• Korean Journal of Ecology and Environment
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• v.53 no.4
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• pp.331-335
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• 2020

The red swamp crawfish (Procambarus clarkii) is native to northeastern Mexico and south-central United States. But the species has been introduced to other parts of the world, and cause ecological problems including habitat destruction and competition with indigenous species. In this study, we identified the distribution of P. clarkii in the freshwater system in Korea. P. clarkii were collected in the field sampling and it is assumed that they have settled in major domestic water systems of Korea including six points in the Yeongsangang River, five points in the Mangyeonggang River, two points in the Seomjingang River, and one point in the Geumgang River. In particular, more than 20 individuals were found in Seobongri, Wanjugun and Mosanri, Hampyeonggun, which are believed to form a relatively large population. Considering high mobility and environmental adaptability of the species, the possibility of their dispersal to other water systems is very high. Therefore, continuous monitoring and assessment of their distribution and potential spread are required and effective management to remove them policy is needed to prevent damage in the Korean ecosystem.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.181-184
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• 2001

The biological fixation of carbon dioxide using microalgae have many advantages over chemicals and remove carbon dioxide simultaneously. A ketocarotenoid astaxanthin is hyper-accumulated in the green freshwater microalga, Haematococcus pluvialis. In the present study, the combine effects of carbon dioxide concentration and light intensity on the growth of H. pluvilais were investigated. The carbon dioxide concentration above 10% caused a severe inhibition and around 5% is optimal for growth. Adaptation to high concentration of carbon dioxide enhanced the $CO_2$ tolerance. Specific growth rate calculated differently based upon cell number or dry weight because of the distinctive life cycle patterns of H. pluvialis : small-sized motile green cell and thick cell walled red cyst cell. Based on the light dependence of H. pluvialis, internally illuminated air-lift photobioreactor was designed and operated. Gradual increase of light supply gave more active growth and more effective productivity of astaxanthin than constant light supply.

• Journal of environmental and Sanitary engineering
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• v.6 no.1
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• pp.31-46
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• 1991

Aeromonas hydrophila which bacause various diseases in human also infects fresh water fish, severly damaging the fishing industries. To prevent disease in humans and reduce damaging on the fishing industries, We have examined several characteristics of Aeromonas hydrophila and obtained the following results. All of the strains gave a posive voges-proskauer, methyl-red, salicin and esculin reaction. Seventeen(94.4%) A. hydrophila strains presented the phenotype SP-PAB- in autoagglut-ination test, but only strain AH 997 showed $SP^{+}PAB^{+}$. in autoagglut ination test, but only strain AH 997 $SP^{+}PAB^{+}$ All of the strains took up the censored to various degrees. Three of 18 strains showed positive reaction in crystal violet binding test. Hemolytic activity ranged from titers of 0 to 1/256. Seven of the 17(38.8%) A. hydrophila strains were positive in sucking mouse assay. Cytotoxin activity on vero and RK cells was displayed various titers.(1/2-1/1024)

• Korean Journal of Fisheries and Aquatic Sciences
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• v.55 no.3
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• pp.338-344
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• 2022

This study evaluated the external form of Rhodeus notatus TSV (transparent-scaled variant) type identified in Korea for the first time and compared it with that of the normal type. The TSV units newly found on Rhodeus notatus are iii10 of dorsal fin and anal fin iii10, which are similar to that in the normal type, considering the observing coefficient of each part's fins. The external form is, transparent enough to see the red gill filament in the operculum, the spiral digestive organ is observed opaquely, and numerous melanophores are stained at the upper part of abdomen. The coloration and scales are different between TSV type and normal type; however, there is no difference in the external form and meristic character.

• Korean Journal of Environmental Biology
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• v.35 no.1
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• pp.57-63
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• 2017

This study was conducted to determined the status and geographical distribution of the alien invasive Red-eared slider (Trachemys scripta elegans) turtle on Jeju Island. We found thirty-two Red-eared slider habitats including twenty-five ponds, five agricultural reservoirs, a puddle and a stream. Among those, thirteen sites are newly determined habitats of the turtle. The remaining nineteen are previously reported. However, we could not find any turtles at nine sites, which were documented as turtle habitats in earlier reports. A total of one hundred thirty-three turtles were observed. Among them, we determined that thirty-nine were juvenile turtles, found in nineteen different habitats, indicating estimating that Red-eared sliders produced their progeny in the wild of this island. Because of geographical isolation by the ocean, no freshwater turtle had been found until $19^{th}$ Century. Therefore, the increased number of finding sites and Red-eared sliders indicate the possibility of human release of their pets or for other purposes, and natural propagation in the wild on Jeju Island. Our findings will be useful for management planning to deal with this invasive species, and implementation of a conservation program for native wildlife on Jeju Island.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.2
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• pp.49-62
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• 2001

Hydrographic surveys were carried out seven times during May 31, 1998 and September 24, 1998 in order to study the physical environments of the coastal area between Narodo Is. and Sorido Is. in the southern sea of Korea (the South Sea) where the occurrence of Cochlodinium polykrikoides red tide is frequently observed in summer. Temperature and salinity of the water column from the surface to the depth of 30 m exhibit large seasonal variations. Mean temperature of the water column increased by 6 and mean salinity of the water column decreased by 2.71 psu during the observation period. Both the freshwater supplied from the adjacent land and the precipitation over the study area cannot account for the observed salinity variations. The influx of the low salinity water from the offshore area is considered to be the main cause for the observed salinity changes. Surface salinity in the study area shows different spatial distribution in the period of outbreaking, mid-stage and disappearance of the red tide. Especially, salinity was abruptly lowered at the stage of disappearance of red tide as compared to salinity of the previous observation period. Vertical structure of water properties also became vertically homogeneous at the disappearance stage, while it was highly stratified in the previous observation. Such changes can only be explained by the inflow of low salinity water from the offshore, which is considered as the most possible cause for the disappearance of the red tide in the study area. This study suggests that exchanges of water, and chemical and biological factors between coastal areas and of shore area in the South Sea need to be studied in association with the general circulation of the South Sea in order for the better understanding of the occurrence and disappearance of the red tide in the coastal area of the South Sea.

• ALGAE
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• v.34 no.4
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• pp.277-288
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• 2019

Freshwater red algae of the order Batrachospermales are poorly studied in India and Nepal, especially on a molecular basis. During a survey in northeast India and east Nepal, six populations of the genus Sheathia were found and analyzed using molecular and morphological evidence. Phylogenetic analyses based on the rbcL gene sequences grouped all populations in a large clade including our S. arcuata specimens and others from several regions. Sheathia arcuata represents a species complex with a high sequence divergence and several smaller clades. Samples from India and Nepal were grouped in three distinct clades with high support and representing new cryptic species: a clade formed by two samples from India, which was named Sheathia assamica sp. nov.; one sample from India and one from Nepal formed another clade, named Sheathia indonepalensis sp. nov.; two samples from Nepal grouped with sequences from Hawaii and Indonesia (only 'Chantransia' stages) and gametophytes from Taiwan, named Sheathia dispersa sp. nov. Morphological characters of the specimens from these three species overlap one another and with the general circumscription of S. arcuata, which lacks the heterocortication (presence of bulbous cells in the cortical filaments) present in other species of the genus Sheathia. Although the region sampled is relatively restricted, the genetic diversity among specimens of these three groups was high and not closely related in the phylogenetic relationship with the other clades of S. arcuata. These data corroborate information from other groups of organisms (e.g., land and aquatic plants) that indicates this region (Eastern Himalaya) as a hotspot of biodiversity.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.2
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• pp.114-121
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• 2014

This study compared the food quality of domesticated(RT-DS) and freshwater (RT-F) rainbow trouts Oncorhynchus mykiss. The proximate composition of RT-DS was 73.8% moisture, 20.6% crude protein, 4.2% crude lipid, and 1.1% ash and was similar to RT-F. No differences were found in the red color, odor and taste intensities, calcium, and potassium between RT-DS and RT-F based on the Hunter a values, volatile basic nitrogen content, odor intensity and using an electronic nose, and taste intensity using an electronic tongue. The crude protein, total amino acid contents, and taurine, glutamic acid, glycine, alanine and anserine contents in free amino acids were higher in RT-DS than in RT-F. There was no difference in hardness between RT-DS and RT-F.

• Journal of fish pathology
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• v.24 no.2
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• pp.121-129
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• 2011

Aquatic animal raised in hatcheries play an important role in supplying seedling to stock enhancement and seed quality, especially, seed health is the key factor for survival in the field after release and for stocking effectiveness. We have inspected the hatchery-reared seeds of 33 marine species and 12 freshwater species for legally designated diseases in stock enhancement program in 2010. Results showed that abalone was the most abundant as 20.0% in the marine species group and then sea cucumber (15.6%), olive flounder (8.4%), rockfish (6.7%), black sea bream (6.3%) and swimming crab (6.1%) were followed. Crucian carp was the most abundant as 19.4%, and then eel (11.8%), Korean bullhead (10.9%), mandarin fish (10.8%), melanian snail (8.4%), catfish (7.7%) were followed in the freshwater species group. The total number of inspection cases for eight pathogens in this study were 2,105 and disqualification cases were 30 by detection of aquatic animals pathogens such as koi herpesvirus (KHV), red sea bream iridovirus (RSIV), white spot syndrome virus (WSSV) or viral haemorrhagic septicemia virus (VHSV).

• Journal of the Korean Society of Food Culture
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• v.2 no.2
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• pp.149-161
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• 1987

The ways of preservation of chotkal which are classified by the principles of fermentation, are analyzed and interpreted. Chotkal is preserved mainly as two forms; one is chot and the other is shikhae. The fact that shikhae is preserved only in the eastern area can be attributed to two main reasons; (1) raw materials are available throughout four seasons and (2) relatively less production of salt. Chotkal is further classified into nine different ways of preservation and shikhae into fourteen. Regional characteristics for chot include that (1) in western part, Kechot is preserved in salty water (2) in central part Origuljot is fermented either with salt and powdered red pepper, or with salt, powdered red pepper and cooked cereal, (3) in southern part, freshwater shrimp with (1) salt only, (2) salt and powdered red pepper, (3) salt and cooked cereal, (4) salt, powdered red pepper and cooked cereal, (4) in northern part, fish with salt and powdered red pepper. Those for shikhae include that malt is used in southern part, shredded radish in northern part and cooked cereal more in southern part than in northern part.