• The Korean Journal of Malacology
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• v.26 no.1
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• pp.97-105
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• 2010

Annual gonad development of the rock shell, Thais clavigera distributed in Jeju Port was investigated over a 12 month period from March 1998 to February 1999. Monthly change in gonad development was examined using histology. Gametogenesis of T. clavigera in the study area initiated as early as in October and fully ripe eggs could be observed from May to July. Percent gonad area (PGA) also increased rapidly from May to July then dropped in August when the water temperature remained $22.6-24.5^{\circ}C$, suggesting that rock shell released their eggs during this period. All female rock shell collected during the course of study exhibited pseudo-penis in the head, indicating that a certain level of imposex had progressed in the study site. Relative penis size index (RPSI), an indicator of level of imposex phenomenon varied 59.5-173.4% and this value was relatively higher than the index reported from elsewhere. It was believed that such imposex phenomenon observed in T. clavigera was caused by endocrine disruption by chemical contaminants such as TBTs released from biocidal paints in the port environment.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.6
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• pp.632-640
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• 2003

Geographic variation in shell morphology of Thais clavigera $(K\"{u}ster)$ (Gastropoda: Muricidae) was investigated using samples collected from 24 sites along the Korean coast. Multivariate statistical analysis was applied to 9 morphometric and 4 categorical variables. The shells of T. clavigera were classified into two distinct morph types (Type-W and -E). Temperature and salinity of the sampling sites were significantly correlated with the incidence of morph types. Relative abundance of Type-W (thin, yellowish brown shell with triangular nodules) was positively correlated with temperature and negatively correlated with salinity. In contrast, relative abundance of Type-E (thick, dark purple shell with round nodules) was negatively correlated with temperature and positively correlated with salinity. Possible correlation between environmental factors (temperature and salinity) and morphological variations in the shells were discussed.

• Journal of the korean society of oceanography
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• v.33 no.3
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• pp.90-99
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• 1998

Butyltin and phenyltin residues were quantified in seawater and biota of the Chinhae Bay System, Korea in 1995. Butyltin compounds were detected in all seawater and biota samples, whereas phenyltin compounds were found only in the biota samples. Tributyltin (TBT) concentrations in seawater ranged from < 8-35 ng Sn/l. Tributyltin concentrations in Crassostyea gigas and Thais clavigera ranged from 95-885 and 23-414 ng Sn/g, respectively, Triphenyltin(TPhT) concentrations in each species ranged 155-678 and 46-785 ng Sn/g, respectively. Spatial distribution of TBT was closely related to boating and dry-docking activities. However, spatial distribution of TPhT was not consistent with that of TBT. The biological concentration factor for TBT in C. gigas was about 25000 that is four times greater than that of T. clavigera. Butyl- to phenyltin concentration ratio was greater than one in C. gigas, but that in T. clavigera was less than one. Major tissues of C. gigas also showed different accumulation patterns for butyl- and phenyltin compounds. Furthermore, 19 and 28% of total body burdens of TBT and TPhT were found in gonadal mass of C. gigas just prior to spawning.

• Proceedings of the Zoological Society Korea Conference
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• 1999.10b
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• pp.172.1-172
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• 1999

No Abstract, See Full Text

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.05a
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• pp.533-534
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• 2000

In general, intertidal gastropods display a considerable amount of intraspecific shell variation (De Wolf et al., 1998). Particularly, thaisid species, including Thais clavigera(=T.c.), have been shown a variety of shell variation in the world ocean (e.g. T, emerginata in Kitching, 1976). Nomura (1926) noted local variation of shell morphology based on five Japanese populations. Ahe (1985) classified Japanese T.c. into two forms (Form-C ＆. -P). In the Korean waters, a strong variation in nodule shape of T.c, shell has also been noted by Choe ＆ Park (1997). Taxonomy of T.c. is controversial so far. (omitted)

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 1997.06a
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• pp.305-306
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• 1997

• Animal cells and systems
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• v.3 no.4
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• pp.375-383
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• 1999

Gonadal development, gametogenesis, reproductive cycle, and first sexual maturity of Reishia clavigera were investigated monthly from July 1998 to June 1999 through cytological and histological observations. R. clavigera had separate sexes, and was an internal fertilizer. The ma1e penis was located near the two tentacles. The ovary and testis were composed of a great number of oogenic lobules and spermatogenic tubules, respectively. The size of ripe oocyte ranged from 130 to 140 ${\mu}$m in diameter. The peripheral cytoplasm of the germinal vesicle of the ripe oocyte in many cases were surrounded by smaller yolk granules, while the eccentric cytoplasm was occupied with larger ones. The reproductive cycle of R. clavigera could be classified into five successive stages: early active, late active, ripe, spawning, and recovery. Spawning of females occurred from early July to August when the seawater reached above 24.8$^{\circ}C$. Spawning of males occurred from early June to August in the water above 22.8$^{\circ}C$. Minimum size for sexual maturity of both sexes was above 10.0 mm in shell height. Each egg capsule was a cylinder or spindle in shape, 4-6 mm in length and 1-2 mm in width. Colors of newly spawned egg capsules showed yellowish white or pale yellow, while those with veliger larvae showed pale black, and released larvae or dead egg capsules showed black violet. The fecundity in an egg capsule ranged from 70 to 91 eggs (mean＝80.28 eggs).

• Proceedings of the Korea Society of Environmental Toocicology Conference
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• 2002.05a
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• pp.69-70
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• 2002

• The Korean Journal of Malacology
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• v.12 no.2
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• pp.123-131
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• 1996

진해만 바위해안 조간대에 서식하는 뿔소라과 2종, 대수리(Thais clavigera)와 뿔두드럭고둥(T. luteostoma), 에서 수컷의 성징이 암컷에게서 발현되는 임포섹스 현상을 조사하였다. 임포섹스는 전 조사정점에서 100% 나타나고 있었으므로 본 조사에서 수컷의 성징을 보이지 않은 암컷은 발견할 수 없었다. 임포섹스의 강도를 나타내는 상대 성기 길이 지수(relative penislength index: RPL)는 34.7%에서 81.1%의 범위에 있었다. 특히 마산만 안쪽의 조사정점에서는 암컷의 구성비가 크게 감소하고 어린 개체를 거의 발견할 수 없는 등 개체군이 임포섹스의 영향을 받고 있음을 알 수 있었다. 두 종의 체내에 함유된 트리부틸주석(TBT)과 트리페닐주석(TPT)의 농도를 분석한 결과 각각 0.18-1.45 $\mu\textrm{g}$/g, 0.42-6.30 $\mu\textrm{g}$/g의 범위에 있었으며, 임포섹스의 정도는 트리부틸주석과 트리페닐주석의 체내 농도와 밀접한 관계를 보였다. s 대수리와 뿔두드럭고등의 임포섹스는 우리 나라에서 유기주석 화합물의 오염을 나타내는 좋은 지표로 사용될 수 있으며, TBT의 사용 규제이후 그 효과를 감시하기 위한 용도로도 유용하게 사용될 수 있다.

• Proceedings of the Korea Society of Environmental Biology Conference
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• 2003.11a
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• pp.7-11
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• 2003

Interactions of both feminizing and masculinizing chemicals inducing imposex in gastropod were investigated with a long-term exposure experiment. Imposex-free rock shell(Thais-clavigera)was exposed to TBT and other antagonistic chemicals (nonylphenol and DDT), P450 inducer (phenobarbital) and natural sex hormone (estrogen) mixtures for 60 days. None of imposexed-females were found in control, sham (ethanol) and testosterone exposure group, on the other hand imposex was induced in the TBT and all the TBT+antagonist mixture groups. After 60-day exposure, frequency of imposexed-female ranged from 31-68%. Female mean penis length (FMPL) of imposexed-female ranged from 0.87-2.58 mm, and relative penis length indices were from 7.2 to 21.2%. However, the degrees of imposex were different among the exposure groups. The FMPLS of three exposure groups (TBT+estrogen, + DDT and +nonylphe- not) were less than that of the TBT exposure group. Ethoxyresorufin-O-deethylase (EROD) activities in gastropod decreased in the TBT and all the TBT+antagonist ekposure groups compared to the control group. A negative correlation was abtained between TBT body residue and EROD activity, while a positive relationship was obtained between 737 body residue and the degree of imposex except for the TBT +DDT exposure group. Although 737 concentration was relatively high in the TBT+DDT exposure group, the TBT +DDT exposure group demonstrated low EROD activity and low degree of imposex. These results indicate that a certain antagonistic effect of DDT occurred in induction of imposex by TBT.