• Journal of Korean Society on Water Environment
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• v.37 no.3
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• pp.217-228
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• 2021

This paper discusses a methodology where an integrated modelling framework is used to quantify the risk derived from anthropic activities on habitats and species. To achieve this purpose, a tool comprising the Delft3D and HABITAT model, was applied in the Yeongsan river. Delft3D effectively simulated the operational condition and flow of weirs in river. In accuracy evaluation of the Delft3D-FLOW, the Bias, Pbias, Mean Absolute Error (MAE), Nash-Sutcliffe Efficiency (NSE), and Index of Agreement (IOA) were used, and the result was evaluated as grade above 'Satisfactory'. The HABITAT calculated Habitat Suitability Value (HSV) for the following eight species: mammal, fish, aquatic plant, and benthic macroinvertebrate. An Area was defined as a suitable habitat if the HSV was larger than 0.5. HABITAT was judged accurately by measuring the Correct Classification rate (CCR) and the area under the ROC curve (AUC). For benthic macroinvertebrate, the CCR and AUC were 77% and 0.834, respectively, at thresholds of 0.017 and 4 inds/m² for HSV and individuals per unit area. This meant that the HABITAT model accurately predicted the appearance of the benthic macroinvertebrates by approximately 77% and that the probability of false alarms was also very low. As a result of evaluating the suitability of habitats, in the Yeongsan river, if the annual "lowest level" (Seungchon weir: 2.5 EL.m/ Juksan weir: -1.35 EL.m) was maintained, the average habitat improvement effect of 6.5%P compared to the 'reference' scenario was predicted. Consequently, it was demonstrated that the integrated modelling framework for habitat suitability assessment is able to support the remedy aquatic ecological management.

• Korean Journal of Ecology and Environment
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• v.55 no.3
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• pp.201-211
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• 2022

The macroinvertebrate community in the Singal reservoir, Yedang and Juam lake was investigated three times from April 2021 to October 2021. Each lake was investigated by dividing it into inflow, middle-flow, and outflow. Additionally, sampling was conducted again by dividing it into the edge and center parts at each inflow, middle-flow, and outflow. Eight families of benthic macroinvertebrates were collected except for chironomids in the sampling sites. Dominant macroinvertebrates were investigated as chironomids, and Tubificidae was sub-dominant organisms. The density of macroinvertebrate community was higher in the edge area than in the center bottom of the lakes. The density of chironomids was low when the water level was high but was high when the water level was low. In the edge area of the middle-flow in Singal reservoir, the density of chironomids was 1,208 ind. m^-2 in April when the water level was high, but it increased to 1,401 ind. m^-2 in July when the water level was low. Similarly, the density of chironomids at the outflow of Yedang lake was high (1,990 ind. m^-2) in July when the water level was low. The density of chironomids also decreased along with the increasing water level at all edge areas of Juam lake. These results indicated that it will be necessary to consider the water level when studying macroinvertebrate communities in the lake.

• Korean Journal of Environment and Ecology
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• v.30 no.1
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• pp.81-91
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• 2016

This study was performed to investigate and monitor changes in aquatic ecological communities, particularly benthic macroinvertebrates from the upper reaches to the down reaches of Songchu valley before the project of Songchu valley translocation initiates. We aimed to verify the translocation effects of the valley on the aquatic macroinvertebrate communities. A field investigation was conducted over three rounds from November 2012 to August 2013. A total of four sites were selected: one to represent the control site (St. 1), two for the translocation sites (St. 2, 3), and one for the downstream sites (St. 4). Our quantitative sampling revealed that the total number of benthic macroinvertebrates were 3,805, which belong to 62 species, 32 families, 9 orders, 5 classes and 4 phyla. As a result of the community analysis at the control site, dominant index was 0.52(${\pm}0.16$), diversity index was 1.95(${\pm}0.44$), evenness index was 0.81(${\pm}0.04$), and richness index was 2.25(${\pm}0.85$). Thus, the community structure was found to be relatively stable. For the EPT ratio of species and individuals that appeared, the control site showed the highest values at 67.60(${\pm}5.66$)% and 66.30(${\pm}2.06$)% respectively, but its value became lower towards the downstream sites. Upon the statistical analysis of the functional feeding groups, it was found that gathering-collectors and filtering-collectors increased toward the downstream sites while shredders decreased. From the point of habitat-oriented group evaluation, sprawlers decreased and burrows increased toward the downstream sites. According to the analysis using Korea Saprobic Index (KSI), the control site is categorized as grade A with average value at 0.75(${\pm}0.10$). However, the grade gradually falls from A to B toward the lower reaches, as the KSI value increases at the translocation and downstream sites.

• Korean Journal of Environmental Biology
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• v.35 no.1
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• pp.83-94
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• 2017

Benthic macroinvertebrates were investigated in thermal discharge that flows Buso stream region from December 2015 to February 2016, Korea. Study site was selected for the upstream, downstream relative to the mixing station and mixing station which thermal effluent flows, water quality analysis and benthic macroinvertebrates composition, taxa of EPT-group individuals, analysis of biological water quality. As a result, a total of 4,015 individuals including 50 species, 30 families, 11 orders, 4 classes, and 3 phyla were recognized. Taxa of species is Ephemeroptera 16 species (32.0%) including 6 families, the density composition was highest in 1,848 individuals (46.03%) Diptera. EPT-group occupied during the study period were a total of 1,876 individuals (46.72%) including 32 species and 17 family, lowest in the mixing station for study period. As a results of community analysis, mixing station in the Limnodrilus gotoi and Chironomidae sp.2, which is dominated by the analysis was Ecdyonurus levis, Cincticostella levanidovae, Nemoura KUa. The dominant species showed a difference in the upstream and downstream. In the functional feeding groups, in the upstream and mixing station Gathering-Collectors, downstream it was analyzed that the ratio of the highest Filtering-Collectors and decreased the ratio of Shredders increasing from upstream to downstream. Habitat orientation group is analyzed that accounted for most of the Clingers and Burrowers, from upstream to downstream toward the higher the ratio of Clingers. Biological water quality assessment results were analyzed the worst state in the mixing station with an average 2.73 (${\pm}0.41$). Correspondence analysis, correlation analysis results of water temperature and the cold-water species, as the water temperature increases were analyzed by reducing cold-water species and EPT-group.

• Korean Journal of Environment and Ecology
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• v.27 no.1
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• pp.52-63
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• 2013

Benthic macroinvertebrates were investigated in Yongdam-dam and Hapcheon-dam resions from June to October 2011, Korea. Yongdam-dam and Hapcheon-dam are geographically contiguous, but they are classified as other water system. Experiment site(YE-1, 2, 3; HE-1, 2, 3) which is thought to be affected by dam, control site(YC-1, 2; HC-1, 2) which is thought not to be affected by dam were selected. Species composition, macroinvertebrate communities, composition of the functional feeding groups, habitat orientied groups and community stability were assessed Yongdam-dam and Hapcheon-dam regions. Ten sites were selected for quantitative(Surber sampler $30cm{\times}30cm$) of benthic macroinvertebrates. As a results, a total of 6,369 individuals including 69 species, 33 families, 12 orders, 6 classes and 4 phyla were recognized in Yongdam-dam region. Also, a total of 5,728 individuals including 81 species, 44 families, 13 orders, 5 classes and 4 phyla were recognized in Hapcheon-dam region. Dominance index was 0.27~0.50(mean${\pm}$SD $0.38{\pm}0.09$), diversity index was 2.22~2.97($2.67{\pm}0.29$), evenness index was 0.63~0.76($0.72{\pm}0.06$) and richness index was 4.43~7.06($5.69{\pm}0.99$) in Yongdam-dam region. Dominance index was 0.40~0.81($0.59{\pm}0.18$), diversity index was 1.40~2.39($2.00{\pm}0.43$), evenness index was 0.38~0.68($0.56{\pm}0.13$) and richness index was 4.04~5.80($4.95{\pm}0.70$) in Hapcheon-dam region. In the functional feeding groups, filtering-collectors and gathering-collectors were the highest in the whole sites. In the habitat orientied groups, burrowers, clingers and swimmers were considerably occupied in all sites. As a result of community stability analysis, experiment sites has been identified much as species high resistance and resilience to environmental changes in Yongdam-dam. Control sites has been identified much as species low resistance and resilience to environmental changes in Hapcheon-dam. Species belonging to the Igroup is considered to be important in the river ecosystem stability of large dams downstream areas.

• Journal of Wetlands Research
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• v.24 no.3
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• pp.185-195
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• 2022

This study conducted a survey over spring and autumn from 2014 to 2020 to confirm the ecological characteristics of the size of streams and habitats, centering on the ecological landscape conservation area, and a total 256 species of benthic macroinvertebrates in 105 families, 25 orders, 8 classes, and 5 phyla appeared. In terms of appearance species, by region, the rate of appearance of Ephemeroptera and Trichoptera was high in regions consisting of lotic area and the rate of appearance of Coleoptera and Odonata was high in regions consisting of lentic areas. When comparing the population of Ephemeroptera-Plecoptera-Trichoptera (EPT) groups by region, they were classified into three groups: upstream area, mainstream area, and lentic areas, and it was confirmed that the population ratio of EPT changed as it moved from upstream to downstream. As the stream order increased, the number of species and populations increased. The Shredder group (SH) tended to decrease as the size of stream increased(r=0.9925), and the Collector-Filtering (CF) tended to increase as the size of stream increased(r=0.9319). It was confirmed that the Scraper (SC) replaced each other between species with the same ecological status as it went downstream from upstream, and it is thought that the SC did not differ significantly by stream order. In order to maintain a healthy ecosystem in the designation and management of ecological landscape conservation areas, it is necessary to consider ecological factors such as competition and physico-chemistry factors such as water quality and substrate conditions. Therefore, if the competent authority designated survey areas including buffer areas that include streams and physical habitats of various sizes, it will be advantageous to the conservative area and securing more biological resources.

• Korean Journal of Ecology and Environment
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• v.55 no.1
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• pp.84-98
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• 2022

Estuary is important in terms of biodiversity because it has the characteristics of transition waters, created by the mixing of fresh- and seawater. The estuarine water circulation provides a variety of habitats with different environments by inducing gradients in the chemical and physical environment, such as water quality and river bed structure, which are ultimately the main factors influencing biological community composition. If the water circulation is interrupted, the loss of brackish areas and the interception of migration of biological communities will lead to changes in the spatial distribution of biodiversity. In this study, among the sites covered by the Estuary Aquatic Ecosystem Health Assessment, we selected study sites where changes in biodiversity can be assessed by spatial gradient from the upper reaches of the river to the lower estuarine area. The α-, γ- and β-diversity of diatom, benthic macroinvertebrates, and fish communities were calculated, and they were divided into open and closed estuary data and compared to determine the trends in biodiversity variation due to estuarine circulation. As results, all communities showed higher γ-diversity at open estuary sites. The benthic macroinvertebrate community showed a clear difference between open and closed estuaries in β-diversity, consequently the estuarine transects were considered as a factor that decreases spatial heterogeneity of their diversity among sites. The biodiversity trends analyzed in this study will be used to identify estuaries with low γ- and β-diversity by community, providing a useful resource for further mornitoring and management to maintain estuarine health.

• Korean Journal of Environmental Biology
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• v.17 no.2
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• pp.159-168
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• 1999

The ophemeropterans such as Epeorus pellucidus, Uracanthella rufa and Drunella uculea were dominated in station 1. It was generally showed the stable aquatic communities with low dominance index values throughout the year in station 2. The first dominant species in station 3 were all mayflies with the average DI value of 0.38. The first dominant species of Uracanthella rufa known as relatively tolerant species in station 4. A crustacean species Gammarus spp. have frequently occurred as the 1st or 2nd dominant species in station 5. Limnodrilus socialis, and Chironomus spp. were dominated in stations 6 and 7 Station 1, 2 and 3 were classified as oligosaprobic status according to their average diversity index values ranging from 3.46 to 3.52. Station 7 showed $\alpha$-mesosaprobic water condition with the overall average diversity value of 1.26. In general, the equitability and species richness values in the same sampling areas had close relations with their diversity values. The dendrogram drawn by dissimilarity values among 7 sampling sites indicates that the macrobenthic communities were divided into 3 groups： stations 1, 2, 3 and 4； stations 6 and 7； and station 5 alone.

• Korean Journal of Ecology and Environment
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• v.37 no.1 s.106
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• pp.87-95
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• 2004

Community dynamics of benthic macroinvertebrates in response to natural disturbances (flooding and water temperature) were investigated in the Suyong and Soktae Streams in Busan from October 1997 to September 1998. Oigochaeta and Chironomus, organic polluted indicators, were dominant and various taxa were observed at the study sites. The density and biomass of two dominant taxa increased in warm months while the indicators were washed away in the flooding season. From October to February when the water temperature was less than $15^{\circ}C$, Oligochaeta appeared to be dominant at the Soktae Stream. In contrast various taxa were collected at the Suyong stream. The densities of Oligochaeta and Chironomus increased at the Soktae and the Suyong streams in March. Due to the big flooding in April, the density of dominant taxa decreased abruptly. The community structure showed differences patterns in the flooding season at two streams from June to August. In the Soktae stream, the density increased in August. The reverse patterns were observed in the Suyong stream, washing out in June followed by slow recovery of densities in the fellowing months. Density and biomass showed relatively higher correlations in most taxa. CCA (Canonocial Correspondence Analysis) showed that taxa was different response to different environmental factors.

• Journal of Korean Society on Water Environment
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• v.24 no.6
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• pp.767-772
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• 2008

Studies regarding the application of the impervious cover rate as a watershed management index have increased in number due to concerns over watershed management. The impervious cover rate is suggested as an index that can manage not only water quality but also water volume and the water ecosystem. This study intends to prove its applicability through the interconnection of the impervious cover rate and the water environment in Korea. Analysis of a selected watershed with reference to impervious cover rates showed that a watershed with an impervious cover rate of over 30% had a direct runoff in excess of 60% of precipitation, while a watershed with an impervious cover rate of 7% had a direct runoff of 39%. Watersheds with higher impervious cover rates were also found to have higher BOD, though different watersheds showed slightly different aspects in connection with BOD. Monitoring of benthic macroinvertebrates showed that species inhabiting clean water appear more frequently in areas with lower impervious cover rates than areas with higher impervious cover rates, and in mainstream areas, relatively larger numbers of species appeared in areas with lower impervious cover rates. This suggests that impervious cover rates can be appropriately used as an index for watershed management, as it effectively represents changes to the water environment.