• Ocean and Polar Research
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• v.43 no.2
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• pp.73-88
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• 2021

The community structure and health status of macrobenthos assemblages were investigated in the subtidal area of the Nakdong River estuary, Southern Coast of Korea. Benthic fauna samples were collected seasonally at 8 stations in the subtidal area of the Nakdong River estuary from February 2013 to October 2015. During the survey, a total of 380 species and 4,603 ind./m² of macrobenthos in all sampling areas were collected. The major dominant species were the polychaetes Minuspio japonica, Pseudopolydora kempi, Heteromastus filifomis, Capitella capitata, the amphipod Grandidierella japonica and the bivalvia Arcuatula senhousia. Some species of polychaetes found in the study area consisted of opportunistic species that showed high densities when habitat condition was poor. On the other hand, macrobenthos assemblages in the study area were divided into brackish water and marine groups. Abundance was high in the brackish group, while the number of species and diversity index were high in the oceanic group. The three indices (AMBI, M-AMBI, and BHI) in the assessment of health levels based on the ecological characteristics and number of species in macrobenthic were commonly shown to be in good condition in the group of oceanic stations, while relatively poor conditions were reflected in the group of brackish stations. Compared to other indices, the M-AMBI index of the three indices for health assessment was considered to be a relatively more suitable one to assess benthic ecological conditions.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.60 no.2
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• pp.101-113
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• 2024

This study investigated the species composition and community structure of aquatic organisms captured using coastal beam trawling in Gomso Bay, Jeollabuk-do, from January to December 2022. Throughout the experimental period, a total of 20,246 individuals belonging to 94 marine species were captured, with a combined biomass of 602,828 g. Fish exhibited the highest abundance, comprising 56 species, followed by crustacea (21 species), bivalvia (8 species), cephalopoda (5 species), gastropoda (3 species), and holothuroidea (1 species). The dominant species was Leiognathus nuchalis, constituting 14.0% of the total individuals, followed by Portunus trituberculatus at 12.1%, Oratosquilla oratoria at 10.4%, Crangon hakodatei at 9.9%, and Metapenaeus joyneri at 7.9%. The diversity index ranged from 1.72 to 2.55, with the lowest diversity observed in March and the highest in July. Cluster analysis based on species composition of the 27 most common species showed that aquatic organisms were divided into three groups: spring and summer organisms (Group A) and summer organisms (Group B) and autumn and winter organisms (Group C).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.42 no.2
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• pp.93-103
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• 2009

To measure the mineral contents of marine invertebrates, we collected 239 individuals from 52 species from the east (Pohang), west (Gunsan), and south (Tongyeong) coasts of Korea: 34 species of molluscan shellfish (Gastropoda and Bivalvia), 6 species of Cephalopoda, 8 species of Crustacea, and 4 other species. The mean contents of the macro mineral in the 100g edible portion of molluscan shellfish were high in the oder of Na (355.1 mg), P (128.1 mg), K (110.8 mg), Mg (83.8 mg) and Ca (57.5 mg). And the mean contents of the micro mineral in the molluscan shellfish were high in the oder of Fe ($41.12{\mu}g/g$), Zn ($30.48{\mu}g/g$), Mn ($3.81{\mu}g/g$), Cu ($3.49{\mu}g/g$) and Ni ($0.35{\mu}g/g$). We could not observe clear regional variation in the mineral content of the molluscan shellfish species. The mean contents of the macro mineral in the 100g edible portion of other marine invertebrates (Cephalopoda, Crustacea, etc.) were high in the oder of Na (400.7 mg), P (145.1 mg), K (105.0 mg), Mg (63.2 mg) and Ca (49.0 mg). And the mean contents of the micro mineral in other marine invertebrates were high in the oder of Zn ($24.4{\mu}g/g$), Fe ($13.8{\mu}g/g$), Cu ($4.88{\mu}g/g$), Mn ($2.14{\mu}g/g$) and Ni ($0.12{\mu}g/g$). The daily average intakes of the macro mineral through fisheries products consisted of P (125.9 mg), Na (119.3 mg), K (101.8 mg), Ca (31.0 mg), Mg (27.6 mg). And the daily average intakes of the micro mineral through fisheries products consisted of Zn (0.92 mg), Fe (0.68 mg), Cu (0.12 mg) and Mn (0.07 mg). The respective intakes of the minerals (P, Mg, Na, Ca, K) from fish were about 18.0, 7.9, 8.0, 4.4 and 2.2% of the dietary reference intakes for Koreans (KDRIs) set by the Korean Nutrition Society. And the respective intakes of micro mineral (Cu, Zn, Fe, Mn) from fish were about 14.6, 9.2, 6.7, and 2.1% of the dietary reference intakes for Koreans (KDRIs). Therefore, fisheries products play a very important role as a source of mineral.

• Development and Reproduction
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• v.14 no.4
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• pp.269-279
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• 2010

Some characteristics of germ cell differntiations and the function of accessory cells during spermatogenesis, and mature sperm ultrastructure in male Protothaca (N.) jedoensis were investigated by transmission electron microscope observations. The morphology of the spermatozoa of this species has a primitive type and is similar to those of other species in the subclass Heterodonta. Accessory cells, which are connected to adjacent germ cells, are involved in the supplying of the nutrients for germ cell development. The morphologies of the sperm nucleus and the acrosome of this species are the cylindrical type and cap shape, respectively. Spermatozoa are approximately $46{\sim}50{\mu}m$ in length including a long sperm nucleus (about $2.44{\mu}m$ in length), an acrosome (about $0.45{\mu}m$ in length), and tail flagellum (about $42{\sim}46{\mu}m$). The axoneme of the sperm tail shows a 9+2 structure. As some characteristics of the acrosomal vesicle structures, the basal and lateral parts of basal rings show electron opaque part (region), while the anterior apex part of the acrosomal vesicle shows electron lucent part (region). These characteristics of the acrosomal vesicle were found in the family Veneridae and other several families in the subclass Heterodonta. These common characteristics of the acrosomal vesicle in the subclass Heterodonta can be used for phylogenetic and systematic analysis as a taxonomic key or a significant tool. The number of mitochondria in the midpiece of the sperm of this species are four, as one of common characteristics appear in most species in the family Veneridae and other families in the subclass Heterodonta. However, exceptionally, only three species in Veneridae of the subclass Heterodonta contain 5 mitochondria. The number of mitochondria in the sperm midpiece can be used for the taxonomic analysis of the family or superfamily levels as a systematic key or an important tool.

• Development and Reproduction
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• v.13 no.2
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• pp.115-122
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• 2009

Spermatogenesis and ultrastructural characteristics of sperm of brackish water diploid Corbicula japonica were investigated by electron microscope observations. Based on the cytological studies, the spermatozoon of this species (brackish water diploid) C japonica is approximately 55 ${\mu}m$ in length. The sperm head (about 12 ${\mu}m$ long) is elongated and tapers with a slight curve. Sperm nucleus is about 7.90 ${\mu}m$ long, and the acrosome is about 2.70 ${\mu}m$ long: The morphologies of the sperm nucleus type and the acrosome shape of this species are a long arrow-like type and long cone-like shape, respectively. The sperm head of this species (external fertilization, dioecious and oviparous species) is partially modified from that of the primitive type, as seen in triploid Corbicula species (internal fertilization, hermaphrodite and ovoviparous species), reported by some authors. However, this species produces uniflagellate spermatozoa, unlike freshwater triploid hermaphroditic clams being possessed of partially modified biflagellate spermatozoa. Diploid C japonica is similar to those of other bivalves being possessed of a short midpiece containing four mitochondria surrounding the centrioles. 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, and from uniflagellate sperm cross sectioned, in particular, wing-like axonernal lateral fins are observed, as seen in external fertilization fishes.

• Journal of Environmental Science International
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• v.21 no.10
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• pp.1275-1286
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• 2012

Coastal marine ecosystem plays important role of spawning and nursery grounds for fisheries resources. Yongil Bay is one of major coastal marine ecosystems, which is located in the southwestern East Sea of Korea. Species composition and abundance of marine organism in the Yongil Bay were investigated by season from March to November 2009. Gill net and pot fisheries were used for survey of pelagic and demersal species composition, and collected 106 species, 67 families, and 7 taxa of fisheries resources from the coastal ecosystem. Species were included 2 species in Ascidiacea, 2 species in Bivalvia, 6 in Cephalopoda, 22 in Crustacea, 5 in Echinodermata, 12 in Gastropoda, and 57 in Pisces. Diversity indices (Shannon index, H') showed seasonal variation with low value of 2.11 in winter, and high value of 2.63 in autumn. Main dominant species were Asterias amurensis, Pleuronectes yokohamae, Siphonalia spadicea fuscolineata, Trachurus japonicas, Sillago japonica, Conger myriaster, Volutharpa ampullaceal, Engraulis japonicus, Asterina pectinifera, and Portunus (Portunus) sanguinolentus that were occupied over 71.5% of total individuals, and 52.9% of wet weight. Seasonal variations of fisheries resources composition were discussed on correlationships with those of environmental factors in the coastal ecosystem of the Yongil Bay in Korea. Those results from this study will provide scientific data and information to develop the ecosystem-based coastal fisheries assessment and management system in Korea.

• Korean Journal of Ichthyology
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• v.25 no.1
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• pp.17-24
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• 2013

The feeding habits of Repomucenus lunatus were studied using 232 specimens collected from January to December 2006 in the coastal waters off Gori, Korea. The size of R. lunatus ranged from 4.7 to 14.0 cm in standard length (SL). R. lunatus was a bottom-feeding carnivore which consumed mainly amphipods and polychaetes. Its diet also included small quantities of shrimps, cumaceans, bivalvies, gastropods, crabs, copepods, euphausia, mysids, stomatopods, ostracods and sipunculides. Amphipods were eaten predominantly for the smallest size class. The proportions of polychaetes increased gradually with increasing fish size and large size class of R. lunatus mainly consumed polychaetes. The feeding strategy graphical method revealed that R. lunatus is a specialized feeder. The mean number and weight of preys per stomach of larger size classes were higher than those of smaller size classes. The mean weight of preys per stomach ontogenetically changed with size classes.

• Journal of fish pathology
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• v.13 no.2
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• pp.129-136
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• 2000

To understand host-defence mechanism of clam(Ruditapes philippinarum) hemocyte against foreign materials, classification and their seasonal change in the number were performed. clams collected from a farm in Julpo Bay, Gochang, Chollabuk-Do were used in this experiment. Lots of hemocytes were found between the muscle fibers and connetive tissue of posterior adductor muscle. Hemocytes of R. philippinarum were classified into granulocytes and agranulocytes. Granulocytes were composed of three types, basophilic granulocyte, acidophilic granulocyte and fibrocyte in accordance with the staining affinities of their cytoplasmic granules. Fibrocyte has filopodia and vesicle in endoplasm and bigger than other granulocytes in size. Agranulocytes were less in the number and smaller in the size compared to those of granulocytes. Hyalinocytes had no granule in their cytoplasm. The nucleus located in the center of the cell was oval or spherical shaped. In electron microscopic observation, granulocytes and hyalinocytes contained electron-dense vesicles and some small lucid vesicles in their cytoplasm, respectively. Granulocytes phagocytosed more zymosan particles than hyalinocytes. Acidophilic granulocytes showed higher phagocytic ratio than basophilic granulocytes. Total hemocyte numbers showed the highest at April to August and the lowest at October to December. In the composition of each hemocyte, basophilic granulocytes were always more than acidophilic granulocytes and hyalinocytes.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.5
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• pp.503-516
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• 1995

Macrobenthic community was studied in Deukryang Bay, southwestern coast of Korea, in November 1991 and Januavy 1992. Hacrobenthic fauna consisted of 118 species with 20,767 individuals. The number of species and occurrence frequency of the major groups were as follows: 52 polychaetes species $(44.1\%)$, 45 crustaceans species $(38,1\%)$, 14 mollusks species $(11.9\%)$ and 7 other group species $(5.9\%)$. The mean density was $1432.2ind/m^2$. The density of major groups showed that mollusks was 920.4$(ind./m^2)$, polyrhaetes 275.8$(ind./m^2)$, and crustaceans 219.6$(ind./m^2)$. The dominant species were Musculista senhousia (Bivalvia), Eteone longa (Polychaeta), Nippopisella nagatai (Amphipoda) with density, 632.8$ind./m^2$, 37.8$ind./m^2$, and 35.3$ind./m^2$, respectively. This area could be divided into four areas by the cluster analysis based on the species composition.

• The Korean Journal of Malacology
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• v.26 no.3
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• pp.235-244
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• 2010

Ultrastructural characteristics of the testis and spermatogenesis of Crassostrea gigas were investigated by Transmission and Scanning Electron microscope observations. The testis is a diffuse organ consisting of branching acini containing differentiating germ cells in a variety of stages. The acinus is surrounded by an intermitent layer of myoepithelial cells andis divided into subcompartments that are partially separated by pleomorphic accessory cells which remain in close contact with germ cells until late stages of development. these accessory cells contain a large quantity of glycogen particles and lipid droplets in the cytoplasm. Therefore, it is assumed that they are involved in the supplying of the nutrients for germ cell development, while any phenomena associated with phagocytosis of undischarged, residual sperms by lysosomes could be find in the cytoplasm of the accessory cells. The morphology of the spermatozoon has a primitive type and is similar to those of other bivalves. Mature spermatozoa consist of broad, cap-shaped acrosomal vesicle, subacrosomal material (containing axial rod embedded in a granular matrix), a oval nucleus showing deeply invaginated anteriorly, two triplet substructure centrioles surrounded by four spherical mitochondria, and satelite fibres appear to the distal centriole and plasma membrane. Spermatozoa of C. gigas resemble to those of other investigated ostreids. In particular, the anterior region of the acrosomal vesicle is transversely banded. It is assumed that differences in this acrosomal substructure are associated with the inability of fertilization between the genus Crassostrea and other genus species in Ostreidae. Therefore, we can use sperm morphology in the resolution of taxonomic relationships within the Ostreidea. The spermatozoon is approximately $42-47{\mu}m$ in length including an oval sperm nucleus (about $0.91{\mu}m$ in length), an acrosome (about $0.42{\mu}m$ in length) and tail flagellum ($40-45{\mu}m$). 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. These morphological charateristics of acrosomal vesicle belong to the family Ostreidae in the subclass Pteriomorphia.