한국의 거제도에 서식하는 수달의 생태학적 연구

Abstract

In the late 1950s, population of river otter was continuously declined. Many different explanations for this decline have been presented; e.g. hunting, habitat destruction and indirect or direct influences of eutrophication, acidification and toxic chemicals. Environmental pollution is a world-wide problem, heavy metals belonging to the most important pollutants recently. The progress of industries and dam construction has led to increase emisson of pollutants into ecosystem. In this study, the concentrations of fourteen metals(Cr, Cd, Pb, Ni, Zn and so on) have been determined. Spraints were collected monthly along the Gucheon(a total number of spraints=167) and Yeonchocheon(a total number of spraints=61), Geoje island, January to December, 2004. Metal concentrations were measured by ICP-AES. Lead concentrations were higher at upper stream in two reservoirs(7.02±0.91㎍/g, 1.60±0.88㎍/g, respectively) The high concentration of lead may be partly associated with agricultural activities. The concentrations of chrome, cadmium, lead of Gucheon and chrome of Yeonchocheon tended to increase by season, especially those were the highest in winter. The river otter is a top predator of most aquatic food chains. This makes otters good integrator of their aquatic environment and a useful surrogate species for determining both wildlife and human chemical exposure and potential harmful effects.;Eurasian otter(Lutra lutra) is an endangered wildlife species that population size is declining in Korea. To manage and conserve habitat for otters, it is curcial to understand which habitat components affect habitat preference for otters. The objectives of this study were to analyze otter habitat characteristics with land-cover map. I investigated otter spraints and sprainting site in Geoje Island from January to December, 2004. with GPS coordinates. The analysis of otter habitat use pattern was used by Arcview ver. 3.2 with 1: 25,000 Topology Map and field data. The results meant that otter habitat use was strongly related to riparian vegetation, dam or river construction and human interferences(presence /absence of residential area, commercial area and public facilities). In this study, Gucheon has a high denstiy of riparian vegetation and unconfined channels. Yeonchocheon was being under construction at lower stream so it limited otters' prey use and migration. This study suggests that searching for suitable habitat conditons for otter is essential in trial for conservation or trans-location.;The population density of the Eurasian otter(Lutra lutra) in Korea has been decreased. The main factor of this decline is the loss of habitat. To address the habitat pattern eight microhabitat variables were used: habitat condition(river or dam), waterside pattern, flow velocity, river width, river depth, bank treatment, water use and pollution source. Surveys were conducted on a monthly basis, from January to December, 2004. in Geoje island of Korea. The relationship between the number of spraint and habitat use pattern was evaluated by using GLM(Generalized linear model). Significant correlations were recorded between otter spraints and habitat condition, pollution source, flow velocity and river width. Otters selected dam area that was assumed high in water level. The narrower(2-5m) and slow velocity(5~30m/s) parts of the stream were preferred. Otter habitat also seems to be affected to living pollution and human disturbance. Dam condition was related to otters' preferred habitat of Gucheon, crossboard of bank treatment types was significant in Yeonchocheon. In this study the relationship between habitat situations and its use was measured. This is essential in order to determine which factors may be limiting the present otter population along the river ecosystem and thus help set up an effective conservation strategy.