• Journal of the Korean earth science society
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• v.36 no.1
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• pp.68-81
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• 2015

In this study, the correlation between the frequency of summer tropical cyclones (TC) affecting areas around Korea over the last 37 years and the western North Pacific monsoon index (WNPMI) was analyzed. A clear positive correlation existed between the two variables, and this high positive correlation remained unchanged even when excluding El Ni$\tilde{n}$o-Southern Oscillation (ENSO) years. To investigate the causes of the positive correlation between these two variables, ENSO years were excluded, after which the 8 years with the highest WNPMI (positive WNPMI phase) and the 8 years with the lowest WNPMI (negative WNPMI phase) were selected, and the average difference between the two phases was analyzed. In the positive WNPMI phase, TCs usually occurred in the eastern waters of the tropical and subtropical western North Pacific, and tended to pass the East China Sea on their way north toward Korea and Japan. In the negative WNPMI phase, TCs usually occurred in the western waters of the tropical and subtropical western North Pacific, and tended to pass the South China Sea on their way west toward the southeastern Chinese coast and the Indochina peninsula. Therefore, TC intensity was higher in the positive WNPMI phase, during which TCs are able to gain sufficient energy from the sea while moving a long distance to areas nearby Korea. TCs also tended to occur more often in the positive WNPMI phase. In the difference between the two phases regarding 850 and 500 hPa streamline, anomalous cyclones were reinforced in the tropical and subtropical western North Pacific, while anomalous anticyclones were reinforced in mid-latitude East Asian areas. Due to these two anomalous pressure systems, anomalous southeasterlies developed in areas near Korea, with these anomalous southeasterlies playing the role of anomalous steering flows making the TCs head toward areas near Korea. Also, due to the anomalous cyclones developed in the tropical and subtropical western North Pacific, more TCs could occur in the positive WNPMI phase.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.15 no.1
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• pp.42-46
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• 1982

Followings are the results of growth of Pacific oysters transplanted from the temperate waters of Korea in February 1981, and cultivated upto early July in the tropical waters of Ambong Bay in Malaysia: The shell length increased from 5.78 mm in February to 25.01 mm in July, and the shell height increased from 7.33 mm in february to 38.91mm in July. The meat weight progressively increased and reached the maximum value of 1.66g in May, but then gradually decreased until July, and the fatness varied from $28\%$ of maximum in March to $11\%$ of minimum in July-Survival rate was $47\%\;and\;39\%$ of the initial number in June and July respectively.

• Journal of Environmental Policy
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• v.1 no.1
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• pp.1-24
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• 2002

Due to the recent increase in greenhouse gases in atmosphere, world climate is rapidly changing and in turn, the earth ecosystem responds upon the climate changes. Comparing the ecosystem in the past, the present shapes of ecosystem is the result of the serious modification. Fishery resources in marine ecosystem, which usually occupy the upper trophic level, are also inevitable from such changes, because they always react to the natural environmental conditions. The northwestern Pacific is the most productive ocean in the world producing about 30% of world catch. From time to time, however, it has been notified that abundance, distribution and species composition of major fish species were altered by climate events. Furthermore, primary productivity of the ocean is not stable under the changing environments, so that carrying capacity of the ocean varies from one climate regime to another. Major climate events such as global warming, atmospheric circulation pattern, climate regime shift in the North Pacific, and El Nino event in the Pacific tropical waters were introduced in relation to fisheries aspects. The current status and future projection of fishery production was investigated, especially in the North Pacific including Korean waters. This new paradigm, ecosystem response to environmental variability, has become the main theme in marine ecology and fishery science, and the GLOBEC-type researches might provide a solution far cause-effect mechanism as well as prediction capability. Ecosystem management principles for multi-species should be adopted for better understanding and management of ecosystem.

• Ocean and Polar Research
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• v.34 no.1
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• pp.65-71
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• 2012

Gambierdiscus toxicus, Adachi et. Fukuyo, is a benthic ciguatoxin-producing armored dinoflagellate, often attached to macroalgae. This organism is the primary causative agent of ciguatera fish poisoning which occurs in tropical and subtropical regions. However, regardless of the fact that the population of Gambierdiscus spp. has expanded to such temperate areas from sub-trophic and trophic areas, monitoring of G. toxicus has been lacking in the Korean coastal waters of temperate areas. This study was performed at the uninhabited Baekdo Islands off the southern coast of Korea and at Seopsom Island in the vicinity of Seogwipo, Jeju Province during April and May, 2011. Cell densities of Gambierdiscus spp. on macroalgae at Baekdo and Jeju Island ranged from zero to 56.4 cells $g^{-1}$. Maximum density was recorded on the brown alga Cladophora japonica at St. 3 of Jeju Island. In particular, the cell densities of Gambierdiscus spp. were influenced by the substrate characteristics of macroalgae. In the future, the continuous monitoring of toxic benthic dinoflagellate is necessary to predict and prevent ciguatera poisoning in Korean coastal waters.

• ALGAE
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• v.33 no.3
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• pp.231-241
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• 2018

Genetic continuity of Digenea simplex outside the Atlantic waters remains less studied, despite its long exposure to oriental folk medicine and wide distribution in tropical waters. Mitochondrial COI-5P and plastid rbcL sequences and morphology were investigated for plants from Mexico and additional specimens from Japan. Two new species, Digenea mexicana and Digenea rafaelii, are described for plants that would previously have been recognized as D. simplex in Mexico. D. mexicana grows to 10.5 cm tall and has cylindrical axes, irregular or di-, trichotomous branches, simple to branched determinate branchlets with eight pericentral cells, and tetrasporangia on inflated upper parts of determinate branchlets. It occurs intertidally in Quintana Roo, Yucatan Peninsula. D. rafaelii grows to 5 cm tall and has cylindrical axes, irregular or di-, trichotomous branches, and simple determinate branchlets with ten pericentral cells. It occurs intertidally in the Gulf of California. Both COI-5P and rbcL sequences revealed the genetic discontinuity between D. mexicana and D. rafaelii.

• Animal Systematics, Evolution and Diversity
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• v.39 no.1
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• pp.27-33
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• 2023

The specimens collected from five localities during the period from 2004 to 2022 were observed. As a result of this study, Jellyella eburnea was found to be new to the Korean fauna and three membraniporids were reviewed. Two species, Jellyella eburnea and Biflustra grandicella, were redescribed and illustrated with the collected specimens in this study. Membranipora perfragilis from Korea is changed into Biflustra grandicella. Jellyella eburnea is new to the Korean fauna and first reported outside subtropical and tropical seas of the South Pacific and Indo-Pacific Ocean. This fact proves that the seas in Korea are warming. Additionally, Biflustra crenulata reported from the West Sea, South Sea and Jejudo waters of Korea is synonymized into Biflustra okadai. Membranipora irregulata is transferred into the genus Biflustra. Five of Korean membraniporids, Biflustra grandicella, Biflustra irregulata, Biflustra okadai, Jellyella eburnea, and Jellyella tuberculata, are reported in the Korean fauna as a result of this study. The photos taken in the field and by Scanning Electron Microscopy of two species, Biflustra grandicella and Jellyella eburnea, are provided herein.

• ALGAE
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• v.28 no.3
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• pp.281-288
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• 2013

Photosynthetic carbon fixation regulates air-sea $CO_2$ fluxes in the waters of coral reefs. However, little has been documented on the effects of solar UV radiation (UVR, 280-400 nm) upon photosynthetic behaviors of phytoplankton dwelling in these ecosystems. In order to evaluate the aforesaid, surface dwelling tropical coral reef phytoplankton assemblages collected from the South China Sea were exposed to solar radiation (i.e., photosynthetically active radiation [PAR] + UV radiation A [UVA] + UV radiation B [UVB], 280-700 nm; PAR + UVA, 320-700 nm; and PAR, 400-700 nm) under static or simulated-mixing conditions. Under the static condition, UVA and UVB significantly reduced the carbon fixation with the maximum of 22.4 and 15.3%, respectively; while lower UVR-related photosynthetic inhibition was observed in case of phytoplankton samples being subjected to mixing. At a moderate level of mixing (i.e., circulation time 80 min), the UVA and UVB caused inhibition were lowered by 52.1 and 79.6%, respectively. Based on this it could be stated that vertical mixing induced by winds and/or tides in the natural environments could reduce the inhibitory effect of solar UVR on phytoplankton productivity in the coral reefs water.

• Animal Systematics, Evolution and Diversity
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• v.11 no.1
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• pp.125-145
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• 1995

The study on the classification of the Chindo Islands ascidians was conducted by collecting the specimens from five localities in July and November, 1994 and the previous records. The ascidians were classified into 7 families, 11 genera and 16 species. They are all known species in Korean waters. Among them nine species were found to be new to the Chindo Is. From the standpoint of water forms, the composition of the ascidians from Chindo Is. is made up of three elements, viz., temperate (8species, 50%), temperature-tropical (7 species, 44%) and tropical (1 species, 6%) . A boreal water species and boreal-temperature species were not found . It may be attributable to the fact that the water of this area is warm because of Kuroshio Water Current.

• Journal of Ecology and Environment
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• v.38 no.2
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• pp.271-279
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• 2015

After the reversion of Okinawa (Ryukyu Islands) to Japan in 1972, extensive urban and agricultural development resulted in a significant increase in sediment discharge to coastal waters. The release of sediment has caused the degradation of freshwater and coastal ecosystems and biodiversity. A consideration for catchment-to-reef continua, as well as agricultural (socioeconomic) factors is necessary to establish proper land-based management plans for the conservation of the island environment. We have set up a framework to integrate biophysics and socioeconomics: 1) setting a conservation target and threshold, 2) identifying the sources and processes, and 3) examining cost-effectiveness and management priorities. The framework may be applicable to other tropical and subtropical islands with similar characteristics.

• Mycobiology
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• v.49 no.6
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• pp.559-581
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• 2021

The coastal marine ecosystems of Vietnam are one of the global biodiversity hotspots, but the biodiversity of marine fungi is not well known. To fill this major gap of knowledge, we assessed the genetic diversity (ITS sequence) of 75 fungal strains isolated from 11 surface coastal marine and deeper waters in Nha Trang Bay and Van Phong Bay using a culture-dependent approach and 5 OTUs (Operational Taxonomic Units) of fungi in three representative sampling sites using next-generation sequencing. The results from both approaches shared similar fungal taxonomy to the most abundant phylum (Ascomycota), genera (Candida and Aspergillus) and species (Candida blankii) but were different at less common taxa. Culturable fungal strains in this study belong to 3 phyla, 5 subdivisions, 7 classes, 12 orders, 17 families, 22 genera and at least 40 species, of which 29 species have been identified and several species are likely novel. Among identified species, 12 and 28 are new records in global and Vietnamese marine areas, respectively. The analysis of enzyme activity and the checklist of trophic mode and guild assignment provided valuable additional biological information and suggested the ecological function of planktonic fungi in the marine food web. This is the largest dataset of marine fungal biodiversity on morphology, phylogeny and enzyme activity in the tropical coastal ecosystems of Vietnam and Southeast Asia. Biogeographic aspects, ecological factors and human impact may structure mycoplankton communities in such aquatic habitats.