• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.18 no.2
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• pp.80-88
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• 2013

The present study was conducted to evaluate relationship between nonylphenol uptake rate and clearance rate of Ruditapes philippinarum, Corbicula japonica and Mytilus edulis. Variation of the temperature and body size of the bivalves was used to modulate clearance rate and nonylphenol uptake rate in this experiment. Clearance rate and nonylphenol uptake rate experiments were determined for two different size classes of the bivalves (R. philippinarum: 0.35, 0.73 g, C. japonica : 0.047, 0.1000g, M. edulis: 0.30, 0.37 g; mean flesh dry weight) and three different temperature regime (5, 13 and $18^{\circ}C$). Weight-specific clearance rate in all animal size and temperature ranges increased in the order of R. philippinarum, C. japonica and M. edulis. The weight-specific nonylphenol uptake rate did not show specific trend among species. The clearance rate and nonylphenol uptake rate generally decreased with animal size and increased with water temperature. For all three species nonylphenol uptake rate had a strong relationship with clearance rate. For a given clearance rate ranges, the nonylphenol uptake rate was in the order of R. philippinarum > C. japonica > M. edulis. The results suggest that water ventilation capacity of filter-feeding organisms is an important physiological factor controlling uptake rate of dissolved nonylphenol.

• The Korean Journal of Malacology
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• v.20 no.2
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• pp.111-120
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• 2004

We investigated the reproductive cycle of Corbicula japonica with its gonadal development by histological observations, and the seasonal changes in biochemical mass and foot muscle of the adductor muscle, visceral mass and foot muscle of the clam by biochemical analysis, from January to December, 2003. The reproductive cycle of this species can be classified into five successive stages: early active stage (February to April), late active stage (April to July), ripe stage (June to August), partially spawned stage (July to September) and spent/inactive stage (September to March). According to ANOVA test, there were significant differences (p < 0.05) in total protein, total lipid and glycogen contents among months for all of the visceral mass, adductor muscle and foot muscle. Total protein content was highest in adductor muscle, while lowest in visceral mass. There was no correlation in total protein content between visceral mass and adductor muscle (p = 0.208). However, strong positive correlation was found between adductor muscle and foot muscle (r = 0.769, p < 0.001). In visceral mass, total lipid content was the highest; it was 2 or 3-fold higher than in adductor muscle or foot muscle. The monthly change was also most dynamic in visceral mass. It decreased from January to March (early active stage), and reached maximum in April (late active stage). From May to August (ripe and partially spawned stage), it dradually decreased and then increased again until October (spent/inactive stage). Multiple comparisons showed that total lipid content in visceral mass between all of the adjacent two months was significaltly different (p < 0.05). There were strong negative correlations in total lipid content between visceral mass and adductor muscle (r = 0.687, p < 0.001), and between visceral mass and foot muscle (r = 0.473, p = 0.008). Changes of glycogen content were more or less similar to the changes of lipid contents in visceral mass, adductor muscle and foot muscle, except for April. In April, glycogen content in visceral mass was over four times higher than that in adductor muscle or foot muscle. There was a positive correlation in glycogen content between adductor muscle and foot muscle (r = 0.686, p < 0.001). Especially, total lipid content showed a negative correlation between the adductor muscle and visceral mass. Therefore, these results indicate that the nutrient content of the adductor muscle, visceral muscle and foot muscle changed in response to gonadal energy needs.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.3
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• pp.230-237
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• 2000

An ecological study of the benthic macrofauna was carried out using a modified van Veen grab in September 1997, in Namdaechon estuary, Yangyang, Korea. A total of 17 macro-invertebrates was collected and examined from eleven stations in the study area, including 3,795 individuals and 738.63 g wet weight. Arthropods, annelids and molluscs were most abundant and occupied more than $95{\%}$ of the total number of species, individuals and biomass. Namdaechon estuary in Yangyang was very poor in macrobenthic biodiversity, and numerically dominated and characterized by the polychaetes Heteromastus filiformis, Hediste japonica, Eteone longa, an unidentified oligochaete Oligochaeta sp., a corbulid bivalve Corbicula japonica, and an estuarine isopod Cyathura higoensis. Species composition, species dominance, density, and species evenness were compared among stations. The macrofaunal azoic zone appeared in the bottom of 7 m in depth nearby the artificial bank to catch the salmons to return to the livers for spawning. It probably resulted from the oxygen depletion following strong stratification in summer, which can cause major effect on the ecological conditions and then finally kill bottom macro-invertebrates in this area. Moreover, some opportunistic species thrived in nearby another station and this is of vital importance in terms of the ecological succession in a benthic polluted area.

• Journal of fish pathology
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• v.16 no.3
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• pp.203-213
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• 2003

The present study was conducted to research some parastic trematodes species in marine bivalves which are widely distributed in the western sea in Korea. From April, 2001 to October, 2002, marsh calm (Corbicula japonica) were obtained from Kochang bay near the Sunun temple and razor calm (Sinonovaculla constricta) from Kaehwado. Short necked calm (Ruditapes philippnarum) were sampled from Ochungdo, Mardo and Kaeyado. Cercaria corbiculae was found in the gonad of C. japonica with a low infection rate of 0.83%. The cercaria and the sporocyst were sized $278{\times}98{\mu}$ and $890{\times}275{\mu}$, respectively. Some encysted larvae of Parvatrema duboisi sized $0.351{\times}0.182mm$ were firstly found in the mantle of S. constricta in Korea. Each S. constricta contained 1-9 cysts and the infection rate was 48.3%. Cercaria tapidis was found in the both gonad and mantle of R. philippinarum. The annual average infection rate in the R. philippinarum from Ochungdo was 7.7%. This rate was much higher than those from Solri near the Kum river estuary in 1981. The infection rate of C. tapidis in R. philippinarum was different in sizes. The maximum rate was 4.8% in size 3.6-4.0cm and the minimum rate 0.8% in size 4-5cm.

• Ocean and Polar Research
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• v.39 no.1
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• pp.23-34
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• 2017

This study was carried out to investigate the spatial distributions of the macrobenthic communities in the Seomjin River estuary from May, 2015 to May, 2016. The number of species was 163, the mean density was $1,865ind.m^{-2}$, biomass was $204g{\cdot}wet\;m^{-2}$ during this study period. The highest number of species and density appeared among polychaetes whereas the most biomass was contributed by mollusks due to the presence of Corbicula japonica in every season. The study area was divided into 3 regions with similar benthic fauna responding to the gradient of the salinity. Praxillella praetermissa was the dominant species in regions of over 30 psu during all seasons. C. japonica and Hediste diadroma were dominant in the upper regions of the Seomjin River where the salinity was less than 10 psu. Heteromastus filiformis showed the broadest distributional range and dominated in all seasons except for the most upper stream at st. 7. From the result of the Bio-Env analysis, salinity was the most important environmental factor affecting the formation of macrobenthic communities in the study area, and salinity and TOC were the highest contributors to the macrobenthic communities. From the correlation analysis between major dominant species and environmental factors, C. japonica, Prionospio japonica and H. diadroma showed a negative correlation with salinity, while P. praetermissa and Scolectoma longifolia showed a positive correlation. H. filiformis was little affected by salinity but showed a positive correlation with TOC or silt content of sediment.

• Journal of Environmental Health Sciences
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• v.13 no.1
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• pp.1-5
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• 1987

The study on shellfish fauna around eleven artificial lakes was carried out from April to September in 1986. The identified shellfishes in total surveyed area are composed of 13 species, 6 families, 4 orders, 2 classes and among them, the dominant species was Semisulcospira forticosta. Corbicula japonica which had been inhabited in Paltangho was collected in Chunchonho and Uiamho in this study. Consequently, the distributional area was gone up north. Especially, Radix auricularia, Parafossarulus manchuricus and Austropeplea ollula were collected in Paltangho and Uiamho are indicators of $\alpha$-mesosaprobe. Therefore it is necessary the countermearsure on management of water quality for the security of the source of water supply.

• Journal of the Korean Applied Science and Technology
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• v.21 no.4
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• pp.352-358
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• 2004

The firing reaction and calcination characteristics of the waste shellfish were examined for the future use as absorbent. The weight variation was measured according to thermal-decomposition using TGA and observed variation of the phase. The qualitative and quantitative analysis of the sample were performed using XRD and the structural analysis, SEM. The results of TGA and XRD experiments showed that the almost all of the raw Corbicula Japonica and Ostrea virginjca were changed from calcite to lime by firing and calcination reaction. The result of SEM experiment showed that the plate type of the raw sample was changed to circle type, so the surface area ratio was increased. Above results suggested that waste shellfish were usable as absorbent in the viewpoint of the reuse of resource and the decrease of environmental pollution.

• The Korean Journal of Malacology
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• v.27 no.4
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• pp.337-343
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• 2011

In order to know the effects of rearing conditions such as water temperature, salinity, larval stocking density, kinds and amounts of food organism and seedling collection method on seedling production of the brackish water clam, Corbicula japonica, the growth and survival rate of the larvae were investigated at each rearing condition. The shell length of larvae showed faster growth at $24^{\circ}C$ and $27^{\circ}C$, and survival rate showed good results at $18^{\circ}C$ and $21^{\circ}C$. Based on growth and survival rate according to water temperature, the optimal water temperature for larvae rearing was $24^{\circ}C$. At the salinity of more than 3 psu, the growth and survival rate were higher than 0 psu. The optimal salinities for larvae were 6-9 psu. Growth and survival rate of larvae were high at low stocking density and the optimum stocking density of larvae was 10 inds./ml. Daily feeding concentrations of 10,000-20,000 cell/ml of food organisms mixed Pavolva lutheri, Isochrysis galbana and Chaetoceros calcitrans were very effective. Full grown larvae collection from various substratum was significantly higt in sand, especially sand size was less than 0.25 mm.

• The Korean Journal of Malacology
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• v.19 no.1
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• pp.53-70
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• 2003

In order to understand freshwater molluscan fauna in Asan area, a survey was conducted on the watersheds of this area during the period of October 1999 to August 2000. For the purpose of easy overlook of the molluscan fauna in Asan area, present survey was undertaken on a total of 101 sampling sites of 4 major watersheds connected along Onyang River, Gokgyo River, Sapgyo Lake, and Asan Lake. The collected freshwater mollusks were analysed based on the environment of their habitats. The freshwater mollusks collected through out the present survey were 27 species, 12 families, 5 orders, and 2 classes. Of these, gastropods were 18 species, 10 families, 3 orders; and bivalves were 9 species, 2 families, and 2 orders. The dominant gastropods in this area were Radix auricularia coreana, Cipangopaludina chinensis malleata, Hippeutis cantori, Physa acuta, Gyraulus convexiusculus and Austropeplea ollula and the dominant bivalves were Anodonta arcaeformis, Anodonta arcaeformis flavotincta, and Anodonta woodiana. Dominant species in rice fields were Fossaria truncatula, Segmentina hemisphaerula and Physa acuta, dominant species in rivers were Radix auricularia coreana, Physa acuta, and Hippeutis cantori. Dominant species in reservoirs were Cipangopaludina chinensis malleata, Radix auricularia coreana, Austropeplea ollula, and Fossaria truncatula. Dominant species collected in lakes were Cipangopaludina chinensis malleata, Hippeutis cantori, Cipangopaludina japonica, and Radix auricularia coreana. Radix auricularia coreana, Cipangopaludina chinensis malleata, and Austropeplea ollula were dominantly inhabiting on the muddy bottoms. Anodonta woodiana, Cipangopaludina japonica, and Corbicula fluminea occurred mainly in the gravel areas. Radix auricularia coreana, Cipangopaludina chinensis malleata, and Hippeutis cantori were dominant in the muddy rock areas. Rock-dominant species were Radix auricularia coreana, Semisulcospira forticosta and Koreanomelania paucicincta. Sand-dominant species were Physa acuta, Radix auricularia coreana, and Hippeutis cantori. Sand gravel-dominant species were Physa acuta, Radix auricularia coreana, and oreanomelania paucicincta. Hippeutis cantori, Cipangopaludina chinensis malleata, and Gyraulus convexiusculus occurred in the sand-muddy areas. Cristaria plicata, appointed as an endangered species from the "Natural Environmental Conservation Law", was collected from 5 sampling sites (site Nos. 45, 47, 48, and 52). For the endangered species found in this survey should be make appropriate protection.

• The Korean Journal of Malacology
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• v.21 no.2 s.34
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• pp.121-132
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• 2005

We investigated the reproductive cycle with gonad developmental phases of Sinonovacula constricta by histological observations, and seasonal changes in biochemical component of the adductor muscle, visceral mass, foot muscle and mantle were studied by biochemical analysis, from January to December, 2004. The reproductive cycle of this species can be classifed into five successive stages: early active stage (March to May), late active stage (May to July), ripe stage (July to September), partially spawned stage (August to October) and spentfinactive stage (October to March). Total protein content was the highest in the following order: adductor muscle, visceral mass, foot muscle, and mantle. Except for mantle, it was generally higher during the ripe and spawning stages, while lower during the spent/inactive stage. There were positive correlations in total protein contents among adductor muscle, foot muscle, and visceral mass. However, the correlations were not statistically significant. Total lipid content was the highest in the visceral mass; it was more than 5 or 6-fold higher than those in the adductor muscle, foot muscle, or mantle. The monthly change was also most dynamic in the visceral mass. It first Increased during the early active stage (March to May), decreased during late active stage (May to July), and then increased again rapidly during the spawning stage (September). There were a strong negative correlation in total lipid contents between foot muscle and adductor muscle (r = -0.634, p = 0.027), and a strong positive correlation between adductor muscle and mantle (r = 0.665, p = 0.018). Glycogen contents showed more or less similar pattern to total lipid contents in the adductor muscle, foot muscle, and visceral mass. It was higher during the early active and spawning stages, while lower during the late active and spent/inactive stages. There was no statistically significant correlation in glycogen contents among different tissues. Especially, total lipid content showed a negative correlationship between the foot muscle, adductor muscle, visceral mass and mantle. Therefore, these results indicate that the nutrient content of the foot muscle, adductor muscle, viseral mass and mantle changed in response to gonadal energy needs.