• 환경생물
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• 제27권2호
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• pp.135-139
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• 2009

2007년 8월과 10월 동안 서해안 선유도의 농생태계 작물재배지역 15지점에서 조사 채집된 지렁이는 3과 4속 12종 1,025개체이며 종 구성은 다음과 같다. Amynthas heteropodus 29.7%, Aporrectodea tuberculata 22.6%, Aporrectodea caliginosa 19.5%, Drawida japonica 11.3%, Amynthas agrestis 5.0%, Amynthas hupeiensis 3.6%, Aporrectodea sp. 3.5%, Amynthas corticis 2.0%, Bimastos parvus 1.6%, Amynthas koreanus 0.8%, Amynthas hilgendorfi 0.2%, Amynthas sp. 0.2%이다. 종 조성 비율을 보면 A. heteropodus와 A. tuberculata 2종이 차지하는 개체수는 537개체로 전체의 52.4%를 차지하여 선유도 농생태계 작물재배지의 우점종이다. 미성숙개체와 성숙개체의 비율은 1.1:1로 미성숙개체가 조금 더 많이 채집되었다.

• Ocean and Polar Research
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• 제30권4호
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• pp.519-536
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• 2008

The relatively tranquil area within the Gogunsan Archipelago was for the first time investigated preliminarily with respect to modern sedimentological processes in association with the emplacement of the Saemangeum Dyke. Basic sedimentological observations, bathymetry and surface sediments were performed twice during 2006-2008 to compare the results and elaborate changes during that period of time. In addition, sediment dynamical observations were carried out with latest measuring equipment along two transects crossing the entrances of the archipelago, including 12-hour onboard measurements of current, suspended sediments, temperature, and salinity. This dataset was used to reveal hydrodynamic characteristics for spring season April-May and to estimate the direction and relative magnitude of the net flux of suspended sediments. There occurred three depositional areas (A to C) within the archipelago, where sediment texture was also changed. In area A, around Yami Island and the dyke, and area B, in the center of the archipelago, surface sediments became coarsened over the two-year period; sand content increased 5% at the expense of silt content in the former, whereas silt content increased 3% at the expense of clay content in the latter. By comparison, area C in the western entrance of the archipelago shows a textural trend of fining with more silt and clay (combined increase of 5%) at the expense of sand content. The accumulation of sediments in areas A and B is attributable to the sand and silt resuspended from the seabed sediments off sector 4 of the dyke during the winter. The origin of the fine materials depositing on area C is uncertain at present, although suspended sediments moving offshore around the archipelago may be one of the most likely candidates for the source. The temperature of seawater increased rapidly from $9-10^{\circ}C$ in April to $14-16^{\circ}C$ in May, whereas salinity remained more or less constant at 31-32%o during the two months. Both of these parameters showed little variations with depth through a tidal cycle, suggesting good mixing of seawater without any help of significant waves. The consistency of salinity during a tidal cycle also indicates no insignificant effects of freshwater from the rivers Mangyung and Donjin emitting through the opening gap near Sinsi Island. The suspended sediment concentrations were higher at the entrance between Sunyu and Sinsi islands than at the entrance between Hoenggyong and Sinsi islands, ranging from 20 and 30 mg/l and from 5 and 15 mg/l, respectively at the sea surface. Although tidal currents were variable across a transect between Sunyu and Sinsi islands, the currents across the entrance between Hoenggyong and Sinsi islands flowed consistently in the same direction all over the transect during a tidal cycle. The estimation of net flux of suspended sediments indicates that suspended sediments are transferred to the Gogunsan Archipelago mainly through a relatively deep trough adjacent to Sinsi Island toward the shallow area around Yami Island and the dyke.