• Journal of Food Hygiene and Safety
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• v.35 no.5
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• pp.447-451
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• 2020

For this study, we conducted a simultaneous multiresidue analysis of veterinary drugs in cultured fishery products in Chungnam Province in 2018. A total of 115 fishery product samples were obtained from fish farms and fishery production sites located in the province. In all, 29 residual veterinary drugs in the samples were analyzed using a validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. As a result, veterinary drug residues were only detected in a small number of the 106 samples (92.2%), and the detection rate was 7.8% (9 of 115 samples). The amounts were also below maximum residual limit (MRL) for fishery products, although one sample exceeded the MRL allowed by the Ministry of Food and Drug Safety and was detected in loach. The nine residual veterinary drugs were detected in 8 samples: loach, eel, catfish, freshwater bream, flatfish, rockfish and shrimp. The detected veterinary drugs were oxolinic acid, enrofloxacin, ciprofloxacin, sulfadiazine, flumequine and oxytetracycline. The most frequently detected antibiotic was oxolinic acid, and enrofloxacin exceeded the MRL in loach sample. Residues of most veterinary drugs were either not detected or were below the MRL, and while the status of fishery products is seen as safe overall, current surveillance efforts over veterinary drugs should be continued.

• Journal of fish pathology
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• v.11 no.1
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• pp.35-41
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• 1998

We investigated the optimal concentration of lidocaine and MS-222 (tricaine methanesulfonate) for the exfoliation and recovery of abalone, Haliotis discus hannai in different shell lengths, for the purpose of preventing the damage of shell and muscle. However, most anaesthetics applied at present have a strong toxic effect on abalone. MS-222 is the only anaesthetic which is approved for use in food fish by FDA, and lidocaine belongs to a group of anaesthetic which are used in human medicine. These chemicals were evaluated as anaesthetic for different shell size of abalone. The response varied for different shell size groups (shell length 1, 2 and 3 cm). In this study, we suggested the result that the exfoliation and recovery time by lidocaine and MS-222 in shell length 1 cm group were more shorter than in 3 cm group. In shell length 1 cm group, the optimal concentrations of lidocaine and MS-222 for anaesthetic were 200 ppm and 100 ppm, respectively. Lidocaine and MS-222 are preferable to other conventional abalone anaesthetics since these are cheap, safe and convenient to use.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.6
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• pp.924-928
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• 2005

Toxin profiles of the paralytic shellfish poison (PSP) detected from domestic shellfishes collected at the market and imported. shellfishes were invested by fluorometric HPLC. Total 9 components in PSP were analysed from the imported ark shell, such as saxitoxin (STX), decarbamoylsaxitoxin (dcSTX), gonyautoxin (GTX) - 1,2,3,4,5, Cl and C2. Among those toxins, 7 components except for GTX1,4 were detected from domestic shellfishes and showed different toxin contents and toxin compositions by species. Only C group toxin (Cl +2) contained in short necked clam and hard clam $(0.06\~0.56\;nmole/g)$ which living under soil but, in the blue mussels and oysters which cultured in the open sea water, showed more higher toxicity and complicate toxin compositions. Toxin compositions in bloody clam and purplish washington clam were very different in some samples even in same species. GTX4 and GTX5 were higher in imported scallop and STX was higher in imported ark shell than other species.

• Journal of fish pathology
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• v.26 no.3
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• pp.193-206
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• 2013

The ark shell, Scapharca broughtonii is a marine bivalve mollusks belonging to the family Arcidae and important seafood for Korean and Japanese, and southern coast is brisk bays for the ark shell aquaculture. However, productivity of ark shell from these regions were rapidly reduced during the last decade due to mass mortality. The reason of this great damage has not yet been identified. To overcome this economic loss, diverse investigations were focused on environmental factors that affects in the physiology of S. broughtonii, but microbiological researches were performed insufficiently. Hemoglobin is one of the major blood component of ark shell and is damaged by some species of bacterial toxins. We concentrated on this red pigment because hemolysis could be the cause of ark shell mortality. In this study, we analyzed microbial diversity of underwater sediments in coastal regions and also existences in the body of S. broughtonii. We investigate about 4,200 isolates collected from June to September for microbial diversity of sediments and ark shell. We screened all of culturable microorganisms, and identified 25 genera 118 species, 24 genera 89 species, 30 genera 109 species and 39 genera 141 species, and selected 140 unique colonies for identification and challenge assay.

• Journal of fish pathology
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• v.26 no.3
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• pp.149-161
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• 2013

Viral haemorrhagic septicaemia virus (VHSV), the causative agent of viral haemorrhagic septicaemia (VHS), is an epidemic virus of cultured olive flounder Paralichthys olivaceus in Korea. In the present study, the entire glycoprotein (G) gene including several hypervariable regions from 36 isolates of diverse geographic and host origin and 8 Korean VHSV isolates from cultured olive flounder were analyzed. Phylogenetic analysis indicated that most of Asian VHSV belong to the genotype IVa group, suggesting that they originated from a common ancestral virus. Comparative sequence analysis of the complete G protein from Korean VHSV isolates revealed 3 Korean strain-specific nucleotide residues (nucleotide number of G-region: A755, T834 and T1221). These results suggest that Korean VHSV originated from a common ancestor, but these regional specific nucleotide sequences suggest that genetic differences of VHSV are more related to geographic areas than to host fish species.

• Korean Journal of Remote Sensing
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• v.37 no.5_2
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• pp.1307-1315
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• 2021

The Changjiang Diluted Water (CDW) spreads over the East China Sea every summer and significantly affects the sea surface salinity changes in the seas around Jeju Island and the southern coast of Korea peninsula. Sometimes its effect extends to the eastern coast of Korea peninsula through the Korea Strait. Specifically, the CDW has a significant impact on marine physics and ecology and causes damage to fisheries and aquaculture. However, due to the limited field surveys, continuous observation of the CDW in the East China Sea is practically difficult. Many studies have been conducted using satellite measurements to monitor CDW distribution in near-real time. In this study, an algorithm for estimating Sea Surface Salinity (SSS) in the East China Sea was developed using the Geostationary Ocean Color Imager (GOCI). The Multilayer Perceptron Neural Network (MPNN) method was employed for developing an algorithm, and Soil Moisture Active Passive (SMAP) SSS data was selected for the output. In the previous study, an algorithm for estimating SSS using GOCI was trained by 2016 observation data. By comparison, the train data period was extended from 2015 to 2020 to improve the algorithm performance. The validation results with the National Institute of Fisheries Science (NIFS) serial oceanographic observation data from 2011 to 2019 show 0.61 of coefficient of determination (R²) and 1.08 psu of Root Mean Square Errors (RMSE). This study was carried out to develop an algorithm for monitoring the surface salinity of the East China Sea using GOCI and is expected to contribute to the development of the algorithm for estimating SSS by using GOCI-II.

• Journal of Wetlands Research
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• v.20 no.4
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• pp.322-329
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• 2018

In this study the community characteristics of benthic macroinvertebrates distributed in stream of Gaya Mountain were figured out and the correlation with the physicochemical water quality factors were calculated. During the study period, total 4 phyla, 6 classes, 13 orders, 36 families, 100 species of benthic macroinvertebrates were recorded. Ephemeroptera were the most dominant followed by Trichoptera, Plecoptera, Diptera, Non-insecta, Hemiptera, and Odonata. The overall dominant species was Cincticostella levanidovae by dominance rate in 17.72%, subdominant species was Hydatophylax nigrovittatus by dominance rate in 6.15%. The biotic indices showed the diversity index 5.17, richness index 12.44, dominant index 0.24 and evenness index 0.78, there is no absolutely dominant benthic macroinvertebrates in the stream of Gaya Mountain. We identified the correlation between the species number and individuals of main taxa and the physicochemical water quality factors. Ephemeroptera and Plecoptera showed a negative correlation with water temperature, but they represented a positive correlation with the dissolved oxygen. This results suggest that water temperature and dissolved oxygen are important physicochemical water quality factors affects the distribution of Ephemeroptera and Plecoptera, the indicators of clean water stream.

• Korean Journal of Environment and Ecology
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• v.35 no.2
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• pp.115-125
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• 2021

This study surveyed the population ecology of Acheilognathus chankaensis (Pisces: Acheilognathinae) in the vicinity of the Churyeongcheon (Stream) and Seomjingang (River) in Jeonbuk, Korea, from February 2006 to May 2007. The survey found the habits mainly in the slow-flowing waters having sand, mud, and gravel bottoms. Age groups estimated by the standard length-frequency distribution of the population indicated that the one-year-olds were 30-46 mm long, the two-year-olds were 47-58 mm long, the three-year-olds were 59-68 mm long, and the four-year-olds were longer than 69 mm. The gonadosomatic index (GSI) and the ratio of ovipositor length/standard length were the highest in March (♀: 12.9%, ♂: 5.0%) and in April (46.3%), respectively. The ratio of mature egg diameters that were 1.6 mm was highest in May (13.2%). The comprehensive analysis of spawning characteristics showed that the spawning season was from March to June with water temperatures in 11.5-22.5℃, and the sex ratio of female:male was 1:1.13. The fecundity in the ovaries and the number of mature eggs were 318±174.5 (50~583) and 220±139.2 (50~406), respectively. The size of the mature eggs was 2.04±0.110 mm on the long axis and 1.55±0.100 mm on the short axis for the study period. Gut contents of A. chankaensis were mainly phytoplankton such as the genera Fragilaria, Synedra, Navicular, Cymbella (Bacillariophyceae), and Cosmarium (Chlorophyceae).

• Korean Journal of Environment and Ecology
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• v.35 no.3
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• pp.285-293
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• 2021

This study was conducted to elucidate spawning period characteristics and early life development of eight barbel loach, Lefua costata (Balitoridae) at the Jusucheon stream, Okgye-myeon, Gangneung-si, Gangwon-do, Korea between January and December in 2018. The spawning period was estimated to be from May to August, considering the change in the gonad-somatic index, the appearance of young fry, and frequency distribution in egg diameter. It was a multi-spawning type. The gender ratio was 1:0.79 with 1,117 females and 879 males collected. The egg size was 0.24-0.93 mm, with mature and immature eggs found during the spawning period. The size of mature eggs was 0.71±0.02 mm, and the average number of fecundity was 1,786±818 (n=31). Observation of the egg development showed that the fertilized eggs were the sticky, gray, segregated, and demersal type with 0.76±0.03 mm in diameter. The hatching of the embryos began at about 34 hours (hatching rate 50%) after fertilization underwater temperature of 25℃. The average length of the newly hatched pre-larvae was 2.7±0.11 mm. The average length of pre-larvae at 4 days after hatching was 4.5±0.16 mm, and the yolk sac was completely absorbed and entered the post-larvae stage. At 20 days after hatching, the average length of post-larvae was 11.5±0.67 mm, and their fin rays were formed before they transitioned to the juvenile stage. At 100 days after hatching, the average length reached 49.8±2.60 mm, and the appearance and the lateral sideband patterns were similar to those of the adult fish.

• Korean Journal of Remote Sensing
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• v.38 no.6_1
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• pp.1541-1555
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• 2022

Red tide has potential to harm marine ecology and aquaculture. Research on detecting red tide using various optical remote sensors has been conducted, but most of existing algorithms for detecting red tide has limitations, especially in shallow coastal waters with high levels of suspended sediment. For enhanced understanding of the optical behavior of red tide waters, analysis on remote sensing reflectance and water constituent is becoming increasingly important. This study analyzed the optical remote sensing data and water quality variables(Chl-a_(Spec), SPM, a_ph, a_d, Turbidity, Chl-a_(HPLC), Dominant species) of red tide waters. The data were collected from ship-based campaigns. In addition to the research on detecting red tide, the remote sensing reflectance and extinction coefficients for mesodinium and cochlodinium species were also analyzed. Through the analysis, it was possible to estimate the red tide chlorophyll concentration based on a specific wavelength of the remote sensing reflectance. The study found that chlorophyll concentration and phytoplankton absorption coefficient were highly correlated(R²=0.9), and that the RE_diff formula provided a more accurate estimate of red tide concentration than the B-G ratio.