• Ocean and Polar Research
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• 제35권4호
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• pp.453-464
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• 2013

본 연구에서는 FSM 축과 코스레 맹그로브 퇴적물 내 7개 중금속(Cr, Ni, Cu, Zn, As, Cd 및 Pb)의 오염도를 평가하였다. 맹그로브 퇴적물 내 중금속의 평균농도는 Cr 642 ${\mu}g/g$, Ni 125 ${\mu}g/g$, Cu 46.9 ${\mu}g/g$, Zn 149 ${\mu}g/g$, As 15.6 ${\mu}g/g$, Cd 0.14 ${\mu}g/g$ 및 Pb 8.55 ${\mu}g/g$으로 Cr의 농도가 가장 높았으며 Cd이 가장 낮은 농도로 존재하고 있었다. 축과 코스레 지역을 비교하면 코스레 맹그로브 퇴적물은 Cr과 Ni의 농도가 축에 비해 높았으며, 나머지 원소인 Cu, Zn, As, Cd 및 Pb는 축 맹그로브 퇴적물에서의 농도가 코스레에 비해 높은 것으로 나타났다. 세계의 맹그로브 지역의 퇴적물 내 중금속의 농도와 비교한 축과 코스레 지역에서 채취한 맹그로브 퇴적물 Cr, Ni 및 As의 농도는 인간활동에 의한 인위적인 오염이 존재하는 다른 지역보다 높은 수준으로 나타났으며, Cu, Zn, Cd 및 Pb은 오염되지 않은 지역과 유사한 농도를 나타내었다. EF와 PLI를 이용하여 농축도(오염도) 평가결과에 의하면, As의 농축도는 높으나 나머지 원소는 오히려 배경농도에 비해 결핍된 것을 알 수 있었다.

• 환경생물
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• 제24권1호
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• pp.81-88
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• 2006

열대 남태평양에 위치한 축 라군에서 flow cytometry와 HPLC를 이용 초미소 식물플랑크톤 조사를 하였다. Synechococcus, Prochlorococcus 그리고 picoeukaryotes의 풍도와 지시색소 분포 양상을 분석하였고 추정된 탄소 생체량에서의 기여율을 조사하였다. 남세균인 Synechococcus와 Prochlorococcus는 축 라군에서 대비되는 분포 특성을 보였다. Synechococcus는 웨노섬 주변 정점에서 높은 풍도를 보인 반면, 북동수로 쪽으로 멀어지며 풍도가 감소하였다. Prochlorococcus는 이와 반대의 분포특성을 나타냈으며, picoeukaryotes는 특정적인 수역별 변화를 보이지 않았다. Prochlorococcus의 지시색소인 divinyl chlorophyll a (Chl. $\alpha2$)는 $1.2\sim180.3\;ng\;L^{-1}$의 농도 범위를 보였으며, 웨노섬 주변 정점들보다 북동수로에 접한 정점들에서 높게 나타났다. 이는 Prochlorococcus의 풍도와 유사한 분포로서, chl. a2가 생체량의 좋은 지표임을 나타냈다. 반면 zeaxanthin은 $61.4\sim135.8\;ng\;L^{-1}$의 농도 범위로 정점별 변화가 풍도변화에 비해 작은 특징을 보였는데 이는 Prochlorococcus로부터 유래된 zeaxanthin의 영향으로 판단된다. Synechococcus의 추정된 탄소 생체량은 전체 초미소 식물플랑크톤 생체량의 68%를 차지하였다. Prochlorococcus와 picoeukaryotes는 각각 17.1%와 14.9%의 생체량을 나타냈다.

• Ocean and Polar Research
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• 제32권1호
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• pp.53-61
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• 2010

The distribution of coral reefs can be an indicator of environmental or anthropogenic impacts. Here, we present a habitat map of coral reefs developed using high-spatial satellite images. The study area was located on the north-eastern part of Weno island, in the Chuuk lagoon of Federated States of Micronesia. Two fieldwork expeditions were carried out between 2007 and 2008 to acquire optical and environmental data from 121 stations. We used an IKONOS image obtained in December 2000, and a Kompsat-2 image obtained in September 2008 for the purpose of coral reef mapping. We employed an adapted version of the object-based classification method for efficient classification of the high-spatial satellite images. The habitat map generated using Kompsat-2 was 72.22% accurate in terms of comparative analysis with in-situ measurements. The result of change detection analysis between 2000 and 2008 showed that coral reef distribution had decreased by 6.27% while seagrass meadows had increased by 8.0%.

• Ocean and Polar Research
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• 제23권1호
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• pp.23-34
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• 2001

Geochemical and Sr-Nd isotopic compositions and K-Ar ages are analyzed in volcanic rocks from Weno Island, Caroline Islands. Seven Weno lava samples of alkali basalt and basaltic trachyandesite are aphyric or sparsely phyric comprising olivine, plagioclase, and clinopyroxene phenocrysts. Whole-rock geochemical variation of Weno lavas reflects main fractional crystallization of olivine and Cr-spinel phenocrysts. Newly determined K-Ar ages of Weno lavas range from 6.7 to 11.3 Ma (late Miocene), indicating their formation during primary volcanic stage of Chuuk Islands. Trace element compositions of Weno lavas are very similar to those of typical ocean island basalts (OIBs), suggesting their formation during intra-plate mantle plume activity. The plume composition is isotopically very similar to that of Hawaiian hot spot. However, the age span of Chuuk volcanism is longer than that of the other individual volcanoes in the Pacific.

• 미생물학회지
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• 제49권4호
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• pp.377-382
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• 2013

2012년 2월 미크로네시아의 축(Chuuk)주에서 채집한 해양해면 Dactylospongia meachromia의 공생세균의 주요 군집구조를 Denaturing Gradient Gel Electrophoresis (DGGE) 방법을 이용하여 분석하였다. D. metachromia의 두 개체 CH607과 CH840를 이용하여 DGGE 분석을 수행한 결과, 동종의 두 개체 해면에서 동일한 밴드 패턴을 나타내었다. DGGE 밴드로부터 DNA를 추출하여 염기서열을 분석한 결과, 알려진 염기서열들과 93-100%의 유사도를 나타내었으며 밴드로부터 밝혀진 모든 서열들은 배양되지 않은 세균 클론들과 높은 상동성을 나타내었다. D. metachromia (CH607, CH840)의 공생세균 군집구조는 Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Acidobacteria, Actinobacteria, Chloroflexi, Cyanobacteria, Spirochaetes로 총 6문 8강으로 구성되었으며 동일한 지역에서 채집한 같은 종의 해면은 동일한 공생세균 군집구조를 나타냄을 확인하였다.

• Ocean and Polar Research
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• 제35권4호
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• pp.415-425
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• 2013

In order to understand phytoplankton and bacterial distribution in tropical coral reef ecosystems in relation to the mangrove community, their biomass and activities were measured in the sea waters of the Chuuk and the Kosrae lagoons located in Micronesia. Chlorophyll a and bacterial abundance showed maximal values in the seawater near the mangrove forests, and then steeply decreased as the distance increased from the mangrove forests, indicating that environmental conditions for these microorganisms changed greatly in lagoon waters. Together with chlorophyll a, abundance of Synechococcus and phototrophic picoeukaryotes and a variety of indicator pigments for dinoflagellates, diatoms, green algae and cryptophytes also showed similar spatial distribution patterns, suggesting that phytoplankton assemblages respond to the environmental gradient by changing community compositions. In addition, primary production and bacterial production were also highest in the bay surrounded by mangrove forest and lowest outside of the lagoon. These results suggest that mangrove waters play an important role in energy production and nutrient cycling in tropical coasts, undoubtedly receiving large inputs of organic matter from shore vegetation such as mangroves. However, the steep decrease of biomass and production of phytoplankton and heterotrophic bacteria within a short distance from the bay to the level of oligotrophic waters indicates that the effect of mangrove waters does not extend far away.

• Ocean and Polar Research
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• 제35권4호
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• pp.395-405
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• 2013

The aim of this study is to suggest an optimal survey method for coastal habitat monitoring around Weno Island in Chuuk Atoll, Federated States of Micronesia (FSM). This study was carried out to compare and analyze differences between in situ survey (PHOTS) and high spatial satellite imagery (Worldview-2) with regard to the coastal habitat distribution patterns of Weno Island. The in situ field data showed the following coverage of habitat types: sand 42.4%, seagrass 26.1%, algae 14.9%, rubble 8.9%, hard coral 3.5%, soft coral 2.6%, dead coral 1.5%, others 0.1%. The satellite imagery showed the following coverage of habitat types: sand 26.5%, seagrass 23.3%, sand + seagrass 12.3%, coral 18.1%, rubble 19.0%, rock 0.8% (Accuracy 65.2%). According to the visual interpretation of the habitat map by in situ survey, seagrass, sand, coral and rubble distribution were misaligned compared with the satellite imagery. While, the satellite imagery appear to be a plausible results to identify habitat types, it could not classify habitat types under one pixel in images, which in turn overestimated coral and rubble coverage, underestimated algae and sand. The differences appear to arise primarily because of habitat classification scheme, sampling scale and remote sensing reflectance. The implication of these results is that satellite imagery analysis needs to incorporate in situ survey data to accurately identify habitat. We suggest that satellite imagery must correspond with in situ survey in habitat classification and sampling scale. Subsequently habitat sub-segmentation based on the in situ survey data should be applied to satellite imagery.

• Ocean and Polar Research
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• 제34권3호
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• pp.297-304
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• 2012

Pylaiella littoralis was collected in the Chuuk lagoon of the Federated States of Micronesia (FSM). The FSM has a variety of coral reef ecosystems, which provide essential materials, such as minerals, vitamins, essential amino acids, for marine organisms. In this study, the antioxidant activities of ethanol and enzymatic extracts of P. littoralis were evaluated by measuring their scavenging activities on DPPH free radical, Alkyl radical, hydroxyl radical and cell viability. The enzymatic extracts were hydrolyzed to prepare water soluble extracts by using five carbohydrate degrading enzymes (AMG, Celluclast, Termamyl, Ultraflo, and Viscozyme) and five proteases (Alcalase, Flavourzyme, Kojizyme, Neutrase, and Protamex). As a result, the enzymatic extracts prepared by Flavourzyme, Ultraflo, and Kojizyme exhibited the greatest effects in DPPH free radical, alkyl radical scavenging activity and cell viability. Also, these enzymatic extracts had a higher antioxidant effect then commercial antioxidants in DPPH free radical and Alkyl radical scavenging activity. This study suggests that P. littoralis might be a useful source of natural antioxidants for the development of dietary supplements.

• 한국패류학회지
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• 제29권4호
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• pp.343-376
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• 2013

The Federated States of Micronesia consists of four states of Yap, Chuuk, Pohnpei and Kosrae, which are located in the West Pacific Ocean. In order to investigate molluscan fauna of Kosrae Island, field survey was made twice from 21st to 30th of January, 2011 and from 6th to 17th of January, 2012 for four localities including 10 intertidal and 14 subtidal zones of Kosrae Island. The mollusk samples collected were identified based on their morphological characteristics, comprising a total of 120 species from 30 families through this survey. In this study, we provided species list and illustrations for 120 species identified, and combined these with the previous record, resulting in a total of 208 species from 47 families in Kosrae Island.

• Ocean and Polar Research
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• 제38권4호
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• pp.287-294
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• 2016

Marine sponges have been a remarkably rich source of pharmacologically active and structurally diverse natural products. As a part of our continuing search for novel secondary metabolites of biomedical importance from marine invertebrate, we encountered the sponge Lipastrotethya sp. from Chuuk, Micronesia. The crude organic extract of this animal exhibited considerable cytotoxicity against the K562 cell line. Guided by the $^1H$ NMR analysis, flash chromatography of the crude extract followed by HPLC yielded a new triterpene glycoside, along with ten known saponins of the sarasinoside class. The structure of this new compound was determined by combined spectroscopic methods such as COSY, HSQC and HMBC experiment. Among these metabolites, six compounds exhibited moderate cytotoxicity against ACHN, MDA-MB-231, NCI-H23 and NUGC-3 cell lines.