• Animal Systematics, Evolution and Diversity
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• v.2 no.1
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• pp.63-78
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• 1986

Two species of Moroco oxycephalus and M. lagowskii were studied to examine patterns of genic variation and morphological difference within and between populations of two species, and to clarify their taxonomic status and geographic distribution. The number of scales above lateral line(SAL) was the key character to classify these species. On the average, M.lagowskii had 22 or more SAL whereas M.oxycephalus had 20 or less. Previously known character of the position of dorsal fin was found to be not appropriate to distinguish them. Five loci, Gp, st-1, Est-2, Est-3 and Got-1 , showed fixed difference electrophoretically between two species and these could be used as genetic markers to identify them. The degree of genic variation of M. oxycephalus was four fold higher(H=0.032) than that of M. lagowskii(H=0.008) but both species were far less than the average genic variation of freshwater fish in general. Rogers' genetic similarity coefficients between two species were S=0.692 and their presumed divergent time was estimated to be sbout 1.8million years ageo. Detailed survey of the geographic distribution of thses revealed that M.lagowskii was distributed in northeastern part of South Korea(Ganseong , Gangreung, Wangsan, and Oggye) and M. oxycephalus was occupied rest of the peninsula. The distrance between Oggye, the southern limit of M. lagowskii distribution , and Samwha (near Samcheog), the northern limit of M.oxycephalus, was aobut 15 Km apart and no symparty was found in between.

• The Korean Journal of Zoology
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• v.35 no.3
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• pp.263-270
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• 1992

Responses of immunoreactive atrial natriuretic peptide (ir-ANP) to environmental temperature were studied in the freshwater catfish, Silums usotus, acclimated at various temperatures for one week. According to increase in environmental temperature, plasma sodium and chloride concentrations, and osmolality were significantly increased, while hematocrit showed a marked decrease. When the catfishes frere acclimated at cold $(3^{\circ}C)$ or warm $(18^{\circ}C)$ temperatures, ir-ANP contents in the atrium and bulbus arteriosus were significantly lower than those at $9^{\circ}C.$ However, ventricular contents of ir-ANP urere not different among the three groups.Levels of plasma ir-ANP in the catfish increased in response to the increment of acclimated temperature. On the basis of these results, we suggest that the environmental temperature may modulate synthesis and secretion of ir-hUP in the fish. We also suggest that changes of plasma ir-ANP levels may be associated with the control of body fluid homeostasis.

• Animal cells and systems
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• v.16 no.3
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• pp.224-229
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• 2012

The Korean shiner (Coreoleuciscus splendidus, Gobioninae), a small freshwater fish native to Korea Peninsula, widely inhabits in most of the major drainages in South Korea. Here we describe the development of 14 novel and polymorphic microsatellites for this species and its effective utilization in estimation of genetic diversity using 72 individuals from three sampling sites in different drainages. Loci were isolated from a microsatellite enrichment procedure using probe-labeled magnetic beads. A total of 242 alleles were detected across all loci with an average of 17.3 alleles per locus ranging 4 32. The loci varied levels of polymorphism as evident from its expecte heterozygosity ranging from 0.111 to 0.957. The average pairwise $F_{ST}$ between two populations examined shows significant differentiation ($F_{ST}$ = 0.215, p<0.05). The 14 microsatellite loci developed here will also be useful to explain for the genetic structures among geographically isolated populations and gene flow dynamics within drainages in this species as well as the closely related species.

• Development and Reproduction
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• v.25 no.1
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• pp.33-41
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• 2021

This study was carried out to observe the development of the autonomous skeletal development of the Favonigobius gymnauchen. Total length (TL) of larvae 3 days after hatching (DAH) were mean TL of 3.34 mm, with a line-shaped parasphenoid ossification in the cranium and basioccipital ossification in the back. The 10 DAH larvae had a mean TL of 5.20 mm, with the number of caudal vertebrae increasing to 15. The urostyle and two hypural bones in the lower part also began to ossify. The 23 DAH juveniles had a mean TL of 8.47 mm. The pectoral girdle's skeleton was completed as the scapula and coracoid were ossified. The pelvic girdle also fully supported the ventral fin as its ossification was completed. Favonigobius gymnauchen and Tridentiger obscurus showed similar characteristics in terms of the anus location of hatched larvae, number of myotomes, and melanophore distribution during the morphological development of the larvae and juveniles. However, this study confirmed differences in the development of the vertebrae and urostyle bone.

• Korean Journal of Environmental Biology
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• v.40 no.4
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• pp.374-386
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• 2022

Phytoplankton communities, with emphasis on picoplankton and nanoplankton, were investigated in Gamak Bay, South Korea, where freshwater input and coastal water intrusion shape ecosystem functions. Shellfish farms and fish farms are located in the inner bay and outer bay, respectively, and tides translocate uneaten food and urine production from aquaculture farms toward the inner bay. Water masses were distinctly different based on a significantly different density between the surface and bottom layer and among three water masses, including the inner bay, outer bay, and Yeosu Harbor. Phytoplankton communities were quantified using flow cytometry and size-fractionated chlorophyll-a (chl-a) was measured. Salinity was a principal variable separating phytoplankton communities between the surface and bottom layer, whereas Si(OH)₄ controlled the communities in the inner bay, and NH₄⁺ and PO₄^3- governed the outer bay communities. While phycocyanin-containing (PC) cyanobacteria dominated in the outer bay, phycoerythrin-containing (PE) cyanobacteria dominance occurred with cryptophyte dominance, indicating that nutrients affected the distribution of pico- and nanoplankton and that cryptophytes potentially relied on a mixotrophic mode by feeding on PE cyanobacteria. Interestingly, picoeukaryotes and eukaryotes larger than 10 ㎛ were mostly responsible for the ecological niche in the western region of the bay. Given that chl-a levels have historically declined, our study highlights the potential importance of increased small phytoplankton in Gamak Bay. Particularly, we urge an examination of the ecological role of small phytoplankton in the food supply of cultivated marine organisms.

• Fisheries and Aquatic Sciences
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• v.26 no.12
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• pp.708-714
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• 2023

This study reports a new record of freshwater fish Macrognathus aral (Bloch & Schneider) from Aiechu-Kalikhola tributary of the Maukhola river in Sarpang, Bhutan. The species was found in shoal of the tributary and was identified using its morphometric characters. It can be identified and distinguished from its congeners reported in Bhutan by dorsal fin rays XIX, 47, anal fin rays III, 52, rostral plates 28, pectoral fin rays 19, caudal fin rays 15, soft rayed part of dorsal and anal fin separated by a notch from rounded caudal fin, and presence of four ocelli at the base of dorsal fins. Further studies are needed to better understand its distribution, ecology, and population dynamics in the country. A key to species belonging to Mastacembelidae of Bhutan including the new record is provided.

• Korean Journal of Ecology and Environment
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• v.51 no.2
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• pp.149-159
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• 2018

Twenty-nine wetlands (20 river type and 9 lake type wetlands) in Gyeongsangnam-do were investigated to understand the characteristics of fish assemblages by the wetland type and to suggest management strategies. As a result, $10.3{\pm}4.8$ species were collected from river type wetlands on average (${\pm}SD$) and $9.1{\pm}4.1$ species from lake type wetlands. Thus, there was no significant difference in the number of species between them (Mann-Whitney U test, P>0.05). However, the species that constitute the fish assemblage showed statistically significant differences between the two wetland types (PERMANOVA, Pseudo-F=2.9555, P=0.007). Furthermore, the species that contribute the most to each type of fish assemblage were Zacco koreanus (river type, 28.51%) and Lepomis macrochirus (lake type, 23.21%), respectively (SIMPER). The results of the NMDS analysis using the fish assemblage by place classified the species into three groups (river type, lake type, and others). The current wetland management is only focused on endangered species, but this study shows a difference in fish assemblage by wetland type. Therefore, a management system based information on endemic species, exotic species and major contribution species should be provided. Furthermore, the classification of some types of wetlands based on the present topography was found to be ambiguous, and wetland classification using living creatures can be used as a complementary method. This study has limitations because only two types of wetlands were analyzed. Therefore, a detailed management method that can represent every type of wetland should be prepared through the research of all types of wetlands in the future.

• Korean Journal of Ecology and Environment
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• v.56 no.1
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• pp.57-69
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• 2023

The objectives of this study were to analyze the fish community structures and distribution characteristics of fisheries resources in the Osip Stream and Wangpi Stream, fishery resources protection areas. For the study, we conducted fish samplings four times in the two streams from April to October 2019. In Osip Stream and Wangpi Stream, we sampled 31 species and 29 species and the dominant species were Zacco platypus (28.6%) and Squalidus multimaculatus(41.7%), respectively. According to the life type of fish species, primary freshwater species were collected 18 species(58.1%) and 21 species(72.4%), and migration fishes were sampled 4 species (12.9%) and 6 species (20.7%) in Osip Stream and Wangpi Stream, respectively. Fisheries resources species showed high relative abundance in June, and the fish biomass was highest in October. As a results of comparing the previous studies with this study, both rivers showed high biodiversity and were found to maintain stable populations of fishes. According to analysis of tolerance guilds, the proportion of tolerant species, based on the number of individuals, was composed of 14.4% and 1.1% in Osip Stream and Wangpi Stream, respectively. This very low ratio of tolerant species confirmed that both streams have very good physiochemical environment conditions. From the above results, it was judged that the fishery resource protection areas of Osip Stream and Wangpi Stream have high ecological function and preservation value. For sustainable use and management of fishery resource protection areas of Osip Stream and Wangpi Stream, it is suggested that biological disturbance management, fish discharge projects considering environmental capacity, efforts to improve the habitat environment, and establishing a fishery resource protection areas management system were necessary as considerations.

• Korean Journal of Ichthyology
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• v.24 no.3
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• pp.160-166
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• 2012

Egg development and early life history of the endangered Korean freshwater fish, Microphysogobio koreensis, was investigated to get a basic information for establishing its conservation strategy. The matured adult fishes were sampled at Imsil-gun, Jeollabuk-do, Korea in May 1 2012 and artificially fertilized. The fertilized eggs were spherical, separated demersal and $1.8{\pm}0.14mm$ in diameter. The hatching of the embryo began at about 29 hours after fertilization under water temperature of $23^{\circ}C$. The newly hatched pre-larvae were average $2.2{\pm}0.48mm$ in total length. At 4 days after hatching, the post-larvae were $3.6{\pm}0.55mm$ in total length and york sac was completely absorbed. At 20 days after hatching, their fin rays were formed and finally the larvae entered juvenile stage and grew up to $6.5{\pm}0.77mm$ in total length. At 60 days after hatching, the total length reached $24.4{\pm}1.71mm$, and the band patterns of he head and lateral side were similar to adult fish. Based on this study, the fertilized eggs of M. koreensis hatched more quickly and the pre-larvae length was also smaller, compared with related species.

• Journal of fish pathology
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• v.26 no.2
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• pp.99-110
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• 2013

Hatchery-reared seeds provides a key source of animal protein for human consumption and restocking for fishery management. For stock enhancement program, we have inspected the hatchery-reared seeds of 33 species in 2009, 44 species in 2010, 43 species in 2011 and 46 species in 2012 for legally designated diseases. Results showed that abalone was the most abundant in the marine species group and then sea cucumber, olive flounder, rockfish and swimming crab were followed. Crucian carp was the most abundant and then mandarin fish, Korean bullhead, melanian snail and Chinese mitten crab were followed in the freshwater species group. The number of inspection for black sea bream, rock bream, scorpionfish, black scraper, and eel has continuously decreased for four years. The inspection for flathead mullet has been carried out only in 2009. The total number of inspection cases for eight pathogens in this study were 8,476 and disqualification cases were 56 (0.67%) by detection of aquatic animals pathogens such as koi herpesvirus, white spot syndrome virus, red sea bream iridovirus or viral haemorrhagic septicemia virus.