• Fisheries and Aquatic Sciences
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• v.19 no.1
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• pp.5.1-5.7
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• 2016

The study was conducted to know the cyclic changes in gonadal maturation and to investigate the developmental stages of oocytes and testicular germ cells of an air-breathing fish, Channa striata. Fish were sampled monthly from lentic and lotic environments of three geographical locations of Bangladesh from December to November and the histological analysis of their gonad was done to evaluate the objectives. The highest mean GSI was $5.95{\pm}0.20$ for female in July and $0.14{\pm}0.01$ for male also in July showing that the gonadal development reached its peak during this month. The highest mean oocyte diameter was $1257.50{\pm}24.17{\mu}m$ observed in July implying that the oocyte reached maturity in this month. Histological study of ovary revealed the evidence of early yolk granule stage and late yolk granule stage from April to July. In case of male four stages of spermatogenesis were distinguished and spermatozoa were highly abundant in June and July. So the monthly pooled values of GSI and the analysis of gonadal histology indicated that the peak breeding season of C. striata occurred in July in the lentic and lotic environments. Samples collected from lentic and lotic habitats are suggestive of no difference in the development of the gonad. The results of the present study will be useful for selective breeding programme, conservation and sustainable fishery management of C. striata in its natural habitat.

• Korean Journal of Ecology and Environment
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• v.51 no.4
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• pp.331-344
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• 2018

Lotic organisms in streams are affected by natural and anthropogenic disturbances such as increase of heavy rainfall event caused by climate change and flow regime change caused by weir constructions. Based on domestic and foreign literature, 157 Korean benthic macroinvertebrate taxa were selected species as potential lotic candidates. Three shoreline sites (total 54 samples) were surveyed consecutively before ('08~'09), during ('10~'12) and after ('13~'16) the construction of the weirs (Gangcheon, Yeoju and Ipo weir) in the Namhan-River for tracing changes of lotic communities. As a result, water flow of the Ipo-wier and water quality variables such as T-N, T-P, BOD5, etc. of the weir section revealed no significant changes. Physical habitat conditions such as the flow velocity and streambed substrate evidently changed. Particulary, flow velocity measured at sampling points along with each microhabitat drastically decreased and particle size of streambed substrate steadily decreased after weir constructions. Lotic organisms also decreased after construction, especially Hydropsychidae (insecta: Trichoptera) acutely decreased from $3,526ind.\;m^{-2}$ to $2ind.\;m^{-2}$ As a result of CCA, lotic species such as Hydropsyche valvata, Hydropsyche kozhantschikovi, Cheumatopsyche brevilineata, Cheumatopsyche KUa, Macrostemum radiatum, etc. correlated with the flow velocity, streambed substrate. Therefore, the decrease of the flow velocity and substrate size after weir construction seemed to be closely related to the decrease of the individual abundances of the lotic organisms independently of water quality. In order to evaluate the influence of the ecosystem on the flow regime change more accurately, it is necessary to study the indicator species based on the resistance or preference of the flow.

• Journal of Environmental Impact Assessment
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• v.20 no.1
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• pp.89-96
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• 2011

This study was carried out to assess the variations of water quality caused by the dam construction on the river. Six dams-Yongdam, Miryang, Hoengseong, Boryeong, Jangheung and Buan- constructed recently in Korea were selected for the study. Chemical oxygen demand(COD) was increased in the initial stage of water storage at dams compared to the lotic(river) environment, but after 3 years it was maintained lower and stabilized concentrations. Five dams except for Jangheung Dam were maintained Ia~Ib grade conditions under the water quality criteria of Korea. The concentrations of total nitrogen(T-N) were decreased under the lentic(reservoir) environment compared to the river status. Total phosphorus(T-P) was decreased 13~63% at the reservoir condition. We concluded that increase of COD concentration was due to the debris organic materials of the land, but temporary phenomenon. T-N and T-P concentrations were decreased at the lentic condition compared to the lotic.

• The Korean Journal of Ecology
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• v.21 no.6
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• pp.759-770
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• 1998

biotic indices scoring with the benthic macroinvertebrates were assessed as pollution monitoring tools in the north branch of the Han River system, Korea. We investigated the temporal variability of water quality at unpolluted, moderately polluted and heavily polluted sites using several biotic indices and assessed appropriate biological monitoring indices for lotic systems in Korea. The following biotic and chemical indices were employed in order to compare their applicability to the lotic systems : Trent Biotic Index (TBI), Chandler's Biotic Index-Average Score per Taxon (CBI-ASPT), Modified Biological Monitoring Working Party Score System-Average Score per Taxon (BMWP-ASPT), Hilsenhoff's biotic Index (BI) and Family-level Biotic Index (FBI) models for biotic analyses and National Sanitation foundation's Water Quality Index (NSFWQI) and comprehensive Chemical Pollution Index (Pb/n) for chemical analyses of water quality. Index and score values were compared with each other and with 24 water chemistry parameters. All biotic indices were significantly auto-correlated (p<0.001) and BI and FBI/ROK among them were highly correlated (r=0.84). BI and BMWP-ASPT models were also highly correlated with NSFWQI, while TBI values showed high correlation with the Pb/n. The BI and BMWP-ASPT were highly correlated with the most water chemistry parameters. We conclude that the BI model, which includes indicator species and abundance of taxa, is best suited for the bioassessment of lotic systems in Korea. For rapid field-based assessments, FBI/ROK and BMWP-ASPT models are also appropriate.

• Animal cells and systems
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• v.8
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• pp.29-29
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• 2004

• Proceedings of the Korea Society of Environmental Biology Conference
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• 2002.05a
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• pp.69-69
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• 2002

• 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.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.24 no.6
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• pp.133-144
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• 2021

This study aims to estimate location of land mammals habitat by analyzing spatial data and investigate how to apply environmental DNA monitoring methodology to lotic system in Yangpyeong-gun, Gyeonggi-do. Environmental DNA sampling points are selected through spatial analysis with QGIS open source program by overlaying Kernel density of wild boar(Sus scrofa), elevation, slope and land-cover map, and 81 samples are collected. After 240 mL of water was filtered in each sample, metabarcoding technique using MiMammal universal primer was applied in order to get a whole list of mammal species whose DNA particles contained in filtered water. 8 and 22 samples showed DNA of wild boar and water deer, respectively. DNA of raccoon dog, Eurasian otter, and Siberian weasel are also detected through metabarcoding analysis. This study is valuable that conducted in outdoor lotic system. The study suggests a new wildlife monitoring methodology integrating overlayed geographic data and environmental DNA.

• Proceedings of the Zoological Society Korea Conference
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• 1999.10b
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• pp.145.2-145
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• 1999

No Abstract, See Full Text

• Earthquakes and Structures
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• v.16 no.6
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• pp.727-741
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• 2019

A reinforced concrete water tank is a typical functional liquid storage structure and cracks are the greatest threat to the liquid storage structure. Tanks are readily cracked due to seismic activity, thereby leading to the leakage of the stored liquid and a loss of function. In order to study the effect of cracks on liquid storage tanks, self-healing and leakage tests for bending cracks and through cracks in the walls of a reinforced concrete water tank were conducted. Material performance tests were also performed. The self-healing performance of bending cracks in a lentic environment and through cracks in a lotic environment were tested, thereby the self-healing width of bending micro-cracks in the lentic environment in the short term were determined. The through cracks had the capacity for self-healing in the lotic environment was found. The leakage characteristics of the bending cracks and through cracks were tested with the actual water head on the crack. The effects on liquid leakage of the width of bending cracks, the depth of the compression zone, and the acting head were determined. The relationships between the leakage rate and time with the height of the water head were analyzed. Based on the tests, the relationships between the crack characteristics and self-healing as well as the leakage were obtained. Thereby the references for water tank structure design and grading earthquake damage were provided.