• Development and Reproduction
• /
• v.18 no.2
• /
• pp.73-78
• /
• 2014

This study attempts to propose the possibility of the sex reversal in Sinonovacula constricta and Gomphina veneriformis by confirming the changes in the sex ratio with the shell length in the same population level. For analysis of sex ratio, 100 individuals of S. constricta (SL 26.5-95.0 mm) and 2385 individuals of G. veneriformis (SL 15.1-60.1 mm) were used. Sex was analyzed histologically. Both species displayed the tendency of increase in the female proportion with increase in shell length. In this study, changes in the sex ratio in accordance with the growth of S. constricta and G. veneriformis are determined to be indirect evidence that signifies their sex reversal.

• Environmental Analysis Health and Toxicology
• /
• v.24 no.4
• /
• pp.341-350
• /
• 2009

This study involves a relationship between butyltins concentrations and histopathological changes of the digestive gland in the equilateral venus, Gomphina veneriformis exposed to TBTCl of 0.4, 0.6 and 0.8 ${\mu}g/L$ for 36 weeks. In the sediment, total butyltin (${\sum}BT$) concentration was detected ND~7.54 (0.4 ${\mu}g/L$), ND~9.76 (0.6 ${\mu}g/L$), 1.22~13.13 ${\mu}g/L$ (0.8 ${\mu}g/L$), respectively. Especially, TBT level in 0.8 ${\mu}g/L$ group was the highest for 36 weeks. In the soft tissue, total butyltin (${\sum}BT$) concentration of the exposure group was 10.14~12.75 (control), 479.29~1,286.56 (0.4 ${\mu}g/L$), 563.32~2,154.82 (0.6 ${\mu}g/L$) and 1,317.70~2,132.60 ${\mu}g/L$ (0.8 ${\mu}g/L$), respectively. Ratio of TBT to ${\sum}BT$ of the tissue of 0.8 ${\mu}g/L$ kept the lowest level for 36 weeks. The ${\sum}BT$ concentrations of sediment were correlated with ${\sum}BT$ concentrations in the tissue. In the exposure groups, necrosis and atrophy of columnar epithelial cell and collapse of epithelial layer in the digestive tubule. And there was a reduction in stain affinity of basophilic cell. Such histological degenerations was more severe in digestive tubule of 0.8 ${\mu}g/L$ group.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.28 no.5
• /
• pp.667-676
• /
• 1995

Settlement, recruitment, growth and production of Mactra venerifomis were investigated at Kunsan tidal flat located in the west coast of Korea from lune 1993 to May 1994. High density of planktonic larvae of M. veneriformis was observed between the mid and early July in 1993. The size of the newly settled larvae ranged from 250 to 350um in shell length with mean density of 601$inds.\cdot m^{-3}$. Recruitment of M. veneriformis larvae was occurred mainly in the mid June to mid July 1993. The larvae have no substratum preference during the larval settlement phase. Mortality of larval was affected by environment (substratum, exposure time, density of adult clams). After settlement they grew until November, and stopped growing in winter from December. The estimated turnover rate of M. veneriformis larvae was estimated as high as 4.91 and 4.94. Annual production of the 0-age group was estimated to be 2,900g $m^{-2}\;\cdot\;yr^{-l}$, which was relatively high compared with those of other age groups.

• The Korean Journal of Malacology
• /
• v.13 no.2
• /
• pp.193-201
• /
• 1997

1990년 3월부터 1991년 2월까지 전라북도 군산 연안에 서식하는 동죽을 채집하여, 순간성장율, 순간사망율, 평균 생체량, 연간 생물생산력에 대하여 조사하였다. 치패는 각장 약 0.75 mm가 7월에 처음 채집되었으며, 0-5세의 6개 cohort로 구분되었다. 순간성장률은 여름철에 ？고 겨울철에 낮았지만, 순간사망률은 여름철에 높았다. 조사지역에서 동쪽 개체군의 연간평균 생체량은 3.865 g/$m^2$이었으며, 연간생산량은 3.933 g/$m^2$이었고, 연간 회전율은 1.020, 회전시간은 0.986년으로 추정되었다.

• Parasites, Hosts and Diseases
• /
• v.55 no.4
• /
• pp.399-408
• /
• 2017

A survey was performed to know the recent infection status of digenetic trematode metacercariae in clams and oysters from 4 sites in western coastal regions of the Republic of Korea (=Korea). Four species of clams (Mactra veneriformis, Ruditapes philippinarum, Cyclina sinensis, and Saxidomus purpuratus) were collected from Taean-gun, Chungcheongnam-do (Province), Buan-gun (County) and Gochang-gun, Jeollabuk-do, and oysters, Crassostrea gigas, from Shinan-gun, Jeollanam-do were transferred to our laboratory on ice and examined by the artificial digestion method. The metacercariae of Himasthla alincia were detected in 3 species of clams, M. veneriformis, R. philippinarum, and C. sinensis from the 3 surveyed areas. The positive rate and the mean density per clam infected were 98.9% (30.8 metacercariae) in M. veneriformis, 60.0% (5.0) in R. philippinarum, and 96.0% (28.4) in C. sinensis. The positive rate (mean density) of Acanthoparyphium tyosenense metacercariae in M. veneriformis was 50.0% (2.1) from Taean-gun and 70.0% (2.8) from Gochang-gun. The metacercariae of Parvatrema spp. were detected in M. veneriformis and R. philippinarum from Taean-gun and Gochang-gun; the positive rate (mean density) was 63.3% (4,123) and 50.0% (19) in M. veneriformis, and 6.7% (126) and 100% (238) in R. philippinarum from the 2 regions, respectively. The metacercariae of Gymnophalloides seoi were detected in all 30 oysters from Shinan-gun, and their average density per oyster was 646. From the above results, it has been confirmed that more than 3 species of metacercariae are prevalent in clams from the western coastal regions, and G. seoi metacercariae are still prevalent in oysters from Shinan-gun, Jeollanam-do, Korea.

• The Korean Journal of Malacology
• /
• v.26 no.1
• /
• pp.63-78
• /
• 2010

The purpose of this study was to investigate the effect of tributyltin (TBT) on histopathological and ultrastructural changes in the digestive gland structure of the equilateral venus, Gomphina veneriformis. Experimental period was 36 weeks. Experimental groups consist of control condition and 3 TBTCl exposure conditions (0.4, 0.6, $0.8\;TBTC\;{\mu}g\;L^{-1}$). Outer envelop of the visceral mass of G. veneriformis exposed to TBTCl was observed disappearance of microvilli and cilia, decrease of mucous cell and partially destruction of epithelium. In the digestive gland showed an increase of number of hemocyte and mucopolysaccaride near the digestive tubule at early time of the exposure. Especially, in $0.8\;TBTC\;{\mu}g\;L^{-1}$ group, collapse of digestive tubule with modification of epithelium was observed. TEM observation revealed the numerous glycogen granules in epithelium of the outer envelop and connective tissue. In the ciliated cell of the primary duct formed the cilia in cytoplasm. Basophilic cell was observed destruction of the rough endoplasmic reticulum and mitochondria. Also, nucleus in the epithelium of the digestive tubule was disappeared heterochromatin and nucleolus, and condense. As the concentration of TBTCl increased, the accumulation of lipofucin increased in the digestive gland, but the collapse of digestive tubule induced a decrease of accumulation of lipofuscin.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.40 no.1
• /
• pp.16-23
• /
• 2007

Nonylphenol (NP) is an estrogen-mimicking compound or xenoestrogen. This study investigated the effects of nonylphenol on the reproductive status of the equilateral venus Gomphina veneriformis. The experiment lasted 24 weeks, Experimental groups consisted of a control and three nonylphenol exposures ($1.0,\;2.5,\;and\;5.0\;{\mu}g\;NP/L$). Mortality did not differ significantly between the control and the exposure groups. The sex ratio (F:M) was 1:1 in nature and 1:1.03 in the control group. However, it changed to 1:3.5 with $5.0\;{\mu}g\;NP/L$ exposure. Gonad maturity in females was higher in the nonylphenol exposure groups than in the control group. By contrast, in males, it was lower in the nonylphenol exposure groups. Intersex individuals constituted 0% in nature, 3.08% in the control group, and 23.6% in the group exposed to nonylphenol, with female characteristics more prevalent than male. As the concentration of nonylphenol increased, the accumulation of lipofuscin increased in the mid-gut gland.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.29 no.5
• /
• pp.614-619
• /
• 1996

Seasonal of gen consumption of surfclam, Mactra veneriformis in Kunsan coastal area had been measured under seasonal ambient temperature condition from January to December 1994. Samples were collected monthly and divided into two groups by shell length of 2 cm (1 year class) and 3 cm (2 year class). The effects of temperature $(15,\;20\;and\;25^{\circ}C)$ and salinity $(10,\;20\;and\;30\%_{\circ})$ showed that oxygen consumption decreased with the lower temperature and salinity. Seasonal changes of oxygen consumption in surfclam varied with ambient temperature; it was showed below $0.5mg{\cdot}g^{-1}{\cdot}h^{-1}$ winter season and $1.93\~2.44\;mg{\cdot}g^{-1}{\cdot}h^{-1}$ in summer season. The difference of oxygen consumption in two groups was appeared markdly in summer season. The relationship between oxygen consumption and the seasonal ambient temperature were obtained exponential equation as $Y=e^{-1.6312+0.0879X}$ for 2 cm group and $Y=e^{-2.2366+0.0994X}$ for 3 cm group. The slop of regression line between two groups was not significant, and so there was no difference in patterns of the oxygen consumption between two groups.

• The Korean Journal of Malacology
• /
• v.29 no.4
• /
• pp.313-323
• /
• 2013

Gonad development, the reproductive cycle, first sexual maturty and size at 50% of group sexual maturity (the biological minimum size) of Gomphina (Macridiscus) veneriformis were investigated for clams collected from the coastal waters of Donghae City, the East Sea of Korea by histological, and morphometric analysis. Monthly variations of the gonad index showed a pattern similar to that of the reproductive cycle. The reproductive cycle with the gonad developmental stages in female and male G. (M.) veneriformis can be classified into five successive stages: early active stage (December to March), late active stage (March to June), ripe stage (June to July), partially spawned stage (June to August), and spent / inactive stage (September to December). The spawning period continued from June to August, with a peak between July and August when the seawater temperature exceeds $20^{\circ}C$. The percentages of first sexual maturities of female and male clams ranging from 25.1 to 30.0 mm were 56.3% in females and 61.1% in males, and for clams over 30.1 mm shell length, it was 100%. Shell lengths at 50% of group sexual maturity (biological minimum size, $RM_{50}$) were 27.71 mm in females and 26.31 mm in males. Because harvesting clams < 26.31 mm in shell length could potentially cause a drastic reduction in recruitment, a measure indicating a prohibitory fishing size should be taken for adequate fisheries management.

• Journal of fish pathology
• /
• v.21 no.1
• /
• pp.67-79
• /
• 2008

This study was conducted to find out biological response of bivalves exposed to tributyltin chloride(TBTCl). The results of the study confirmed that TBTCl induce the reduction of oxygen consumption rateand histopathological feature in the gill structure of equilateral venus, Gomphina veneriformis. The experi-mental groups consisted of a control and 3 TBTCl exposure groups (0.4, 0.6 and 0.8 yg TBTCl L') and theexperimental period was 36 weeks. For histological analysis, gill tissues were fixed in Bouin's fluid andthen stained H-E stain, AB-PAS (PH 2.5) reaction and Masson's trichrome stain after having serially sec-tioned the tissue by paraffin method at thickness of 4-6 (an. The oxygen consumption rate was not signifi-cantly different between the control and exposure groups at 4 weeks, but in all exposure groups at 28 weeks,it was significantly different to the control. Gill of G. veneriformis had demibranch that attached two sheetsof lamellae and a lamella was composed of numerous filaments, numbering 25 on average. The frontal fila-ment zone had three types of cilia; frontal, latero-frontal and lateral depending on locations while the lateralcilia were the longest and largest in number. The mucous cells observed in filaments were more abundant in(542c) in AB-PAS (PH 2.5) reaction. Gill exposed to TBTCl was extended hemolymph sinus and increased hemocytes at 4 weeks, and then it showed increases of mucous cells and partially disappearance of frontalcilia. In the group of 0.8 yg TBTCl L' at 12 weeks, hypertrophy of frontal and latero-frontal epithelia wasobserved. Also it observed m decrease of mucous cell containing weekly acid mucosubstance and appearedpartially destruction muscle fiber bundle, In the groups of 0.4 and 0.6 ug TBTCl L' at 36 weeks, it appearedpartially modification of epithelia and in 0.8 us TBTCl L' group, observed filaments that come out chiti-nous rod from disappearance of frontal and latero-frontal epithelia.