Young-Sang Suh

Summer primary productivity and phytoplankton community composition driven by different hydrographic structures in the East/Japan Sea and the Western Subarctic Pacific

The East/Japan Sea (EJS) is a highly productive marginal sea in the northwest Pacific, consisting of three basins (Ulleung Basin: UB, Yamato Basin: YB, and Japan Basin: JB). To find causes of the reportedly high primary productivity in summer in the EJS, especially in the UB, we measured primary productivity, phytoplankton composition, and other environmental variables. The water column was strongly stratified in the EJS compared with the Western Subarctic Pacific (WSP). Integrated primary productivity was two times higher in the EJS (612 mg C m−2 d−1) than in the WSP (291 mg C m−2 d−1). The vertical distributions of physicochemical and biological factors confirmed that production in the subsurface chlorophyll maximum layer in the study regions was an important factor regulating primary productivity within the water column. While picoplankton (<2.7 µm) dominated in the WSP, JB, and YB, micro/nanoplankton (≥2.7 µm) dominated in the UB. Contribution by picoplankton to total biomass and primary productivity in the UB was significantly lower than in the other regions. CHEMTAX analysis using marker pigments showed that diverse phytoplankton groups inhabited the study regions. Cluster and canonical correspondence analyses showed high correlation between the spatial variation in phytoplankton assemblages with the water mass properties mainly represented by water temperature and nitrate concentration. Overall, our results suggest that the hydrographic structure of water column in the study region is an important controlling factor of the biomass and productivity of phytoplankton as well as their diversity in size and taxonomic groups.

Grimontia marina sp. nov., a marine bacterium isolated from the Yellow Sea

A novel species belonging to the genus Grimontia is described in this study. A Gram-negative, chemoheterotrophic, obligately aerobic, catalase- and oxidase-positive, motile by a single polar flagellum, and rod-shaped bacterium, designated IMCC5001T, was isolated from surface seawater of the Yellow Sea. Strain IMCC5001T grew optimally at 30°C in the presence of 3.5% NaCl. Phylogenetic analysis based on 16S rRNA gene sequences showed that the isolate was related most closely to Grimontia hollisae with a sequence similarity of 95.8%, and formed a robust phyletic lineage with Grimontia hollisae. Differential physiological characteristics between the new strain and Grimontia hollisae KCCM 41680T and chemotaxonomic characterization including determination of DNA G+C content, fatty acid methyl esters, quinone composition, and polar lipid profiles justified the assignment of strain IMCC5001T to the genus Grimontia as a novel species. In conclusion, strain IMCC5001T represents a new species, for which the name Grimontia marina sp. nov. is proposed, with the type strain IMCC5001T (=KCTC 22666T =NBRC 105794T).

A study on the Characteristics of Urban Dryness in Busan

It is well known that urban relative humidity has continuous decreasing trend owing to the influence of urbanization. The change of relative humidity is directly influenced by two factors, namely, temperature effect and water vapor effect in various urban effects. In this study, the temperature and tile water vapor effects on the relative humidity change were analyzed by using monthly mean relative humidities for a long period() in Daegu and Chupungnung. The major results obtained in this study can be summarized as follows. Firstly, the urban dryness was caused mainly by water vapor effect in summer. But, for the other seasons, the urban dryness is mainly due to the temperature effect. Secondly, the relative humidity in Daegu is on the decrease until now. This phenomenon is similar to another Korean huge cities such as Seoul, Daejeon and Incheon. But, it is different compared with Japanese huge cities such as Tokyo, Osaka and Nagoya, indicating a standstill in relative humidity change after 1980s.

Effects of Environmental Characteristics on the Production of Shellfish in Deukryang Bay, Korea

This study was carried out to determine marine environments and phytoplankton community in Deukryang Bay during the period of summer in 1987-2010. Water temperature, salinity, pH and dissolved oxygen were shown in much yearly fluctuations. In August, water temperatures in surface and on bottom were the highest, compared with average surface (24.54 o C) and bottom (22.90 o C) water temperature for 18 years in Deukryang Bay. The main reason is assumed to longer duration of sunshine during the period of August. Although the amount of the rainfall in August was the highest, significant impact of marine environment did not show. Most of dissolved inorganic nitrogen and phosphate in Deukryang were lower concentration during summer and N:P ratio also showed below 18 in Redfield. In particular, extreme increasing of N:P ratio in August was occurred by intensive precipitation. Distribution of phytoplankton community was a consistent occurrence for 18 years. The genus of Chaetoceros, Cosinodisucs and Skeletonema were regarded as the represent diatom, whereas the highest occurrence of genus among dinofagellates was Ceratium. It is thought that the relationship between phytoplankton and nutrient has a strong positive signal, although nutrients persist a little concentration and much fluctuations in marine environments were observed. High availability in phytoplankton is contributed to consistently provide the food organism of shellfish. Consequently, recent decreasing production of shellfish and seed are probably associated with higher temperature during the period of summer. However, higher temperature is also occurred ago and after 2000. On the basis of geography, Deukryang Bay had a small mouth and long channel, which is attributed to decreasing genetic diversity. It is assumed that higher temperature and lower genetic diversity have a extreme impact of larvae and shellfish for reproduction in Deukryang. It is necessary to persistently monitor based on water quality and phytoplankton community.

Characteristics of Variation of Sea Surface Temperature in the East Sea with the Passage of Typhoons

In this study, the wind direction and the wind speed of the nearest temperature observations point of the National Weather Service was analyzed in order to investigate the rapid rise and drop of water temperature in the East Coast appeared after passing of the 2015 typhoon No. 9 and 11. Then the figures were simulated and analyzed using the WRF(weather research and forecast) model to investigate in more detailed path of the typhoon as well as the changes in the wind field. The results were as follows. A sudden drop of water temperature was confirmed due to upwelling on the East coast when ninth typhoon Chanhom is transformed from tropical cyclones into extra tropical cyclone, then kept moving eastwards from Pyongyang forming a strong southerly wind after 13th and this phenomenon lasted for two days. The high SST(sea surface temperature) is confirmed due to a strong northerly wind by 11th typhoon Nangka. This strong wind directly affected the east coast for three days causing the Ekman effect which transported high offshore surface waters to the coast. The downwelling occurred causing an accumulation of high temperature surface water. As a results, the SST of 15m and 25m rose to that of 5m.

Analysis of Long-term Oceanic Data for the Prediction of Undaria pinnatifida Aquaculture Production off the Coast of Busan

미역(Undaria pinnatifida)은 갈조식물문 다시마목 미역과에 속하는 해조류로서 동아시아지역의 주요 양식 종으로 활성화 되어 있는 해조류이다. 우리나라에서는 1970년대부터 미역 양 식산업이 활발히 이루어지고 있으며, 총 해조류 양식의 약 48% 정도를 차지하고 있다(Park et al., 2008). 부산연안에서도 해조 류 양식이 활발히 이루어지고 있으며 주요 양식종인 김, 미역, 다시마 양식의 생산량은 국내 총 생산량의 5.9%를 차지하고 있 으며, 품종 별로는 미역 7.1%, 김 6.7%, 다시마 3.1%를 차지하 고 있다(Gijang Gun Office, 2012). 각 해조류 양식종별 생산액 의 국내 비율을 살펴보면, 김은 6.0%, 미역은 18.7%, 다시마는 13.1%를 차지하고 있어, 특히 미역양식은 생산량에 비하여 생 산액이 전국 비율의 2.5배 이상 높아 품질 좋은 미역생산이 이 루어지고 있음을 시사하고 있다. 부산연안에서 이루어지고 있 는 미역생산의 시기를 살펴보면 일반적으로 조기산 미역양식에 서 후기산 건조용 미역까지 주로 9월 중순 이후에서 이듬해 4월 까지 미역양식이 활발히 이루어지고 있으며, 9월 중순-12월까 지는 조기산 물미역을 양성하여 10-12월에 수확을 하며, 11월 에서 이듬해 3월까지는 후기산 물미역 및 건조용 미역을 양성 하여 주로 이듬해 1-3월 사이에 수확을 한다. 또한 12월에서 이 듬해 4월까지 양성하는 후기산 건조용 미역의 경우 수확은 이 듬해 1-4월 사이에 이루어지고 있다(Gijang Gun Office, 2012). 해조류의 성장 및 생육에는 다양한 해양, 기상 요소가 작용 을 하는 것으로 알려져 있으며(Lobban and Harrison, 1994; Dring, 1982, Dawes, 1981), 우리나라의 다양한 연구에서도 수 온, 광도, 파고 등이 중요한 원인으로 알려져 있다(Nam, 1986; Koh et al., 1989; Koh and Sung, 1983; Nam et al., 1996). 특 히, 수온과 해조류 양식과는 밀접한 관련이 있는 것으로 알려져 있으며 김 생산량과 수온 등 환경과의 해역 별 상관성에 관한 연구는 다양하게 수행되어 왔다(Lee, 1988; Hong et al., 1987; Jang et al., 1983). 부산연안에서 미역 생산량과 수온과의 상관

Wind-induced Spatial and Temporal Variations in the Thermohaline Front in the Jeju Strait, Korea

We investigated the short-term and local changes in the thermohaline front in the Jeju Strait, Korea, which is usually formed during winter and spring. To do so, we compared Real-Time Observation System by Ferryboat (RTOSF) data with wind data and routinely collected oceanographic data. During February and April 2007, a thermohaline front formed in the Jeju Strait around the 13-14°C isotherms and 33.0-33.5 isohalines. The thermohaline was clearly weakened and began moving southward in mid-March. The variations in the surface temperature and salinity showed a continuous north-south oscillation of the thermohaline front with a period of 3-10 days. The speed of the short-term and local fluctuation of thermohaline front was about 5-30 cm/s. We confirmed these findings by examining the variation in the maximum temperature gradient and 14°C isotherm during the study period. These short-term and local changes had not been previously detected using serial oceanographic and satellite data. Analysis of local wind data revealed a northerly wind fluctuation with a period of 3-10 days, which was clearly related to the short-term and local changes in the thermohaline front. The short-term and local changes of the thermohaline front in the Jeju Strait originated from local changes in the winter monsoon in this area.

Analysis of Correlation between the Cause of Urbanization and Urbanization Effect of Busan by Using Daily Minimum Temperatures

This study examined urbanization effects and the causes of urbanization, urban population growth, increase of the city scale, land cover change, and human cultures and economic activities, using the daily minimum temperatures of the past 50 years (1961-2010) with the subject of Busan and analyzed correlations between urbanization effects and the causes of urbanization. Thereby, this paper drew a conclusion as below: 1) Due to the urbanization effects, the average annual daily minimum temperature increased as about ; however, except for the factor of urbanization, the increase was shown as about . The occupancy of urbanization effects in the total temperature increase was quite high as about 83%. 2) Just like other cities experiencing urbanization, Busan, too, sees population growth and the expansion of city area as well as increased urbanization effects. First of all, correlation between population growth and urbanization effect was high as 0.96 before 1985 while it was lowered as 0.19 after 1985. Also, correlation between the increase of city area and urbanization effect was high as 0.64 and 0.79 before and after 1985. 3) Regarding the correlation between long-term land use change and urbanization effect, urbanization effect was affected greatly by the increase of city area (0.97) and reduction of green area (0.92). 4) Concerning human activities possible to affect the climatic factors of a city, this paper found the following factors: road length, car increase, power use, and the consumer price index, etc. And regarding the correlation between the three factors and urbanization effect, the correlation was higher in the consumer price index (0.97), the number of registered cars (0.89), power use (0.75), and road length (0.58) in order.

Development of Real-time Oceanographic Information System for Long Line Hanging Aquaculture Farm and Temperature Variation in the Coastal Area of the East Sea

Abstract Mass mortalities of cultivated organisms have occurred frequently in Korean coastal waters causing enormous losses to cultivating industry. The preventive measures require continuous observation of farm environment and real-time provision of data. However, line hanging aquaculture farm are generally located far from monitoring buoys and has limitations on installation of heavy equipments. Substituting battery pack for solar panels and miniaturizing size of buoy, newly developed system can be attached to long line hanging aquaculture farm. This system could deliver measured data to users in real-time and contribute to damage mitigation and prevention from mass mortalities as well as finding their causes. The system was installed off Gijang and Yeongdeck in Korea, measuring and transmitting seawater temperature at the sea surface every 30 minutes. Short term variation of seawater temperature, less than one day, in Gijang from June to July 2009 corresponded tidal period of about 12 hours and long term variation seemed to be caused by cold water southeast coast of Korea, particularly northeast of Gijang. Seawater temperature differences between Gijang station and the other station that is about 500 m away from Gijang station were 1 ℃ on average. This fact indicates that it is need to be pay attention to use substitute data even if it is close to the station. Daily range of seawater temperature, one of crucial information to aquaculture, can be obtained from this system because temperature were measured every 30 minutes. Averages of daily range of temperature off Gijang and Yeongdeok during each observation periods were about 2.9 ℃ and 4.7 ℃ respectively. Dominant period of seawater temperature variation off Yeongdeok was one day with the lowest peak at 5 a.m. and the highest one at 5 p.m. generally, resulting from solar radiation.Key Words :Long line hanging, Aquaculture farm, Oceanographic information, Real-time, Temperature variation, East Sea

Delayed Mode Quality Control of Argo Data and Its Verification in the Pacific Ocean

Quality control of Argo(Array for Real-time Geostrophic Oceanography) data is crucial by reason that salinity measurements are liable to experience some drift and offset due to biofouling, contamination of sensor and wash-out of biocide. The automated Argo real-time quality control has a limit of sorting data quality, so that WJO program is adopted as standardized method of Argo delayed mode quality control (DMQc) in the world that is a precise quality control method. We conducted DMQC on pressure, temperature and salinity measured by Argo floats in the Pacific Ocean including expert evaluation. Particularly, salinity data were corrected using WJO program. 4 salinity profiles of Argo delayed mode were compared with nearby in situ CTD data and other Argo data in deep layer where oceanographic conditions are stable in time and space. The differences of both salinities were lower than target accuracy of Argo. As compared with the difference of salinities before DMQC, those after DMQC decreased by 60-80 percent. Quality of delayed mode salinity data seemed to be improved correcting salinity data suggested by WJO program.