• Journal of Environmental Science International
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• v.24 no.6
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• pp.731-741
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• 2015

The objectives of study were to evaluate fish species compositions of trophic guilds and tolerance guilds and apply ecological fish assessment (EFA) models to Bekjae Weir, Keum-River Watershed. The EFA models were Stream Index of Biological Integrity (SIBI) used frequently for running water and Lentic Ecosystem Health Assessment (LEHA) used for assessments of stagnant water. The region of Bekjae Weir as a "four major river project" was originally a lotic ecosystem before the weir construction (2010, $B_{WC}$) but became more like lentic-lotic hybrid system after the construction (2011, $A_{WC}$). In the analysis of species composition and ecological bioindicator (fish), fish species with a preference of running water showed significant decreases (p < 0.05), whereas the species with a preference of stagnant water showed significant increases (p < 0.05). After the weir construction, relative abundances of tolerant species increased, and the proportion of insectivores decreased. This phenomenon indicated the changes of biotic compositions in the system by the weir construction. Applications of SIBI and LEHA models to the system showed that the two model values decreased at the same time after the weir construction ($A_{WC}$), and the region became more like lentic-lotic hybrid system, indicating the degradation of ecosystem health. The model values of SIBI were 19 and 16, respectively, in the BWC and AWC, and the health conditions were both "C-rank". In the mean time, the LEHA model analysis showed that the values was 28 in the BWC and 24 in the AWC, thus the health was turned to be "B-Rank" in the BWC and "C-Rank" in the AWC. indicating a degradation of ecological heath after the weir construction.

• Korean Journal of Environment and Ecology
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• v.35 no.3
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• pp.265-276
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• 2021

This study investigated the characteristics of fish communities and river health in the Sincheon stream of Imgin River between April and October 2019. The survey collected 3,677 objects in 30 species belonging to 12 families from 23 survey stations. The dominant and subdominant species were Zacco platypus (28.4%) and Oryzias sinensis (13.6%), respectively, followed by Z. koreanus (11.8%), Rhynchocypris oxycephalus (11.7%), Carassius auratus (9.6%), and Pseudorasbora parva (7.9%) in that order. Among the fish species collected, 10 (33.3%) were endemic species in Korea. The exotic species were 5 (16.7%), including Micropterus salmoides, Lepomis macrochirus, Cyprinus carpio (Israeli type), Poecilia reticulata, and Xiphophorus maculatus. The land-locked species included Cottus koreanus and Rhinogobius brunneus, while C. koreanus was a climate change-sensitive species. The dominance of the fish community was low, and the diversity was high in the Sincheon mainstream, Sudongcheon and Cheongdamcheon, whereas Dongducheon and Sangpaecheon showed higher dominance and low diversity. The river health was very good and good in the uppermost and Sudongcheon areas, whereas the upper stream was normal, and the middle and lower streams were poor and very poor, respectively. The water quality was also mostly poor or very poor from the midstream to the downstream, and only Sudongcheon was very good. Therefore, the water quality had a great impact on fish habitat and eventually affected river health significantly. Although the water quality of Shincheon has improved each year, the introduction of several foreign species had a very negative effect. Improvement of river health in Shincheon requires water quality improvement and management of exotic fish species.

• Korean Journal of Environment and Ecology
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• v.34 no.2
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• pp.142-156
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• 2020

This study surveyed Gyeongan Stream, a tributary of the Han River Drainage System, from April to October 2017 to investigate the characteristics of fish communities. The survey collected 40 species of 11 families from 48 survey stations using kick nets and cast nets. The dominant and subdominant species were Zacco platypus (48.0%) and Rhynchocypris oxycephalus (17.7%), respectively. The next most abundant species were Pungtungia herzi (6.8%), Z. koreanus (5.0%), Carassius auratus (4.3%), Squalidus gracilis majimae (2.7%), and Rhodeus notatus (2.5%). Among the fish collected, 14 species (35.0%) were Korean endemic species, and the exotic species were Micropterus salmoides, Lepomis macrochirus, and Cyprinus carpio (Israeli type). The land-locked species were Plecoglossus altivelis, Rhinogobius brunneus, and Cottus koreanus, while the species sensitive to climate change was C. koreanus. The community analysis showed that the dominance was higher at the uppermost stream station, whereas diversity and abundance tended to be lower at the upstream station and higher toward the downstream station. The community structure was largely divided into rivers (uppermost stream, upstream, and middle-lower stream) and lake. The river health was mostly good (23 stations, 47.9%) and fair (15 stations, 31.3%). Comparison with past surveys showed that 12 species identified in the past surveys did not appear in this survey; nine species appeared for the first time in this survey; and the ecosystem disturbance species - M. salmoides and L. macrochirus - tended to spread more widely gradually.

• Korean Journal of Environment and Ecology
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• v.33 no.3
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• pp.266-279
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• 2019

We investigated the characteristics of fish communities and habitat status of endangered species Rhodeus pseudosericeus in Heuk Stream, a tributary of the Han River, from April to October 2018. During this period, we collected 47 species of 14 families from 10 survey stations using kick nets, cast nets, and long bag set nets. The dominant and subdominant species were Zacco platypus (37.6%) and Z. koreanus (13.8%), respectively. The next most abundant species were Squalidus gracilis majimae (11.1%), Pungtungia herzi (7.7%), Rhodeus pseudosericeus (5.0%), Microphysogobio yaluensis (4.3%), and Hemibarbus longirostris (3.0%). Among the fish collected, 19 species (40.4%) were Korean endemic species. Endangered species were R. pseudosericeus and Acheilognathus signifer while exotic species were Micropterus salmoides and Oncorhynchus mykiss, and land-locked species were Plecoglossus altivelis and Rhinogobius brunneus. The community analysis showed that the dominance and evenness indexes were mostly low and that the diversity and richness indexes were high. Moreover, the river health (index of biological integrity) was mostly excllent (1 site is good, 9 sites are very good). R. pseudosericeus inhabited widely from St. 3 to St. 9 in Heuk Stream, and its population size was large. Age groups for R. pseudosericeus estimated by the frequency distribution of total length in spawning season (April) indicated the 32~45 mm group as 1-year old, the 46~59 mm group as 2-years old, 60~69 mm group as 3-years old, and the 70~89 mm group as 4-years or older. Total length range of male and female was similar, and the sex ratio of female (426) to male (394) was 1 : 0.95. A. signifer, which had been released in Heuk Stream, inhabited from St. 4 to St. 5, but its population size was small. Lastly, this paper discusses a conservation plan for fish in Heuk Stream.