• Journal of Korea Water Resources Association
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• v.52 no.spc2
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• pp.845-853
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• 2019

The aim of this study is to investigate the factors affecting the habitat characteristics of largemouth bass (Micropterus salmoides), which is one of exotic fishes in Korea. Based on field observation, the laboratory experiments were performed in order to investigate the relationship between water temperature and the habitat characteristics of largemouth bass. It was found that largemouth bass preferred a relatively high water temperature in winter and a low temperature in summer. When the small largemouth bass coexisted with large largemouth bass, the separation of habitats depending on the size of each largemouth bass are observed. In the separated habitat areas, it is also observed that the largemouth bass preferred vicinity of the obstacle such as boulder. From the experiments for preference between water temperature and obstacle, it was observed that a primary consideration in habitat selection was obstacles. It was also observed that when light device was turned on, largemouth bass formed a new habitat.

• Journal of Korea Water Resources Association
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• v.52 no.spc2
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• pp.823-833
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• 2019

This study presents the impact of natural flow patterns on downstream fish habitat and economic outcomes in the Dal Stream, Korea. The study reach is 3.35 km long, located downstream form the Goesan Dam. To assess such impact, this study performed physical habitat simulations. The River2D model was used for the computation of the flow and the HSI model for the habitat simulation. Two physical habitat variables, flow depth and velocity, were used. The Zacco platypus, Zacco temminckii, Coreoleuciscus splendidus, and Opsariichthys bidens were selected as the target species in the study area. Using the building block approach (BBA), the scenarios for the hydropeaking mitigation were presented. Scenario 1 and scenario 2 were proposed by using the magnitude - duration concept and averaged the hydrologic data over the each month, respectively. Simulation results indicated that the scenarios effects significantly increased by about 18.6% for the weighted usable area (WUA). In addition, hydroelectric power benefits with both scenarios were investigated. It was revealed that the change of storing and releasing water decreased by about 27% for hydroelectric power benefits. In order to increase economic benefits, the scenario was modified with the discharges corresponding to the hydropeaking condition except the flood season. As a result, the hydroelectric power benefits were almost the same, however the aquatic habitat for the target species increased by about 5%. The change of dam re-operations through natural flow patterns provides an opportunity to minimize environmental and economic benefits in order to balance water management.

• Ecology and Resilient Infrastructure
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• v.6 no.1
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• pp.58-68
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• 2019

This present study conducted the impact of the restoration of low-flow channel on fish habitat in a reach of the Wonju Stream, Korea. The target species were Zacco koreanus, a dominant species in the middle- and upper-stream of Wonju Stream. The River2D model was used for the computation of the flow and the habitat suitability index model was used to estimate the quantity and quality of fish habitat using habitat suitability curves. In order to restore the study area, the low-flow channel was identified through the bankfull discharge of the study reach, and the best hydraulic section was designed. In addition, various restoration techniques were applied to the low-flow channel through rocks, pool/riffle structures, and the change of the channel width. Simulation results indicated that the restoration of the best hydraulic section effects decreased habitat suitability for the target species. However, when various restoration techniques were applied, the WUA (Weighted Usable Area) was improved by about 11%.

• The Journal of Fisheries Business Administration
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• v.49 no.4
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• pp.109-129
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• 2018

This study is to evaluate economic effect of the creation project of Octopus Ochellatu spawning and habitat ground in Taean County. The main results of this study are summarized as follows: first, the creation project cost of Octopus Ochellatus spawning and habitat ground invested in Taean from 2015 to 2017 was 3,400 million won. Second, The creation project of Octopus Ochellatus spawning and habitat ground directly provides fishing benefits, recreational boat fishing benefits, festival benefits, research and development benefits, and employment benefits. Third, on the basis of above benefits, the creation project of Octopus Ochellatus spawning and habitat ground has a net present value of 14,478 million won, internal rate of return 60.8%, and benefit-cost of 5.03 under a 4.5% social discount rate. Also, the creation project creates 47 jobs. This indicates that the creation project of Octopus Ochellatus spawning and habitat ground contributes not only to the increase in the income of coastal fishery, recreational boat fishing business and fishing villages but also to the job making. In conclusion, with all these results, a project for making spawning grounds and habitats in the specified region gives species more numerically abundant and this gives more profits to fishermen in the coastal area. In addition, this project helps to make attractions to visitors or people who came to those specified regions to participate in events or have recreation, which means it improves profits to that fishing village and improve a settlement condition.

• Journal of Ecology and Environment
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• v.43 no.3
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• pp.314-319
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• 2019

Background: The dramatic worldwide decline in the butterfly species Leptalina unicolor (Bremer & Grey) is largely the result of continuous habitat decline and disturbance by humans. The discovery of a narrow habitat in riverside wetlands utilized by L. unicolor raises the hope that such restricted key areas could be rather easily protected. Results: Here, we explain the environmental variables and habitat characteristics that primarily influence the distribution of L. unicolor discovered at the riverside areas along the Geum River. L. unicolor larvae were found at 9 of 13 study sites, and their abundance was strongly positively correlated with plant biomass. Our investigation showed that among four plant species (Miscanthus sinensis, Spodiopogon cotulifer, Setaria viridis, and Imperata cylindrica), L. unicolor larvae were the most abundant on the leaves of M. sinensis. They were not abundant on the leaves of S. cotulifer, S. viridis, or I. cylindrica. Interestingly, the number of L. unicolor larvae was positively correlated with the coverage area ($m^2$) of M. sinensis (F = 41.7, $r^2=0.74$, P < 0.0001). Conclusions: It appears that water (e.g., wetlands, ponds, and watersides) located along the riverside areas along the Geum River is important for the constant maintenance and conservation of L. unicolor. This is based on the habitat characteristics (water preference) of M. sinensis, which is used as a habitat by L. unicolor larvae. However, the waterside is dry and terrestrialization is in progress owing to the decreased water levels and water supply caused by an opened weir. Hereafter, this area will likely require management to secure a stable habitat for L. unicolor.

• Ecology and Resilient Infrastructure
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• v.7 no.4
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• pp.300-307
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• 2020

This study was conducted to evaluate the impact of weir gate operation in aquatic fish habitats through a physical habitat simulation of Geum River, Korea. The target species was Zacco platypus, which is a dominant species in the study area. The River2D model was used to compute the flow, and the habitat suitability index model was used to estimate the quality and quantity of the habitat using a habitat suitability curve. An unopened case and a partially opened case were investigated to assess the impact of weir gate operation on the aquatic fish habitat. The simulation results showed that the aquatic habitats of the target species in the partially opened case improved significantly, compared to the case without a gate opening. Furthermore, the weighted usable area increased by a factor of approximately 13, owing to weir gate operation in the study area.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.58 no.2
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• pp.106-112
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• 2022

As a series of basic research to draw the pilot design measures for developing the habitat apparatus of Sulculus diversicolor supertexta inhabiting the coastal area of Jeju island, this study conducted a water tank experiment to understand the habitat marine environment of Sulculus diversicolor supertexta and the preference of habitat space focusing on the research fisheries performing the discharge of marine products. In the composition degree of marine algae in both fisheries, Donggwi-ri showed the highest gulfweed (79.3%) as brown algae and there were some coralline algae (17.2%) as red algae. Hansu-ri yielded the highest gulfweed (48.1%) as brown algae, which was followed by sea lettuce (10.4%) as green algae. In the preference of habitat space, the shelter angles 40° showed the highest adhesion as number of 82.9, which was followed by 60° and 70° as 69.2 and 68.2 respectively (P<0.05) by reviewing the environmental characteristics of habit of Salculus diversicolor supertexta in the coastal fishery of Jeju Island, when considering the adhesion rate in each of five shelters with different angles. In the future, there should be continuous research and monitoring for designing the fish shelters suitable for the coastal fisheries of Jeju island, and it would be also necessary to add the field-centered sustainable concrete research.

• Ecology and Resilient Infrastructure
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• v.8 no.1
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• pp.64-78
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• 2021

This study was conducted to find out the effect of the construction and operation of river-crossing structures on the habitat landscape characteristics in the Geum-gang River, South Korea. A total of three study reaches were selected in the downstream of the Daecheong Dam: the Buyong-ri reach, which is a control that is not affected by the construction and operation of the weir of the Four Rivers Project and Sejong-bo Weir reach and Gongju-bo Weir reach of the upper and lower sections of each weir that are affected by the weir construction and operation. The habitat type was classified, and then the structural characteristics of the landscape were analyzed using aerial photographs taken before and after the construction of the Daecheong Dam, before and after the construction of the weir, and before and after the weir gate operation. After the construction of Daecheong Dam in Geum River, the area of the bare land greatly decreased, and the area of grassland and woodland increased in the downstream of the dam. In addition, the patch number in the river landscape increased, the patch size decreased, and the landscape shape index and the habitat diversity increased. Therefore, after the construction of the dam, the bare land habitat was changed to a vegetated habitat, and the habitat was fragmented and diversified in the downstream of the dam. After the construction of the weirs, the area of open water increased by 18% in the Sejong-bo reach and by 90% in the Gongju-bo reach, and the landscape shape index of the open water decreased by 32% in the Sejong-bo reach and by 35% in the Gongju-bo reach, and the habitat diversity index decreased to 25% in the Sejong-bo reach and to 24% in the Gongju-bo reach. Therefore, the open water habitat was expanded, the shape of the habitat was simplified, and the habitat diversity decreased according to the construction of the weirs. After water-gate opening of the weir, the bare land that disappeared after the construction of the weir reappeared, and the landscape shape index and habitat diversity index increased in both terrestrial and open water habitats. Therefore, it was found that the landscape characteristics of the river habitats were restored to the pre-construction of the weir by the operation of the weir gate. The effect of weir gate opening was delayed in the downstream than in the upstream of the weir. Although the characteristics of the landscape structure in the river habitat changed due to the construction of the river-crossing structures, it is thought that proper technology development for the ecological operation of the structures is necessary as the habitat environments can be restored by the operation of these structures.

• Korean Journal of Environment and Ecology
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• v.17 no.1
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• pp.83-91
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• 2003

This study was conducted to clarify the characteristics of bird communities due to different habitat types on 3 sites in Han river area from May 2001 to January 2002. Water area was the most dominant habitat type in each site and also forest was dominant habitat type in site 1(Paldang area). Site 2(Bam island area) had various habitat types e.g. shrub field sandv plain, reed bed and grass field. Total 52 bird species were recorded on 3 sites in Han river. Ducks were the most dominant species, especially in January 2002. Density of individuals were higher in site 1 and 2, but lower in site 3(Nanjido area). In January 2002, dabbling ducks were dominant in site 2, and diving ducks were in site 1. Among diving ducks, common merganser Mergus merganser showed high density in site 2 and pochard Aythya ferina did in site 1. In site 1, coot Fulica atra showed also high density Diverse habitat types could be support foraging resources for dabbling ducks in site 2. High density of pochard and coot would be related to abundant aquatic plants and stable water depth in site 1. Manipulation of riparian zone in site 3 into natural vegetation would increase the bird species diversity. By the manipulation of habitat, habitat potentiality of birds would be increase in Han river area.

• Journal of Environmental Impact Assessment
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• v.24 no.3
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• pp.287-299
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• 2015

If the Nakdong River estuary is to be sustainable, land use management practices need to consider bird habitat requirements, especially given that the area serves as an important migratory bird sanctuary. In this study, bird habitats found in the Nakdong River estuary were classified into 11 different types including Phragmites australiss, mud flat, farmland, open surface in freshwater, sand bar, riparian forest, Scirpus planiculmis, waterway, construction, grasslands, and open surface in sea or brackish water. Taking into consideration the regional characteristics, habitat properties, and landscape indices, a total of 12 study sites were analyzed. Mud flat, construction, farmland, and P. australis account for 80% of the total land area. The high area ratio of construction and farmland to other types of habitat revealed a high amount of historical human activity and intervention in the area. Both patch numbers as well as patch density were high in West Nakdong River, Samrak Waterfront, Maekdo River, and Daejeo Floodgate, with these areas showing the greatest fragmentation as well. Total numbers of species and individuals had a positive correlation with the area and the number of habitat types. Findings suggest that protecting the habitat area, especially in S. planiculmis, is the most important factor for bird habitat management and that future development could result in habitat loss, having a profoundly adverse impact on bird populations. Therefore, it is important that the total area should be carefully protected by land use regulations in order to ensure that the Nakdong River estuary maintains its functional integrity as a migratory bird sanctuary.