• ALGAE
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• v.38 no.2
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• pp.141-150
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• 2023

Light quality is a common environmental factor which influences the metabolism of biochemical substances in algae and leads to the response of algal growth and development. Pyropia yezoensis is a kind of economic macroalgae that naturally grows in the intertidal zone where the light environment changes dramatically. In the present study, P. yezoensis thalli were treated under white light (control) and monochromatic lights with primary colors (blue, green, and red) for 14 days to explore their physiological response to light quality. During the first 3 days of treatment, P. yezoensis grew faster under blue light than other light qualities. In the next 11 days, it showed better adaptation to green light, with higher growth rate and photosynthetic capacity (reflected by a higher rETR_max = 61.58 and E_k = 237.78). A higher non-photochemical quenching was observed in the treatment of red light than others for 14 days. Furthermore, the response of P. yezoensis to light quality also results in the difference of photosynthetic pigment contents. The monochromatic light could reduce the synthesis of all pigments, but the reduction degree was different, which may relate to the spectral absorption characteristics of pigments. It was speculated that P. yezoensis adapted to a specific or changing light environments by regulating the synthesis of pigments to achieve the best use of light energy in photosynthesis and premium growth and metabolism.

• Journal of the Korean earth science society
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• v.42 no.6
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• pp.605-622
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• 2021

Seasonal forecasting has numerous socioeconomic benefits because it can be used for disaster mitigation. Therefore, it is necessary to diagnose and improve the seasonal forecast model. Moreover, the model performance is partly related to the ocean model. This study evaluated the hindcast performance in the upper ocean of the Global Seasonal Forecasting System version 5-Global Couple Configuration 2 (GloSea5-GC2) using a multivariable integrated evaluation method. The normalized potential temperature, salinity, zonal and meridional currents, and sea surface height anomalies were evaluated. Model performance was affected by the target month and was found to be better in the Pacific than in the Atlantic. An increase in lead time led to a decrease in overall model performance, along with decreases in interannual variability, pattern similarity, and root mean square vector deviation. Improving the performance for ocean currents is a more critical than enhancing the performance for other evaluated variables. The tropical Pacific showed the best accuracy in the surface layer, but a spring predictability barrier was present. At the depth of 301 m, the north Pacific and tropical Atlantic exhibited the best and worst accuracies, respectively. These findings provide fundamental evidence for the ocean forecasting performance of GloSea5.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.4
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• pp.947-956
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• 2016

This study analysed the documents of Sea Area Utilization Consultation of JongChun and ApHae located in West Coast of Korea and NaJeong located in East Coast of Korea in order to find out problems of site surveys and numerical simulations for coastal erosion projects of ocean physics, and suggested the improvement way to go. Current especially like wave-induced current is the one of the important external forces to handle coastal erosion but underestimated in the west coast. In case of east coast the various tests including wave-induced current were conducted but less efficient to find out the reasons of coastal erosion. The stiffness structure to protect coastal line like beach made the secondary erosion by using them without sufficient analysis for the erosion. In order to consult a Sea Area Utilization Consultation those are needed to review the scenarios for external forces such as wave and tidal currents, the site surveys for external forces, the net sediment analysis for years, the long periods of monitoring, and the guide line and revision of the rule for coastal erosion.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.56 no.3
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• pp.265-276
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• 2020

The objective of this study is to develop education programs for cultivating smart aquaculture experts through a education demand survey of industries, high school students, university (graduate) students and field workers. The industry demand analysis was conducted as an in-depth interview on representives from seven companies. Education demand surveys were conducted on 96 students and field workers in the Jeonnam region. Results on the demand survey were analyzed using frequency analysis and cross-analysis. The company representatives responded that they want to participated in internship and retraining programs to proactively secure manpowers with convergence capabilities about smart aquaculture. Seven companies preferred manpowers with basic competencies on ICT (Information and Communications Technologies) or aquaculture. The most respondents in the demand survey want to participate in the education program for experience on advanced technology, self-development and enhancement of work capability. On the other hand, some respondents said that the education is time-consuming and that the education program does not fit their level. Thus, the education program should be developed in a way to minimize the spatial and temporal limitations of education targets and to improve understanding of non-majors by reflecting the demands of human resources in the industrial field.

• Journal of Chitin and Chitosan
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• v.22 no.3
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• pp.185-193
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• 2017

Red tide Heterosigma akashiwo (H. akashiwo), a microscopic alga of the class Raphidophyceae, causes extensive damage to all marine ecosystems. It is essential to reduce the damage to marine ecosystems for them to be used as a resource. In this study, we used organic solvent fractionation to obtain an ethyl acetate-methanol extract from H. akashiwo (HAEM80) and then evaluated its anti-inflammatory activity in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells and a zebrafish model. HAME80 markedly inhibited the production of nitric oxide (NO) and prostaglandin $E_2$ ($PGE_2$). It also down-regulated the protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) and decreased the secretion of interleukin-$1{\beta}$ ($IL-1{\beta}$) in LPS-stimulated RAW 264.7 cells. HAME80 reduced yolk edema and improved the survival rate of LPS-stimulated zebrafish embryos; in addition, the extract significantly reduced the production of ROS and NO and attenuated cell death in this model. Gas chromatography-mass spectrometry (GC-MS) of the extract was used to confirm the identity of peaks 1-20. Taken together, our data suggest that H. akashiwo is a beneficial anti-inflammatory agent.

• Journal of Marine Bioscience and Biotechnology
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• v.10 no.2
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• pp.62-72
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• 2018

An active ingredient with hyaluronidase (HAse) inhibitory effect is one of the anti-aging approaches in cosmeceuticals. Here, red sea cucumbers (RSCs), Stichopus japonicus, from Jeju Island were evaluated to examine their HAse inhibitory and antioxidant activity effect. In this study, RSCs were extracted by six enzymatic hydrolysis (Alcalase; Al, Trypsin; Try, Neutrase; Neu, Pepsin; Pep, Alpha-chymotrypsin; Chy and Protamex; Pro). Alcalase hydrolysate (AlH) showed the highest antioxidant capacities for both of oxygen radical absorbance capacity (ORAC) and trolox equivalent antioxidant capacity (TEAC) methods, compared to those of other hydrolysates, at $66.59{\pm}0.78{\mu}M\;TE/mg$ and $135.78{\pm}3.24{\mu}M\;TE/mg$, respectively. Furthermore, AlH performed the highest capacity of HAse inhibitory with $IC_{50}$ value of 3.21 mg/ml. Thus, RSCs hydrolyzed by Al were chosen to determine the cellular antioxidant activity and hyaluronic acid (HA) production effect on Human immortalized keratinocyte cell line (HaCaT). The results showed that AlH improved the cell viabilities and intracellular reactive oxygen species (ROS) induced by 2,2'-Azobis(2-amidinopropane) dihydrochloride (AAPH) were significantly decreased. In addition, AlH increased HA amount by regulating HYAL2 and HAS2 expressions in the HaCaT cells. Taken together, AlH of RSCs collected from Jeju Island showed HAse inhibitory and antioxidant activities against skin-aging which shows its potentials can be an optional natural bioactive ingredient for novel cosmeceuticals.

• Ocean and Polar Research
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• v.38 no.1
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• pp.21-33
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• 2016

Gametogenesis of the comb pen shell, Atrina pectinata (Linnaeus, 1767) (Bivalvia: Pinnidae) on the southern coast of Ulleungdo Island, Korea was assessed monthly (November 2013 to October 2014) using histology. Gametogenesis commenced in January when the surface water temperature was $12.6^{\circ}C$ and pen shells evidenced an early development phase with small oogonia from January to April, although few females exhibited ripe eggs in their follicular epithelium. In April, the oocyte diameter increased rapidly, and fully mature eggs appeared in May. First spawning males and females were observed in June as the surface water temperature reached $19.3^{\circ}C$ and July ($23.2^{\circ}C$) respectively. The spawning activity continued until the end of September. Histology indicated that the spawning peak of the females in Ulleungdo Island was July to August. During October to January, most of the pen shells were in spent and resting stages. Our data suggested that A. pectinata is a summer spawner, and their annual gametogenesis is closely associated with the seasonal variation in the surface water temperature. The present study is the first provided fundamental information on the life history of A. pectinata in Ulleungdo Island, and this can be put to good use in the management of this pen shell in the study area.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.54 no.1
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• pp.89-95
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• 2018

The maturation and spawning of black scraper, Thamnaconus modestus were studied using samples collected monthly from March, 2015 to February, 2016 in the coastal waters off Middle East Sea, Korea. The gonadosomatic index (GSI) of female was the highest in June. The spawning periods lasted from March to September based on histological observation of female gonad development. The percentage of sexually mature females estimated from a logistic function was over 50% for the size group 18.02 cm (total length, TL). The size of eggs spawned was between 0.40 to 0.58 mm. Fecundity varied between 185,648 and 9,747,250 eggs. The relationship between the fecundity and TL of the fish was expressed in the fecundity equation as $F=0.0297TL^{5.4835}$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.6
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• pp.745-751
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• 2019

Seasonal variation in species composition of fishes in the Sannam reservoir in Changwon, Korea was determined using samples collected by a three-sided fyke net in 2018. During the study period, we collected 2,181 individuals of 9 species, with a total weight of 111,552.2 g. The dominant species were Lepomis macrochirus, Carassius carassius, Erythroculter erythropterus, and Cyprinus carpio. These species accounted for 96.1% of the total number of individuals. The number of fish species, number of individuals, biomass and species diversity indices fluctuated with the seasons. The peak number of fish species occurred in May and August, the biomass of fishes was highest in May. Whereas the number of individuals was highest in February.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.55 no.4
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• pp.327-334
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• 2019

The feeding habits of the bighead croaker Collichthys niveatus were studied using 745 specimens collected by bottom trawl net in the West Sea, Korea, in April and October of 2016, 2017 and 2018. The size of C. niveatus ranged from 4.8 to 16.0 cm in total length. The stomach contents analysis indicated that C. niveatus consumed mainly euphausiids and copepods. C. niveatus consumed mainly euphausiids and copepods in all size classes. The dietary compositions of C. niveatus was not significantly different among size classes (One-way ANOVA, P > 0.05). As body size of C. niveatus increased, the mean weight of prey per stomach (mW/ST) tended to increase.