Impacts of 2007 Hebei spirit oil spill on the reproductive physiology of Pacific oyster, Crassostrea gigas, in Taean off the west coast of Korea

양현성,이희중,박흥식,최광식 한국해양환경·에너지학회 2010 한국해양환경공학회 학술대회논문집 Vol.2010 No.6

Pathologic Survey on the Manila Clam Ruditapes philippinarum (Adams and Reeve 1850) from Haeju off the Western Coastal Yellow Sea

양현성,최광식,박광재 한국해양과학기술원 2010 Ocean science journal Vol.45 No.2

Pathologic condition of Manila clam, Ruditapes philippinarum collected from Haeju off the west coast of North Korea in February and March 2007 was investigated in this study. The diagnostics included a protozoan parasite, Perkinsus olseni, the brown ring disease (BRD) caused by bacteria Vibrio tapetis and metazoan parasites Trematod and Cestod. P. olseni infection was examined using histology and Ray’s fluid thioglycollate medium (RFTM) assay along with Choi’s NaOH digestion technique. Trematode and cestode infection was also examined from the histology. A total of 140 clams with 35-45 mm in shell length (2-3 years old) were analyzed. Condition factor (CF), a ratio of the wet tissue weight to the shell dry weight, ranged from 0.445±0.074 (February) to 0.544±0.132 (March). Total body burden of P. olseni (i.e. infection intensity) ranged from 18,644±37,755 (February) to 26,933±80,611 cells/g wet tissue (March) with the prevalence of 76.7-43.3% (March) respectively. Prevalence of trematode and cestode infection in February and March varied 22.5-25.0 and 15.0-22.5% respectively. Infection intensity of V. tapetis ranged 1-2 and the prevalence was 1.4 (February) and 5.7% (March). Prevalence and infection intensity of P. olseni in clams from Haeju was comparatively lower than those of clams reported on the west coast of Korea. BRD and the other metazoan parasite infection were also relatively lower or similar to the condition of the clams reported previously. CF of Haeju clams was also relatively higher than the clams in Gyeonggi Bay and Taean, suggesting that Haeju clams had relatively better pathologic and health condition.

Pathology Survey of the Manila Clam <i>Ruditapes philippinarum</i> from Hwangdo Tidal Flat in Cheonsu Bay on the West Coast of Korea

양현성,조영강,신종섭,박흥식,최광식 한국해양과학기술원 2021 Ocean and Polar Research Vol.43 No.4

Manila clam Ruditapes philippinarum is present at high rates of density in tidal flats in Cheonsu Bay on the west coast of Korea, where clams often exhibit mass mortalities in late summer. We monitored the pathologic condition of clams at Hwangdo tidal flat (HD) to understand the parasitic impacts on clam fitness. Manila clams were fully ripe in July and spawned during August and September, as the histology indicated. The histology revealed that clams in HD tidal flats were heavily infected by the protozoa parasite Perkinsus olseni, as the monthly prevalence ranged from 53% (September) to 93% (August). In addition, Manila clams were co-infected by the metazoan parasite Cercaria tapetis and Parvatrema duboisi with the prevalence of 0-33% and 0-14%, respectively. Massive hemocyte infiltration and subsequent inflammation were commonly observed from the gills of P. olseni infected clams. Clusters of P. olseni trophozoites and heavy hemocyte infiltration were also observed from the female gonad, suggesting that P. olseni interferes with host gonad maturation. The larval trematode occupied almost the entire host gonad, resulting in gonad castration. In addition, Metacercaria of P. duboisi were observed from the subsurface of the mantle. Ray’s fluid thioglycollate medium assay (RFTM) indicated that clams collected in August and September contained approximately 4.0x106 P. olseni cells/g gills. Condition Index (CI) declined gradually from spring to early summer, and the decline in CI was interpreted as a consequence of the heavy parasitism, as the parasites drain the host’s net energy to be used in somatic growth and gamete production.

First Report on the Occurrence of the Comb Pen Shell, Atrina pectinata (Linnaeus, 1767) (Bivalvia: Pinnidae) in Ulleungdo Island in the East Sea: Ecology and Molecular Identification of the Species using COI Gene Sequence

양현성,강현실,박흥식,노충환,정의영,최광식 한국해양과학기술원 2015 Ocean science journal Vol.50 No.4

Pen shell is one of the largest marine bivalves inhabiting shallow subtidal soft bottoms in the west Pacific and Indian Oceans. In Korea, the comb pen shell Atrina pectinata fisheries has been established on the south and west coasts. Recently, a pen shell population has been discovered from a subtidal sand flat (25–30 m depth) in Ulleungdo Island located in the East Sea of Korea, suggesting a potential shellfish resource in this area. In the present study, we first surveyed the population density and size of the unique pen shell using SCUBA, and identified the pen shell to species level using mitochondrial cytochrome oxidase I gene (COI) sequence. An underwater survey carried out from July to September 2013 revealed that populations of pen shell patched on subtidal sand flat at a depth of 20–25 m. Grain size analysis indicated that sand particles accounted for 99% of the 600 × 700 m sand flat. The underwater survey also indicated that density of the pen shell ranged between 6–19 ind/m2, with a mean of 11 ind/m2. Shell height (i.e. longest axis of the shell) of the pen shell on the sand flat varied between 17.2 cm to 28.8 cm, with a mean of 25.1 cm, and the age was estimated to range between 1.5–7.5 yrs, with a mean of 5 yr. COI DNA sequence obtained from the pen shell in this study showed 98.9–99.2% similarity to Atrina pectinata (Linnaeus 1767) reported from Japan. In the cluster analysis, the COI DNA sequence of the pen shells from Ulleungdo Island was grouped with A. pectinata reported from Japan and China, indicating that the pen shell discovered in this study was A. pectinata, commonly distributed on the west and south coasts of Korea.

Autonomous Reef Monitoring Structures를 활용한 제주의 해양생물다양성 모니터링

양현성,이경태,김태훈,김태호,강도형 제주학회 2022 제주학회 학술발표논문집 Vol.2022 No.2

Morphology and Immune-related Activities of Hemocytes of the Mussel Mytilus coruscus (Gould, 1861) from East Sea of Korea

양현성,홍현기,루도빅도나지,노충환,박흥식,김동성,최광식 한국해양과학기술원 2015 Ocean science journal Vol.50 No.1

Mytilus coruscus is a cold water mussel commonly occurring on shallow subtidal rocky substrata along the east coast of Korea. Despite its abundance, there have only been a few studies conducted reporting on its biology and ecology. In this study, we investigated the immune-related activities of hemocytes of M. coruscus using light microscopy and flow cytometry. Based on the morphology and cellular activities, 3 types of hemocytes were identified, as granulocytes, hyalinocytes, and blast-like cells. Granulocytes, containing numerous intra-cytoplasmic granules, were intermediate-size (11.8 μm) and the most abundant cells (70.2%), while hyalinocytes were the largest cells (16.0 μm), with no or few granules in their cytoplasm. The granulocytes exhibited higher lysosomal content, phagocytosis activity and oxidative capacities than the hyalinocytes. In contrast, the blast-like cells were the smallest cells (6.4 μm) and displayed a lack of phagocytosis and oxidative capacities. In M. coruscus, the granulocytes appear as the major cell type involved in cellular defense, whereas the blast-like cells may not be directly involved in cell-mediated immune response.

울릉도 남해역에 서식하는 키조개의 연중 번식주기에 관한 연구

양현성,노충환,윤성진,김윤배,최광식,강도형 한국해양과학기술원 2016 Ocean and Polar Research Vol.38 No.1

Gametogenesis of the comb pen shell, Atrina pectinata (Linnaeus, 1767) (Bivalvia: Pinnidae) on the southern coast of Ulleungdo Island, Korea was assessed monthly (November 2013 to October 2014) using histology. Gametogenesis commenced in January when the surface water temperature was 12.6oC and pen shells evidenced an early development phase with small oogonia from January to April, although few females exhibited ripe eggs in their follicular epithelium. In April, the oocyte diameter increased rapidly, and fully mature eggs appeared in May. First spawning males and females were observed in June as the surface water temperature reached 19.3oC and July (23.2oC) respectively. The spawning activity continued until the end of September. Histology indicated that the spawning peak of the females in Ulleungdo Island was July to August. During October to January, most of the pen shells were in spent and resting stages. Our data suggested that A. pectinata is a summer spawner, and their annual gametogenesis is closely associated with the seasonal variation in the surface water temperature. The present study is the first provided fundamental information on the life history of A. pectinata in Ulleungdo Island, and this can be put to good use in the management of this pen shell in the study area.

Bi-LSTM과 강화학습을 이용한 고가 예측 기반의 자동 주식 매매 모델 설계 및 구현

양현성,박성욱,박준,김준영,정세훈,심춘보 한국멀티미디어학회 2022 멀티미디어학회논문지 Vol.25 No.12

Quant Investment research has become more active with the development of deep learning technology. In this paper, we propose an auto-selling model based on reinforcement learning with higher returns using Bidirectional Long Short-Term Memory (Bi-LSTM) high-priced predictive models. The proposed model adjusts the immediate compensation and delay compensation values by applying the predicted high price to the compensation function. In addition, we compared the automatic trading model of the closing price with the automatic trading model applied with the auxiliary index value. As a result of the experiment, the maximum return of the proposed model was higher, and based on this, it was concluded that the expensive automatic trading model generates higher profits than the existing automatic trading model.

Annual Gametogenesis and Reproductive Effort of the Limpet Cellana grata (Gould, 1859) (Gastropoda: Nacellidae) in a Rocky Intertidal Beach at Ulleungdo Island off the East Coast of Korea

양현성,강도형,박흥식,최광식 한국해양과학기술원 2017 Ocean science journal Vol.52 No.4

Widely distributed from the northern coast of Vietnam to the northern Japan, the limpet Cellana grata (Gould, 1859) occurs commonly on the south and east coasts of Korea. Despite their wide distribution range, few studies have investigated the annual gametogenesis and reproductive effort of C. grata. In an attempt to understand the reproductive physiology of the limpet, we investigated the annual gametogenesis and reproductive effort of C. grata from Ulleungdo Island off the east coast of Korea. Histology revealed that the gonial mitosis commenced in January, as the female exhibited small oogonia (10–40 μm) in the follicle. From March to June, the oocyte size increased dramatically, and fully mature eggs (110–170 μm in diameter) appeared in early summer. First spawning males and females were observed in July, as the surface seawater temperature (SST) reached 22.1°C. The spawning male and females could be observed until the end of December. Gonad somatic index (GSI), a ratio of gonad mass to the total tissue weight, of the male ranged from 0.6 (April) to 17.9 (July), while the female GSI varied from 1.0 (February) to 18.3 (July). GSI of male and female declined rapidly from July to August, suggesting that the major purse of the spawning at the study site was between July and August. Our study suggested that the commercial catch of C. grata during July and August must be suspended at Ulleungdo Island, in order to protect the spawning limpets, which enhances C. grata recruitment and the population.

제주항내에 서식하는 신복족류 Thais clavigera의 연중 생식주기 및 임포섹스 현상에 관한연구

양현성,김봉규,박흥식,최광식 한국패류학회 2010 The Korean Journal of Malacology Vol.26 No.1

제주 항 내에 서식하는 대수리 Thais clavigera를 조직학적 방법을 이용하여 1998년 3월부터 1999년 2월까지 생식소발달과 생식주기 그리고 imposex 현상에 대해 조사하였다. 조직학적 관찰 결과, 배우자형성은 암,수 모두 10월에 처음 시작 되었고, 성숙한 알들은 주로 5월에서부터 7월 사이에 관찰되었다. 생식소단면적 지수 역시 알이 성숙하는 5월과 7월 사이 급격히 증가하였으며, 8월에 급격히 낮아져, 7월과 8월 사이에 집중적인 산란이 있었던 것으로 사료되었다. 유기주석화합물에 의한 imposex 현상의 진행 정도를 나타내는 RPSI는월 평균 59.5-173.4%로 다른 지역에 비하여 비교적 높게 나타났으며, 이는 제주 항 내의 유기주석화합물에 의한 것으로추정되었다. Annual gonad development of the rock shell, Thais clavigera distributed in Jeju Port was investigated over a 12month 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 ºC, 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.