• Fisheries and Aquatic Sciences
• /
• v.20 no.6
• /
• pp.8.1-8.18
• /
• 2017

Background: Metallothionein (MT) is a multifunctional protein playing important roles in homeostatic regulation and detoxification of metals. Mollusk species have been considered as useful sentinel platforms for MT-based biomarker approaches, and they have been reported to display an extraordinary structural diversity of MT proteins. However, potential diversity of molluskan MTs has not been fully explored and recent updates have suggested the need of revision of evolutionary hypothesis for molluskan MTs. Results: Based on bioinformatic analysis and phylogenetic evidences, novel divergence mechanisms and paths were hypothesized in both gastropod and bivalve MT groups. Our analyses are suggestive of the taxon- or lineage-specific domain multiplication/duplication from the ancestral or prototypic MT. Diversification and selection of molluskan MTs might be driven by the needs for acquiring metal selectiveness, specialized novel function, and improved capacity of metal detoxification under environmentally stressed conditions. Conclusion: The structural diversity and variations of molluskan MTs are significantly larger than previously understood. Undoubtedly, molluskan MTs have undergone dynamic divergent processes in their evolutionary histories, giving rise to the great diversity of domain structures in extant MT isoforms. Novel evolutionary paths for molluskan MTs newly proposed in this review could shed additional light onto the revision of the hypothesis for evolutionary differentiation of MTs in the molluskan lineage.

• Korean Journal of Ichthyology
• /
• v.27 no.1
• /
• pp.33-38
• /
• 2015

The diet composition of Leiognathus nuchalis were studied using 350 specimens collected from October 2010 to September 2011 in the coastal waters of Gadeok-do, Korea. L. nuchalis was carnivorous feeder that consumed mainly copepods, crab larvae, and shrimp larvae. Its diet also included small quantities of polychaetes, amphipods, euphausiids, bivalve larvae, and gastropod larvae. The size of L. nuchalis ranged from 3.0 to 9.8 cm in body length (BL). L. nuchalis underwent an ontogenetic dietary shift. 3~5 cm size individuals fed mainly on copepods. 5~7 cm size individuals fed mainly crab larvae and shrimp larvae. 8~10 cm size individuals fed mainly polychaetes. The size increases, the weight of food organisms are constantly increased.

• The Korean Journal of Ecology
• /
• v.20 no.5
• /
• pp.355-365
• /
• 1997

Macrozoobenthic community structure was studied on the mud-tidalflat around Mokpo coastal area, Korea, from September 1995 to May 1996. Ten sampling stations were chosen along the 1km transect with a 100 m intervals. Triple macrozoobenthos sampling were conducted with a stainless box core sampler (size $13{\times}22{\times}30$ cm) at each station on the seasonal basis. A total of 119 species of macrobenthos was sampled with a mean density 2,357 $ind./m^2$ and biomass of 180. 94 $g/m^2$ during the study period. Of these species, there were 51 species of mollusce (43%), 36 of crustaceans (30%), 27 of polychaetes (23%). Molluscs were density-dominant faunal group with a mean density of 1,804 $ind./m^2$, comprising of 75% of the total density of the benthic animals. It was followed by polychaetes with 347 $ind./m^2$ (15% of the total density). Molluscs were biomass-dominant faunal group with a mean biomass of 147.51 $g/m^2$ (82% of the total biomass). The number of species, abundance and biomass showed increasing trends toward the lower intertidal stations from the higher stations. Major dominant species were Musculista senhousia (bivalve), Capitellidae spp. (polychaetes) with a density of 1,640 $ind./m^2$ and 179 $ind./m^2$ , respectively. The density of M. senhousia was more than 63% of the total density of benthic organism on the tidal area. Small gastropod Cerithideopsilla umumriensis was another dominant epifaunal species between st.1 and 2 with a mean density of 100 $ind./m^2$. Cluster analysis showed that the benthic community could be divided into three stational groups, that is, upper, middle and lower groups by the exposure duration.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.17 no.6
• /
• pp.543-548
• /
• 1984

Three kinds of cercaria were deleted through the gonad investigation of Neverite didyma, Lunatia fortuni, and Rapana thomasiana in the vicinity sea of Naecho-do, the estuary of the Keum river in the western coast of Korea from March, 1982 to April, 1983, Cercaria yamagutii was found in Neverita didyma and Lunatia fortuni, and the infection rate was quite high-$12.32\%$ and $30.24\%$, respectively. Cercaria isoninae in Neverita didyma and Cercaria pseudogranifera in Rapana thomasiana were also detected, and their infection rates were $0.19\%\;and\;0.83\%$ respectively. Therefore, it would be added that Neverita didyma and Lunatia fortuni as the intermediate hosts of Cercaria yamagutii and Cercaria isoninae, and Rapana thomasiana as the intermediate host of Cercaria pseudogranifera.

• Animal Systematics, Evolution and Diversity
• /
• v.27 no.1
• /
• pp.1-17
• /
• 2011

Thais Roding, 1798, commonly known as rock-shell, is among the most frequently found gastropod genera worldwide on intertidal rocky shores including those of Japan, China, Taiwan and Korea. This group contains important species in many marine environmental studies but species-level taxonomy of the group is quite complicated due to the morphological variations in shell characters. This study examined the genetic variations and relationships among three Korean Thais species based on the partial nucleotide sequences of mitochondrial cox1 gene fragments. Phylogenetic trees from different analytic methods (maximum parsimony, neighbor-joining, and maximum likelihood) showed that T. bronni and T. luteostoma are closely related, indicating the most recent common ancestry. The low sequence divergence found between T. luteostoma and T. bronni, ranging from 1.53% to 3.19%, also corroborates this idea. Further molecular survey using different molecular marker is required to fully understand a detailed picture of the origin for their low level of interspecific sequence divergence. Sequence comparisons among conspecific individuals revealed extensive sequence variations within the three species with maximum values of 2.43% in T. clavigera and 1.37% in both T. bronni and T. luteostoma. In addition, there is an unexpectedly high level of mitochondrial genotypic diversity within each of the three Korean Thais species. The high genetic diversity revealed in Korean Thais species is likely to reflect genetic diversity introduced from potential source populations with diverse geographic origins, such as Taiwan, Hong Kong, and a variety of different coastal regions in South China and Japan. Additional sequence analysis with comprehensive taxon sampling from unstudied potential source populations will be also needed to address the origin and key factors for the high level of genetic diversity discovered within the three Korean Thais species studied.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.47 no.2
• /
• pp.160-167
• /
• 2014

The feeding habits of Tridentiger bifasciatus were studied using 733 individuals collected in the tidal creek at Sangnae-ri, Suncheon, Korea, using a push net, monthly, from April 2011 to March 2012. The standard length (SL) of the specimens ranged from 1.5 to 8.2 cm. The stomach content analysis indicated that T. bifasciatus consumed mainly amphipods, such as Corophium sp., while copepods, polychaetes, and shrimps were other important prey species. In addition T. bifasciatus ate small quantities of crab larvae, fish, gastropod larvae, and insects. T. bifasciatus is a generalist that feeds on various zoobenthos, including fish. T. bifasciatus underwent an ontogenetic dietary shift. Smaller individuals (1-2 cm SL) fed mainly on amphipods. The proportion of amphipods decreased as body size increased, whereas the consumption of polychaetes increased gradually. The seasonal variation in the diet composition of T. bifasciatus was significant. Insects were common prey during summer, while the amounts of other prey, including polychaetes, were similar during spring, autumn, and winter.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.50 no.6
• /
• pp.675-683
• /
• 2017

Total mercury (T-Hg) and methyl mercury (MeHg) were determined in marine fisheries (41 species, n=87) commonly consumed in Korea, using a gold amalgamation method and gas chromatography-cold vapor atomic fluorescent spectroscopy, respectively. Concentrations of T-Hg and MeHg in all samples (31 fish, 4 crustaceans, 4 cephalopods, and 2 gastropod species) were in the range of 0.016-0.495 (mean, 0.093) mg/kg-wet and not detected-0.338 (mean, 0.067) mg/kg-wet, respectively. The concentrations of MeHg in marine fisheries were significantly correlated with T-Hg concentrations (P<0.001). The highest mean concentrations of T-Hg and MeHg were found in fish species, followed by crustaceans. The contribution of MeHg to T-Hg was in the range of 64-95% (mean, 83%) in cephalopods, 28-98% (mean, 69%) in fish, and 26-88% (mean, 57%) in crustaceans. The weekly intakes of T-Hg and MeHg by fisheries consumption for the Korean general population were estimated to be 0.463 and $0.338{\mu}g/kg$ body weight/week, respectively. The concentrations and intakes of T-Hg and MeHg were less than the allowable residue levels and in the range of 12 to 17% of the provisional tolerable weekly intake (PTWI) applied in Korea.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.39 no.spc1
• /
• pp.132-141
• /
• 2006

Artificial structures have been designed as pilot structures to promote the creation and restoration of tidal flats. However, little information is available as to whether such artificial construction affects the macrobenthic community structure. We monitored the variation of the macrobenthic community structure and species composition near natural and artificial structures (seaweed and a timber fence) on the tidal flats near the Iwon Dike, Korea. In total, 137 macrobenthic species were recorded during this study, predominantly crustaceans (47%), polychaetes (18%), and molluscs (27%). Polychaetes comprised over 50% of the total density, followed by gastropods (38%) and crustaceans (11%). Macrobenthic species composition in the artificial and natural areas, was initially similar, but it differed after 7 months. The gastropod Umbonium thomasi, the most dominant species, was present at both sites in the first month after the start of the experiment, but disappeared at the artificial sites within 7 months, suggesting disturbance by the environmental factors. The number of species and diversity (H') varied significantly within sites at the beginning of the experiment, but no difference was observed after 7 months. Multivariate analysis (multidimensional scaling) revealed significant differences in community structure between the artificial and the natural areas from 7 months after the start of the experiment, except from 18 to 21 months. The community structures were mainly influenced by U. thomasi. Community structure at the artificial sites was affected by environmental variables, such as carbon, COD/IL sulfide, loss of ignition, kurtosis and silt, which changed over time. We observed no significant correlations between environmental variables and the dominant species, except in the case of Spio sp. and Macrophthalmus dilatatus, suggesting that the biological interactions and temporary disturbances such as typhoon, as well as the effects of artificial structures may also be important regulating factors in this system.

• Korean Journal of Environmental Biology
• /
• v.30 no.2
• /
• pp.143-150
• /
• 2012

To determine the spatial distribution of marine invertebrate communities in intertidal rocky shore on Dokdo, 10 times investigation was carried out at 7 stations during the year of 2009~2011. The marine invertebrate community can be divided into three different groups based on cluster analysis of Bray-Curtis similarity. As a first group, the pebble beach community, Omphalius rusticus, Monodonta perplexa, and Chlorostoma lischkei which were movable gastropod with dominant occurrence. Secondly, the still rocky shore community, O. rusticus, Serpulorbis imbricatus and Aplysia kurodai occurred dominantly. Finally, the wave-exposed rocky shore community which dominantly occurred by two sessile arthropods, Barnacles, Chthamalus challengeri and Pollicipes mitella. The three groups were likely to be determined by texture of substrate and hydrodynamic conditions of rocky shore in Dokdo. The results indicated that diversity of marine intertidal invertebrate community around Dok do was mainly affected by habitat characteristics and the surrounding physical properties.

• Korean Journal of Environmental Biology
• /
• v.31 no.4
• /
• pp.458-470
• /
• 2013

Haliotis discus, a useful abalone of herbivorous gastropod, shows feeding preference to marine algae depending upon their growth stage and recognition of taste. This study was carried out to investigate this abalone's algal preferences and the presence of feeding stimulants. In single-choice experiments the small (S) group generally preferred Ulva pertusa (Chlorophyta), whereas the medium (M) and large (L) group preferred both Laminaria japonica (Phaeophyta) and Undaria pinnatifida (Phaeophyta). In multi-choice experiments using 4 algal species of L. japonica, U. pertusa, U. pinnatifida and Ecklonia cava (Phaeophyta), the results were same as in the single-choice experiments; the S group preferred U. pertusa the most, while the M and L group preferred both U. pinnatifida and L. japonica. However E. cava was not preferred by any groups. In order to examine the presence of feeding stimulant, chemical compounds from algae used as feed were isolated and identified. The abalone responded to water soluble matters of L. japonica, U. pinnatifida and U. pertusa, but those of E. cava and Sargassum sagamianum (Phaeophyta) were not attractive to them. In feeding stimulant experiments using fat soluble matters, the S group preferred the fat soluble matter of U. pertusa the most, while the M group and the L group preferred those of U. pertusa and U. pinnatifida, and those of L. japonica, respectively. However the fat soluble matter of S. sagamianum was not attractive to the abalone. The results of feeding stimulant experiments were same as those of single-choice or multi-choice experiments, which showed that compound lipids in fat soluble matter might act as feeding-stimulant.