• Journal of Korean Society on Water Environment
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• v.25 no.1
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• pp.102-111
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• 2009

Turbid storm runoff from intensive highland agriculture area has emerged as the major problem of water quality deterioration in the upstream region of the Han River. High slope of the upland combined with high rate of fertilization and intensive plowing causes high rate of soil erosion, and subsequently high suspended sediment and phosphorus content in the runoff water. The variations of water quality during rain spells were surveyed for two years (2005 and 2006) in the Jawoon Stream that is one of hot spots of intensive horticulture discharging turbid storm runoff. SS and TP showed large increase according to the increase of flow rate, whereas TN and BOD showed less fluctuations. Mean EMCs of SS and TP measured for nine rain events were as high as $207mgSS{\cdot}L^{-1}$ and $0.27mgP{\cdot}L^{-1}$, respectively. The export coefficient of SS and TP per area of cultivated field were calculated as $11,912kgSS{\cdot}yr^{-1}{\cdot}km^{-2}$ and $785kgP{\cdot}yr^{-1}{\cdot}km^{-2}$, repectively, which are significantly higher than reports of other area. It can be concluded that SS and TP in the runoffs were high enough to impose major threat to aquatic habitats, and the highland agriculture should be the main target of water quality management or habitat conservation in the study area.

• Journal of Ecology and Environment
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• v.30 no.1
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• pp.81-86
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• 2007

Human activities have enhanced the influx of heavy metals to aquatic ecosystem and hanged the abiotic environment such as the sediments supporting benthic organisms. The levels of heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) in the benthic gastropod Oxyloma hirasei and the sediments around their habitat were investigated to examine heavy metal levels and the potential of the gastropod as a bioindicator. We detected different levels of heavy metals in the sediments of two wetland areas, Upo and Mokpo, in the relatively well-conserved Upo wetland, Ramsar Convention Area. Oxyloma hirasei had higher concentrations of heavy metals except Cr and Ni in their soft tissues than in their shells (Cd: $2.10{\sim}3.16$, Cu: $19.73{\sim}28.66$, Pb: $0.67{\sim}1.17$, Zn: $216.1{\sim}285.7\;{\mu}g/g$ dry weight in the soft tissues; Cr: $1.19{\sim}2.58$, Ni: $0.47{\sim}1.16\;{\mu}g/g$ dry weight in the shells). Differences in the Cd, Cu, Ni and Pb concentrations in O. hirasei soft tissues reflected differences in heavy metal concentrations in the sediments at the sampling sites. The coefficients of variation for Cd, Cu and Pb were lower than those for other metals in the soft tissues. Levels of Cd in the tissues of O. hirasei were the highest among the metals examined in this study. Therefore, the soft tissue of O. hirasei appears to be a promising bioindicator particularly for Cd.

• Korean Journal of Ichthyology
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• v.12 no.3
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• pp.186-191
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• 2000

Population ecology of Abbottina springeri has been investigated from March to November, 1995 at Musimchon stream of Kadok-myon, Chongwon-gun, Chungchongbug-do. The favorite habitat was a sluggish area with muddy bottom, but larger individuals more than 60 mm in total length were also collected at rapids of low velosity. Judging from the total length frequency in this population on June, total length 30~50 mm group is one year old, 50~65 mm group is two years old, and longer than 65 mm is regarded over three years old. Sexual dimorphism was revealed conspicuously in genital papilla, nuptial tuberles and nuptial pigmentation in the males at spawning season. Peak season of spawning was June when the water temperature reaches $20\sim25^{\circ}C$ and they start spawning at the age of two. The sex ratio of female to male was 1:0.93. The mean of egg number and egg size in ovary were 652 and 0.43~0.06 mm respectively. According to the contents of stomach, this species feeds mainly on botton algae at all ages and some aquatic insects in adult.

• Korean Journal of Ichthyology
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• v.28 no.3
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• pp.186-191
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• 2016

Distribution status and threatened assessment of endangered species, Pungitius sinensis (Pisces: Gasterosteidae), were investigated from March to October 2015 in Gangwon-do and Gyeongsangbuk-do etc., Korea. During the study period, a total of 854 individual P. sinensis were collected from 21 of 71 sampling stations using skimming nets. P. sinensis appeared in 23 streams during the past 30 years. However, it was only collected in 12 streams. Therefore, its habitats and populations were drastically reduced. The preferred habitat of P. sinensis was pool of the lower stream with lots of aquatic plants. Given these evidences of small occupying areas ($84km^2$) and drastic reduction in its habitats and populations, P. sinensis is considered as an endangered (EN) [B2ab(ii,iii,iv,v)] species based on IUCN Red List categories and criteria.

• Development and Reproduction
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• v.17 no.1
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• pp.25-35
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• 2013

We investigated the effects of shell height on reproductive potential of the female Rapana venosa in three regions of different salinities (the coastal zone of the Gwangyang Bay (S-1); the upper reaches (S-3); lower reaches (S-2) of the Seomjin River). The number of egg capsules, egg capsule height, and fecundity associated with reproductive potential of larger female rapa whelks were higher than those of smaller individuals in all three regions. Correlation analyses showed that there is a significant positive correlation between egg capsule and female shell height. Mean of shell heights, egg capsule heights, the number of egg capsules in an egg mass, and fecundity in an egg capsule produced from female individuals inhabiting S-1 region were markedly higher than those inhabiting S-2 and S-3 regions. In particular, the fecundity of the rapa whelk increased with the salinity and shell height. Although large rapa whelks produced a large number of egg capsules at S-1 region, those at S-3 habitat laid less egg capsules with smaller size. If these rapa whelks were put into S-2 region, the number of egg capsules produced by a female at S-2 region was slightly larger than those produced by a female at S-3 region. This provides a clear evidence that the number of the egg capsules can be controlled by the salinity. In the coastal zone of the Gwangyang Bay and the upper reaches of Seomjin River, the fecundity of this species was estimated to be approximately 182,000-1,302,000 eggs/ind./yr.

• Journal of the Korean association of regional geographers
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• v.9 no.1
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• pp.66-76
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• 2003

Wetland is the ecotone between aquatic ecosystem and land ecosystem, and is much valuable in terms of ecology and economic. The stream wetland among inland fresh wetlands occupies the largest area but has been recognized as only a channel not a habitat. The purposes of this paper are to consider the characteristics of natural wetlands formed in the tributary flowing into the downstream reach of Nakdong River and to find its optimal management policy. Natural wetlands in the middle-size streams (2nd${\sim}$3rd order) are large marshlands, and were formed at the places from the mainstream away, because natural wetlands were formed in the reach of longitudinal profiles during the last glacial and the post-glacial period meet in disharmony. In order to conserve these natural wetlands effectively, we should compile the inventories of wetlands and make precise distribution maps. And we should do 'reverse-reclamation' which means the alteration of some farmlands reclaimed from natural wetland into natural wetland ecosystem, and develop the place or the space for wildlife education and ecotourism.

• Animal cells and systems
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• v.4 no.3
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• pp.223-229
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• 2000

Limbs and supporting structures of an organism experience a full weight of its own when it lands from water, because neutral buoyancy in the aquatic habitat will be no longer available in the terrestrial world. Metamorphosis of anuran amphibians presents 8 good research model to examine how this transition from non-loading to weight-loading affects development of motor capacity at the time of their first emergence on land. Our video analysis of the transitional anurans, Rana catesbeiana, at Gosner stage 46 (the stage of complete transformation) demonstrated that the take-off speed increased 1.23-fold after the first six hours of weight-loading on the wet ground. It did not increase further during the following three days of loading, and was close to the level of mature frogs with different body mass. During development of larvae in deep water with no chance of landing through metamorphosis, both tension and power of a hindlimb anti-gravity muscle increased 5-fold between stages 37 and n. However, the muscle contractility increased more rapidly when the larvas could access the wet ground by their natural landing behavior after stages 41-42. Muscle power, one of major factors affecting locomotory speed, was 1.29-fold greater in the loaded than in the non-loaded larvae at the transitional stage. Thus, weight-loading had a potentially significant effect on the elevation of motor capacity, with a similar extent of increment in locomotory speed and muscle power during the last stages of metamorphosis. Such a motor adjustment of the froglets in a relatively short transitional period would be important for effective ecological interactions and survival in their inexperienced terrestrial life.

• Journal of Korean Society on Water Environment
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• v.33 no.5
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• pp.587-599
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• 2017

Physical environmental factors (water depth, current velocity and substrate) and fish community were surveyed in the Gapyeong stream, Korea. The fish group of Gapyeong Stream was divided into three types. Lithophilic fish, Koreocobitis rotundicaudata and Pseudopungtungia tenuicorpa preferred shallow depth, low-velocity current, and coarse bed condition, whereas Coreoleuciscus splendidus and Microphysogobio longidorsalis were adapted to high-velocity current and bed materials. Nektonic fish, Zacco koreanus and Zacco platypus appeared in a wide range of physical conditions. Intermediate fish, Hemibarbus longirostris, Pungtungia herzi and Coreoperca herzi adapted to moderate water depths and current velocities. Among them, H. longirostris and C. herzi were adapt to various bed materials. C. splendidus, M. longidorsalis and P. herzi showed high niche overlap for current velocity, water depth and substrate with Z. koreanus and Z. platypus. The occurrence of M. longidorsalis in a relatively low-velocity current compared to Z. koreanus and Z. platypus suggests that the current velocity act as a isolation factor for these species. The competition, isolation and character displacement among these species investigated detail in the future. Based on canonical correspondence analysis, the relative importance of each environmental factor was determined as substrate > water depth > current velocity.

• Journal of the Korean Society for Marine Environment & Energy
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• v.13 no.1
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• pp.30-42
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• 2010

The effects of internal waves on dynamics of hypoxic waters were investigated by numerical simulation by means of a hydrostatic-ecosystem coupled numerical model for Lake Biwa. The numerical model consists of hydrostatic and ecosystem submodels. Numerical simulation was carried out for a period during April 2007 and March 2008, after preliminary numerical simulation for three years. As a result, the numerical model could capture the vertical profiles of the observed water quality. During September 30 and October 21 in 2007, the major internal waves were Kelvin and Poincare waves, the periods of which were 1.63 or 1.77 days and 0.48 days, respectively. Hypoxic waters appeared in bottom boundary layer around October and were still when thermocline locates in upper layer. During late autumn and winter seasons, differences in density between upper and lower layers were reduced and the amplitude of internal waves increased. Hypoxic waters began to move under the effects of internal waves. Movement of hypoxic waters will diminish the habitat for aquatic organisms in deeper waters.

• Journal of the Korean Institute of Landscape Architecture
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• v.34 no.1 s.114
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• pp.107-119
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• 2006

The Korea Water Resources Corporation(KOWACO) proposed bidding for an alternative design for Hwabuk Multi-purpose Dam in March of 2004. The site is located in Hakseong-ri, Goro-myeon, Gunwi-gun, Gyeongsangbuk-do and has adrainage area of $87.52km^2$. The purpose of this project is to establish an environmentally friendly plan for minimizing the damage that was caused by the construction of the Hwabuk Multi-purpose Dam. The design principle of KOWACO was the restoration of the natural environment, a harmonious landscape, and the creation of a space of regional and local culture. The basic concept of this project involves an ecological-restoration axis and a functional-connection axis. The site is divided into four spaces: (1) the space of memory and symbol, (2) the space of nature and ecology, (3) the space of regional and local culture, and (4) the space of the regional economy. There are four sub-spaces in the space of memory and symbol: the track forest, the time forest, the memory room, and the sun plaza. There are three sub-spaces in the space of nature and ecology: the habitat of aquatic birds, the wind forest, and the eco-corridor. There are five themed parks in the space of regional and local culture: the culture and relic room, the wildflower garden, the ecological pond, the insect observation park, and the pyogo maze. There are three areas in the space of the regional economy: the forest pension, the waterside pension, and the community center, as Dungdungi village was reorganized to serve as a lodging complex. These themed parks, working together, can offer an effective space for nature, culture, rest, and experience.