Nakdong River Environment Research Center

South Korea

Nakdong River Environment Research Center

South Korea
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Choi J.-Y.,National Institute of Ecology | Jeong K.-S.,Pusan National University | Kim S.-K.,Nakdong River Environment Research Center | Son S.-H.,National Institute of Ecology | Joo G.-J.,Pusan National University
Journal of Ecology and Environment | Year: 2016

Background: Macrophytes are commonly utilised as habitat by epiphytic species; thus, complex macrophyte structures can support high diversities and abundances of epiphytic species. We tested the hypothesis that the presence of aquatic macrophytes is an important factor determining Sida crystallina (O.F. Müller, 1776) distribution. Results: An ecological survey was conducted in 147 lentic freshwater bodies. S. crystallina was frequently observed, and its density was strongly associated with macrophyte abundance. S. crystallina was found on emergent plant species such as Phragmites australis and Paspalum distichum, attached to the stem surfaces by adhesive substances secreted by the nuchal organ. Thus, S. crystallina was more strongly attached to macrophytes than to other epiphytic cladoceran species. We found higher densities of S. crystallina in filtered water with increased macrophyte shaking effort (i.e. 10, 20, 40, or 80 times). S. crystallina attachment was not related to fish predation. Stable isotope analysis showed that S. crystallina utilises epiphytic organic matter (EOM) on macrophytes as a food source. Conclusions: Consequently, S. crystallina seems to have a strong association with species-specific macrophyte biomass than with other cladoceran species, which may contribute to this species’ predominance in various freshwater ecosystems where macrophytes are abundant. © The Author(s). 2016.

Jeong K.-S.,Pusan National University | Kim H.-G.,GIS United Inc. | Jeong J.-C.,Namseoul University | Kim D.-K.,Seoul National University | And 4 more authors.
Annales de Limnologie | Year: 2011

Stream restoration is an important process affecting the ecological health of stream ecosystems. There have been numerous cases of restoration, dealing with either structural or biological changes. In Korea, most restoration projects have merely dealt with improving hydrological characteristics or water quality; however, in recent years the improvement of ecological characteristics has been an increasing focus for restoration projects. In this study, we utilized data collected from 5675 stream sites in May 2007 to discover general patterns of anthropogenic modification in Korean streams. The survey results after application of the stream modification index (SMI; presence or absence type; high scores indicate more disturbed) provided a general distribution of disturbed/undisturbed streams or rivers in the watershed. We then compared the level of modification with the socio-geographical patterns (population, land coverage, elevation, and slope) for the watershed. The results show that streams in highly populated areas suffered from human modification compared with other well-preserved stream sites. In metropolitan cities, urbanized areas had positive relationship as identified by a high SMI. On the other hand, agricultural land cover identified an SMI increase for lowland river area. In general, mountainous streams possessed a better status in stream morphology due to different land-cover patterns (i.e., mainly forested area); however, some mountainous areas were impacted by concentrated summer rainfall. We could distinguish the forcing variables (i.e., land use pattern) for the disturbed streams through a comparison between the SMI and geographical information; the SMI application was able to identify areas of high necessity for restoration. © EDP Sciences, 2011.

Ahn J.M.,Nakdong River Environment Research Center | Lyu S.,Changwon National University
KSCE Journal of Civil Engineering | Year: 2016

The instream flow of the Ara River is to be supplied from the Han River, and so an Environmental Fluid Dynamics Code (EFDC) model was applied to investigate the impact of water-intake to the Ara River on the total river flow and saline water intrusion. Through the numerical simulation of flow and saline water intrusion under different drainage conditions, it was found that the water intake for the Ara River has an impact not only on the hydraulic characteristics (water level and flow rate), but also on the extent of saline water intrusion in the Han River. It was also found that the change of discharge in the Han River, caused by the water supplying to the Ara River, can increase the salt concentration in the vicinity of the Singok Submerged Weir by 0.5 psu. As agricultural productivity can be affected by even this small amount of salt concentration change, much closer attention should be paid to the relation between water-intake condition and its effect on the Han River. © 2016 Korean Society of Civil Engineers and Springer-Verlag Berlin Heidelberg

Jeong H.,Nakdong River Environment Research Center | Kotov A.A.,RAS Severtsov Institute of Ecology | Lee W.,Hanyang University | Jeong R.,Hanyang University | Cheon S.,Nakdong River Environment Research Center
Journal of Ecology and Environment | Year: 2015

We investigated cladoceran fauna from 71 study areas in South Korea. Sixty-two taxa were found, of which there were 30 planktonic and 25 littoral-benthic cladoceran species. In the present study, taxa of cladocera were identified by biographical traits. Species endemic to the Far East were found in the northernmost areas of South Korea, whereas Palearctic species were found in the southernmost areas. Generally, coexistence of cladoceran species in northern and southern areas was observed, implying possible faunistic complexes of cladocera in various areas of South Korea. We believe that further studies conducted in different habitats will greatly expand our knowledge of the biodiversity of cladocera in South Korea. © 2015 The Ecological Society of Korea. All rights are reserved.

Ahn J.M.,Nakdong River Environment Research Center | Lee S.J.,K water Research Institute | Kang T.,K water Research Institute
Desalination and Water Treatment | Year: 2016

The accurate prediction of the water quality of a river is very important in identifying instream flow and water supply requirements and solving relevant environmental problems. The purpose of the study is to develop a water quality forecasting system for the Geum River in Korea. The water quality forecasting system was composed with the Streamflow Synthesis and Reservoir Regulation (SSARR) for watershed runoff simulation and Qual2E for calculation of river quality. The SSARR model was improved by applying the Optimal Linear Correction method and was also used to predict probabilistic streamflow with the ensemble stream prediction. The water quality forecasting system was validated with data measured at the Geum River Basin in 2007 and 2008. As the results, it was found that the proposed model simulated the values of BOD, T-N, and T-P within acceptable reliability. The developed system will contribute to various prediction of water, and improvement of current water quality management practice. © 2015 Balaban Desalination Publications. All rights reserved.

Ryu H.S.,Nakdong River Environment Research Center | Jang S.H.,Daegu University | Lee J.H.,Daegu University | Lee J.J.,Daegu University
Journal of Ecology and Environment | Year: 2014

This study was undertaken to suggest an effective fisheries resources management system by using stock assessment and potential yield analyses of crucian carp population in the mid-upper system of the Seomjin River. Fieldwork was conducted seasonally from 2008 to 2009 in the mid-upper system of the Seomjin River. The stock assessment was carried out by the swept area method and the potential yield was estimated by improved fisheries resource potential estimation system based on the Allowable Biological Catch. Also, the yield-per-recruit analysis was used to review the efficient management implication of the resource, Carassius auratus. As a result, the age at first capture (tc) was estimated as 1.468 year, converted body length (BL) was 10.8 cm. Meaning the current fishing intensities, the instantaneous coefficient of fishing mortality (F) was 0.067 year-1, and the yield-per-recruit analysis showed that the current yield per recruit was estimated to be 15.999 g with F and tc. The instantaneous rate of fishing mortality that provides for Allowable Biological Catch (FABC) based on the current tcand F was estimated as 0.618 year-1. Therefore, the optimum fishing intensities could be achieved at the higher fishing intensity for Carassius auratus. The calculated annual stock of C. auratus was estimated as 7,608 kg, and the potential yield was estimated as 343 kg with tcand F at the fixed current level. Using yield-per-recruit analysis, if F and tcwere set at 0.618 year-1and 2 year, the yield per recruit and total allowable catch would be predicted to increase to 62 g and 2,531 kg by about 3.9 times and 7.3 times, respectively. © 2014 The Ecological Society of Korea. All rights are reserved.

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