶ viral genome copies/mg, while the thresholds of spleen index over 2.0 and dead was 2.51×10⁷ viral genome copies/mg and the thresholds of spleen index over 2.5 and 3 was 3.98×10⁷ viral genome copies/mg. These findings suggest the possibility of quantitatively analyzing the characteristics and development process of RSIV infection.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.57 no.3
• /
• pp.262-277
• /
• 2024

The mid-eastern coast of Korea is located at the boundary between cold and warm currents, which causes changes in the distribution and composition of marine organisms in response to fluctuations in the marine environment. To understand the seasonal changes in the seaweed community, we investigated its species composition, biomass, coverage, and frequency from November 2022 to August 2023. A total of 45 species (7 green, 18 brown, and 20 red algae) were found in the study area. In the intertidal zone, the number of species decreased from autumn to summer; the biomass peaked during winter (471.94 g wet weight m^-2). Seaweed groups were the dominant functional groups, which were coarsely branched, filamentous, and sheet-like during autumn, winter, spring, and summer. The morpho-functional group was dominated by turf species. In the subtidal zone, the number of species increased during autumn to spring, whereas the biomass peaked during spring (655.27 g wet weight m^-2). The functional group was dominated by coarsely branched species throughout all four seasons, whereas the morpho-functional group was dominated by canopy species. Consequently, changes in the biomass of brown and red algae are recognized as key drivers of seasonal changes in seaweed communities.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.42 no.1
• /
• pp.19-29
• /
• 2006

To investigate the fishery and fishing ground environment of red horsehead (Branchiostegus japonicus), the author analyzed the fishery data and examined the amount of catches and oceanic environment on the adjacent seas of Jeju island and East China Sea. It was turned out that the favourable season of the red horsehead fishery is the month from March to June, the main fishing ground is located in 60 mile radius from the position $32.5^{\circ}N,\;125.7^{\circ}E$. The bottom seawater temperature in fishing ground was shown between $l3^{\circ}C\;and\;16^{\circ}C$, the salinity was appeared between 33.5 and 34.0psu without the seasonal variation of the year. Concentrations of materials(e.g, $NO_3^-\;and\;NO_2^-$) in spring and summer time in main fishing ground were higher than any other seasons, but that of phospheric materials were lower than any other seasons. Concentrations of $chlorophyll\;-\;{\alpha}$ in the main fishing ground was the highest in spring and summer at the surface layer, but the vertical profile of the $chlorophyll\;-\;{\alpha}$ concentrations in all seasons were not variable at bottom layer. Mean density of zooplankton abundance according to the vertical structure was higher and much stable in summer and autumn than spring and winter.