• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.2 no.4
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• pp.259-273
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• 2021

We conducted a study to investigate the characteristics of the carbon cycle of two streams (located in Shig a Prefecture, Japan), having similar size, namely, the Adokawa stream (length: 52 km, area: 305 km², watershed population: 8,000) and the Yasukawa stream (length: 62 km, area: 380 km², watershed population: 120,000), but with different degree of human activity. Samples were collected from these two streams at 14 (Adokawa stream) and 23 (Yasukawa stream) stations in the flowing direction. The dissolved inorganic carbon (DIC) concentration and the stable carbon isotope ratio of DIC (δ¹³C-DIC) were measured in addition to the watershed features and the chemical variables of the stream water. The δ¹³C-DIC (-9.50 ± 2.54‰), DIC concentration (249 ± 76 µM), and electric conductivity (52 ± 13 µS/cm) in Adokawa stream showed small variations from upstream to downstream. However, the δ¹³C-DIC (-8.68 ± 2.3‰) upstream of Yasukawa stream was similar to that of Adokawa stream and decreased downstream (-12.13 ± 0.43‰). DIC concentration (upstream: 272 ± 89 µM, downstream: 690 ± 37 µM) and electric conductivity (upstream: 69 ± 17 µS/cm, downstream: 193 ± 37 µS/cm) were higher downstream than upstream of Yasukawa stream. The DIC concentration of Yasukawa stream was significantly correlated with watershed environmental variables, such as, watershed population density (r = 0.8581, p<0.0001, n = 23), and forest area percentage of the watershed (r = -0.9188, p<0.0001, n = 23). δ¹³C-DIC showed significant negative correlation with the DIC concentration (r = -0.7734, p<0.0001, n = 23), electric conductivity (r = -0.5396, p = 0.0079, n = 23), and watershed population density (r = -0.6836, p = 0.0003, n = 23). Our approach using a stable carbon isotope ratio suggests that DIC concentration and δ¹³C-DIC could be used as indicators for monitoring the health of stream ecosystems with different watershed characteristics.

• The Korean Journal of Ecology
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• v.20 no.1
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• pp.69-78
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• 1997

The development of stream ecology, especially the progress of that field in North America, has been briefly reviewed, and stream studies in Korea were analyzed through literature survey. During the last two decades, theoretical advances in stream ecology and understanding of the structure and function of stream ecosystem were made from the studies mainly in North America. Early studies (1960-1970) focused on determination of the environmental factors controlling the distribution and abundance of organisms dwelling in streams. Introduction of conceptual development, such as the functional feeding concept, river continuum concept, and nutrient spiraling was notable in the late 70's and the 80's. For last 20 years, experimentation approaches to apply ecological principles were very fruitful in the understanding of community structure. Even though studies on the stream ecosystem is Korea have a long history, most of works were concentrated on limited subjects: water quality, abundance and distribution of aquatic insects and fishes. Basic ecological attributes of stream organi는 and test of ecological principles have rarely been a subject of research topics. We must concentrate our effort to enhance our understanding of stream and river ecosystem through qualitative, experimental and interdisciplinary approaches.

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.2 no.1
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• pp.53-61
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• 2021

Distribution of fish community depends largely on environmental disturbance such as habitat change. In this study, we evaluated the impact of environmental variables and microhabitat patch types on fish distribution in Yudeung Stream at 15 sites between early May and late June 2019. We used non-metric multidimensional scaling to examine the distribution patterns of fish in each site. Gnathopogon strigatus, Squalidus gracilis majimae, Zacco koreanus, and Zacco platypus were associated with riffle and boulder areas, whereas Iksookimia koreensis, Acheilognathus koreensis, Coreoleuciscus splendidus, Sarcocheilichthys nigripinnis morii, and Odontobutis interrupta were associated with large shallow areas. In contrast, Cyprinus carpio, Carassius auratus, Lepomis macrochirus, and Micropterus salmoides were found at downstream sites associated with large pool areas, sandy/clay-bottomed areas, and vegetated areas. On the basis of these results, we suggest that microhabitat patch types are important in determining the diversity and abundance of fish communities, since a mosaic of different microhabitats supports diverse fish species. As such, microhabitat patches are key components of freshwater stream ecosystem heterogeneity, and a suitable patch composition in stream construction or restoration schemes will support ecologically healthy food webs.

• Proceedings of the Korean Society of Environment and Ecology Conference
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• 2010.04a
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• pp.112-117
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• 2010

• Proceedings of the National Institute of Ecology of the Republic of Korea
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• v.3 no.2
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• pp.84-96
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• 2022

Most of the islands of Korea are distributed in the South and West Sea, and it consists of independent small stream. As a result, the fish community that inhabits the island's stream is isolated from the mainland and other island. This study utilized a Self-Organizing Map (SOM) and a random forest model to analyze the relationship between environmental variables and fish communities inhabiting islands in South Korea. Through the SOM analysis, the fish communities were divided into three clusters, and there were differences in biotic and abiotic factors between these groups. Cluster I consisted of sites with relatively larger island areas and a higher number of species and population. It was found that 15 out of 16 indicator species were included. Meanwhile, the remaining clusters had fewer species and populations. Cluster II, especially, showed the lowest impact from physical variables such as water width and depth. As a result of predicting the species richness using the random forest model, physical variables in habitats, such as stream width and water depth, had a relatively higher importance on species richness. On the other hand, forest area was the most important variables for predicting Shannon diversity, followed by maximum water depth, and gravel. The results suggest that this study can be used as basic data for establishing a stream ecosystem management strategy in terms of conservation and protection of biological resources in streams of islands.

• Proceedings of the Korean Society of Environment and Ecology Conference
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• 2003.10a
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• pp.231-233
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• 2003

• Ecology and Resilient Infrastructure
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• v.2 no.3
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• pp.247-254
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• 2015

Changes in land-use type can affect soil and water properties in stream ecosystems. This study examined the effects of different land-use types on biogeochemical properties and microbial activities of a stream. We collected water and sediment samples in a stream at three different sites surrounded by varying land-use types; a forest, a radish field and a rice paddy. Nitrogen contents, such as nitrate, nitrite and total nitrogen in the stream water body, showed significant differences among the sampling sites. The highest nitrogen values were recorded at the site surrounded by cropland, as fertilizer runoff impacted the stream. Soil organic matter content in the sediment showed significant differences among sites, with the highest content exhibited at the forest mouth site. These differences might be due to the organic matter in surrounding terrestrial ecosystems. Microbial activities determined by extracellular enzyme activities showed similar values throughout all sites in the water body; however, the activities in the sediments exhibited the highest values near the forest site and mirrored the soil organic matter content values. From these results, we conclude that different land-use types are important factors affecting water and sediment properties in stream ecosystems.

• Journal of Korea Water Resources Association
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• v.43 no.5
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• pp.421-431
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• 2010

The hydromorphological structure assessment of the urban streams of Anyang stream, Yangjae stream, Osan stream, Jangsu stream, and Hakui stream 5 years the after close to nature stream restoration work was performed using LAWA (Laenderarbeitsgemeinschaft Wasser) for the investigation of the ecology of streams in urban areas. Based on the results, the effectiveness of stream restoration in urban areas was least in spite that existing various types of stream improvements were applied. Significantly, the grade of the longitudinal, the waterfront, and the use of land nearby waterfront was poorly evaluated. It would be estimated that this trend was due to the discontinuity of the longitudinal, the lack of diversity in waterfront, the installation of facilities nearby waterfront, and was due to the use of hard materials as like stones, blocks, frames, and mats in waterfront. The further studies on the implementation of structural diversity in waterfront should be performed for the improvement of the ecology of urban streams.

• Proceedings of the Korean Society of Environment and Ecology Conference
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• 2009.10a
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• pp.177-181
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• 2009

• Proceedings of the Korean Society of Environment and Ecology Conference
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• 2007.04a
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• pp.219-222
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• 2007