• Korean Journal of Environment and Ecology
• /
• v.23 no.4
• /
• pp.353-364
• /
• 2009

This study was conducted to evaluate the effect of erosion control works on the stream ecosystem in a mountain torrential stream. The species composition of benthic macroinvertebrates and biological water quality were investigated before and after construction of erosion control works at 5 sites. The total number of benthic macroinvertebrates before construction was 3,086 individuals including 4 phyla, 6 classes, 11 orders, 22 families, and 25 species, but after construction it has decreased to 1,208 individuals including 4 phyla, 6 classes, 10 orders, 17 families, and 19 species. Especially, the diversity, richness, and evenness indices, which were calculated based on existing number of biological species, have decreased or not produced at the erosion control sites, where biological species were not found or the minimum number of species were found. The results of community analysis of benthic macroinvertebrates and ESB(Ecological Score of Benthic macroinvertebrate community) indicated that the environmental qualities of the stream based on saprobity, environmental condition, and water quality decreased after the construction at all sites: before construction, the top of the stream was satisfactory and some satisfactory, the middle was some defectiveness, and the lower was defectiveness and very defectiveness; after construction, all parts of the stream except some parts of the top were very defectiveness. Moreover, the water quality of torrential stream was rated between I to III before construction, but after construction, it declined to $IV{\sim}V$ except control. The habitat damage of benthic macro invertebrates occurred at all investigation sites after the construction of erosion control works led to reduction of the number of biological species and water quality deterioration. The results reported in this study were collected directly after the construction of erosion control works. Therefore, additional studies are needed to further explore the effect of disaster-prevention of erosion control works and the recovery process of stream ecosystem through long term monitoring.

• Journal of Environmental Science International
• /
• v.16 no.7
• /
• pp.831-838
• /
• 2007

In order to improve the water environment at urban streams in Korea, several river restoration projects have been initiated for past few years. This study evaluates the impact of diverting water application at the riverhead of Onchun stream through the monitoring program for several water quality and ecological parameters. Various water quality parameters and ecological item such as benthic macroinverterates has been investigated between 09/05 and 12/06. Analysis indicates that the application of diverting water from Nakdong river to Onchun stream distinctly improved several water quality parameters such as, PH, BOD, TN, TP and concentrations of heavy metals. Low flow augmentation also improve ecological indicies such as the diversity index of benthic macroinvertebrates. Generally speaking, releasing addition water from head water of Onchun stream improves various water environmental characteristics.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.30 no.5
• /
• pp.771-781
• /
• 1997

In order to select an effective and appropriate evaluation method for the marine environmental protection and management, it is necessary to evaluate the present status of environmental conditions and to monitor and regulate the harzadous waste continuously. Among the evaluation methods that use benthic fauna, some graphical methods and biological index methods such as species abundance-biomass (SAB), Rank-frequency diagram (RFD), Abundance-Biomass comparison (ABC), log-normal distribution (LND), and Benthic Pollution Index (BPI) modified by Infaunal Trophic Index were used for the assessments of marine environment in the Inchon coastal area. Even though the graphic methods are convenient for easy glimpse of general trend of environmental condition but because they require sufficient ecological data, those methods do not fit for analysis or comparison of regional and detailed environmental condition. On the other hand, when BPI was applied, it was able to compare the spatial benthic conditions. Through considering the functional aspects of benthic fauna which can not be obtained in the cluster analysis, BPI was made it possible to measure or trace down the source of pollution. In the case of the environmental assessment result analyzed in Inchon coastal area, the north eastern part of Yongjongdo was more influenced by the pollution than the outer area of Inchon. The research indicates that especially Inchon harbor has been greatly affected.

• Ocean and Polar Research
• /
• v.29 no.3
• /
• pp.233-244
• /
• 2007

Nine surface sediments from Masan Bay and Gadeog Channel were taken for grain size and geochemical and foraminiferal analyses in August 2002. The sediments consist of mud with 7.29-8.54 $\phi$ in mean grain size. Average concentrations of Al, Fe and Mn are higher in Gadeog Channel than those in Masan Bay. On the other hand, average concentrations of Pb, Cu, Zn, Cd, Cr, Ni and V are higher in Masan Bay than those in the channel. The latter group of elements show the highest concentration at station M4, off the outfall of treated wastewater disposal. Eighty-one foraminiferal species are identified in total assemblages, including 21 species of living populations. The number of individuals, species number, species diversity and equitability in Masan Bay have lower values than those in Gadeog Channel. The foraminiferal fauna off the outfall is relatively poor. Compared to geochemical and foraminiferal data obtained in 1996, heavy metals are more enriched, and the characteristics of foraminifera are little changed. These features indicate that the pollution of Masan Bay has not been reduced.

• Korean Journal of Environment and Ecology
• /
• v.29 no.2
• /
• pp.228-235
• /
• 2015

Stream ecosystems are closely related to many human activities. Therefore, streams are affected by anthropogenic disturbances such as riverine development and gravel-mining as well as deterioration of water quality. The goal of this study was to elucidate the recolonization process of the macroinvertebrate community after a small-scale anthropogenic disturbance. Field studies were conducted at three sites in a natural stream. The number of recolonizing species tended to increase slightly over time, exceeding the total species number of the control. Ephemeroptera contributed the most to shaping the recolonizing pattern of the entire community. From the result of changes in dominant species, the early recolonizers of each site were the species that showed more frequent occurrence particulary at each sites. But the late recolonizers are Chironomidae at all the sites commonly. This result implies that the actual differences exist among the recolonizing trends of each benthic macroinvertebrate taxon. Collector-gatherers and scrapers comprised about 70% of the recolonizing species. These results indicate that the recolonizing process of an aquatic community after an artificial disturbance depends on the environmental conditions(particularly substratum composition or organic pollution) of the habitat.

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

• Journal of Ecology and Environment
• /
• v.36 no.4
• /
• pp.371-390
• /
• 2013

Remarkable diversity of diatom taxa occurs in intertidal sand-flats of the Nakdong River estuary, one of the most dynamic and productive ecosystem in Korea. Benthic diatoms were collected from the sandy sediments to clarify the taxonomic accounts and distribution of the old genus Navicula, i.e., the naviculoid flora. Total 92 taxa belonging to Navicula sensu stricto and 22 genera separated from Navicula sensu lato are reported with brief descriptions and micrographs, and many species remain unidentified. The genera are ranked by the number of diatom species: Navicula of 33 species and varieties, Fallacia of 17 species, Placoneis of five species, Fogedia and Parlibellus of four species, Austariella, Hippodonta and Petroneis of three species, Cosmioneis, Diadesmis, Luticola, Moreneis and Sellaphora of two species and variety, Berkeleya, Chamaepinnularia, Cocconeiopsis, Diademoides, Dickieia, Eolimna, Geissleria, Haslea, Lyrella and Mayamaea of one species. Through 32 samplings of the 12 areas, the important species were identified Navicula perminuta, N. gregaria, N. torneensis, Fallacia cunoniae, F. litoricola, F. subforcipata, F. tenera. The naviculoid diatoms constitute an average of 27% (range: minimum to maximum, 5-75%), of the benthic diatom assemblages. The diatom assemblages are characterized by the colonizing of a few dominant or frequent species and many occasional or rare species. The dominant species were observed to fluctuate with sampling site and time. Among the reported naviculoid diatoms, 46 taxa are newly reported in Korea.

• Korean Journal of Ecology and Environment
• /
• v.45 no.4
• /
• pp.420-443
• /
• 2012

An Individual-Based Model (IBM) was developed by employing natural and toxic survival rates of individuals to elucidate the community responses of benthic macroin-vertebrates to anthropogenic disturbance in the streams. Experimental models (dose-response and relative sensitivity) and mathematical models (power law and negative exponential distribution) were applied to determinate the individual survival rates due to acute toxicity in stressful conditions. A power law was additionally used to present the natural survival rate. Life events, covering movement, exposure to contaminants, death and reproduction, were simulated in the IBM at the individual level in small (1 m) and short (1 week) scales to produce species abundance distributions (SADs) at the community level in large (5 km) and long (1~2 years) scales. Consequently, the SADs, such as geometric series, log-series, and log-normal distribution, were accordingly observed at severely (Biological Monitoring Working Party (BMWP<10), intermediately (BMWP<40) and weakly (BMWP${\geq}50$) polluted sites. The results from a power law and negative exponential distribution were suitably fitted to the field data across the different levels of pollution, according to the Kolmogorov-Smirnov test. The IBMs incorporating natural and toxic survival rates in individuals were useful for presenting community responses to disturbances and could be utilized as an integrative tool to elucidate community establishment processes in benthic macroin-vertebrates in the streams.

• Journal of Aquaculture
• /
• v.9 no.1
• /
• pp.65-71
• /
• 1996

To estimate the variation of food organisms on the corrugated PVC sheets, we analysed the chlorophyll a and. pheopigments of the benthic microalgae on the sheets from the oyster culture ponds. We estimated the standing crops as the amounts of chlorophyll a, and the physiological state of cells as the pheopigments level in the benthic microalgae. The amount of chlorophyll a was increased by immersion time in winter but the peak was observed every two weeks in summer, while the ratio of pheopigments was highest in summer but the low level was observed in spring and autumn. These seasonal variation were well coincided with the natural spawning season and the good microalgae nutritional valance.

• Journal of Wetlands Research
• /
• v.7 no.4
• /
• pp.51-65
• /
• 2005

The insects and Benthic Macro-Invertebrates are very important for index of investigation. This reserch is executed a field investigation with a date analysis of the laboratory under such as above hypothesis and we have grasped the change of the creature according to the season through the executing of field investigation(We executed six times about the insects, seven times about the Benthic Macro-Inbertebrates each expending from Apr. to Oct. 2004). The result of summary in 2004 show that, we have grasped 12 orders 56 familys 116 species on 2001 and 10 orders 42 familys 78 species on 2002 through the investigation. Also we have grasped 13 orders 53 familys 114 species on 2003 and 12 orders 63 familys 121 speceies on 2004 through the investigation. In the case of enthic Macro-Invertebrates, we executed the analysis through the investigation result expending from 2003 to 2004 due to there is no literature investigation record from 2001 to 2002. We have grasped 8 orders 17 familys 24 species on 2003 and 7 orders 11 familys 24 species on Aug. 2004 through the investigation. We executed the analysis about an each condition due to it is difficult to compare the above result simply by the various variable at the investigation. We expect that it become the fundamental reference data to establish a efficient mode of life undo plan after grasped the inhabitation and movement route of creature inside the river through this reserch.