• Korean Journal of Ecology and Environment
• /
• v.44 no.1
• /
• pp.1-8
• /
• 2011

We investigated developmental stages of embryo and early life history of the Korean indigenous fish, the northern loach, Cobitis pacifica in 2009 in order to understand fundamental knowledges for conservation of this species. Eggs were obtained after hormones injections (LHRH-a, HCG) and were artificially fertilized by the dry method. The embryo was spherical, separative demersal, faint white, and averaged $1.09{\pm}0.04\;mm$ (n=20) in diameter. The hatching of the embryo took place in about 48 hours after fertilization under water temperature of $21.0{\sim}24.0^{\circ}C$ and the newly hatched larvae averaged $2.87{\pm}0.05\;mm$ (n=20) in total length (TL). Four days after hatching, the larvae grew up to $6.86{\pm}0.10\;mm$ (n=10) in TL and york sac absorption, mouth and anus opening were shown. Fourteen days after hatching, most of fin-rays appeared at $10.71{\pm}0.34\;mm$ (n=10) in TL and color spots on the body surface were attained. Twenty six days after hatching, the larvae grew up to $14.88{\pm}0.45\;mm$ (n=10) in TL, and all their fin-rays were formed. Therefore, according to current study regarding the morphological development of Cobitis pacidica, the conversion from larval to juvenile stages occurred at 26 days after hatching. Eighty days after hatching, the larvae were $33.3{\pm}1.25\;mm$ (n=10), and their body shape and color pattern were similar to adult fish. In this study, embryonic development and early life history of the northern loach, Cobitis pacifica show morphological characteristics of Cobitidae family. We expected that our results can be used as an fundamental knowledges for restoration study of indigenous fish species.

• Korean Journal of Environmental Biology
• /
• v.41 no.3
• /
• pp.229-246
• /
• 2023

The bitterling (Cyprinidae, Acheilongnathinae) is a temperate freshwater fish with a unique spawning symbiosis with host mussels. Female bitterlings use their extended ovipositors to lay eggs on the gills of mussels through the mussel's exhalant siphon. In the present study, in April of 2020, we investigated spawning frequencies and patterns of three bitterling fish species in host mussel species in the Nakdong River basin (Hoecheon). During field surveys, a total of four bitterling and three mussel species were found. We observed bitterling's spawning eggs/larvae in the three mussel species: Anodonta arcaeformis(proportion spawned: 45.5%), Corbicula fluminea(12.1%), and Nodularia douglasiae (45.2%). The number of bitterlings' eggs/larvae per mussel ranged from 1 to 58. Using our developed genetic markers, we identified the eggs/larvae of each bitterling species in each mussel species (except for A. macropterus): A. arcaeformis (spawned by Acheilognathus yamatsutae), C. fluminea (A. yamatsutae and Tanakia latimarginata), and N. douglasiae (A. yamatsutae, Rhodeus uyekii, and T. latimarginata). Approximately 57.6% of N. douglasiae mussel individuals had eggs/larvae of more than one bitterling species, suggesting that interspecific competition for occupying spawning grounds is intense. This is the first report on bitterling's spawning events in the Asian clam C. fluminea from Korea; however, it should be ascertained whether bitterling's embryo undergoes successful development inside the small mussel and leaves as a free-swimming juvenile. In addition, the importance of its conservation as a new host mussel species for bitterling fishes needs to be studied further.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.11 no.3
• /
• pp.124-132
• /
• 2006

We have investigated morphological development with growth and survival rates of juvenile for 158 days after parturition to get a basis data in the way of establishment of breeding techniques in the common seahorse species of Barbour's seahorse, Hippocampus barbouri. At 1 day after parturition, seahorse larvae were $8.82\sim10.36mm(mean\;9.48{\pm}0.69mm,\;n=4)$ in standard length (SL) with 17 dorsal fm rays, 14 pectoral fin rays and 4 anal fin rays. At 20 days after parturition, the size of seahorse larvae were $14.37\sim15.79mm(14.97{\pm}0.62mm,\;n=4)$ in SL, snout of seahorse larvae became slender was long, and body was coloration to the full as adult seahorse. At 41 days after parturition, seahorse larvae were grew $20.14\sim24.89mm(22.89{\pm}2.22mm,\;n=4)$ in SL with development of several spines in coronet, and their have 11 trunk rings and 35 tail rings. At 158 days after parturition, seahorse were grew to $59.07\sim63.76mm(61.42{\pm}3.32mm\;n=2)$, and head length (HL), trunk length (TrL) and tail length (TaL) were composed respectively $19.1{\pm}0.3%,\;25.2{\pm}0.7%$ and $55.8{\pm}0.3%$ of SL. In this time, survival rate is 15.6%.

• Fisheries and Aquatic Sciences
• /
• v.15 no.2
• /
• pp.117-123
• /
• 2012

The starry flounder Platichthys stellatus, like all flatfish, exhibits conspicuous lateral asymmetry in numerous traits, most obvious of which is the migration of one eye to the other side of the head during metamorphosis. Additional changes related to eye migration include asymmetrical pigmentation, and a behavioral shift from larvae that exhibit upright, open-water swimming to juveniles and adults that lie on the ocean floor, eye side up. However, the morphology of these juveniles has been quite plastic in recent years, a phenomenon which is thought to be related to a diverse suite of semi-intensive and intensive larviculture methods. The cause of morphological abnormalities in the farmed flatfish is poorly understood. In the present study, we observe the features of morphological specificity and abnormality of immature fish (mean total length 23 cm) and survey the occurrence frequency of the specificity and abnormality of juvenile (mean total length 6.70 cm) in artificial culture facility. We find 2 types of abnormality (e.g., albino in ocular side and hypermelanosis in blind side) and 1 type of specificity (e.g., lateral polymorphism). These considerably differ from normal individuals (has sinistral eye and pigmented on only one side) by several characteristics (dextral eye, ocular side albinism, blind side hypermelanosis). The incidences of albinism, hypermelanosis, and body reversal are $10.1{\pm}2.56%$, $91.7{\pm}1.7%$, and $13.1{\pm}1.1%$, respectively. These suggest that these morphometric and morphological differences occur more in artificial environment during and just after metamorphosis.

• International Journal of Industrial Entomology and Biomaterials
• /
• v.23 no.1
• /
• pp.129-135
• /
• 2011

Cathepsins are well-characterized proteases that are ubiquitously expressed in lysosomes. Previous work revealed that $Bombyx$ $mori$ cathepsins B and D are expressed in the fat body and undergo decomposition during larval-pupal metamorphosis. Quantitative RT-PCR was performed to detect cathepsin gene expression at the transcription level when challenged by $B.$ $mori$ nuclear polyhedrosis virus (BmNPV), temperature and hormones (20-hydroxyecdysone (20E) and juvenile hormone analogue (JHA)). mRNAs encoding cathepsins B and D were significantly enhanced after the larvae were infected with BmNPV, and the peak of the induction appeared at 1 day before spinning. This attenuated the inducing effect on cathepsin expression caused by infection. Temperature shock induced cathepsin expression at the later stage of the $5^{th}$ instar, and transcription levels varied with development stage and temperature. Cathepsin B and D mRNA expression in the fat body were significantly induced by JHA at the day before spinning, and with 20E, the expression reached a peak at the last day of the $5^{th}$ instar. Cathepsin B and D mRNA expression exhibited detectable changes post-treatment, without significant differences between or among the hormone concentrations.

• Proceedings of the Korea Society of Environmental Biology Conference
• /
• 2002.11a
• /
• pp.123-126
• /
• 2002

Pollutants that are persistent, bioaccurnulative, and toxic have been linked to numerous adverse effects in human and animals, PBTs include heavy metals, polychlorinated biphenyls (PCBs), dioxins, polycyclic aromatic compounds (PACs) in addition to pesticides. This study focuses on toxic effects of the PBTs except pesticides on insects. Eight PBTs were selected from subgroups: three heavy metals (Pb, Hg, and Cd), two PCB mixtures (Aroclor mixtures 1 and 2), 2,3,7,8-tetrachlorodibenzo-p-dioxin, two monophenols (4-octylphenol and 4-nonylphenol), and tetrabutyltin, Beet armyworm, Spodoptera exigua, was used as test target insect species. Three physiological markers (metamorphosis, immune reaction, and follicle patency) were assessed in each exposure to different doses of the PCBs. Heat-shock proteins as molecular markers were also analyzed in response to the PCBs. All tested PBTs were toxic to metamorphosis from larvae to pupae when they were applied with diet. Two PCB mixtures were the most toxic compounds in this assay by giving significant toxicity at 0.005 ppm, while others had from 10 to 1000 ppm. Dioxin (0.1 ppb), tetrabutyltin (0.1 ppb), Pb (10 ppb), and Hg (0,01 ppb) were potent to inhibit immune reactions analyzed by inducing phenoloxidase activity and blocked phospholipase $A_2$ enzyme, Tetrabutyltin and dioxin significantly induced follicle cell patency, but their effects were lower than that of endogenous juvenile hormone, Dioxin, Pb, Hg, and Cd could induce the expression of heat shock proteins that were detected by immunoblotting against human HSP70 monoclonal antibody. HSP78 and HSP80 were upregulated in response to the PBTs. This expression was detected from the fat body and epidermis at as fast as 4h after injection. All these results clearly suggest that PBTs give significant ecotoxicity to insects that are valuable organisms in our environment.

• Parasites, Hosts and Diseases
• /
• v.56 no.6
• /
• pp.567-575
• /
• 2018

Present study was performed to describe the morphological and molecular characterization of Toxocara tanuki (Nematoda: Ascaridae) from Korean raccoon dog, Nyctereutes procyonoides koreensis, naturally infected in the Republic of Korea (Korea). Juvenile and adult worms of T. tanuki were recovered in 5 out of 10 raccoon dogs examined and the larval worms were detected in 15 out of 20 muscle samples (75%). Small lateral alae were observed on the cranial end of the body in male and female adults and 2 long spicules (3.0-3.5 mm) were characteristically observed in the posterior end of males. In SEM observation, 18 pairs of proximal precloacal, a precloacal median, a postcloacal median and 5 pairs of postcloacal papillae were uniquely revealed in the posterior portion of males, but the proximal papillae were not shown in the lateral ends of females. Molecular analysis on the 18S rRNA partial DNA sequences was revealed the same finding in both samples, adult worms and muscle larvae, which are closely related to T. tanuki. In conclusion, it was confirmed for the first time that T. tanuki is indigenously distributed, the Korean raccoon dog is acted as the natural definitive host of this nematode in Korea and the morphological characteristics of T. tanuki were shown in specific structure for single postcloacal median papilla in male.

• Korean Journal of Ecology and Environment
• /
• v.40 no.2
• /
• pp.337-345
• /
• 2007

Changes of feeding habitat and feeding organ of a land-locked sweetfish, Plecoglossus altivelis related to their growth process were investigated in the Lake Okjeong, Sannae-myeon, Jeongeup-si, Jeollabuk-do, Korea from 2004 to 2005. In the lake, the post-larvae from 25 to 40 mm in standard length fed mainly on animal organisms such as Copepoda, Branchiopoda and Rotatoria. Also, the juveniles from 50 to 60 mm (SL) fed on Chironomidae of Diptera, Copepoda and Branchiopoda. However, the juvenile from 60 to 70 mm (SL) in the Churyeong Stream fed on animal organisms and aquatic algae, the immature fishes more than 70 mm (SL) fed on only periphyton such as Synedra, Cymbella, Navicula and Pinnularia. Also, the feeding organs of the tooth and stomach were changed according to its growth and food change.

• Journal of Aquaculture
• /
• v.15 no.2
• /
• pp.95-101
• /
• 2002

During the periods from lily to October, 2000 in Hongseong and lucy to October, 2001 in Taean in the west coast of Korea, the following environmental conditions prevailed : water temperature : 22.0~26.817, salinity 27.23 ~30.80%, dissolved oxygen 4.12 ~6.26 ml/l, pH 7.89 ~8.09, phosphate 0.39 ~0.65 $\mu m$ , inorganic nitrogen 5.05~9.26 $\mu m$, suspended solid 5.4~20.8 mg/l and chemical oxygen demand 1.12~1.87 mg/l. The B-shaped veliger larvae of the Ark shell occurred in maximum number at $25^{\circ}C$ prevailing from mid-August at Hongseong and Taean. Full grown larvae reached maximum abundance from late August. To identify the effectiveness of the substratum for spat collection, raschel net were tested to Larval settlement. The most effective depth to collect the larvae in natural environment was the collectors suspended at 7~8 m depth. At these depths, about 49 to 94 spats were found on the collector (40$\times$50 cm), The growth of shell height (Y) to shell length (X), and total weight (W) to shell length (L) could be formulated as follows respectively: Hongseong: SH = 0.7168 SL -0.6466 ( $r^2$ = 0.9839), TW = $0.0001SL^{3.1705}$ ($r^2$ = 0.9882) Taean: SH = 0.736 SL -0.8824 ($r^2$ : 0.9899), TW : 0.00005 $SL^{3.3731}$ ($r^2$ : 0.9899)

• Korean Journal of Ichthyology
• /
• v.24 no.2
• /
• pp.94-100
• /
• 2012

The spine loach, Cobitis hankugensis endemic to Korea were collected at the Nokdong River, Unbong-eup, Namwon-si, Jeollabuk-do during June 2007 for study its eggs development and early life history. The eggs were obtained by injecting gonadotropin (LHRH-1) to female and were fertilized by dry method in the laboratory condition. The matured eggs were separative, demersal and light yellowish with $1.29{\pm}0.07mm$ in diameter average. Under $23{\sim}25^{\circ}C$, the eggs were hatched in 45~52 hours after fertilization, and just hatching larvae were $4.5{\pm}0.24mm$ in total length. On 5 days after hatching, they were $6.6{\pm}0.13mm$ in total length and their yolk sacs were completely absorbed. From 25 days after hatching, they became the juvenile stage with $9.0{\pm}0.49mm$ in total length. On the 100 days after hatching, their external forms and band patterns were similar to those of adults with average $27.3{\pm}2.82mm$ in total length.