• Korean Journal of Ichthyology
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• v.18 no.3
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• pp.216-222
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• 2006

Feeding habits of Pagrus major collected in the coastal waters off Busan from January to December 2004 were studied. P. major ranged form 8.5 to 44.6 cm in standard length. P. major was a carnivore which consumed mainly hermit crabs, amphipods, crabs, shrimps, polychaetes, echinoderms, and fishes. Its diets included small quantities of gastropods, bivalves, stomatopods, cephalopods, cnidarians, and isopods. It showed ontogenetic changes in feeding habits. Small individuals (8~15 cm SL) preyed mainly on shrimps. However, individuals from 15 cm to 25 cm SL preyed mainly on hermit crabs and polychaetes. Individuals over 25 cm SL preyed mainly on fishes and echinoderms.

• The Korean Journal of Malacology
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• v.22 no.1 s.35
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• pp.1-11
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• 2006

The gonadosomatic index (GSI), oogenesis and reproductive cycle in female Neptunea (Barbitonia) afhritica cumingii were investigated by light and electron microscope observations. In the early vitellogenic oocyte, the Golgi complex and mitochondria were involved in the formation of glycogen, lipid droplets and yolk granules. Late in the vitellogenic oocytes, the rough endoplasmic reticulum and multivesicular bodies were involved in the formation of proteid yolk granules in cytoplasm. In particular, compared with the results of other gastropods, it showed a different result that appearances of cortical granules at the cortical layer and microvilli on the vitelline envelope, which is associated with heterosynthetic vitellogenesis, were not observed in vitellogenic oocytes during oogenesis. A mature yolk granule was composed of three components: main body (central core), superficial layer, and the limiting membrane. Monthly changes in the gonadosomatic index in females studied in 2004 and 2005 were closely associated with ovarian developmental phases. Spawning occurred between May and August in 2004 and 2005 and the main spawning occurred between June and July when the seawater temperature rose to approximately $18-23^{\circ}C$. The female reproductive cycle can be classified into five successive stages: early active stage (September to October), late active stage (November to February), ripe stage (February to June), partially spawned stage (May to August), and recovery stage (June to August).

• The Korean Journal of Malacology
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• v.26 no.3
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• pp.185-199
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• 2010

Correlation between community structure of herbivore and succession of macro-algal flora was examined in subtidal area of Dang-Sa Province, eastern coast of Korea from April 2008 to December 2009. For examination, the authors hypothesized that there are significant correlation between the foregoing two variables. Samplings were conducted every two months quantitatively with SCUBA diving at -3, -6 and -10 depth in the two line transects (barren and forest grounds). As results, rhodophyts was predominated in the algal flora based on the number of species and biomass; molluscs was predominated in the herbivores based on the number of species and echinoderms was predominated in that based on the biomass. There was no significant correlation between the foregoing two variables in the whole survey area and barren/forest grounds. Consequently, the hypothesis was rejected. The authors proposed that examination of correlation between the foregoing two variables should focus on the specific herbivore group(s) (e.g., amphipods) afterward.

• Korean Journal of Environment and Ecology
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• v.18 no.1
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• pp.75-91
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• 2004

Biodiversity and seasonal community composition of benthic macroinvertebrates were studied from Upo wetlands in Gyeongsangnam-do, Korea, comprising Upo (4 sites), Mokpo (2 sites), Sajipo (1 site), Jjokjibeol (1 site), Yeobeol (1 site), and Topyeongcheon (2 sites) areas from October 2002 to August 2003. As a result, it was known that Upo wetlands retained relatively well-preserved littoral zones which may provide good habitats for benthic macroinvertebrates; however, frequent disturbances of littoral zones caused by flood were the major factor affecting on the survival and distribution of benthic macroinvertebrates in the areas. During the study period, a total of 135 species of benthic macroinvertebrates in 10 genera, 59 families, 16 orders, 7 classes, and 3 phyla were collected those of which are the highest degree of diversity of the taxa ever known in Korean wetlands: aquatic insects 103 spp. (Diptera 27 spp., Odonata 24 spp., Coleoptera 19 spp., Hemiptera 16 spp., Ephemeroptera 9 spp., Trichoptera 7 spp., and Collembola 1 sp.), Crustacea 2 spp., Mollusca 19 spp. (Gastropoda 12 spp. and Bivalvia 7 spp.), and Annelids 11 spp. (Oligocaeta 1 sp. and Hirudinea 10 spp.). Sajipo (St.G) and Jjokjibeol (St.H) areas yielded relatively larger numbers of species, 54 spp. and 53 spp., respectively, while more than 40 species occurred at most other sites. Based on quantitative sampling (0.5m${\times}$2m), aquatic insects (88.0％), particularly chironomids in Diptera (61.0％), occupied major proportion of the total individuals of benthic macroinvertebrates, while Mollusca (5.3％), Annelida (3.5％), and Crustacea (3.2％) occupied minor proportions. In standing water areas, diverse groups of benthic macroinvertebrates such as chironomids, demselflies, aquatic bugs, aquatic beetles, crustaceans, and gastropods were dominant in terms of individual number; in the running water areas, on the other hand, chironomids and baetid mayflies were dominant. However, gastropods, i.e. viviparids, were the dominant group of benthic macroinvertebrates in most study areas in terms of biomass. Dominance indices were 0.22-0.51 (mean$\pm$sd 0.42$\pm$0.09) in autumn, 0.31-0.96 (0.02$\pm$0.23) in winter, and 0.30-0.89 (0.57$\pm$0.18) in summer; diversity indices were 3.50-4.26 (3.80$\pm$0.24) in autumn,1.55-4.50 (3.10$\pm$1.01) in winter, and 1.35-3.77 (2.55$\pm$0.09) in summer. Highly movable or true aquatic benthic macroinvertebyates such as aquatic bugs, aquatic beetles, and gastropods recovered earlier after flood. In the study sites of Upo wetlands, Upo and Sajipo areas showed relatively higher values of average diversity index which may indicate a good habitat condition for benthic macroinvertebrates.

• Korean Journal of Ichthyology
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• v.17 no.4
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• pp.258-263
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• 2005

Feeding habits of Hapalogenys mucronatus (10.1~22.1 cm) collected from coastal waters off Sori Island, Yeosu, from June 2003 to May 2004 were studied. H. mucronatus is a carnivore which consumes mainly caridean shrimp, crabs, polychaetes, and amphipods. Its diet includes small quantities of bivalves, cephalopods, seagrass, hermit crabs, isopods, eggs, mysids, gastropods, and copepods. H. mucronatus undergoes significant size-related changes; smaller fish (10~11.9 cm) prey mainly on amphipods, shrimps and bivalves, while the proportion of caridean shrimp increases with fish size (12~17.9 cm). The larger fishes (18~22.1 cm) eat caridean shrimps and polychaetes.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.67-67
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• 2003

Tributyltin chloride (TBTCI) is an organotin compounds that have been widely used as antifouling agents and bioaccumulated in the food chain. TBTCI has been known to induce imposex in female gastropods. There are several reports that TBTCI increased testosterone level and inhibited the conversion of testosterone to estradiol by the aromatase cytochrome P450 enzyme. In this studies, we investigated the effects of TBTCI on steroidogenesis in testes, We dosed to 4-week-old Spragus-Dawleys (SD) male rats with TSTCI (0, 1, 5, 10, and 20mg/kg/day) daily by gavage for 14 days. TBTCI significantly decreased the weights of seminal vesicle, prostate, cowper's gland and LABC at 10 and 20mg/kg/day but significantly Increased the weights of liver at 10 and 20mg/kg/day and adrenals at 20mg/kg/day. mRNA levels of steroidogenic acute regulatory (StAR) and P450 aromatase were decreased and mRNA levels of cytochrome P450 17$\alpha$-hydroxylase/$C_{17-20}$ lyase (P450c17) were increased by TBTCI. TBTCI significantly increased serum testosterone level in dose-dependent manner. From above results, we found that TBTCI altered mRNA levels of enzymes related steroidogenesis, weights of organs and serum testosterone levels. This suggests that change of hormone levels may be due to alteration of mRNA levels of steroidogenic enzyme in testes, but further studies are necessary to investigate hormone levels in testis organ in order to find a relation of enzyme related to steroidogenesis with hormone levels. This work was supported by the Korea FDA Grant KFDA-03131-EDS-010.

• The Korean Journal of Malacology
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• v.26 no.1
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• pp.19-31
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• 2010

Seogundo is a small island adjacent to the southern coast of Jeju Island and connected to it by a boulder beach at low tide Surveys of this area were conducted from 2001 to 2009 to enumerate the mollusks there and also to examine their diversity, relative abundance, and ecological relationships. Both the boulder beach itself and several large tide pools were studied, including the coarse sand substrate and several species of seaweed and coralline algae found in the tide pools. Of the 121 species obtained or observed, there were 97 gastropods, 16 bivalves, and 8 polyplacophorans. Live specimens were obtained for about half of those species. About one third were found on rocky substrate, with the most common species being Nodilittorina radiata and Nerita japonica in the upper intertidal zone, N. radiata and Littorina brevicula in the middle intertidal, and Turbo (Lunella) coronata coreensis and Acanthopleura japonica in the lower intertidal and shallow subtidal. The seaweeds and coralline algae contained about 40% of all mollusk species. The most common mollusks in two species of brown seaweed were Ittibittum parcum, Musculus nanus, and Euplica scripta. In a species of red seaweed, Komaitrochus pulcher was the most frequent, as in the coralline algae, along with M. nanus. The coarse sand in the tidepools contained about 25% of the species, with the Cerithiidae having the largest number. A sample of beach drift contained 17 species, with Bittium aleutaceum and Rissoina (Phosinella) pura being most common. Most species, about 60%, were found in a variety of habitats, especially the marine flora; few species exhibited any habitat preferences. Biographically, Jeju Island is part of the Warm Temperate Northwest Pacific Province and the East China Sea ecoregion with a strong faunal affinity with southern Japan, eastern China, and northeastern Taiwan. Zonal-geographical groupings reveal that the fauna is mainly subtropical-low boreal, preferring moderately warm water, with a somewhat smaller number of tropical-subtropical species.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.3
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• pp.372-379
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• 1998

Feeding habits of Favonigobius gymnauchen collected from the eelgrass bed in Kwangyang Bay from January 1994 to December 1994 were studied. Favonigobius gymnauchen was a carnivore which consumed mainly gammarid amphipods, polychaetes, crabs and copepods. Its diets included minor Quantities of gastropods, tanaids and isopods. It showed ontogenetic changes in feeding habits. Small individuals (1$\~$2 cm) fed mainly on gammarid amphipods, polychaetes, and copepods. While the portion of the stomach contents attributable to polychaetes and crabs increased steadily with incensing fish size, consumption of copepods decreased progressively. Gammarid amphipods were the most selected prey item for all size classes. Although gammarid amphipods, polychaetes, crabs and copepods were major prey organisms for all seasons, the relative proportion of these food items changed with season. Consumption of copepods was relatively high in spring and fall and consumption of gammarid amphipods, polychaetes and crabs was relatively high in summer.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.2
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• pp.168-175
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• 1998

Feeding habits of Sebastes inermis collected from the eelgrass bed in Kwangyang Bay from January 1994 to December 1994 were studied. S. inermis ($1\~9\;cm\;SL$) was a carnivore which mainly consumed amphipods (gammarid amphipods and caprellid amphipods) and copepods. Its diets included small quantities of caridean shrimps, crabs, gastropods, and fishes. It showed ontogenetic changes in feeding habits. In an initial stage, copepods were major food organisms. However, amphipods were heavily selected as the body size of S. inermis increases. Although consumption of copepods increased during spring, amphipods were major prey organisms for all seasons.

• The Korean Journal of Malacology
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• v.27 no.3
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• pp.253-259
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• 2011

Boring behaviour and drilling mechanism were investigated by visual observations. In this study, of two kinds of holes (the outer and inner holes) which are formed by drilling of boring gastropod Lunatia fortunei (Naticidae), the diameters of the outer holes are broader and larger than those of the inner holes, and their holes look like the crater in shape, as seen in all valves of bivalves bored by Naticidae species. Two kinds of glands (the accessory boring gland and accessory salivary gland) on the foots of boring gastropods have been investigated. Of them, it has been confirmed that only the accessory salivary glands on the foots secreted sulphuric (acidic) components in the mucus (secretion), while the accessory boring glands on the foots did not secrete their components. In this study, we confirmed that L. fortunei possess the accessory boring gland on the foot, as seen in most species in Naticidae. Accoeding to the results of the experiment of the blue litmus paper tests of the mucus (secretions) secreted from the accessory boring gland the color of the blue litmus paper did not turn red in color because chemical components of mucus (secretion) secreted from the accessory boring gland on the foot of L. fortunei (boring gastropod) were not acidic components. It is supposed that the mucus, which is secreted from the accessory boring gland, contained gelatin-like substances or enzymes without acidic components, as already reported in Naticidae species. Therefore, these substances may be involved in softening the surface of the valves of M. veneriformis. Consequently, it is assumed thar L. fortunei bores holes through the shells of molluscs by means of following 3 methods: (1) a softening of the calcareous shells of M. veneriformis with chemical secretions (including gellatin-like substances or enzyme except for acidic components) from the accessory boring glands, (2) mechanical rasping with the radula, (3) a combination of both. In this study, particularly, acidic components, which are involved in softening the surface of the shells, are not associated with the boring mechanism of L. fortunei because chemical acidic components were not detected in the mucus (secretion), as found in Naticidae species.