Eun-Seob Cho

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.

Variations in Marine Environments and Phytoplankton Community around Mokpo Harbour

This study was carried out to determine marine environments and phytoplankton community around Mokpo harbour on March to November during the period of 2004-2009. The remarkable fluctuations of marine environments were shown around Mokpo harbour depending on monthly and yearly. Among seasons, summer was a great that was associated with extremely releasing the freshwater from Youngsan River Weir, contributing to effect the fluctuations of water quality. Nevertheless of monthly and yearly, the molecular ratio of N:P was always shown in above 16 that was mainly attributed to freshwater discharge on March to November. This indicates that phosphorus playes an important role in limiting factor as growth in phytoplankton. During this study, Skeletonema costatum was found to be richer than the other groups of diatoms in terms of abundance and species number. Mokpo harbour, with the presence of a narrow avenue for exchange with offshore waters, has limited growth in phytoplankton, but this species is able to well adapt and fast grow under even high level of suspended solid and low intensity of light compared with other species. The discharge of freshwater is associated with significantly fluctuation of marine environments in this region, but it does not affect the quantitative and qualitative distribution of phytoplankton. It is necessary to persistently monitor based on water quality and phytoplankton community.

Marine Environments and Ecological Characteristics of Phytoplankton in Southern Coastal Waters During June to October in 2004-2006

This study monitored marine environments and ecological characteristics of phytoplankton in southern coastal waters during June to October in 2004-2006 and provided an information to how Cochlodinium blooms have occurred. A total of sampling sites was 16 (Dukyang bay, Goheung, Yeoja bay, Gamak bay, Gwangyang bay, Yeosu, and Namhae). Temperature ranged from , which all of sampling in Yeoja bay was the highest temperature of during summer. On June, July, September, and October did not show a remarkable difference regardless of sampling sites. Yeoja and Gwangyang bays had 25-27 in salinity that was lower approximately 5-6 compared with other sampling sites. Chlorophyll had considerable fluctuations depending on sampling sites on July and October, in particular, Gwangyang bay was the highest value of that had five times as much as. Unlikely to temperature, salinity, and chlorophyll, transparency ranged from 2 m to 5 m regardless of sampling sites. Gwangyang bay was the highest DIN (Dissolved Inorganic Nitrogen) of on July and August that had ten times as much as, whereas DIP (Dissolved Inorganic Phosphorus) did not show a significant difference between sampling sites. On July, the correlation of DIN and chlorophyll was a negative that should extremely require DIN to grow phytoplankton, but was a positive liner on August. Mean cell number of phytoplankton reached to encounter a peak of 500 cells in July and August, which diatoms were dominant species and attained an abundance of >60% regardless of months. In August, the occurrence of dinoflagellates ranged from 20% to 30%. Skeletonema costatum, one of dominant speicies, was the highest occurrence to throughout sampling sites during 2004 to 2006. On the basis of cluster analysis for phytoplankton, they were distributed in all of sampling sites. Consequently, significant fluctuations of marine environments were shown in summer and S. costatum was regarded as the representive phytoplankton in southern coastal waters. In particular, the outbreaks of Cochlodinium polykrikoides have occurred in Dukyang bay, Gamak bay, Goheung, Yeosu, and Namhae, but Yeoja and Gwangyang bays did not occur. The distinguish characteristics of occurring sampling sites and non-occurring in Cochlodinium blooms based on this study was DIN that was enough to persistently grow and maintain them even a litter dissolved in water. This suggests that Cochlodinium red tide seems to be occur in off waters.

The Massive Blooms of Gonyaulax polygramma (Gonyaulacales, Dinophyceae) in the Southern Coastal Areas of Korea in Summer, 2009

This study was carried out to determine the characteristics of the marine environment, including nutritional content, in order to clearly understand the outbreaks of Gonyaulax polygramma in the southern coastal areas in August, 2009. Samples were collected at 13 sites and water temperature and salinity were measured using a CTD. Field surveys were twice: the first between August 5-7, the second between August 22-24. The cell density of G. polygramma was 6,500-10,000 cells during the survey, whereas during the survey the range of the cells was recorded from 8,000 to 12,500 cells . Cochlodinium polykrikoides ranged from 0 to 105 cells during the field survey. In water environments, the majority stations during the survey showed a nearly homogeneous water column below in temperature, as well as similar profiles of salinity. However, the stratification between the surface and bottom was observed in the survey. Regarding nutrients, Dissolved Inorganic Nitrogen (DIN) in the surface ranged from 0.144 to 0.236 mg during the survey, and 0.082-0.228 mg during the survey. DIP (Dissolved Inorganic Phosphorus) did not show any difference in concentration between the and survey. During August of 2009, the wind speed in the southern waters remained at around for about 60% of time, and there was very little precipitation during the month. Irradiance of hr was shown in the late of August. It is thought that a low level of DIN and salinity play an important role as an essential factor for rapid growth, wide distribution and longer duration of red tide in G. polygramma.

Report on Protoperidinium sp. fed on Cochlodinium polykrikoides (Gymnodiniales, Dinophyceae)

In 2005, harmful dinoflagellate Cochlodinium polykrikoides was first occurred on July 18 and disappeared on September 12 in the Yeosu waters of the South Sea of Korea. During C. polykrikoides blooms, the species of Protoperidinium was isolated from Jabong Island in Yeosu in the middle of August, 2005. The surface water temperature at the sampling site was , and salinity was 33.1 psu. The specimen was somewhat large in size and was longer than its width. The shape was close to being ovoid, with an apical horn. This study discovered cells with colorless and transparent ingested chain-forming C. polykrikoides. However, this species was not abundant, implying low grazing impact on C. polykkoides.

Effects of Oils and Dispersant on the Red Tide Organism Cochlodinium Polykrikoides

Oil spill caused severe effects on the marine fauna and flora due to direct contact of organisms with the oil and even in regions not directly affected by the spill. This study was conducted to understand the effects of the oil spill accidents and the use of dispersant on the red tide of Cochlodinium polykrikoides. Crude oil produced in Kuwait, bunker-C, kerosene and diesel oil, and a chemical dispersant produced in Korea, were added with a series of 10 ppb to 100 ppm in the f/2-Si medium at under a photon flux from cool white fluorescent tubes of in a 14: 10 h L:D cycle for the culture of C. polykrikoides. In low concentrations of 1 ppm of examined oils no impact on the growth of C. polykrikoides was recorded, while in high concentration of 10 ppm, cell density was significantly decreased with the range of 10 to 80% in comparison with the control. The growth of C. polykrikoides after the addition of the dispersant and the mixtures combined with oils and a dispersant of 10 ppm appeared to decrease, whereas the growth of C. polykrikoides exposed to 100 ppb showed little serious impact. However, almost all the C. polykrikoides cells were died regardless of a dispersant and combined mixtures within a few days after the addition of high concentrations.

Evaluation of the ETR max in Microalgae Using the PHYTO-PAM Fluorometer

【In this study, the PHYTO-PAM-fluorometric method was used to evaluate the ETR

Phylogenetic Relationships Using ITS2 Sequence and RAPD-PCR Data from Four Species of Korean Pseudo-nitzschia (Bacillariophyceae)

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Phylogenetic position of five Korean strains of Alexandrium tamarense(Dinophyceae), based on internal transcribed spacers ITS1 and ITS2 including nuclear-encoded 5.85 rRNA gene sequences

in terms of sensitivity to DIN/DIP against 14 microalgae: Prorocentrum micans, Heterocapsa triquetra, Gymnodinium impudicum, Cymnodinium catenatum, Amphidinium caterae, Chlorella vulgaris, Chroococcus minutus, Microcystis aeruginosa, Chlorella ellipsoidea, Nannochloris oculata, Oocystis lacustris, Chroomonas salina, Gloeocystis gigas, and Prymnessium parvum. We found that P. micans, H. triquetra, and A. caterae exposed to the maximum level of DIN/DIP were significantly smaller in the ETR

Long-term Variation and Characteristics of Water Quality in the Yeoja Bay of South Sea, Korea

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