• 한국발생생물학회지:발생과생식
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• 제16권4호
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• pp.385-388
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• 2012

The sex ratio (F:M) in the same population of oyster, Crassostrea gigas at the commencement of the study (2007) was 1:1.0, but changed to 1:2.8 by the end of the study (2008). The sex reversal rate in two-year-old oysters was 40.2%. Specifically, female to male sex reversal rate was 66.1%, which is higher than the male to female sex reversal rate of 21.1%. The sex reversal pattern of C. gigas appears to go from male ${\Rightarrow}$ female ${\Rightarrow}$ male, and as such is determined to be rhythmical hermaphroditism.

• Ocean Science Journal
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• 제41권4호
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• pp.211-219
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• 2006

A comparison was made of population of the economically important cockle Anadara (=Scapharca) broughtoni (Bivalvia, Arcidae) inhabiting different areas of the Razdolnaya River estuary at the head of Amurskii Bay (Peter the Great Gulf, East Sea). Also, changes in cockle population density and structure, as well as in cockle growth rates during the last 20 years were studied. In all years of investigation, the morphometrical parameters and growth rates of cockles were smaller at the sites located close to the River mouth than farther down-estuary. The differences can be attributed to higher concentration of suspended particulate matter, decreased salinity and water temperature, as well as a longer exposure to these unfavorable environmental factors at sites located close to the River mouth, compared to farther sites. For two decades, cockle population density had decreased by almost 30 times at some sites in the River estuary. The main reason for this population decline is commercial over-fishing of the cockle. Besides, for the last 20 years, linear parameters of the cockles in the population decreased approximately by 30% and weight parameters, almost two times. Cockle growth rates also decreased for this period. Evidently, these facts are due to the damaging effect of dredging.

• 한국수산과학회지
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• 제36권4호
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• pp.352-357
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• 2003

Gonadal development and gametogenic cycle of the equilateral venus, Gomphina collected in the coastal waters of Gangneung, Gangwon-do, Korea were investigated by means of histological method from March 2001 to February 2002. Sex of the clam was dioecious. The gonads are composed of a number of gametogenic follicles. The gonad index (GI) was reached the maximum in June (3.87), and the minimum in August (0.66). The condition index (CI) was reached the maximum in May (0.051), and the minimum in January (0.028). The gametogenic cycle of the clam could be divided into five stages inactive (September to November), early active (November to March), late active (April to May), ripe (June and July) and spent/degenerative stage (July to August). Sex ratio (male/female) was 1:0.9.

• 한국발생생물학회지:발생과생식
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• 제15권3호
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• pp.239-247
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• 2011

Spermatogenesis and taxonomic values of mature sperm morphology of in male Septifer (Mytilisepta) virgatus were investigated by transmission electron microscope observations. The morphologies of the sperm nucleus and the acrosome of this species are the cylinder shape and cone shape, respectively. Spermatozoa are approximately 45-50 ${\mu}m$ in length including a sperm nucleus (about 1.26 ${\mu}m$ long), an acrosome (about 0.99 ${\mu}m$ long), and tail flagellum (about 45-47 ${\mu}m$). Several electron-dense proacrosomal vesicles become later the definitive acrosomal vesicle by the fusion of several Golgi-derived vesicles. The acrosome of this species has two regions of differing electron density: there is a thin, outer electron-dense opaque region (part) at the anterior end, behind which is a thicker, more electron-lucent region (part). In genus Septifer in Mytilidae, an axial rod does not find and also a mid-central line hole does not appear in the sperm nucleus. However, in genus Mytilus in Mytilidae, in subclass Pteriomorphia, an axial rod and a mid-central line hole appeared in the sperm nucleus. These morphological differences of the acrosome and sperm nucleus between the genuses Septifer and Mytilus can be used for phylogenetic and taxonomic analyses as a taxonomic key or a significant tool. The number of mitochondria in the midpiece of the sperm of this species are five, as seen in subclass Pteriomorphia.

• 한국수산과학회지
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• 제40권1호
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• pp.16-23
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• 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.

• 한국패류학회지
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• 제13권2호
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• pp.185-192
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• 1997

1990젼 3월부터 1991년 2월까지 전라북도 군산시 내초도 연안에 서식하는 동죽의 성장을 조사하였다. 1.조사해역의 연간 수온분포는 2.0-26.3$^{\circ}C$이고, 간석지 온도는 0.7-36.2$^{\circ}C$이었다. 2. 동죽의 패각에 나타나는 윤문은 연 1회 형성되며 윤문 형성시기는 3-4월로 조사되었다. 3. 초륜 형성기간은 9개월(0.75년)로 나타났다. 4. 각장(SL: mm)과 체중(TW: G)간의 관계는 TW=1.090 x $10^{-4}$ S $L^{3.2798}$( $r^{2}$=0.99)이었으며, 각장과 각고(SH:mm)간의 관계는 SH=0.865 SL + 0.250( $r^{2}$=0.99)이고, 각장과 각폭(SW: mm) 간의 관계는 SW=0.599 SL - 0.203 ( $r^{2}$=0.98; 각장 22 mm미만), SW=0.724 SL - 2.796( $r^{2}$=0.91; 각장 22 mm이상)이었다.5. 연령(t)에 대한 각장(S $L_{t}$ )의 Bertalanffy성장식은 $L_{t}$ =51.399(1- $e^{0.585}$8(t+0.064)이고, 연령(t)에 대한 체중 (T $W_{t}$ )의 Bertalanffy성장식은 $W_{t}$ =44.467(1- $e^{0.585}$8(t+0.064)$^{3}$로 나타났다.타났다.

• 한국패류학회지
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• 제24권1호
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• pp.1-10
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• 2008

Spermatogenesis and the reproductive cycle in male Spisula sachalinensis were investigated by cytological and histological observations. The morphology of the spermatozoon has a primitive type and is similar to those of other bivalves in that it contains a short midpiece with four mitochondria surrounding the centrioles. But spermatozoon of this species has not axial rod and satellite body in the midpiece. The morphologies of the sperm nucleus type and the acrosome shape of this species have a globe-shape type and modified cap-like shape, respectively. The spermatozoon is approximately $40-45{\mu}m$ in length including the sperm nucleus length (about $1.35{\mu}m$), acrosome length (about $1.50{\mu}m$) and tail flagellum. The axoneme of the sperm tail flagellum consists of nine pairs of microtubules at the periphery and a pair at the center. The axoneme of the sperm tail shows a 9+2 structure. The spawning period of these species lasts from June to July, and the main spawning occurs in July when seawater temperatures are greater than $20^{\circ}C$. The male reproductive cycle of this species can be categorized into five successive stages: early active stage (October to January), late active stage (February to April), ripe stage (April to June), partially spawned stage (June and July), and spent/inactive stage (August to September).

• Animal cells and systems
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• 제11권2호
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• pp.227-234
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• 2007

Spermatogenesis, the reproductive cycle, and the size at first sexual maturity in male Mactra chinensis were investigated by cytological and histological observations. The spermatozoon exhibits a primitive type morphology and is similar to those of other bivalves in that it contains a short midpiece with four mitochondria surrounding the centrioles. The morphologies of the sperm nucleus type and the acrosome shape of this species are cylindrical and modified cap-like, respectively. The spermatozoon is approximately $40-45\;{\mu}m$ in length including the sperm nucleus (about $1.46\;{\mu}m$), acrosome (about $1.20\;{\mu}m$) and tail flagellum. The axoneme of the sperm tail flagellum consists of nine pairs of microtubules at the periphery and a pair at the center. The axoneme of the sperm tail shows a 9+2 structure. The spawning period of this species lasts from June to September, and the main spawning occurs in July and August, when the seawater temperature is greater than $20^{\circ}C$. The percentage of individual male clams at first sexual maturity was 56.5% for those whose shell lengths were 35.1-40.0 mm, and 100% for over 45.1 mm. Accordingly, harvesting clams <35.1 mm in shell length could potentially cause a drastic reduction in recruitment, and a measure indicating a prohibitory fishing size should be taken for adequate fisheries management.

• 한국어류학회지
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• 제12권1호
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• pp.54-61
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• 2000

등가시치의 식성을 조사하기 위해 가덕도 주변해역에서 1998년 3월부터 1999년 2월까지 채집된 등가시치의 위내용물을 분석하였다. 등가시치의 주요 먹이생물은 새우류 (Caridea), 옆새우류 (Gammaridea), 어류 (Pisces), 이매패류 (Bivalvia) 그리고 쿠마류 (Cumacea)였다. 그 외에 요각류 (Copepoda), 카프렐라류 (Caprel1idea), 패충류 (Ostracoda), 게류 (Brachyura), 두족류 (Cephalopoda), 복족류 (Gastropoda), 거미불가사리류 (Ophiuroidea) 및 갯지렁이류 (Polychaeta)가 위내용물 중 발견되었으나, 그 양은 많지 않았다. 등가시치가 성장함에 따라 먹이생물 조성에 있어서 변화를 보였는데, 작은 체장에서는 옆새우류, 이매패류 치패, 쿠마류 및 패충류 등 소형 먹이생물을 비교적 다양하게 섭취하였다. 그러나 성장하면서 소형 먹이생물들이 위내용물 중 차지하는 점유율이 급격히 낮아졌으며, 반면 새우류와 어류 등 비교적 큰 먹이생물의 점유율이 크게 증가하였다.

• 한국양식학회지
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• 제20권2호
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• pp.75-80
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• 2007

백합과(科)에 속하는 유용패류인 살조개, 바지락, 백합, 개조개 및 가무락조개 등 5종간의 아미노산 조성과 그에 따른 유연관계를 밝히고자 하였다. 백합과(科) 5종의 주요아미노산 구성은 ureanine, taurine, proline, glycine, alanine, arginine 등으로 나타났다. 백합과(科) 5종간 아미노산 함량으로 유사도를 분석한 결과 살조개와 바지락간에는 0.89, 가무락조개와 백합간에는 0.94, 개조개는 살조개와 바지락간에 0.88을 보였으며, 가무락조개와 백합, 살조개, 바지락 및 개조개간에는 0.52의 유사도를 보였다.