• Korean Journal of Ecology and Environment
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• v.55 no.1
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• pp.35-48
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• 2022

Fish assemblage of total 325 of Korean peninsula estuaries were surveyed to analyze the characteristics of community structure and diversity by sea areas for three years from 2016 to 2018. The scale (stream width) of Korean estuaries were various (14~3,356 m), and 68.9% of all estuaries showed salinity of less than 2 psu. Total 149 species classified into 52 families of fish were identified, and the dominant and sub-dominant species were Tribolodon hakonensis (relative abundance, RA, 12.5%) and Mugil cephalus (RA, 9.5%), respectively. The estuary of the Korean Peninsula had different physical and chemical habitat environments depending on the sea area, and accordingly, fish community structure also showed statistically significant differences (PERMANOVA, Pseudo-F=26.69, P=0.001). In addition, the NMDS (nonmetric multidimensional scaling) results showed the patterns that indicating fish community difference by sea areas, even though low community similarity within sea area (SIMPER, 21.79~26.39%). The estuaries of east sea areas were distinguished from the others in the aspects of which, the higher importance of migratory fishes and endangered species, and that of brackish species were characterized at south sea estuaries. However, the estuaries of west sea showed higher importance of species that have a relation with freshwater (primary freshwater species, exotic species), which is the result that associating with the lower salinity of west sea estuaries because of the high ratio of closed estuaries(78.2%). The SIMPER analysis, scoring the contribution rates of species to community similarity, also showed results corresponding to the tendency of different fish community structures according to each sea area. So far, In Korea, most studies on fish communities in estuaries have been conducted in a single estuary unit, which made it difficult to understand the characteristics of estuaries at the national level, which are prerequisite for policy establishment. In present study, we are providing fish community structure characteristics of Korean estuaries in a national scale, including diversity index, habitat salinity ranges of major species, distribution of migratory species. We are expecting that our results could be utilized as baseline information for establishing management policies or further study of Korean estuaries.

• Korean Journal of Ichthyology
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• v.34 no.3
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• pp.160-171
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• 2022

This study investigated the characteristics of fish communities, habitat characteristics and the age of Lefua costata in the Jusucheon of Gangneung-si, Korea from January to December 2013. The survey collected 23 species belonging to ten families from 6 survey stations. The dominant and subdominant species were Zacco koreanus (relative abundance, 22.1%) and Rhynchocypris steindachneri (20.1%), respectively. The next most abundant species were Tridentiger brevispinis (10.7%), Orthrias nudus (9.7%), Zacco platypus (8.6%), Lefua costata (7.9%), Iksookimia koreensis (6.0%) and Pungitius sinensis (3.0%). Among the fish species collected, one species, P. sinensis, was class II endangered wildlife by the Ministry of Environment, and four species (Z. koreanus, I. koreensis, Silurus microdorsalis and Cottus koreanus), were endemic to Korea. Additionally, five migration fish species (Tribolodon hakonensis, Hypomesus nipponensis, Gasterosteus aculeatus, Oncorhynchus keta and Plecoglossus altivelis) were collected. The similarity index based on species composition and numbers separated fish communites in the Jusucheon according to main section, i.e., uppermost(St. 1), upper (St. 2~4), middle (St. 5), lower (St. 6). Ecosystem health of Jusucheon Stream (fish assessement index) evaluated using fish was assessed as very good (5 stations) and good (1 station). The main inhabit of L. costata was the middle-lower stream of aquatic plants habitats with mud bottoms, very slow water velocity and water depth 40~80 cm. The age groups for L. costata (female) estimated by the frequency distribution of total length in the spawning season (May) indicated that the 24~37 mm is 1-year old, the 38~51 mm group is 2-year old, the 52~63 mm is 3-year old, 64~77 mm is 4-year old and the 80~91 mm is more than 5-year old. Finally, characteristics of fish communities, habitat characteristics and the age of Lefua costata in the Jusucheon was discussed.

• Korean Journal of Ecology and Environment
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• v.56 no.4
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• pp.348-362
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• 2023

This study analyzed the monitoring results of fishways at 16 weirs constructed on four large Rivers to provide data helpful for the operation and management of fishways. The average utilization rate of the fishways at the weirs was confirmed to be 64.9%. When comparing the dominant species in the mainstream and fishway monitoring results, differences were observed in 9 weirs (56.3%). This indicated that the species prevalent in the mainstream were not necessarily the ones most frequently using the fishways. The average number of individuals using the fishways per day was 336. When classifying the fish species using the fishway by life type, 92.3% were primary freshwater fish, and migratory species accounted for only 5.6%. Analysis based on the season of fishway usage revealed that an average or higher number of fish species used the fishways from May to October, with the highest number of individual users occurring from June to August. Between May and July, 80% of the fish species using the fishways were in their spawning period, while during other season, less than 40% were species that move during the spawning period. The fishways that showed a significant alignment between the spawning period and the fishway passage period were Rhinogobius brunneus, Leiocassis nitidus, Squalidus chankaensis tsuchigae, Pseudogobio esocinus, Acheilognathus rhombeus, and Pungtungia herzi, in that order. When comparing the fishway monitoring results of the Gangjeong-Goryeong Weir and the Dalseong Weir with the upper part water level of the weir, both the number of fish species and individuals using the fishway showed positive correlations with the upper part water level of the weir. This suggests that a higher water level of the weir increases the inflow discharge within the fishway, leading to increased use by fish (number of individuals in Gangjeong-Goryeong Weir, P<0.001; number of species in Dalseong Weir, P<0.05). This study summarized and analyzed the results of fishway monitoring at 16 weirs built on four large Rivers, considering fishway efficiency, operation and management, monitoring period, and regulation of water level in the upper part of the weir. It is thought that this will help understand the status of fish use in fishways on large River and aid the construction, operation, and management of fishways in the future.

• Korean Journal of Ecology and Environment
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• v.57 no.1
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• pp.39-50
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• 2024

In ecosystems within limited resources, interspecific competition is inevitable, often leading to the competitive exclusion of inferior species. This study aims to provide foundational information for the conservation and restoration management of Microphysogobio rapidus by evaluating species' ecological response to biological factors within its habitat. To understand this relationship, we collected food web organisms from site where M. rapidus coexist with Microphysogobio yaluensis, a specie ecologically similar to M. rapidus, and evaluated the trophic levels (TL), isotopic niche space (INS), and the overlap of INS among fishes within the habitat using stable isotope analysis. Our analysis revealed that the M. rapidus exhibited a higher TL than M. yaluensis, with TL of 2.6 and 2.4, respectively. M. yaluensis exhibited a broad INS, significantly influencing the feeding characteristics of most fish. Conversely, M. rapidus showed a narrow INS and asymmetric feeding relationships with other species, in habitats with high competition levels. This feeding characteristics of M. rapidus indicate that the increase in competitors sharing the similar resources lead to a decrease in available resources and, consequently, is expected to result in a decrease in their density.

• Korean Journal of Ecology and Environment
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• v.51 no.1
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• pp.71-85
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• 2018

A recent topic of interest within ecology is ecosystem services that are importantly connected with biodiversity. Biodiversity is a fundamental component of ecological studies and has been the subject of many studies worldwide. However, studies on the diversity and distribution of freshwater fish were not undertaken in earnest until 2000, and the number of internationally available studies is therefore still limited. In this study, we used data from "The Survey and Evaluation of Aquatic Ecosystem Health (hereafter SEAEH)" within the framework of which whole water systems on the Korean peninsula are annually monitored to investigate and determine the current status of the diversity and distribution of freshwater fish, as well as to elucidate major factors impacting freshwater fish. A total of 130 species from 28 families were identified at around 953 sites in the SEAEH investigation of 2014. The species Zacco platypus (relative abundance: 28.2%) and Z. koreanus (19.3%) were identified as the most abundant species on the Korean peninsula, and besides these 20 endangered species, 51 endemic species and 4 exotic species were also collected. Highest (96 species) and lowest (72 species) diversity were identified in the Han River Watershed and the Yeongsan/Seomjin River Watershed, respectively. The mean endemic rate was 32.7%, which is higher than the previous rate determined in 1995. The exotic species Micropterus salmoides, Lepomis macrochirus and Carassius cuvieri were found in the whole river system except north Yeongdong, whereas Oreochromis niloticus occurred only at three sites due to the cold water temperatures in winter. Totally, 28 species were found to be translocated to different water systems not connected with known original habitats, most translocations occurring in the Nakdong River and the Yeongdong region. Among the translocated species, Opsariichthys uncirostris amurensis, and Erythroculter erythropterus were dominantly distributed in the mid- to lower reaches of Nakdong River where they may be harmful to the native fish assemblages due to their strong predation. The construction of weirs in connection with the "4 River Project" generated changes in fish assemblages before, during and after the project, resulting in altered habitat condition. Especially, a decrease in the number of endemic species and an increase in the abundance of lentic species were seen. Human-induced global warming will allow exotic species requiring high water temperatures to adapt to the environmental conditions of the Korean peninsula, which may enhance the diversity of native fishes and create changes in distribution. For the establishment of realistic and efficient management and protection strategies for Korean freshwater fish, SEAEH, which produces fundamental and quantitative data for Korean streams, is an important and necessary tool.

• Korean Journal of Ecology and Environment
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• v.42 no.2
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• pp.260-269
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• 2009

Hwabuk Dam has been under construction to reduce flood damage in Nakdong River watershed and to supply stable water for middle area of Gyeongbuk Province. Therefore, fish investigation in up and downstream of the dam was conducted from 2004 to 2008 in order to determine any negative effect on fish community due to dam construction and to use as fundamental data for conserving species diversity and maintaining stream health. According to data analysis on water quality, temperature, dissolved oxygen, pH, suspended solids, and total E-coli had seasonal variation, but they did not significantly differ in sites. However, biological and chemical oxygen demand, chlorophyll-a, nitrogen, and phosphorus representing organic matter and nutrient concentration were higher in upper site and decreased to lower site so that they differed by site. Concentration of arsenic among the heavy metals was less than 0.05 mg $L^{-1}$, which is regulated for protection of human health in water quality standard, except for 0.092 mg $L^{-1}$ in June 2005. During the study period, the total number of fish caught from the 6 sites was 10,263 representing 7 families 19 species. Among them, dominant and subdominant species were Korean chub (Zacco koreanus, 62.5%) and Chinese minnow (Rhynchocypris oxycephalus, 10.6%) which inhabit mostly in mid and upper streams, Korea. Among the 19 species, Korean endemic species were 9 species (47.4%) including Korean slender gudgeon (Squalidus gracilis majimae), Korean dark sleeper (Odontobutis platycephala), and Korean shiner (Coreoleuciscus splendidus). There was several individuals of the $1^{st}$-class endangered species, Naktong nose loach (Koreocobitis nahtongensis), caught in 2005${\sim}$2007, and no introduced species of fish was found in entire sampling period. According to result of community analysis, dominance index decreased toward lower site, but diversity and richness indices increased toward lower site. The equation of length-weight relationship on the dominant species was TW=0.000003$(TL)^{3.2603}$. The parameter b in the equation was greater than 3.0 indicating good nutritional condition in the populations. Compared to populations of Korean chub in other streams, the population in Hwabuk Dam watershed had higher mean of condition factor by size indicating better growth rate. With fish fauna and multi-metric health assessment model in each sampling attempt, index of biotic integrity (IBI) was evaluated and it resulted mostly in good (26${\sim}$35) and excellent (36${\sim}$40) condition in all sites, and the mean of IBI was the highest in site 5. The results indicate that it is very important to study not only environmental impact assessment with fish composition but also stream health assessment in order to conserve healthy aquatic ecosystem.

• Korean Journal of Ecology and Environment
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• v.55 no.2
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• pp.132-144
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• 2022

The fish community in the Seomjin River-Seomjin River Estuary-Gwangyang Bay coast continuum was investigated three times from March 2019 to October 2019. The collected species at the eight sites during the survey period were 49 species belonging to 31 families, including two endangered species. According to Bray-Curtis similarities, observations were divided into four groups based on the fish community composition; two groups (group 1, 2) and two uncategorized groups (group 3, 4). ANOSIM based on spatial and temporal groupings indicated that the spatial differences in fish communities (R=0.398, P=0.001) were relatively more important than the temporal differences (analysis of similarities, R=0.273, P=0.002). In particular, there were significant differences between groups 1 and 2 (analysis of similarities, R=0.556, P=0.001), and similarity percentage analysis revealed that Argyrosomus argentatus (9.4%), Favonigobius gymnauchen (6.9%) and Konosirus punctatus (5.9%) contributed to these differences of fish assemblages for each group. The fish fauna distributed in the Seomjin River-Gwangyang Bay ecosystem were spatially divided and the number of species and number of individuals showed seasonal differences. This study could be a basis for understanding changes in the fish community and implementing conservation and management strategies on major species within a continuous environment of the river-estuary-ocean continuum.

• Korean Journal of Ichthyology
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• v.10 no.1
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• pp.87-97
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• 1998

The freshwater fish fauna and distribution were investigated in Kojedo from 1982 to 1997. The collected fishes were classified into twenty four species of ten families. Dominant species was Zacco temmincki (relative abundance: 18.1%) and subdominant species was Rhinogobius brunneus (16.4%). Also Iksookimia longicorpus (12.3%), Oryzias latipes (7.5%), Chaenogobius urotaenia (7.5%) and Carassius auratus (6.9%) were numerous. The endemic species of Korea were six species (25.0%) and endangered species were C. splendidus, S. microdorsalis and C. kawamebari. In this study, species diversity index was high at Yoncho stream, dominance index at Aju and Oaepo stream and evenness index at Oaepo stream in community structure. There was a tendency of fish distribution in Kojedo that more longer the stream and more larger the water volume were, there were more species and more individual numbers. It was considered that the dominance of upper and middle reach dwelling fishes resulted in the dominance of Aa type stream mainly. Liobagrus mediadiposalis and L. mediadiposalis ssp. 1 showed different distribution pattern in Kojedo : that is, the former inhabited in east-northern part but the latter in south-western part separately. And the importance of this distribution pattern was discussed in relation to paleogeography.

• Korean Journal of Environment and Ecology
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• v.29 no.4
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• pp.552-563
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• 2015

The characteristics of ichthyofauna and fish community in Lake Goesan were examined from April 2010 to October 2012. During the survey period thirty six species belonging to 11 families were collected. Dominant species by number were Hemibarbus labeo (29.9%) and Zacco platypus (20.0%). In biomass, the dominant species were H. labeo (37.2%) and Carassius auratus (17.9%). Also, fourteen Korean endemic fish species (38.9%) and one endangered species (Acheilognathus signifer) were collected. Further, one catadromous species was observed for stock enhancement (Anguilla japonica), in addition to two land-locked anadromous species (Hypomesus nipponensis, Plecoglossus altivelis) and three exotic species (Cyprinus carpio (Israeli type), C. cuvieri, Micropterus salmoides). According to the length-weight relation of C. auratus and M. salmoides, the b values were 3.13~2.99, 3.11~2.99, showing a declining tendency annually. However, for H. labeo and Z. platypus, the b values were 2.98~3.07, 3.06~3.23 respectively, showing an increasing trend. The slope values for C. auratus and M. salmoides population conditions were controlled by K factor showing a tendency to decrease, but H. labeo and Z. platypus were showing a tendency to gradually increase.

• Korean Journal of Ecology and Environment
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• v.47 no.spc
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• pp.66-73
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• 2014

In order to determine whether vegetation would be one of the factors for the selection of otter home range, vegetation structure and other potential factors were studied in Hwacheon, Korea. Thirteen sites, otter's activity found and not found, were investigated in North Han River and connected tributary streams of Hwacheon-gun. Three types of vegetation were classified by cluster analysis, which is short grass, tall grass and shrub type. Vegetation zone of each channel is composed of either one type, or mosaic of tall grass and shrub type. Short grass type is common in Lake Paro and upper North Han-river where water level is highly variable throughout a year. Therefore, annual species such as Persicaria nodosa, Fimbristylis dichotomam and Chenopodium ficifolium are the most dominant. Shrub type is common at the downstream sites of Jichon stream and along mainstream of North Han River down Lake Paro. A shrub species, Salix koreensis, is the most common. Tall grass type is dominant occupying the most vegetation zone of the tributary channels. Phragmites japonica is absolutely dominant. Due to its dense cover, a few plant species are co-existed. Otter activity was found in all three vegetation types and no marked activity was found at some sites of tall grass type. There is no difference in species composition and physiognomy between tall grass sites with and without otter activity, while it shows significant difference in fish availability between two groups. Overall we found that home range of otters in the region is along the mainstream and downstream of tributary streams with high fish availability in all vegetation types and in various human activity levels.