• Ocean and Polar Research
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• v.30 no.4
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• pp.475-484
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• 2008

The word 'Saemangeum' indicates an estuarine tidal flat in the southwestern part of the Korean peninsula. The Saemangeum Reclamation Project was launched as a national project in 1991 to reclaim a large coastal area of $401\;km^2$ by constructing a 33-km long dyke. The final dyke enclosure in April 2006 has transformed the tidal flat into lake and land. An integrated oceanographic study has been conducted since 2002 as a part of the Government Action Plan to monitor and assess changes in the marine environment. Prior to the dyke enclosure, the coastal environment in the Saemangeum was a complex system governed by tidal motion, estuarine processes, and coastal circulation of the Yellow Sea. The dyke construction has radically changed not only the estuarine tidal system inside the dyke, but also the coastal marine environment outside the dyke. Post to the dyke enclosure, subsequent changes such as red tide, hypoxia, and coastal erosion/deposition occur successively. Red tides appear almost the year round in the inner area. Even under the condition that the sluice gates are fully open, the water quality does not improve as much as the developers would expect, mainly due to the critical reduction of the hydrodynamic stirring power. We will introduce details of our monitoring program and significant changes in the Saemangeum marine environment, based on observations and model results.

• Proceedings of KOSOMES biannual meeting
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• 2017.04a
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• pp.193-193
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• 2017

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.4
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• pp.479-487
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• 2014

Leptin plays an important role in energy homeostasis and reproductive function in fish, especially in reproduction. Migrating fish, such as salmonoids, are affected by external environmental factors, and salinity changes are a particularly important influence on spawning migrations. The aim of this study was to test whether changes in salinity affect the expression of leptin, estrogen receptors (ERs), and vitellogenin (VTG) in chum salmon (Oncorhynchus keta). The expression and activity of leptin, the expression of ERs and VTG, and the levels of estradiol-$17{\beta}$ and cortisol increased after the fish were transferred to FW, demonstrating that changes in salinity stimulate the HPG axis in migrating female chum salmon. These findings reveal details about the role of elevated leptin levels and sex steroid hormones in stimulating sexual maturation and reproduction in response to salinity changes in chum salmon.

• Journal of Aquaculture
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• v.20 no.4
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• pp.205-211
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• 2007

Stress-inducible proteins may function in part as molecular chaperones, protecting cells from damage due to various stresses and helping to maintain homeostasis. We examined the mRNA expression patterns of a 68-kDa heat shock protein (HSP68) and 78-kDa glucose-regulated protein (GRP78) in relation to physiological changes in Pacific oyster Crassostrea gigas under osmotic stress. Expression of HSP68 and GRP78 mRNA in the gill significantly increased until 48 h in a hypersaline environment (HRE) and 72 h in a hyposaline environment (HOE), and then decreased. Osmolality and the concentrations of $Na^+$, $Cl^-$, and $Ca^{2+}$ in the hemolymph of HRE oysters significantly increased until 72 h (the highest value) and then gradually decreased; in HOE oysters, these values significantly decreased until 72 h (the lowest value), and then increased. These results suggest that osmolality and $Na^+$, $Cl^-$, and $Ca^{2+}$ concentrations were stabilized by HSP68 and GRP78, and indicate that these two stress-induced proteins play an important role in regulating the metabolism and protecting the cells of the Pacific oysters exposed to salinity changes.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.6
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• pp.726-734
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• 2018

The total number of Sea Area Utilization Consultation in the environment management sea areas reviewed from 2015 to 2017 were 60. The number of development projects in the environment conservation sea areas decreased steadily, but special management sea areas increased. Development types in environment management sea areas showed that artificial structure installation was the highest ratio, followed by fishery port development and construction of habor and coastal maintenance and sea water intake and draining. By comparing the trend of water quality changes using marine environment information system (MEIS) data in the environment management areas from 2006 to 2017, COD showed no significant changes but the environment conservation sea areas increased slightly, and the concentration of TN and TP decreased. Gwangyang and Masan bays in the special management sea areas and Gamak bay in the environment conservation sea areas displayed oxygen deficient mass in the summer. As the use of development projects of the environment management sea areas are performed continuously, an analysis of the status of sufficient water quality changes is necessary for environmental impact assessment (Sea Area Utilization Consultation) in the marine environment and should be evaluated mainly for management of contamination by diagnosing thoroughly water quality effects and the pollution of sediment. Especially, the water quality goal for the purpose of designation in each of the environment management sea areas is set clearly, connection with pollution source control and the total pollution load management system (TPLMS) should be proposed and measured to reduce the amount of contaminated water.

• Development and Reproduction
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• v.17 no.4
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• pp.399-407
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• 2013

Morphological changes in the reared rock bream, Oplegnathus fasciatus, from hatching to six days after hatching were examined during the early growth stage under starvation. All the larvae died within five days when feeding was delayed for three days after hatching. These results imply that initial larval food should be supplied within two days of hatching. Changes in the pectoral angle and the ratios of eye height to head height, gut height to standard length, and gut height to myotome height in the rock bream are alternative indicators for the identification of starving fish. These indicators might prove useful in evaluating the successful transition from endogenous to exogenous feeding in this species.

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.2
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• pp.105-110
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• 2009

Marine pollution prevention manager system has been operated for the purpose of preventing marine pollution from ships and marine facilities in Korea. As a new "marine environment management act" replacing an old "marine pollution prevention low" had entered into force from January 20, 2008, the education system for marine pollution prevention manager is to change in some ways. Major changes in education/training institutions, education/training courses, trainees, marine pollution prevention manager's works and business, marine facilities and educational subjects are summarized, comparing between old "marine pollution prevention act" and new "marine environment management act".

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.8
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• pp.1196-1202
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• 2009

In this paper, an estimator design of underwater environment changes is proposed by using observer techniques for ROV control system. The underwater environment changes are considered as an external disturbance term for ROV model and it is added into the input term of ROV model. To estimate the environment changes, a PI observer which does not effect the external disturbance input term is proposed. To verify the effectiveness of the proposed method, the step and the sinusoidal environment changes are considered in simulation. The proposed method will be applied to design the haptic controller for ROV in future.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.46 no.4
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• pp.424-436
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• 2013

Organic enrichment was investigated in surface sediments from the Yeoja and Gangjin Bays of Korea, which contain dense shellfish farms, in order to evaluate the contamination status and temporal changes in shellfish farming along these coasts. The degree of organic enrichment was determined using geochemical indicators (chemical oxygen demand, ignition loss, acid volatile sulfide, total organic carbon in sediments, and total nitrogen in sediments, ammonium and nitrate in pore water, and bioluminescence inhabitation for sediments). Temporal changes in organic enrichment conditions were detected by comparing our 2012 data to those previously reported from a survey conducted in 1999/2000. Organic enrichment was significantly higher in September than in May and July, in Gangjin Bay than in Yeoja Bay, and significantly higher in shellfish farms than in reference sites not used to culture shellfish. Ammonium concentrations in pore water were two orders of magnitude greater than nitrate concentrations, suggesting that these bays represent nitrogen-reducing environments.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2001.05a
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• pp.265-266
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• 2001

PCDDS and PCDFs are very stable chcmicals and have very long residence times in the environment and in organisms, including humans. Their hydrophobicity promotes accumulation in sediments and organisms, resulting in high concentrations in both sediments and organisms. Among toxicological effects reports arc teratogenicity, reduce reproduction, liver toxicity, decreased growth rate and behavioral changes (Zeise et al., 1990; Huff, 1992). PCDDs/DFs are inadvertently produced from various combustion sources and manufacturing processes, such as municipal solid waste incineration (Olie et at., 1977), motor vehicles (Marklund et al., 1987), steel mills (Tysklind et al., 1989), and chemical production processes (Hutzinger et al., 1985). (omitted)