• Ecology and Resilient Infrastructure
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• v.7 no.4
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• pp.366-373
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• 2020

This study investigated habitat diversity changes by conducting weir operations at the Sejongbo site in the Geum River basin. High-resolution aerial photographs taken before and after the weir-opening operation were used for habitat analyses. We classified water and bar areas into 17 types, such as lotic habitats, including riffles, runs, and glides, and lentic habitats, including reservoirs, pools, bar-head backwaters, and bar ponds. Then, we estimated each habitat area quantitatively, calculated a habitat diversity index, and established a habitat diversity map. Our results indicated that after the weir-opening operation, lotic habitats and new types of shallow lentic habitats increased in the water area. In addition, for the bar area, bare lands without cultivation increased distinctively. Finally, we observed that the habitat diversity index drastically increased after the weir-opening operation, which could provide a relatively simple channel of diverse habitats.

• Korean Journal of Environmental Biology
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• v.17 no.4
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• pp.401-405
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• 1999

Comprehensive collecting survey were performed fer study on ovipositioning habits and developmental process of Rana temporaria dybowskii from mid February 1998 to late May 1998 from Kyunggi-do, Kangwon-do and other areas in South Korea. Oviposition occurred in both running water and pool between late February and late May. In lotic habitat, they laid egg mass in irregularly ball shaped, and eggs were sticked to substrates such as stone or macrophytes. On contrary, in the pool, they laid an oval shaped egg mass not sticked to any other substrates. Every egg was hatched at day 7, and all developmental processes were completed at days 71 after oviposition. Developmental process of this species was relatively short, and this may increase predation activities during abundant prey season.

• Proceedings of the KSRS Conference
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• v.2
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• pp.647-650
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• 2006

Compact Airborne Spectrographic Imager (CASI) hyperspectral imagery was acquired over the Little Miami River Watershed (1756 square miles) in Ohio, U.S.A., which is one of the largest hyperspectral image acquisition. For the development of a 4m-resolution land cover dataset, a hierarchical approach was employed using two different classification algorithms: 'Image Object Segmentation' for level-1 and 'Spectral Angle Mapper' for level-2. This classification scheme was developed to overcome the spectral inseparability of urban and rural features and to deal with radiometric distortions due to cross-track illumination. The land cover class members were lentic, lotic, forest, corn, soybean, wheat, dry herbaceous, grass, urban barren, rural barren, urban/built, and unclassified. The final phase of processing was completed after an extensive Quality Assurance and Quality Control (QA/QC) phase. With respect to the eleven land cover class members, the overall accuracy with a total of 902 reference points was 83.9% at 4m resolution. The dataset is available for public research, and applications of this product will represent an improvement over more commonly utilized data of coarser spatial resolution such as National Land Cover Data (NLCD).

• Animal Systematics, Evolution and Diversity
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• no.spc9
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• pp.45-50
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• 2016

Freshwater benthic macroinvertebrates were investigated from five sampling sites on Jindo Island located in the southwestern end of the Korean Peninsula. A total of 47 species (average $14{\pm}3.16$ species per site, 40 species in lotic area, and 13 species in lentic area) belonging to 38 families, 14 orders, 5 classes, and 3 phyla were sampled. Coleoptera, Diptera, Ephemeroptera, and Trichoptera were the major groups of benthic macroinvertebrates with relatively high species richness. Species diversity indices (H') and richness indices (RI) of upper streams were relatively higher than those of lower streams, which were affected by agricultural effluent from the paddy fields.

• Journal of Ecology and Environment
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• v.39 no.1
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• pp.11-16
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• 2016

Declines in amphibian populations are occurring worldwide, and have been attributed to many factors, including anthropogenic environmental changes. One of the ramifications of such declines is abnormalities in many amphibian species. A strong association has been detected between human activities and abnormalities in amphibian populations, but studies on this association are largely focused on lentic species. In this study, it was analyzed whether the degree of local human activity was associated with the rate of abnormalities in Bombina orientalis which inhabited lotic environments. We found that the proportions of abnormalities in wild populations of B. orientalis increased, when i) the closest human land use was located within 100 m from the frogs' habitat, and ii) the proportion of human land use within a 300-m radius was high. Our findings suggest that human activity has a negative impact on the fitness of nearby amphibian populations, and that wild populations very close to human-induced disturbance are affected.

• Journal of Ecology and Environment
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• v.32 no.4
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• pp.221-227
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• 2009

This study describes time lag responses between hydrological variables and phytoplankton biomass in a regulated river system, the lower Nakdong River in South Korea. The lower Nakdong is a typical flow-controlled lotic system, and its limnological characteristics are influenced by climatic variation such as monsoons and summer typhoons. Mean rainfall in the area during summer is about 1,200 mm, which comprises >60% of annual rainfall. Our results show that the regulation of flow in the Nakdong by multi-purpose dams from 1995 to 2004 affected phytoplankton dynamics. Diatom blooms occurred in winter, when the limited discharge allowed for proliferation of the phytoplankton community. Using multiple regression analysis, we detected significant time-delayed relationships between hydrological variables and phytoplankton biomass. These results may be useful for water resource managers, and suggest that 'smart flow' control would improve water quality in large regulated river systems of the Republic of Korea.

• Journal of Environmental Science International
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• v.26 no.3
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• pp.373-380
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• 2017

This study identified the effect of changes in the riverbed on the benthic macroinvertebrate communities. The benthic macroinvertebrates collected from the surveyed sites belonged to 119 species, 65 families, 20 orders, and 7 classes in 4 phyla. The number of Ephemeroptera, Plecoptera, and Trichoptera (E.P.T) species was 42, 10, and 8, respectively, in the tributary, confluence, and Nakdong River sites. Lotic species (Hydropsychidae) showed a high density at the tributary sites, whereas lentic species (Chironomidae) showed a high density at the confluence and Nakdong River sites. Community analysis showed that the Dominance Index (DI) was 0.54 in tributary sites, and dominance indices increased closer to the Nakdong River sites. The diversity index (H') was inversely proportional to DI. The ratio of Burrowers species (BU) at the surveyed sites increased closer to the Nakdong River sites. Analysis of common species showed 37 species (34.6%) between the tributary and confluence sites and 66 species (51.5%) between the confluence and Nakdong River sites.

• Journal of Korean Society on Water Environment
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• v.33 no.3
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• pp.311-325
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• 2017

Habitat suitability index (HSI) of 17 benthic macroinvertebrate taxa, which were lotic insects of generic category except Potamanthidae in mayfly, was developed for three physical habitat factors (current velocity, water depth and substrate) based on an ecological monitoring in a Korean stream (Gapyeong). Weibull model was used as a probability density function to analyze the distribution of individual abundance related with physical factors, which showed it was so available. Number of species and total individual abundance increased along with the increase of current velocity and the mean diameter of substrate, and decreased along with the increase of water depth. Most taxa showed a clear preference for a fast current velocity, shallow water depth and coarse substrate except Ephemera, Potamanthidae (mayfly), and Plectrocnemia (caddisfly) which were rheophobic, potamophilic and lithophobious. Based on the canonical correspondence analysis, the relative importance of each factor was determined as follows: current velocity > substrate > water depth.

• Journal of Ecology and Environment
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• v.42 no.4
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• pp.150-154
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• 2018

In lotic wetlands, runner reed (Phragmites japonicus) plays a role as a pioneer, which helps other plant species to settle by making dense roots trapping floating-sediments. In lentic wetlands, on the other hand, P. japonicus could play a role as an invader threatening biodiversity by forming tall and dense stands. To conserve an abandoned paddy terrace in mountainous areas, a habitat of an endangered dragonfly species (Nannophya pygmaea), from the monotypic-occupation by P. japonicus, we applied three kinds of treatment: (1) hand-clipping in 2009, (2) mechanical excavating in 2012, and (3) planting of alternative vegetational unit in 2012. We have monitored vegetation changes in the wetland in 2008~2012 and 2017. Vegetation cover of P. japonicus sharply decreased from 43% in 2011 to 16% in 2012 by the mechanical excavation. After 5 years from applying the treatment, Schoenoplectiella mucronata that was utilized in the planting became the predominant species instead of P. japonicus and the number of wetland plant species increased from 16 to 25 with the shift in species composition. This study showed the utility of three control methods of P. japonicas in a lentic wetland.

• Fisheries and Aquatic Sciences
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• v.26 no.4
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• pp.256-267
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• 2023

The suitability of any fish species for successful aquaculture requires basic information on its reproduction and growth. This study investigated some facets of the reproductive biology of Synodontis shall (Mochokidae) from River Siluko in Nigeria. Fish samples were collected forth-nightly for a duration of fourteen (14) months-March 2015 to April, 2016 with the assistance of artisanal fishermen. Fishes were identified using taxonomic guides and standard techniques were used for determination of sex ratio, gonad maturation and fecundity. Linear regression method was used to define the correlation between fecundity and fish length, body weight and ovary weight. Results showed that sex ratio did not indicate a significant divergence (p > 0.05) from the 1 male to 1 female distribution ratio (1:1.41). Gonad morphology revealed paired gonads. Testes and ovaries were classified into four maturity stages: immature, resting, ripening and ripe. Gonadosomatic index ranged from 0.04 to 5.68 (males) and 0.03 to 20.19 (females). Absolute fecundity ranged from 1,014 to 4,520 eggs (mean = 2,592 eggs) and did not correlate significantly (p > 0.05) to ovary weight. This study has contributed to existing data on the biology of freshwater fish species in Nigeria and provided valuable information for fishery management tools in the conservation and utilization of this valuable freshwater fish species.