• Journal of Ecology and Environment
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• 제47권2호
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• pp.42-48
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• 2023

An adult male Eurasian river otter (Lutra lutra) with ataxia and lethargy was rescued. Through the necropsy of this otter with neurological symptoms, a broad range of vascular damage caused by mercury toxicity in several organs, hepatocellular necrosis, and vacuolation in the brain. In mercury examination, liver, kidney, and hair showed values of 0.878 ± 0.027, 1.807 ± 0.049, and 5.712 ± 0.102 ㎍/g, respectively. Compared with certified reference material, it was confirmed that the concentration of mercury were 6.7 times, 13.7 times, and 43.3 times higher, respectively. When the symptoms and diagnosis results were comprehensively reviewed, this otter's demise was revealed due to mercury poisoning. The mercury concentration in the liver does not exceed the lowest observed effect level of 3.4 ㎍/g. However, even at low concentrations, long-term accumulation can cause symptoms including neuropathy, and the possibility that these heavy metals have accumulated in other wild animals cannot be ruled out. It seems that continuous monitoring using sentinel animals is necessary.

• 한국임상수의학회지
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• 제41권1호
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• pp.54-59
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• 2024

A 12-year-old female small-clawed Asian otter (Anoyx cinereus) with a one-week history of anorexia, chills, and abdominal distension was found dead. Grossly, yellowish-brown turbid fluids accumulated in abdominal cavity of the otter, and yellowish thread-like fibrinous materials were found on the surface of abdominal organs. Several variable sized yellowish-white crystalloids were scattered on the medullary space of kidneys. Histologically, diffuse serositis (peritonitis) characterized by the fibrinous exudates, thickened serosal capsule and the swelling of mesothelial cells were observed in the serosa of liver, spleen, stomach, and intestine. Multifocal necrosis, hemorrhage, infiltration of macrophage, and brown pigments were presented in the liver. Isolated bacteria from ascites and fibrinous materials in abdominal visceral surface were white, smooth and convex with characteristic mousy odor on blood agar plate. These bacteria were confirmed as Pasteurella (P.) multocida type A by polymerase chain reaction analysis. Based on the gross examination, histopathologic findings and bacterial experiments, this otter was diagnosed as severe peritonitis associated with P. multocida and necrotic hepatitis.

• Journal of Species Research
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• 제1권2호
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• pp.240-248
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• 2012

We used a non-invasive technique with microsatellite primers to investigate genetic variation among Eurasian otters Lutra lutra in eastern South Korea. We collected twenty two otter spraints in January and six in August 2008. We used spraints from five dead otters from five different river systems for the present genetic analysis. We extracted DNA from 20 spraints from the January sample. Ten microsatellite primers (Lut435, Lut453, Lut457, Lut604, Lut615, Lut701, Lut715, Lut717, Lut733, and Lut832) for Eurasian otters were tested, and four loci were successfully amplified for further analyses. The results of genotyping the otter population with microsatellite loci lead to the identification of 9 individuals from the Ungokcheon Stream. The Ungokcheon population also showed a genetic structure represented by the Hardy-Weinberg equilibrium.

• 한국환경생태학회:학술대회논문집
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• 한국환경생태학회 2004년도 학술대회지
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• pp.3-12
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• 2004

• Animal cells and systems
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• 제8권3호
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• pp.231-233
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• 2004

Sequences of cytochrome b gene and control region of mitochondrial DNA from Korean common otters (Lutra lutra lutra L.) were examined to provide the genetic information for the conservation of this subspecies. Two haplotypes and one haplotype were revealed in cytochrome b gene and control region, respectively. The available sequences of European common otter (L. l. lutra) from GenBank were compared together with those of Korean common otter in order to determine the degree of sequence variation between them. In cytochrome b gene sequences, two haplotypes from Korea and two haplotypes of Europe showed differences in 12 of 1,045 sites. The Tamura-Nei nucleotide distances between two European haplotypes was 0.10% and those between two Korean haplotypes was also 0.10%, but those between Korean haplotypes and European ones ranged from 0.96% to 1.16%. In the control region, one Korean haplotype and seven European ones showed differences in seven of 300 sites; the Tamura-Nei distances among seven European haplotypes were 0.34% to 1.01%, but those between Korean haplotype and European ones ranged from 1.01% to 1.69%. Although further molecular and morphological studies with specimens from eastern Asia including Amur region and northeast China are needed, it is possible that the Korean common otter might be closer or identical to the far-eastern Asian common otter, L. l. amurensis Dybowski.

• 수산해양기술연구
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• 제37권1호
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• pp.1-8
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• 2001

This study deals with the experimental and numerical investigations to design the high performance otter board. Experiment was carried out to determine the most effective slot size of single-slot cambered otter board in the circulation water channel of BAEK KYUNG IND. Co. LTD. Numerical analysis was done by the commercial CFD code, FLUENT, to provide some valuable physical interpretations and finally to design the otter board section by numerical method. The major results are as follows ; 1. In experiment, the maximum lift and drag coefficients of simple cambered type otterboard were 1.41, 0.55, respectively, at the angle of attack $28^\circ$, while those of slot one with slot size 0.02C (C denotes the chord length) were 1.72, 0.42 at the angle of attack $24^\circ$. 2. The hydrodynamic characteristics depending upon slot size shows the greatest at 0.02C of the slot size. 3. Numerical results well visualized the streamlines, pressure fields, and speed vectors of a simple cambered and slot cambered otter board with slot size 0.02C. The slot cambered one with slot size 0.02C was shown that pressure field was distributed moderately on front and back side of otter board. And, the delay and decrease of separation were favorably achieved by flow through slot. 4. Computed result on the pattern of hydrodynamic field and the values of $C_L$ and $C_D$ by the commercial CFD code, FLUENT, show almost the same as those of the experimental result.

• Spatial Information Research
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• 제12권1호
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• pp.29-42
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• 2004

본 연구는 2002년 10월부터 2003년 9월까지 경상북도 봉화군 운곡천을 대상으로 수달의 배설물(Spraint) 및 배설지(Sprainting site)등의 흔적조사를 통해 얻은 GPS좌표를 중심으로 하여 국립지리원에서 발행한 1/25000 수치지도 및 현장조사에서 얻은 정보를 ESRI사의 Arcview를 통하여 수달의 최적 서식지분석에 이용하였다. 분석 결과 수달의 서식지 이용에는 먹이자원인 어류의 종다양도와 풍부도가 깊은 연관을 맺고 있으며 식생 등의 서식환경이 밀접한 연관을 맺고 있음을 확인하였다. 또한, 밀집된 주거지 등의 인간의 간섭은 수달의 서식지 이용에 교란요인으로 작용한다는 것을 알 수 있었다. 결국 수달의 이주(Trans-location)등 보전 및 복원을 위한 시도에서 적합 서식지를 선정하기 위해서는 인간의 간섭으로부터 배제와 풍부한 어족자원, 좋은 식생을 두루 갖춘 서식지를 찾아내는 것이 선행되어야 함을 시사한다.

• Journal of Animal Science and Technology
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• 제56권5호
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• pp.16.1-16.9
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• 2014

Fatty acids (FA) have recently been used in several studies to infer the diet in a number of species. While these studies have been largely successful, most have dealt with predators that have a fairly specialized diet. In this paper, we used FA analysis as a tool to infer the diet of the nearctic river otter (Lontra canadensis). The river otter is an opportunistic predator known to subsist on a wide variety of prey including, fishes, crayfish, molluscs, reptiles and amphibians, among others. We analyzed the principle components of 60 FA from otters and 25 potential prey species in Illinois, USA. Prey species came from 4 major taxonomic divisions: fishes, crayfish, molluscs and amphibians. Within each division, most, but not all, species had significantly different profiles. Using quantitative FA signature analysis, our results suggest that, by mass, fish species are the most significant component of Illinois River otters' diet ($37.7{\pm}1.0%$). Molluscs ranked second ($32.0{\pm}0.8%$), followed by amphibians ($27.3{\pm}4.3%$), and finally, crayfish ($3.0{\pm}0.6%$). Our analysis indicates that molluscs make up a larger portion of the otter diet than previously reported. Throughout much of the Midwest there have been numerous otter reintroduction efforts, many of which appear to be successful. In regions where mollusc species are endangered, these data are essential for management agencies to better understand the potential impact of otters on these species. Our analysis further suggests that quantitative FA signature analysis can be used to infer diet even when prey species are diverse, to the extent that their FA profiles differ. Better understanding of the otter's metabolism of FA would improve inferences of diet from FA analysis.

• 환경생물
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• 제24권1호
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• pp.89-94
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• 2006

본 연구는 수달의 배설물에 근거해 한국 수달의 서식지 분포 및 그 패턴을 유추하기 위하여 수행되었다. 본 연구에서 분포 조사에 사용한 총 750개의 조사 격자 (13.75X11\;km) 중 34%에 이르는 255개의 구획에서 수달의 배설물이 존재한다는 것을 확인하였다. 수달 배설물의 지역적 분포 빈도는 경상북도(49.62%), 강원도 (49.56%), 충청북도 (41.67%), 경상남도 (38.00%), 전라북도 (37.93%), 전라남도 (24.24%), 충청남도 (20.29%), 경기도(7.36%)순이었다. 수달의 배설물이 발견된 대부분 지역에서 아주 적은 수(평균 1.7 spraints/sprainting site)의 배설물만을 확인하였으므로 지역별 개체군의 크기는 크지 않은 것으로 추정된다. 수달의 배설물에 근거해 유추한 수달 서식지의 분포 패턴은 한국에 서식하는 수달의 보전 및 관리를 위한 기초 생태자료로써 중요한 기여를 할 것으로 사료된다.

• 한국환경복원기술학회지
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• 제27권4호
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• pp.1-14
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• 2024

Otters, designated as Class I endangered wildlife due to population declines resulting from urban development and stream burial, have seen increased appearances in freshwater environments since the nationwide ban on stream filling in 2020 and the implementation of urban stream restoration projects. There is a pressing need for scientific and strategic conservation measures for otters, an umbrella and vulnerable species in aquatic ecosystems. Therefore, this study predicts potential otter habitats using the species distribution model MaxEnt, focusing on Hwangguji Stream in Suwon, and proposes conservation strategies. Otter signs were surveyed over three years from 2019 to 2021 with citizen scientists, serving as presence data for the model. The model's outcomes were enhanced by analyzing 'river nature map' as a boundary. MaxEnt compared the performance of 60 combinations of feature classes and regularization multipliers to prevent model complexity and overfitting. Additionally, unmanned sensor cameras observed otter density for model validation, confirming correlations with the species distribution model results. The 'LQ-5.0' parameter combination showed the highest explanatory power with an AUC of 0.853. The model indicated that the 'adjacent land use' variable accounted for 31.5% of the explanation, with a preference for areas around cultivated lands. Otters were found to prefer shelter rates of 10-30% in riparian forests within 2 km of bridges. Higher otter densities observed by unmanned sensors correlated with increasing model values. Based on these results, the study suggests three conservation strategies: establishing stable buffer zones to enhance ecological connectivity, improving water quality against non-point source pollution, and raising public awareness. The study provides a scientific basis for potential otter habitat management, effective conservation through governance linking local governments, sustainable biodiversity goals, and civil organizations.