• Korean Journal of Ichthyology
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• v.31 no.2
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• pp.101-109
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• 2019

This study investigated the characteristics of fish communities at the Lake Yedang, in 2013 to 2014 and 2017. During the survey period, there were 29 species of 10 families collected from 3 survey stations. Of them, Cyprinidae occupied 34.5% (14 species), Bagridae, Gobiidae 10.3% (3 species), and Cobitidae, Centrachidae were 6.9% (2 species) in the number of species, respectively. Korean endemic species were 4 species (13.8%) Abbottina springeri, Cobitis nalbanti, Pseudobagrus koreanus, Odontobutis interrupta and accounted for a low rate. There were 3 species (10.3%) exotic species including Carassius cuvieri, Lepomis macrochirus, Micropterus salmoides. As a result of community analysis, dominant index was 0.45~1.00, diversity index was 0.19~2.30 and richness index was 0.41~1.94.

• Ecology and Resilient Infrastructure
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• v.9 no.1
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• pp.59-67
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• 2022

The purpose of this study is to provide essential data necessary to assess ecological flow requirements by understanding habitat conditions for fish species through monitoring an ecological environment in the Korea stream (Dal Stream) and building related database. On-site surveys were conducted for identifying ecological and habitat conditions at the four monitoring sites. Fish sampling was carried out at the selected four sites (St.) during the period ranging from September, 2008 to September, 2009. At the four sampling sites, we measured water surface elevation, depth and velocity at the cross-sections. Optimal Ecological Flowrates (OEFs) were estimated using the Habitat Suitability Index (HSI) established for four fish species Zacco koreanus (St.1), Pungtungia herzi (St.2), Coreoleuciscus splendidus (St.3), and Zacco platypus (St.4) selected as icon species using the Physical HABitat SIMulation system (PHABSIM). Eighteen species (56.3%) including Odontobutis interrupta, Coreoperca herzi and C. splendidus were found endemic out of the 32 species in eight families sampled during this study period. The endangered species was collected Acheilognathus signifier, Pseudopungtungia tenuicorpa and Gobiobotia macrocephala, and this relative abundance was 9.4%. The most frequently found one was Z. platypus (31.3%) followed by C. splendidus (17.6%) and Z. koreanus (15.7%). The estimated IBI values ranged from 27.3 to 34.3 with average being 30.3 out of 50, rendering the site ecologically poor to fair health conditions. For C. splendidus (St.3), the dominant fish species in the stream, the favored habitat conditions were estimated to be 0.3-0.5 m for water depth, 0.4-0.7 m/s for flow velocity and sand-cobbles for substrate size, respectively. An OEFs of 8.5 m³/s was recommended for the representative fish species at the St.3.

• Korean Journal of Environment and Ecology
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• v.37 no.2
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• pp.151-162
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• 2023

This study investigated the characteristics of fish communities and inhabiting status of the endangered species, Rhodeus pseudosericeus, in the Geumdang Stream in Korea from March to October 2021. A total of 1,698 fish in 5 families and 25 species were collected from 7 survey stations during the survey period. The dominant species was Zacco platypus (relative abundance, 46.5%), and the subdominant species was Squalidus gracilis majimae (16.7%), followed by Rhynchocypris oxycephalus (12.0%), Z. koreanus (5.7%), Pungtungia herzi (3.2%), R. pseudosericeus (2.0%), R. notatus (1.9%), and Acheilognathus rhombeus (1.8%). Nine Korean endemic species (36.0%) were collected, including R. pseudosericeus, R. uyekii, Sarcocheilichthys variegatus wakiyae, Microphysogobio yaluensis, S. gracilis majimae, Z. koreanus, Cobitis nalbanti, Iksookimia koreensis, and Odontobutis interrupta. An exotic species, Micropterus salmoides, designated as an invasive alien species (IAS), was collected downstream. The investigation of the habitat patterns of the endangered species (class II), Rhodeus pseudosericeus, showed a habitat range of about 6 to 7 km in the middle of Geumdang Stream (RP-1 to RP-4), and this species inhabited the edge with water depths of 0.3 through 1.0 m with slow water flow and many aquatic plants. According to the community analysis results, the overall dominance and evenness indexes were low, while diversity and richness indexes were high, and the cluster structure was largely divided into upstream and middle-downstream areas. The river health (fish assessment index) evaluated using fish was assessed as good (3 stations), normal (3 stations), and bad (1 station), and water quality was evaluated as good both upstream and downstream. Compared to previous studies, the number of species was relatively similar, and among the species that appeared in the past, 13 species did not appear in this survey, while 6 species appeared for the first time in this survey. Disturbance factors included river construction, many weirs, and the appearance of the ecosystem-disturbing species, M. salmoides. Since Geumdang Strem has high conservation value because it is home to many species in the Acheilognathinae subfamily, including the endangered species R. pseudosericeus, continuous attention and systematic conservation measures are required.

• Korean Journal of Environment and Ecology
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• v.38 no.2
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• pp.189-203
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• 2024

This study conducted a survey two times at 20 points from April to June and from August to October 2022 to characterize the fish community and reveal the health of the Anyang stream. The survey collected 3,186 individuals belonging to 5 orders, 10 families and 34 species. The dominant species was Zacco platypus (43.4%), followed by Carassius auratus (10.1%), Cyprinus carpio (7.6%), Zacco koreanus (6.2%), Pungtungia herzi (5.2%), Oryzias sinensis (5.1%), Pseudorasbora parva (4.7%), Squalidus gracilis majimae (4.4%), Rhynchocypris oxycephalus (3.5%), Hemiculter eigenmanni (3.3%), Rhodeus ocellatus (1.4%), and Chelon haematocheilus (1.0%). Among the emerged species, 5 species (14.7%), including Rhodeus uyekii, Squalidus japonicus coreanus, and Odontobutis interrupta, were endemic to Korea, and 4 species (11.8%), including Cyprinus carpio (Israeli type), Lepomis macrochirus, Micropterus salmoides, and Poecilia reticulata, were exotic. The fish community analysis showed that the dominance was higher at the upper reaches of the Anyang stream and decreased downstream, and diversity, richness, and evenness were higher in tributary than mainstream. Stream health (fish assessment index, FAI) was generally poor, as it was rated as moderate (C) at seven sites, poor (D) at eight sites, and very poor (E) at five sites. Water quality was evaluated at eight sites, and it was rated as poor (V) at two sites, slightly poor (IV) at one site, moderate (III) at four sites, and slightly good (II) at one site, indicating that the overall water quality was poor and that the water quality had a significant impact on river health and fish habitat. Moreover, it was found that many weirs without fishways were constructed in the Anyang stream and became an obstacle to fish migration. Therefore, a systematic management plan to improve water quality and add fishways is necessary to improve the stream's health and conserve stable fish habitat.

• Korean Journal of Environment and Ecology
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• v.38 no.3
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• pp.263-276
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• 2024

Fish community characteristics and the influence of sampling gear were investigated in Lake Singal, South Korea, from August 2020 to October 2021. The employed sampling gears included a kick net, cast net, gill net, and fyke net, which are commonly utilized within the lake. Across three survey stations, a total of 18 fish species from seven families, comprising 3,501 individuals and contributing to a total biomass of 117,670 grams, were identified. Dominance among species was assessed based on individual count and biomass. Pseudorasbora parva was the most abundant, constituting 29.9% of the total catch, followed by Zacco platypus (25.1%) and Micropterus salmoides (19.3%). In terms of biomass, Carassius auratus was predominant, accounting for 45.1%, followed by Cyprinus carpio (17.4%) and M. salmoides (14.3%). Among the sampled species, three were identified as endemic to Korea: Squalidus japonicus coreanus, Cobitis nalbanti, and Odontobutis interrupta. Additionally, four exotic species were recorded, including M. salmoides and Lepomis macrochirus, both classified as invasive alien species, along with C. cuvieri and a variant of Cyprinus carpio (nudus type). Analysis of the average standard length (SL) and body weight (BW) revealed significant size variations among species. P. parva, the dominant species, measured 60 ± 24.1 mm (SL) and weighed 4.4 ± 3.42 g (BW). The subdominant species, Z. platypus, exhibited an SL of 82 ± 17.6 mm and a BW of 10.4 ± 7.27 g. M. salmoides, another dominant species, registered 96 ± 25.1 mm (SL) and 24.9 ± 96.02 g (BW), while C. auratus measured 125 ± 77.3 mm (SL) and weighed 168 ± 336.5 g (BW). In terms of gear-specific performance, the kick net captured eight species from three families, totaling 302 individuals with a biomass of 1,269 g. The cast net was more effective in coastal zones, collecting 11 species from four families, amounting to 948 individuals and 31,343 g of biomass. The gill net yielded the highest biomass, capturing 13 species from four families with 682 individuals weighing 69,695 g. The fyke net recorded the highest species diversity and number of individuals, capturing 15 species from seven families, totaling 1,569 individuals and 15,362 g of biomass. The fyke net proved most efficient in species and individual counts, whereas the gill net was superior for biomass collection. Conversely, the kick net demonstrated effectiveness in collecting small benthic species in coastal areas.

• Ecology and Resilient Infrastructure
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• v.2 no.3
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• pp.198-205
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• 2015

Impacts of climate change on aquatic ecosystems range from changes in physiological processes of aquatic organisms to species distribution. In this study, MaxEnt that has high prediction power without nonoccurrence data was used to simulate fish distribution changes in the Geum river watershed according to climate change. The fish distribution in 2050 and 2100 was predicted with RCP 8.5 climate change scenario using fish occurrence data (a total of 47 species, including 17 endemic species) from 2007 to 2009 at 134 survey points and 9 environmental variables (monthly lowest, highest and average air temperature, monthly precipitation, monthly lowest, highest and average water temperature, altitude and slope). The fitness of MaxEnt modeling was successful with the area under the relative operating characteristic curve (AUC) of 0.798, and environmental variables that showed a high level of prediction were as follows: altitude, monthly average precipitation and monthly lowest water temperature. As climate change proceeds until 2100, the probability of occurrence for Odontobutis interrupta and Acheilognathus yamatsuatea (endemic species) decreases whereas the probability of occurrence for Microphysogobio yaluensis and Lepomis macrochirus (exotic species) increases. In particular, five fish species (Gnathopogon strigatus, Misgurnus mizolepis, Erythroculter erythropterus, A. yamatsuatea and A. koreensis) were expected to become extinct in the Geum river watershed in 2100. In addition, the species rich area was expected to move to the northern part of the Geum river watershed. These findings suggest that water temperature increase caused by climate change may disturb the aquatic ecosystem of Geum river watershed significantly.

• Parasites, Hosts and Diseases
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• v.31 no.2
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• pp.99-108
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• 1993

An epidemiological study of Metogonimus infection was undertaken along the upper reaches of the Nmhn River, with special consideration on the species (type) of the worms collected from humans. Eggs of Metogonimus spp. were detected from 15 (9.7%) of 154 people examined in Umsong-gun, and from each Infected person (5 cases) 6.015- 24,060 worms (mean 13,2331 were recovered after treatment with praziquantel (10 mg/kg). Eggs were also detected from 37 (48.1% of 77 people In Yongwol-gun, from whom (27 casesl 1-4,965 worms (mean 1,2151 were collected. The worm from Umsong-gun consisted of both Metagonimus Miyata type and Metagonimus takohashii, whereas those from Yongwol-gun consisted of only Metqsonimus Miyata type. When the uterine eggs of the two kinds and M. yokogawoi (obtained from people In Tamjin River basin) were morphologically compared, it was suggested that the egg size should be a good Indicator for discrlmination of the species or type. The source of human Infection was proved to be fresh water fleshes: 49 of 52 Znsco plntvpus examined, 6 of 8 Hemibcrbus loniroskis, 13 of 15 Pseunogobio esuinl:, 4 of 6 Odontobutis obscura intemfptn, and 17 of 18 Corqssiw carassiw were found Infected with Metosonimw metacercariae. From the results, it is concluded that the upper reaches of the Namhan River are endemic foci of Metogonimn Miyata type and M. takahashii.

• Parasites, Hosts and Diseases
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• v.24 no.2
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• pp.121-136
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• 1986

Recently there have been some reports on human infections of Echinostoma hortense in Korea. It was found that a few species of freshwater fishes were playing the role of the second intermediate host of E. hortense. However, molluscan intermediate host has not been identified yet in Korea. The present study aimed to establish the life cycle of E. hortense in laboratory. Experimental studies such as egg production from the rat, development of the eggs in vitro, exposure of miracidia to freshwater snails, shedding pattern of cercariae from infected snails, morphology of cercariae, cercarial infection to the second intermediate host and infection of metacercariae to the definitive hosts were done. In addition, epidemiological surveys on the infection status in inhabitants and house rats, and on the natural infection of larval echinostomes in the snails and fishes were carried out along the South Hangang-river. The results obtained were as follows: 1. The eggs deposited from adults in physiological saline were cultivated at room temperature($20{\sim}24^{\circ}C$). The miracidia were firstly observed on 8 days after cultivation, and 85.5% of the eggs contained the mature miracidia on 11 days after cultivation. More than 90% formed the miracidia when cultivated at temperature $22{\sim}27^{\circ}C$. Hatching of the miracidia began on 12 days after cultivation and continued for a week. The size of the miracidia was $103.0{{\times}}51.4{\mu}m$ in average. The motility of the miracidia were active up to 8 hours after shedding, but they were all dead within 10 hours after shedding. 2. A freshwater snail, Radix auricularia coreana was cultivated in aquaria. A hatched $F_1$ snails from the egg masses were exposed to 20 miracidia respectively. Escape of cercariae started on 15 days after infecton. Radix auricularia coreana was experimentally identified as the first intermediate host of E. hortense in Korea. 3. Cercarial shedding started on $15{\sim}20$ days after infection by snail, continued for about 10 days (8.8 days in average). Infected snails were dead within 32 days after the miracidial infection. About 1,335 cercariae($328{\sim}1,994$) per snail were shed in its life, and 119 cercariae in average per snail per day were shed. The cercariae were motile for more than 24 hours, and then squirming at the bottom until death. The body and tail sizes of cercariae were $356{\times}186{\mu}m$ and $510{\times}68{\mu}m$ in average, respectively. The rediae parasitized in the snail hosts were found mainly around the pericardial regions, and their size was $1,575{\times}258{\mu}m$ in average. The numbers of developing cercariae in a mature redia were 14 in average ($7{\sim}20$ in range). The numbers of rediae in a snail were 102 in average on 15 days after miracidial infection and 221 in average on 28 days. 4. Three uninfected Misgurnus anguillicaudatus, less than 6.5cm long were used in for the cercarial infection. They were all exposed with 755 cercariae, and examined at 5-day intervals starting from 10 days after infection. All the fishes were infected with metacercariae of E. hortense and a total of 275 was found infected(36.4%). The metacercariae were fed to rats and the adult worms were obtained on 15 days after infection. 5. The infected rats began to deposit the eggs on 11 days after infection. The number of eggs deposited per day per worm (EPD/worm) was $400{\sim}500$ on 3 weeks after infection and was increased to $1,000{\sim}1,500$ on 4 to 17 weeks, then decreased to 800 on 21 weeks after infection. 6. A total of 745 stool specimens collected from 576 male and 169 female residents of 8 different villages along South Hangang basin was examined. Out of 745 specimens, the eggs of Echinostoma sp. were found in 2 cases (0.3%). Of 34 house rats one showed egg-positive (2.9%). 7. Total 971 Radix auricularia coreana collected from 7 sampling stations were examined for shedding of cercariae. Three snails (0.3%) shed the cercariae of E. hortense. A total of 119 out of 542 freshwater fishes (22.0%) had the metacercariae of E. hortense. The fishes parasitized with the metacercariae were 4 out of 14 examined species. The infection rates of 4 species were 34.1% (106 out of 311) in Misgurnus anguillicaudatus, 30.4% (7 out of 23) in Misgurnus mizolepis, 4.3% (2 out of 46) in Moroco oxycephalus and 22.2% (4 out of 18) in Odontobutis obscura interrupta. In summarizing the above results, the first intermediate host of E. hortense was found as Radix auricularia coreana in Korea. Also, it took about 46 days for the shortest completion of a life cycle of E. hortense in summer; that is, 10 days for miracidial development in eggs, 15 days for cercarial development in the snail, about 10 days for metacercarial development in the second intermediate hosts, and 11 days for the maturation as the adults in the definitive hosts. The natural infection rates of E. hortense in the intermediate hosts were relatively high but those in the definitive hosts were low in the middle areas of South Hangang basin.