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어류군집과 하천주변 토지이용에 따른 회야강 수계와 인근하천의 건강성 평가
김정희 ( Jeong Hui Kim ),윤주덕 ( Ju Duk Yoon ),조현빈 ( Hyun Bin Jo ),장광현 ( Kwang Hyeon Chang ),장민호 ( Min Ho Jang ) 한국하천호수학회(구 한국육수학회) 2012 생태와 환경 Vol.45 No.4
In this study, to analyze the stream health using fish assemblage and make effective management, we conducted fish monitoring in the Hoeya River basin and neighboring streams. A total of 33 species classified into 12 families were collected from 29 sites in 2007. Dominant species was Zacco platypus (Relative abundance, RA: 24.8%), and subdominant species was Rhynchocypris oxycephalus (RA: 16.2%). Eight Korean endemic species and 4 exotic species were identified. Moreover, two species (Opsariichthys uncirostris amurensis and Hemiculter eigenmanni) were translocated from other basin. To evaluate stream health of the study sites, Index of Biological Integrity (IBI) was applied, based on fish assemblages. Overall, IBI values were "C (Fair)" or "D (Poor)" condition, according to the grade except two sites which recorded "B (Good)". The correlation between land use pattern of surrounding watershed and IBI was analyzed to verify impact of development on stream health using fish assemblage. As a result, when percentage of the developmental groups increased, IBI values were decreased (Pearson correlation, r=-- 0.425, p=0.022). In contrast, increment of percent forest and grass land was positively correlated with IBI (r=0.556, p=0.002). The agricultural group and IBI did not significantly correlate with each other (r=-- 0.231, p=0.333). In this study, we identified a relationship between land use of surrounding watershed and stream health using fish data (i.e. IBI). These results could be provided useful fundamental information to establish management and restoration plan in the Hoeya River basin and other rivers distributed in Korea.
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Multiferroic h-HoMnO₃의 자기적 성질 연구
김성백(Sung Baek Kim),금복연(Bok Yeon Kum),김철성(Chul Sung Kim),안성용(Sung Yong An),N. Hur(N. Hur),S. Park(S. Park),S.-W. Cheong(S.-W. Cheong),장광현(Kwang-Hyun Jang),박제근(J.-G. Park) 한국자기학회 2005 韓國磁氣學會誌 Vol.15 No.2
Multiferroic HoMnO₃ single crystal was prepared using 4-point focused floating zone furnace, and polycrystalline HoMn_(1-x)(57)^Fe_xO₃ (x=0.00, 0.01, 0.02, 0.05) powders have been prepared by solid state reaction. Their magnetic and crystallographic properties are studied using MPMS, PPMS, and Mossbauer spectroscopy. The crystal structure is found to be a hexagonal and a magnetic easy-axis is (110) direction. As the external applied magnetic field increases, temperature of the dielectric constant anomaly is decreased. HoMn_(0.95)(57)^Fe_(0.05)O₃ shows huge quadrupole splitting value from the Mossbauer spectra.
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Chang, Kwang-Hyeon,Hwang, Soon- Jin,Jang, Min-Ho,Kim, Hyun-Woo,Jeong, Kwang-Seuk,Joo, Gea-Jae 한국육수학회 2001 생태와 환경 Vol.34 No.4
낙동강에서 치어섭식이 동물플랑크톤에 미치는 영향을 채집된 치어의 소화관조사를 통해 고찰하였다. 조사지역인 낙동강 하류 물금에서는 유량이 감소하고 수체가 정체되는 5월에서 6월사이 5종류의 치어가 높은 밀도를 나타내었다. 같은 시기, 동물플랑크톤 군집내에서는 대형윤충류인 Asplanchna spp.와 Brachionus spp., 지각류인 Moina micrura 및 Bosminopsis deitersi의 밀도가 큰 폭으로 감소하였다. 반면, Polyarthra속의 소형윤충류는 최대 밀도를 나타내었다. 채집된 치어의 소화관 조사 결과, 15㎜ 이하의 치어는 대형윤충류 및 지각류를, 15㎜ 이상의 치어인 경우 지각류를 선택적으로 섭식하는 것으로 나타났다. 큰입배스의 치어의 경우, 같은 시기 채집된 치어에 비해 대형이었으며 동물플랑크톤 군집내의 대형 윤충류와 지각류의 급격한 밀도 감소는 치어의 섭식으로 인한 것으로 사료된다. 반면, 이러한 밀도감소는 치어의 수가 감소함에 따라 회복되는 경향을 보였다. 부영양화된 낙동강의 경우 배스치어의 섭식으로 인한 치어밀도의 급속한 감소, 풍부한 먹이농도 등이 감소한 지각류의 밀도회복을 유도하는 것으로 사료된다. In the large regulated Nakdong River, the predation effect of juvenile fish on the zooplankton community was evaluated by gut and stomach analyses of fish in 1999. Juvenile fish of five species showed high density from May to early June when river discharge was low and water body became stagnant. During this period, large rotifers, Asplanchna spp. and Brachionus spp. declined and the decrease of cladoceran (Moina micrura and Bosminopsis deitersi) density was also observed. At this time, small rotifers including Polyarthra spp. reached maximum density. Gut analysis of fish demonstrated that small=sized juvenile fish(<15㎜ in total length) preferred large rotifers as well as cladocerans, while large sized fish(>15㎜) selected only cladocerans. On the other hand, juvenile Micropterus salmoides of which size was larger than other juvenile fish consumed not only zooplankton but also other small juvenile fish. Based on these results, the decline of large rotifers and cladocerans during early summer in the river seems to be result of predation by juvenile fish. However, the period when juvenile fish maintained their high density was as short as one month and the decreased density of cladocera rapidly recovered as soon as juvenile fish became scarce. Such a short period of juvenile fish development in the river can be attributed to the consumption of juvenile fish by the young-of-the-year cohorts as well as adults of M. salmoides. The high trophic state of the river might permit the rapid recovery of the cladoceran community. The predation impact of juvenile fish in the Nakdong River seems to be affected by the existence of piscivore as well as high trophic status.
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