• Development and Reproduction
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• v.10 no.2
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• pp.135-140
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• 2006

The small octopus(Octopus minor), a species in the cephalopod class spawns the fewer eggs compared with its relatives such as Octopus vulgaris and Octopus ocellatus and exerts special efforts in nursing eggs hiding in the deep cave beneath the mud flat. Correspondingly, its embryogenic process had been hardly observed. In this study, we induced the small octopus to spawn its eggs in the artificial spawning tube and to nurse the developing embryos under the periodical observation. The early embryogenic change in the fertilized eggs was appearance of blastodisc on the animal pole at 4 days after spawning. A mass of rudiments of several organs developed in the middle of the yolk sac at 28-th day and it moved gradually toward the animal pole. At 38 days after spawning, two eyes appeared on the head and the trunk with heart developed on the apical part of the yolk sac. At 45-th day of embryonic development, the trunk and head occupied a half of the egg capsule and consequently the yolk sac was reduced to a half of its original size. Two eyes became prominent at the bottom of the trunk with several spots at day 60. Embryonic development was completed at about 80 days after spawning and the arms stuffed the lower half of egg capsule. The young fry squeezed out of the egg capsules with their long and slender arms first and mantles later. Soon after hatching, it swam actively and squirted ink.

• Journal of Aquaculture
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• v.20 no.4
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• pp.232-238
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• 2007

The distribution of stock density and larvae of Atrina pectinata was examined in Deukryang Bay. Sampling of adult stock was seasonally conducted from 29 stations in the bay in May, August, and November 1995 and February 1996. And the larvae were sampled with interval of 3 to 7 days from 12 stations from July to October 1996. Seasonal abundance of the adult in number and in biomass were the highest in August ($18\;inds./m^2$) and in November ($2,790\;g/m^2$), respectively, at G1 station located in the most inner bay. In frequency distribution of shell height, the mode in May appeared in 10-14 cm group with 62%, and that of the other seasons in $15{\sim}19\;cm$ group. The larvae were also distributed mainly at G1 as the adult were. The larval abundance showed a periodical cycle which seemed to be related to lunar cycle. The highest abundance of the larvae occurred on August 16 with $8\;inds./m^3$, and then decreased continuously. With regard to frequency distribution of larval shell height, the larvae less than $200\;{\mu}m$ occurred from July to October. And the mode in July appeared in small size group ($200{\sim}249\;{\mu}m$) with 38%. These results mean that A. pectinata spawned from July to October, mainly middle July to middle August. The larval distribution showed the same geographical tendency to adult distribution. Both the adult and the larvae mainly distributed in the most inner bay and west area of Deukryang island, where was shallower, warmer, and higher primary productivity than the entrance area of the bay and east area of the island. However, larval abundance of A. pectinata in this study was so low compared to adult biomass. The reason for this unusual phenomenon should be understood with the detail research in future.

• Animal cells and systems
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• v.8 no.1
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• pp.33-40
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• 2004

Reproductive cycle and spawning rhythm with lunar cycle of the ascidian, Halocynthia hilgendorfi ritteri were investigated by histological examination. The specimens were sampled in the coastal waters of Yongdam, northwest of Jeju Island, Korea, from November 2001 to January 2003. H. hilgendorfi ritteri is a synchronous hermaphrodite; the gonads are located in the mantle. The reproductive cycle can be grouped into the following successive stages in the ovary: growth (February to June), vitellogenesis (April to September), mature (July to December), spent (November to February), and recovery (December to April). Likewise, in the testis, the stages observed were: growth (October), mature (October to December), spent (November to February), and resting (January to September). Major spawning probably occurs between November and January, when water temperatures decrease. The histological observations of the gonads suggested that this species is a multiple spawner during the spawning period. Spawning occurred between the new moon and full moon, and again between the full moon and new moon, suggesting that the spawning rhythm is influenced by the lunar cycle.

• Journal of Aquaculture
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• v.19 no.4
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• pp.288-298
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• 2006

Larval distribution of bivalve from 29 stations in Deukryang Bay was examined from May to November in 1995. The abundance of total larvae increased from May ($3,736\;inds/m^3$) and reached maximum in August ($174,616\;inds/m^3$). But it decreased continuously until November ($2,171\;inds/m^3$). D-shape, early umbone and advanced umbone stage larvae composed of 76%, 18% and 6%, respectively, of total bivalve larvae. Nine larval species of bivalve were identified in this study. The mean abundance of Scapharca subcrenata larvae was $14,030\;inds/m^3$, which was 33.5% of total identified larvae. S. broughtonii (16.2%), Crassostrea gigas (12.5%), Mytilus edulis (10.2%) were also major species in order of their abundance. Considering the monthly larval occurrence in Deukryang Bay, main spawning month of bivalves except M. edulis and M. senhausia was estimated as July. Even though the spatial distribution of bivalve larvae in Deukryang Bay was different by the species, the larvae were generally abundant in the inner and west area of the bay, where was shallower and higher water temperature than the entrance and east area of the bay.

• Journal of fish pathology
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• v.19 no.3
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• pp.243-251
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• 2006

The internal defense system of mollusks consists of circulating haemocytes. In order to understand the morphological characterization of haemocytes, light and electron microscopy were carried out in oyster, Crassostera gigas. Four types of haemocytes were recognized: type Ⅰ small hyalinocytes, type Ⅱ large hyalinocytes, type Ⅲ large granulocytes and type Ⅳ small granulocytes. Additionally, the activities of alkaline phosphatase (ALP), acid phosphatase (ACP), peroxidase (POD), α-naphthyl acetate esterase, β-glucuronidase, PAS, sudan black B and oil red O in haemocytes were analysed by immunocytochemical methods. The results indicate that enzymatic activities were abundant and more active in granulocytes than in hyalinocytes. After incubation with haemoctyes and Vibrio FKC, phagocytic index and percentage of phagocytic cell were and shown to be increased from 15 to 120 min. In addition, the enzymatic activities were higher than those of controls: ALP, ACP, α-naphthyl acetate esterase and β-glcuronidase, indicating that these enzymes can be related with phagocytosis in oyster.

• Journal of fish pathology
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• v.20 no.1
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• pp.71-81
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• 2007

Photobacterium damselae subsp. damselae and 4 Vibrio spp.(V. anguillarum, V. splendidus, V. harveyi and V. ordalii) were isolated from the diseased olive flounders, Paralichthys olivaceus. The isolates were tested on the pathogenicity in vitro. The properties of extracellular products(ECPs) were investigated with enzymatic activities, hemolytic activities toward the sheep and olive flounder erythrocytes, and cytotoxicity activities on the cell-line. And potential signal transduction pathways of the bacterial internalization were detected by using signal transduction inhibitors. P. damselae was high in phospholipase activity, hemolytic activity to olive flounder erythrocytes and cytotoxicity activity. And P. damselae had diversified internalizing pathways as compared to isolated vibrios. Therefore, these activities may be related with pathogenicity of P. damselae.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.37 no.2
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• pp.98-104
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• 2004

Early development and metamorphosis of the ascidian (Halocynthia hilgendorfi ritteri) were investigated from fertilized egg. The samples were collected in the coastal waters of Yongdam, northwest of Jeju Island in November 2002. H. hilgendorfi ritteri was solitary ascidian and produced spheral eggs with egg size ranging from $0.33\pm0.01\;mm.$ On the outer surface of the vitelline coat are attached many follicle cells. At $21.0\pm0.5^{\circ}C$ of water temperature, first cleavage took place in about 1.5 hrs after fertilization, and gastrulation followed in about 12.5 hrs. The formation of tailbud embryos and free swimming larvae were observed 13.3 hrs and 20.5 hrs after fertilization, respectively. The size of newly hatched tadpole larva was 1.30-1.45 mm, the larva swam for 2 hrs to 14 hrs. At 4 hrs after hatching, the palpi were lost and tail absorption began with an abrupt rupture of the anterior end of the notochord. At 17-18 hrs after hatching, tail completely absorption and remained trunk. The coniform adhesive papilla began protrusion at 30 hrs after hatching. The oral and atrial siphon formed at 6-7 days after settlement. At 17-18 days after settlement, metamorphosed the larvae developed into protoascidian of which the external morphology was similar to their adult.

• Journal of Navigation and Port Research
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• v.29 no.8 s.104
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• pp.709-714
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• 2005

The purpose of this research is to verify the strategic fitness and relevance of the hub port strategy by SCM in Northeast Asia and to find a method to be a hub-port with a competitive edge. The fitness of the hub port development strategy is analysed by the structural equation model. The essential results of the research show that minimizing lead time from arrival of ship to inland transport and maximizing logistic services of each stage are important to provide optimal logistic service. And value-added port supply chain strategy is highly co-related with all the parts of port operation system, port transport system, distribution park and port information system. It shows that: various value added logistic service activity is more important than lowing cost; inland multimodal system should be rightly connected; distribution park should be connected to industry park to be a port cluster; and port information system should be developed.

• Journal of fish pathology
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• v.22 no.1
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• pp.67-73
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• 2009

It was examined whether the common belief that "cultured puffer fishes do not contain tetrodotoxin (TTX)", the major lethal substance that accidently causes death in consumers of those fishes, is true in river puffer fish Takifugu obscurus. In mouse bioassay, lethal levels of toxins were detected in the ranks: gonad>liver>intestine>muscle>skin in wild puffer fish. In contrast, no mortality occurred in the mouse bioassay on cultured fish. However, there were sleepiness, sluggish behavior, and hind limb paralysis with the tissue extracts of cultured fish suggesting the presence of TTX or other similarly acting toxins. An attempt to confirm the presence of TTX in cultured fish with high performance liquid chromatography (HPLC) was not very successful. The results suggest possible existence of TTX toxins or similarly acting toxins.

• Development and Reproduction
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• v.12 no.2
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• pp.133-139
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• 2008

The eggs of Luciogobius grandis attached beneath the small stone were collected at Ocheon-dong, Yeosu-city from February to May, 2006. We carried them to the laboratory of Chonnam National University to investigate their development. The fertilized eggs were elliptical in shape (mean long axis: $2.06{\pm}0.23\;mm$; mean short axis: $0.74{\pm}0.04\;mm$) and transparent. There were filaments on the egg membrane. Their hatching was occurred at 120hrs 54mins after the morula stage at $18.4{\sim}21.0^{\circ}C$ (mean $19.4^{\circ}C$). The newly hatched larvae were $3.30{\pm}0.07\;mm$ (n=30) in total length (TL), with $34{\sim}36$ myotomes, and their mouth and auns were already open. Their melanophores were appeared over the gas globule, around the anus and a part of caudal peduncle. At 9 days after hatching, the larvae was $5.06{\pm}0.18\;mm$ (n=30) in TL and transformed to postlarval stage with yolk absorption. At 29 days after hatching, the larvae attained full fin ray count and reached the juvenile stage with $11.46{\pm}0.12\;mm$ (n=30) in TL.