• Journal of Aquaculture
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• v.12 no.4
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• pp.283-292
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• 1999

Physiological responses (cortisol, glucose, GPT, GOT, hematocrit, sodium, chloride, potassium, total protein and osmolality), growth and survival rates of grey mullet and Nile tilapia were tested by the gradual salinity changes for 70 days. Three different sizes of grey mullet, small (MS, $13.3\pm1.8cm$), middle(MM, $28.9\pm3.6cm$) and large (ML, $36.0\pm2.0cm$), and three different sizes of tilapia, small (TS,$16.5\pm1.7cm$), middle (TM, $20.6\pm1.8cm$) and large (TL, $27.2\pm2.7cm$)were used. Salinity of reareing water was increased $\5textperthousand$ in every 5 days until it reached at $0\textperthousand$. The cortisol concentrations in all size groups of grey mullet were increased at both full strength seawater (SW) and fresh water (FW) at the end. The cortisol concentrations of TM and TL groups were higher in SW than FW (0 and 70 days). The GOT values of grey mullet were lower than those of Nile tilapia. The sodium concentrations of grey mullet in SW were ranged 160~184 mEq/$\ell$, while those of Nile tilapia were the highest in the SW. No mortality was observed in MM and ML groups but survival rate of MS group was 76$\textperthousand$. Overall survival rate of Nile tilapia was lower than grey mullet. Survival rate of TS, TM and TL groups were $79\textperthousand$, $29\textperthousand$ and $55\textperthousand$, respectively.

• 한국해양학회지
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• v.28 no.4
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• pp.292-304
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• 1993

The east Sea circulation is numerically modeled with refined grid resolution elaborated open boundary condition, and by directly imposing the measured surface temperature and salinity typical the east Korean Warm current are clearer than those in previous works. among others, The Ulleung warm Water and the Intermediate Water of minimum salinity are nicely reproduced. The latter is formed in the northern/northwestern coastal region in winter and is advocated southward by strong under-current. the former is associated with a locally generated anti-cyclonic gyres. The model indicates strong seasonal variation of Nearshore Current along the Japanese coast from wintertime barotropic to summertime baroclinic structures. the associated strong reversed under-cur-rent in summer is not well understood. Global circulation pattern is characterized by two regions of cyclonic and anti-cyclonic gyres in the north and south, respectively. The presence of these gyres indicates importance of local dynamics in East Sea circulation. This model, however, does not completely resolve the problem of overshooting of the East Korean Warm current.

• Proceedings of KOSOMES biannual meeting
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• 2004.11a
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• pp.117-122
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• 2004

In order to investigate the initial stage of deep water formation between Vladivostok and the subpolar front in the East Sea, the factors, temperature, salinity, dissolved oxygen, measured by multi-ship surveys in 1969 have been used Deep water formation in the East Sea occurs in essentially two different forms: near continent and open ocean formation the position of eddy derived from potential vorticity matches well with that of deep water formation. The vertical and horizontal distributions of potential vorticity, geostrophic current, temperature, salinity and dissolved oxygen give clues for the preconditioning phase of open ocean formation like a doming of isotherm, associated with a cyclonic circulation

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.3
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• pp.276-283
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• 2011

The growth and tolerance for water temperature and salinity were compared among red sea bream Pagrus major (RSB) black sea bream Acanthopagrus schregeli (BSB) and their hybrid ($F_1$), female RSB ${\times}$ male BSB. The growth of the $F_1$ fish did not differ until 27 days after hatching (dAH), after which the most rapid growth was observed until approximately 300 dAH, followed by RSB and BSB. However, the RSB had out grown the $F_1$ fish by approximately 303 dAH. By 480 dAH, the RSB were largest, followed by the $F_1$ and BSB groups. The tolerances for high and low water temperature were significantly different for each species and growth stage. The largest tolerance spectrum was observed in the BSB group, and the tolerance spectrums gradually decreased with increasing final body weight. During the salinity tolerance trials, all of the species started to die following transfer into freshwater (0 psu). BSB showed the highest survival rate when kept in fresh water for an average of 29.9 hours, while the $F_1$ fish were more tolerant than the RSB fish. The fish were increasingly tolerant to fresh water and changes in water temperature as they grew, while the size of the temperature spectrum remained unchanged but shifted to a lower temperature range with growth. Our results demonstrate that $F_1$ performed well in terms of growth compared to parental fish, with higher temperature and salinity tolerances than RSB, and is thus suggested to be a suitable aquaculture species for Korea and northeast China.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.5
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• pp.612-619
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• 2016

In this study, we crossbred Epinephelus akaara and E. lanceolatus to produce a hybrid grouper with faster growth and adaptation to domestic aquaculture environments. The plasma cortisol and glucose levels and osmoregulation (stress response indicators) of the hybrid grouper, E. akaara ♀ × E. lanceolatus ♂, were investigated under several salinity levels (32, 24, 16, and 8 psu). The body lengths and weights of E. akaara (8.2 ± 0.1 cm, 8.3 ± 0.4 g) and the hybrid (8.6 ± 0.1 cm, 10.0 ± 0.4 g) were similar at the start of the experiment, but were significantly different at the end of the experiment. Juveniles of both E. akaara and the hybrid showed greater weight gain, specific growth, and feed conversion rate (FCR) under low salinity of 16 psu. Under the 8 psu treatment, the juvenile E. akaara all died, while the hybrid juveniles survived. Plasma cortisol levels were not affected by lower salinity in both species. The above results indicate that the hybrid is more tolerant of low salinity than is E. akaara, although both species exhibited higher growth and FCR at 16 psu, lower than the salinity of natural seawater. Thus, juveniles of both E. akaara and the hybrid can be more effectively cultured in brackish areas or waters with salinity lower than that of seawater.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.4
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• pp.620-627
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• 2020

Oxygen consumption and blood physiology of olive flounder Paralichthys olivaceus (mean body weight 106.6±6.8 g, mean±SD) was investigated at salinities of 34.0 (control), 33.7, 33.3, 32.6, 31.3, 28.6, 23.1, 12.2 and 0.0 psu at 20.0℃, respectively. Stepwise salinity changes (34.0→33.7→33.3→32.6→31.3→28.6→23.1→12.2→0.0 psu) with an interval of 24 h for each salinity induced a significant (P<0.05) increase of oxygen consumption rate (OCR) in fish exposed from 31.3 to 0.0 psu compared to that of control fish. The maximum OCR was found in fish exposed to 23.1 psu, which was accompanied by 36.2% higher energy consumption than the control fish. Fish exposed to each salinity for 24 h induced a significant decrease of blood plasma Na⁺ in 0.0 psu and Cl^- in 12.2 and 0.0 psu (P<0.05), and increase of plasma glutamic oxaloacetic transaminase (GOT) in 0.0 psu compared to the control fish (P<0.05). The results of this experiment show that P. olivaceus exposed to concentrations below 31.3 psu requires more energy costs to adapt to salinity changes than 34.0 psu under our experimental conditions.

• Journal of Korea Water Resources Association
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• v.31 no.2
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• pp.209-219
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• 1998

Sea water volume intruded from the lock gated was compted by a one-dimensional numerical model and the extent of diffusion of sea water was evaluated for that. The volume of intruded sea water, in the exchange processes of salt and fresh waters, was computed by the conceptual model considering the tidal level, volume of chamber, volume of canal, and operation period only, It was divided into some cases according to whether ships enter or leave the canal and whether the level of tide is lower or higher than that of water level in canal. The model, developed in this work, assumed that intruded sea water is well mixed in the canal; and complete is the exchange of waters between sea and canal. The simulation case was divided into two categories according to whether the water was added from the Han River or not.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.531-533
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• 2013

In this paper, to study the IPMC (Ionic exchange Polymer Metal Composite) material consisting of a sulfonic acid ion and fluoride combination of carbon with Nafion film greatly affected the electro-active polymer (Electro Active Polymer) characteristics and the presence of water and cationshave properties. Use or electrical energy into mechanical energy, mechanical energy, electrical energy, and can be utilized to its characteristics, depending on the water and cations in water varies greatly. Configure the device simulations in order to study the electrical properties of these IPMC. Stepper Motor using MCU and simulator designed for the electrical characterization due to the movement and to the implementation of the mechanical movement of ocean currents. In this study, configuration the IPMC and simulation device to the area of the IPMC to the efficient use of energy currents, frequency, salinity concentration, through the efficient use of the IPMC due to the bend angle of the electrical analysis and research methods we propose.

• 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.

• Journal of Environmental Impact Assessment
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• v.21 no.4
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• pp.553-565
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• 2012

영산강 하구에서 담수유입에 따른 저염수의 거동을 파악하기 위하여 EFDC 모델을 수행하였다. 모델의 수행은 홍수기 배수갑문 확장 전 후로 나누어 수행하였으며, 모델의 마지막 담수유입시점으로부터 16일 후 해역이 준 정상상태에 도달하기까지 저염수의 확산양상을 시간 경과순으로 살펴보았다. 그 결과, 담수유입이 멈춘 후에 저염수는 방류시점으로부터 약 6시간 경과 후에 배수갑문 전면 해역으로부터 해측으로 최대의 확산을 보였으며, 약 2~7일 후 염분의 분포 양상은 담수가 유입되기 전으로 회복되는 경향을 보였다. 한편, 배수갑문을 확장하기 전보다 배수갑문을 확장한 후에 담수유입 후 해역이 준 정상상태에 도달하는 시간이 더욱 짧았는데, 이는 시간당 방류량의 증가가 난류혼합을 강하게 하고, 해측으로 더 멀리 확산된 저염수는 외해수에 의해 보다 쉽게 혼합되기 때문인 것으로 판단된다. 따라서, 본 해역에서 일정한 양의 담수가 유입되는 경우, 저염수의 확산은 시간당 방류량이 크고 방류지속시간이 짧을수록 해역이 준정상상태에 도달하는 시간이 더욱 짧아질 것으로 사료된다.