• Korean Journal of Environmental Biology
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• v.38 no.4
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• pp.578-585
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• 2020

A new free-living marine nematode species of the genus Belbolla Andrássy, 1973 belonging to the family Enchelidiidae is described based on specimens collected from the sediment of a subtidal benthic environmental habitat in the East Sea, Korea. Belbolla wonkimi sp. nov. differs from its congeners by the combination of the following characteristics: a relatively long body (3263-3396 ㎛), the absence of ocelli, nine oesophageal bulbs in the posterior pharynx, well-developed two winged precloacal supplements, longer spicule length(115-130㎛, 1.6-1.8 anal body diameter long), and a triangle-shaped shorter gubernacular apophysis (17-18 ㎛). Comparative tables on the biogeographical and morphological characteristics of Belbolla species are presented. A DIC (differential interference contrast) photomicrograph of the new species is also provided. This is the first taxonomic report on the genus Belbolla from Korean waters.

• Journal of Species Research
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• v.12 no.1
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• pp.55-67
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• 2023

Two new records of marine nematodes, belonging to the family Ironidae de Man, 1876, are reported based on the specimens collected from intertidal sediments from the west coast of Korea. Conilia sinensis is characterized by a relatively long body length, a well-developed buccal cavity with three claw-like teeth, the presence of a single spicule with transverse striations, the presence of rib-shaped telamons, and single precloacal supplement. Pheronous donghaiensis is distinguished from other species of the genus by a well-developed buccal cavity with four claw-like solid teeth and minute denticles, relatively short and thick spicules with the central septum, the presence of 8-9 curved tubular-shaped precloacal supplements, and a sharp pointed tail with three small tubular supplements arranged into two rows in males. In this report, we provide a taxonomic description and illustrations of two unrecorded species of the family Ironidae by differential interference contrast microscopy. This is the first taxonomic report on the species of the family Ironidae from Korea.

• Journal of applied mathematics & informatics
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• v.29 no.5_6
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• pp.1193-1204
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• 2011

In the present paper we consider a differential-algebraic prey-predator model with stage structure for prey and harvesting of predator species. Stability and instability of the equilibrium points are discussed and it is observed that the model exhibits a singular induced bifurcation when the economic profit is zero. It indicates that the zero economic profit brings impulse, i.e. rapid expansion of the population and the system collapses. For the purpose of stabilizing the system around the positive equilibrium, a state feedback controller is designed. Finally, numerical simulations are given to show the consistency with theoretical analysis.

• ALGAE
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• v.35 no.1
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• pp.61-78
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• 2020

Species belonging to the dinoflagellate genus Prorocentrum are known to cause red tides or harmful algal blooms. To understand the dynamics of a Prorocentrum sp., its growth and mortality due to predation need to be assessed. However, there are only a few Prorocentrum spp. for which heterotrophic protist predators have been reported. We explored feeding by the common heterotrophic dinoflagellates Gyrodinium dominans, Oxyrrhis marina, Pfiesteria piscicida, Oblea rotunda, and Polykrikos kofoidii and the naked ciliate Strombidinopsis sp. (approx. 90 ㎛ cell length) on the planktonic species Prorocentrum triestinum, P. cordatum, P. donghaiense, P. rhathymum, and P. micans as well as the benthic species P. lima and P. hoffmannianum. All heterotrophic protists tested were able to feed on the planktonic prey species. However, O. marina and O. rotunda did not feed on P. lima and P. hoffmannianum, while G. dominans, P. kofoidii, and Strombidinopsis sp. did. The growth and ingestion rates of G. dominans and P. kofoidii on one of the seven Prorocentrum spp. were significantly different from those on other prey species. G. dominans showed the top three highest growth rates when it fed on P. triestinum, P. cordatum, and P. donghaiense, however, P. kofoidii had negative growth rates when fed on these three prey species. In contrast, P. kofoidii had a positive growth rate only when fed on P. hoffmannianum. This differential feeding on Prorocentrum spp. between G. dominans and P. kofoidii may provide different ecological niches and reduce competition between these two common heterotrophic protist predators.

• Korean Journal of Environment and Ecology
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• v.26 no.3
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• pp.313-321
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• 2012

To analyze the bird communities by the land use type, we surveyed 43 plots in Siheung City, Korea from Mar. 2009 to Feb. 2010 and classified the community by TWINSPAN and DCA. Classification result by TWINSPAN was classified into 4 communities. In the first division, waterbirds, such as spot-billed duck(Anas poecilorhyncha) and great egret(Egretta alba) operated as the differential species. In the second and third division, little grebe(Tachybaptus ruficollis) and eurasian sparrow(Passer montanus) were operated as the differential species. The relationship between land use types and classified bird communities, all plots of community I were located in the forest. Community II plots were contained all urban and several semi-natural land use types. Community III contains stream and rice paddy. Plots in the reservoir were classified community IV. The stream and rice paddy were classified into different communities, which were colsely related with the size of wetland paddy. Community III had the highest species diversity index and community II had lowest. Community III also had the highest maximum species diversity index and evenness index. The result of this study, small stream and small rice paddy located within the city have insignificant characteristics as the habitat for birds. Management size of semi-natural land use for wildbird habitat in the urban area should be considered for showing their habitat characteristics. If the classification of biotope type based on the scale of rice paddy and urban park and the type of landuse type in the riverside then we should be consider the standard of minium area.

• Korean Journal of Weed Science
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• v.16 no.3
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• pp.187-193
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• 1996

To supply seeds with a good quality as plant materials for herbicide screening and to know whether the germination characteristics could be associated with a differential response to herbicides, germination characteristics and differential responses to herbicides were investigated with 3 species of a genus Setaria ; Yellow foxtail(Setaria glauca P. Beauv, SETGL), Giant foxtail(Setaria faberi Hetrm, SETFA), and Green foxtail(Setaria viridis P. Beauv, SETVI). Degree of dormancy was high in the order of SETGL, SETVI and SETFA. The dormancy of SETGL seed was relatively well removed by room temperature and drying storage, but SETFA and SETVI by low temperature and wetting storage(stratification). For breaking dormancy of SETGL, SETVI and SETFA, it was necessary for being kept under the above storage conditions for at least 2, 4 and 4-5 months, respectively. When the dormancy-breaked seeds were transfered to low temperature($4^{\circ}C$) and drying condition, SETGL showed germination rate of 96% even after 2 month storage. However, SETVI and SETFA showed a decreased germination of 54% and 69%, respectively, with a decreased velocity of germination, indicating that secondary dormancy might be induced. On the other hand, a significant change in germination rate was not observed as the seeds were transfered to room temperature($25^{\circ}C$) and drying condition. The germinability of SETGL seed began to decline from 6th year after storage in room temperature and drying condition. All of 3 species showed relatively high germination rate at alternating temperature of $30^{\circ}C$/$20^{\circ}C$(14hr/10hr) and their germination were not increased by light. All of 3 species exhibited similar responses to cycloxydim, sethoxydim and primisulfuron in greenhouse experiment. In contrast, SETVI and SETFA were relatively susceptible to fenoxapropethyl, SETFA to fluazifop-butyl, SETGL and SETFA to clorimuron-ethyl, and SETGL to EK-2612. The difference in herbicidal response among 3 species was the highest in the treatment of EK-2612. These results suggest that there is no a consistent tendency in responses of 3 species to herbicides which have the same target site. And the relationship between germination characteristics and differential responses to herbicides was not found.

• The Korean Journal of Ecology
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• v.16 no.3
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• pp.287-303
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• 1993

A phytosociological study of forest vegetation of Mt. Kaya was carried out from August 1988 to September 1992. The forest vegetation of the area was classified into 3 communities (Quercus monogolica community, Lindera erythrocarpa community, Pinus densiflora community) and 3 subunits (Rhododendron mucronulatum subunit, Platycarya strobilacea subunit, typical subunit of Pinusdensiflora community). The Pinus densiflora community was located at the lower altitudes (100~300m) than those of other communities. The Lindera erythrocarpa community was located at the upper altitude (500m). Most of the inverstigated area were occupied by the secondary forest of Pinus densiflora community in the actual vegetation map and the profile diagram, suggesting that it was frequently destroyed by human interference

• Natural Product Sciences
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• v.10 no.6
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• pp.325-329
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• 2004

The composition of essential oil from O. javanica was analyzed by gas chromatography-mass spectrometry. Using the broth dilution method and disk diffusion test, anti-microbial activities of the oil fraction and its main components were evaluated against various antibiotic-susceptible and resistant strains of pathogenic microorganisms. As a result of GC-MS analysis, 57 compounds, including ${\alpha}-terpinolene$ (28.1%), dl-limonene (16.0%), ${\gamma}-terpinene$ (10.3%), ${\beta}-pinene$ (9.7%) and ${\alpha}-pinene$ (6.0%) were identified in the essential oil fraction. The essential oil fraction of O. javanica and its main components exhibited significant inhibitory activities, particularly against Candida albicans (antibiotic-susceptible strains) and Streptococcus pneumoniae (antibiotic- susceptible and resistant strains). The main components of the O. javanica oil fraction displayed different patterns of activity against the three tested Candida species as exemplified by the differential minimum inhibiting concentration (MIC) values. The disk diffusion test showed that the activities were dose dependent.

• ALGAE
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• v.17 no.1
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• pp.1-9
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• 2002

Diel vertical distribution of phytoflagellates and interactions between the phytoplankton components and environmental and biological factors were studied in a small artificial pond for three days on the December 18, 1998 and April 9 to 10, 1999. The phytoplankton population was dominated by Mallomonas akrokomos of chrysophytes and Cryptomonas marssonii and Chroomonas sp. of cryptophytes. The vertical distribution of these phytoflagellates taxa exhibited clear diel migration pattern. Moreover their migration patterns are showed differential fluctuation between M. akrokomos, C. marssonii and Chroomonas sp. The later two species upward migrated in the evening as well as night, whereas the former species migrated downward. Their distinctive migration pattern was found during the night but was not observed in the morning. During daytime C. marssonii and Chroomonas sp. showed maximum density above 2 m depth but M. akrokomos below 2 m depth. The diel vertical distribution of the dominant phytoflagellates did not show significant correlation between physical, chemical and biotic factors.

• Proceedings of the KAIS Fall Conference
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• 2009.05a
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• pp.842-844
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• 2009

The major group which contains all the organisms that are commonly termed Dinoflagellates is called the division Pyrrophyta or Dinophyta in botanical systems and the order Dinoflagellida or Dinoflagellata in zoological systems. Most dinoflagellates are biflagellated solitary planktonic cells. A taxonomic survey of the dinoflagellate family, Triadiniaceae Dodge was conducted for plankton monitoring network in the coastal waters of Korea. Identification of species in water samples was usually done by using differential interference contrast (DIC), which revealed especially well lighted thecal structures. For the apparent three-dimensional image, scanning electron microscope (SEM) was used. Two species were identified and described, which were Triadinium orientale(Lindemann)Dodge and Triadinium sphaericum(Murray and Whitting)Dodge.