• Environmental Analysis Health and Toxicology
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• v.25 no.4
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• pp.287-294
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• 2010

Objectives : The aim of this study was to verify the intersexuality of Crassostrea gigas and Ruditapes philippinarum in southern coastal waters of Korea. Methods : Specimens of Crassostrea gigas (n=363) were collected from six areas of Tongyeong, Geoje and Yeosu. Ruditapes philippinarum (n=221) was collected from five areas of Yeosu. The sex ratio and intersexuality were determined after observing gonad preparations. Results : The rate of intersexuality in Crassostrea gigas was 16.25%, with females (24.79%; n=30/121) exhibiting a higher rate than males (11.98%; n=29/242). The rate of intersexuality in Ruditapes philippinarum was 24.43%, with females (37.76%; n=37/98) exhibiting a higher rate than males (13.82%; n=17/123). Conclusions : The results of this study suggest that intersexuality is induced by aquatic pollutants such as endocrine disrupting chemicals (EDCs).

• Ocean and Polar Research
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• v.28 no.3
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• pp.215-224
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• 2006

Spatial variation of heavy metal accumulation was investigated in Manila clam Ruditapes philippinarum collected from several tidal flats. Sediment metal levels varied highly among the sites, which was attributed primarily to differences in Fe and organic carbon contents and in part to gain size. Significant differences in metal concentrations also were found in the clam tissue among the different sampling sites. However, except for a few metals (Mn, Zn, Pb), which showed some elevation, the variations in the clam tissue were not related to the variations in the sediment. This is likely because most metals in filter-feeding herbivores such as R. philippinarum accumulated as a result of feeding on suspended particles such as phytoplankton and organic detritus in the water column, not in bottom sediment. In addition, tissue weight for a specific shell size varied significantly among the sites, and increased tissue mass indicating a good nutritive condition likely caused a subsequent dilution of body metals leading to reduced weight-specific concentrations of some metals (Cd, Zn, Cu, Co).

• Proceedings of the Korean Aquaculture Society Conference
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• 2004.05a
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• pp.506-507
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• 2004

• Proceedings of the Malacological Society of Korea Conference
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• 2003.11a
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• pp.12-12
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• 2003

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.3
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• pp.190-193
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• 2001

To investigate the effects of the dissolved oxygen concentration (DO) on Scope for growth (SFG) of the manila clam, Ruditapes philippinarum, we measured $LC_{50}$, filtration, respiration, ammonia excretion, and assimilation rates under $23\pm0.5^{\circ}C$ as a function of DO. The $LC_{50}$ of DO for R. philippinarum, was 2.4 mgDO $L^{-1}$. With decreasing DO, filtration and respiration rates of R. philippinarum decreased, while ammonia excretion rate increased, The assimilation rate was $68.2\%$ at 6.5 mgDO $L^{-1}$, decreased to $29.8\~39.3\%$ at 3.5 mgDO $L^{-1}$. R. philippinarum had positive SFG's at the $DO{\geq}2.5mgDO\;L^{-1}$.

• The Korean Journal of Malacology
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• v.28 no.1
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• pp.29-35
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• 2012

Growth patterns of the Manila clam, Ruditapes philippinarum in each tidal level were studied in the intertidal zone in Tae-an on the west coast of South Korea from April to August 2009. Environmental factors and the specimens of R. philippinarum were monthly collected at three intertidal locations: low intertidal zone, low-middle intertidal zone and middle intertidal zone. Temperature of sediment in low intertidal zone were lower than those in other intertidal locations. Concentrations of Chl-${\alpha}$ were not significantly different between in each tidal level. Exposure hours in low intertidal zone were shorter than those in other intertidal locations. Density of each year class in low intertidal zone were higher than those in low-middle intertidal zone and middle intertidal zone. Growth factors of R. philippinarum in low intertidal zone were better than those in other intertidal locations. The growth rate of under one year class individuals of low intertidal zone were higher than those in low-middle intertidal zone and middle intertidal zone, before the main recruitment period of R. pilippinarum. Although the growth patterns of R. philippinarum may be affected by various environmental factors, we suggests that the exposure duration is the main affect in the growth patterns of R. philippinarum in intertidal zone.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.2
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• pp.137-145
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• 2016

This study screened the biological activity of an acidified gill extract of the Manila clam Ruditapes philippinarum including antimicrobial, hemolytic, membrane permeabilization, and DNA-binding activity, and purified the antimicrobial material. The acidified gill extract showed potent antimicrobial activity against Bacillus subtilis and Escherichia coli without significant hemolytic activity, but showed no membrane permeabilization or DNA-binding ability. An antimicrobial material was purified from the acidified gill extract using C₁₈ reversed-phase and cation-exchange high-performance liquid chromatography (HPLC). Treatment of the purified material with trypsin completely abolished all of the antibacterial activity against Bacillus subtilis, suggesting that the purified material is a proteinaceous antibiotic. The molecular weight of the purified material was 2571.9 Da, but no primary structural information was obtained due to N-terminal blocking. A future study should confirm the primary structure. Our results suggest that the Manila clam gill contains proteinaceous antibiotics that have a role in first-line defense. This information could be used to better understand the Manila clam innate immune system.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.39 no.spc1
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• pp.123-131
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• 2006

Immmune parameters of the Manila clam Ruditapes philippinarum collected from four tidal flats, Nudong, Gonam, Hwangdo and Bangpo on Anmyeon-do, Korea were optimized and evaluated at the single cell level using flow-cytometry Hemocytes were withdrawn from the sinus of each clam, and total hemocyte counts (THC), phagocytosis rate, hemocyte mortality (HM) and DNA damage of hemocyte were analyzed. The highest hemocyte counts was recorded from the clams collected from Gonam, followed by Hwangdo, Nudong and Bangpo (P<0.001). Phagocytosis rate and hemocyte mortality of Gonam and Nudong clams were significantly higher than those of clams from Hwangdo and Bangpo (P<0.001). DNA damage in the clams from Nudong was higher twice than that of clams from Gonam (P<0.05). We suggest that the flow-cytometry has a high potential for evaluation of immunity of marine bivalves.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.5
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• pp.511-518
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• 2019

Evaluating the habitat suitability of potential aquaculture sites for cultured species is critical to the sustainable use of tidal flats. This study evaluated the habitat suitability index (HSI) of 12 sites in a tidal flat aquaculture farm at Geunso Bay, Taean, in June 2016. The parameters used to model the suitability index were Growth (water temperature, chlorophyll ${\alpha}$, hydrodynamics), Survival (sediment-sand, mean size, air exposure), and Environment (DO, salinity). The HSI was calculated using weighted and No weighted geometric means. The results showed high habitat suitability at the bay's entrance (HIS; No weighted, 0.60-0.70; weighted, 0.60). Hydrodynamics, air exposure, sediment-sand and mean size are thought to have a significant impact on habitat selection by Manila clams Ruditapes philippinarum. This study explored the optimum habitat for Manila clams by calculating the HSI, providing basic data for tidal flat management.

• The Korean Journal of Malacology
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• v.29 no.1
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• pp.7-13
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• 2013

This study was conducted to find out biological response of Manila clam, Ruditapes philippinarum exposed to lead (Pb). Experimental period was four weeks. Experimental groups were composed of one control condition and three lead exposure conditions (0.25, 0.50 and 1.00 mg/l). The results of the study confirmed that lead induces reduction of survival rate and oxygen consumption rate and histopathology of organ structure of the bivalve. Oxygen consumption rate was observed exposure groups lower than control decline by 25%-72%. Histological analysis of organ system illustrated expansion of hemolymph sinus, disappearance of epidermal layer and degeneration of connective tissue layer of the mantle. Also, histological degenerations as epithelial necrosis and hyperplasia of mucous cells are recognized in the gill and it was observed expansion of hemolymph sinus, disruption of epithelial layer, decrease of mucous cell and degeneration of connective tissue layer in the foot. In the digestive diverticulum, it was showed atrophy of basophilic cell and degeneration of epithelial cell in the digestive tubules, and as the concentration of lead increased the accumulation of lipofuscin increased.