• Ocean and Polar Research
• /
• v.36 no.2
• /
• pp.157-163
• /
• 2014

This study analysed the economic feasibility per hectare of grow out phase production of Oyster farming by rising water temperature in Ocean. Elevated Water temperature by climate change had a bad influence for oyster production and economic feasibility. In the case of production units, the total output of oyster decreases from 213,840 to 205,594 units. Using cost-benefit analysis with discounting rates (5.5%), we estimated the net present value (NPV) and benefit cost ratio (BCR) until 2100 years. The model results showed that the NPV without water temperature rise was 1,565,619,893 won and the NPV with water temperature rise was 1,540,493,059 won. Also, BCR estimated that the former was 2.095 better than the latter was 2.077. To summarise, the economic effect per hectare of water temperature rise in ocean did the damage to the economic loss about 25,126,834 won.

• 한국해양학회지
• /
• v.22 no.2
• /
• pp.80-86
• /
• 1987

Five species of marine cladocerans, Evadne nordmanni, Evadne tergestina, Podon leuckarti, Podon polyphemoides and Penilia avirostris, were found in Chinhae Bay during the years 1982-1983. Incidence of E. nordmanni(April-May) in spring and of E. tergestina(June-December), E. avirostris(June-November) in summer through autumn was noticed during the present study. But P. polyphem oides appeared throughout the year except February. P. avirostris was the most abundant species(21,491indiv./㎥), followed by P. polyphemoides and E. tergestina. Population of E.normanni and P. leuckarti was extremely poor and recorded to be less than 1,000indiv./㎥. Seasonal change in size composition was noticed in E. tergestina and P. avirostris. Increase of length was recorded in P. polyphemoides when water temperature lower than 15$^{\circ}C$.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.26 no.3
• /
• pp.120-130
• /
• 2014

Change of mean sea level in the western coast of Korean peninsula was estimated with the observed tide data of the KHOA. The cause of the change was investigated. Mean sea levels in the western coast have been changed due to coastal development projects in the coastal zone. The estimated variations, which are significantly different regionally, vary from -6.8 cm in Incheon to 38 cm in Gunsan. The changing rate of mean sea level occurred by natural factors such as global warming varies from 1.1 mm/year in the north to 4.4 mm/year in the south of western coast of Korean peninsula. In Jeju, sea level rise and rise of sea temperature showed a close relationship. Water temperature rise of one degree increases mean sea level to 0.6 mm in Jeju. Rising rate of mean sea level has increased rapidly after the mid-1980s.

• Korean Journal of Ichthyology
• /
• v.29 no.1
• /
• pp.80-86
• /
• 2017

We examined monthly variations in community structure of larval fish assemblage in the coastal waters of south-central Korea in spring and summer, 2016. A total of 31 taxa of larvae were collected during the study period. Engraulis japonicus larvae were predominated in spring than summer. The larvae of Cynoglossus abbreviates, a spring spawners, were exclusively collected in spring, while those of Nibea albiflora, a summer spawners, were exclusively caught in summer. Due to those seasonal differences in abundance of the dominant species, larval fish community was divided into two main seasonal groups (i.e. April~May and June~August). In addition, summer group was divided into two significant subgroups (June~July and August). During August, the larvae of E. japonicus and N. albiflora sharply decreased in abundance due to abnormally high sea water temperature that was raised up to $28^{\circ}C$, with the temperature being out of range of their optimum spawning temperature.

• 한국해양학회지
• /
• v.19 no.1
• /
• pp.11-17
• /
• 1984

The abnormal cooling phenomenon occurred in the coastal areas of East Sea of Korea in summer, 1981 is studied on the basis of the oceanographical data obtained by the National Fisheries University of Pusan, in July, 1981 and by Fisheries Research and Development Agency of Korea during 1961 to 1981 and by Japan Meteorological Agency in 1975 and 1981. Th vertical section of temperature along 130 E showed that the warmer waters more than 10 C occupied at upper layer of about 75m depth in south of 35 30'N the layer changed rapidly thinner as 20m th 30m depth. In the areas of East Sea during 1966 to 1981, the temperature fluctuations at 100m depth ranged greatly in standard deviation from 2 C to 4 C. The temperature anomaly in 1981 was about 1.5 times of the standard deviation and at the upper layer of 150m depth the temperatures became colder by 5 -10 C than average values in August, 1961-1975. The 10 C isotherm at 100m depth in 1981 appeared between 35 and 36 N, shifting southward 20 to 120 miles than mean year. These results showed that the abnormal cooling phenomenon in the areas of East Sea of Korea in summer occurred mose predominantly in 1981 in period from 1966 to 1981

• Journal of Aquaculture
• /
• v.10 no.2
• /
• pp.213-218
• /
• 1997

Experiments on the feeding activity and environmental tolerance of geoduck clam, Panope japonica caught at the coastal water of Kangwon province located in the East Sea of Korea were performed from January to December, 1994. Twenty genera and 33 species of plankton were found in the digestive tract, and most of them are phytoplankton. In spring, 21 species of planktonic foods were indentified, but in sumer, only 11 species were identified. Nitzschia longissima and Rizosolenia alata were present evey month. Weight of the digestive tract was fluctuate seasonally : higher winter and spring, and lower summer. Adult geoduck clams could be tolerated within the range of 5 to $20^{\circ}C$ water temperature, and they could tolerated considerably well temperature than higher temperature within the range.

• Journal of Aquaculture
• /
• v.16 no.4
• /
• pp.223-228
• /
• 2003

An exfoliation, the detachment of juvenile abalones from a culture substrate, is essential for selection and population density control in abalone culture. Physical instruments and anesthetics are currently available for the exfoliation but the latter is regarded as more effective in reducing physical damage to the animals. In the present study, urea ($Co(NH_2)_2$), a chemical fertilizer, was selected as a anesthetic, and its optimal concentration and sea water temperature for exfoliation of Haliotis discus were determined in order to develop an exfoliation technique which is more economical and effective. A 97% cumulated exfoliation rate was observed within 3 min at all temperatures observed when the concentration rate of urea was 9∼15%. This range of urea concentration can be ideal for both exfoliation and recovery. Also it was found that the higher concentration of urea and temperature the higher exfoliation rate, however, these conditions reduced the recovery rates of the animals tested. These results could indicate that urea is a good tool for exfoliation of various species of young abalones, and urea could substitute for all techniques and anesthetics methods currently available for abalone exfoliation.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2023.05a
• /
• pp.502-502
• /
• 2023

지난 140여년(1880~2022)간 지구의 연평균 기온은 약 1.5℃ 상승하였다. 이에 따라 폭염, 홍수, 가뭄 등 이상기후 발생이 급증하고 있으며, 생태계가 급격히 변화하여 담수호의 산소량 또한 급속히 감소하고 있다. 소양호는 총길이 60 km, 유역면적 2.703 km², 최대저수량 29억톤으로, 유역면적은 북한강 유역의 25%에 달하며 북한강 상류에 위치하고 있는 국내 최대의 인공호이다. 따라서 소양호 유역의 관리는 북한강 유역의 수질 관리와 수도권 수자원 공급의 핵심 중 하나라고 볼 수 있다. 그러나 기후변화에 따라 소양호의 성층현상에도 변동이 생겼을 것으로 판단되고 있다. 호소의 성층현상은 수심에 따른 온도의 변화로 발생하는 현상으로, 성층현상이 심하면 유체는 연직운동이 제한되고 상대적으로 수평방향 운동이 활발해진다. 소양호는 수심이 매우 깊으며, 열용량이 크기 때문에 여름에 성층이 형성되는 온대일순환호(warm monomictic lake)로 분리된다. 성층현상이 심하면 호소 하부의 저층에서는 용존산소가 거의 없어 혐기성 상태가 되고, 침전된 유기물이 혐기성 미생물에 의해 분해되기 때문에 수질은 크게 악화된다. 따라서 본 연구는 30년간의 소양호의 수온과 DO의 변동을 분석하여 성층현상의 변동성을 파악하고자 하였다. 이에 따라 약 30년간(1993년 1월~2022년 12월) 0~90 m까지 측정한 수온, DO 데이터를 이용하였다. 데이터는 매달 최소 1회~최대 5회 측정된 자료 중 가장 수심이 깊게 측정된 날의 자료를 이용하였다. 1월과 2월의 데이터는 동절기로 인해 소양호 조사를 실시할 수 없어 제외하였다. 수온의 경우 30년간 서서히 증가하는 경향을 보였으며 0~90m 전반에 걸쳐서도 대체로 증가하는 경향을 보였다. 또한 6월에 성층현상이 더 심해지고, 겨울에는 연직운동이 감소하는 모습을 보였다. DO의 경우 용존산소가 중층에서 최저를 보이는 Metalimnetic oxygen minimum을 보였으며, 2008년까지는 거의 매년 농도 2.0mg/L 이하인 달이 있었으나 그 이후에는 회복되어 대부분 2.0 mg/L 이상을 보였다. 그러나 심층의 경우에는 2014년부터 DO 농도 3 미만으로 떨어지는 경우가 증가하였다.

• Korean Journal of Environmental Biology
• /
• v.17 no.4
• /
• pp.379-387
• /
• 1999

During the past several decades, electricity generating plant increased with remarkable rapidity in Korea. Recently the increase has been much more rapid as the rate of industrialization has accelerated. Construction of nuclear power plants in coastal areas inevitably caused the perturbation of critical coastal habitats and thus influenced marine algal species composition. Particularly, an increase in the building of nuclear power plants led the amounts of heat discharged to increase exponentially. As far as the effects of cooling water and thermal discharges are concerned, benthic marine algae are likely to be vulnerable to a discharge. Heated effluents from nuclear power plants, with the temperature rises of 7~12$^{\circ}C$ under normal operating and design conditions, are discharged through the discharge canal and into natural water bodies. It is clear that the characteristic marine algal community is developed in the area affected by the thermal discharges; i.e. low species richness and low species diversity. Nevertheless, it is worthwhile to note that elevated temperatures exert differential effects depending on the algal populations. Benthic marine algae grown at the discharge canal can be regarded as warm tolerant species. 35 species (4 blue-green, 9 green, 8 brown and 14 red algae) of marine algae occurred more than 20eye frequency at discharge canal of three nuclear power plants in the east coast during 1992 ~ 1998 and thus can be categorized as warm tolerant species in Korea. To minimize the ecological impacts of waste heat on benthic marine algae, it is recommended that, in the future, nuclear power plants will have to employ some form of closed-cycle cooling for the condensers.

• Journal of fish pathology
• /
• v.26 no.3
• /
• pp.173-183
• /
• 2013

From July to early September 2012, there was mass mortality of fishes, particularly black rockfish, which were being raised in the floating fish cage along the coast of Gyeongsangnam-do. The amount of damage was 1,802,000 fishes and the causes were confirmed to be rapidly rising water temperature and repeated daily changes in water temperature. The water temperature in this area of the sea rose to the maximum $28.4^{\circ}C$ and the daily range of changes in water temperature was maximum $6.5^{\circ}C$. As a result of investigating biological diseases of 194 fishes in 49 fishery areas, major pathogenic organisms such as red seabream iridovirus (RSIV), Vibrio sp. and Vibrio spp. or Microcotyle sp. were detected in rockfish in some fish farms. It is considered that the major causes of the mass mortality were high water temperature accompanied by repeated daily changes in water temperature, it is considered that biological diseases influenced the increase in the perish of fishes.