• Journal of Aquaculture
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• v.11 no.1
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• pp.113-118
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• 1998

This study was carried out to investigate feeding of bacteria by Tigripus japonicus (Copepoda : Harpacticoida) under axenic culture. The ovigerous females and nauplii were grown with feed of aquatic bacteria. Growth of RT bacteria strain was suppressed by feeding of co-existing T. japonicus. T. japonicus of non-axenic culture was observed with oil bead in the egg sac. On the other hand, early nhauplius stage did not develop to the next stage without stage took bacteria as food. And the adult of T. japonicus may utilize the baxteria as nutrient source for egg development.

• Korean Journal of Microbiology
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• v.30 no.2
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• pp.129-133
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• 1992

Zooplankton feeding was investigated with epilluorescence microscope in Lake Soyang in August 1991. Zooplankton. which ingested fluorescence bead or fluorescently labeled bacteria (FLB). was regarded as bacterivore. The algavores wert. easily distinguished with autofluorescence of chlorophyll in gut. Copepoda nauplius and Copepodids. 7'hermocyclop.s spp, Pleosomcl spp. Brachionus spp were algavores. and DuphnB hpp. Bosmincr spp. Kerutrlla spp and Hrxuthru spp werc identified as bacterivc~res.T he mixo\ory was not detected. The percentages of algavores and bacterivores in Lake Hoyang were 65 7% and 34.3%. respectively. The bacterivorous zooplankton had trend to ingcst the beads bigger than 0.5 pm. Use of 0.5 pm bead as grazing tracer gave similar estin~ates of ingestion to FLR.

• Journal of Species Research
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• v.6 no.2
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• pp.177-180
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• 2017

Diploscapter coronatus (Cobb, 1893) Cobb, 1913 was first reported on oriental melon (Cucumis melo vars. makuwa Makino) roots from plastic film houses, Gyeongsangbuk-do, Andong, Korea (latitude $N36^{\circ}33^{\prime}$. longitude $E128^{\circ}29^{\prime}$). Diploscapter coronatus is most similar to D. pachys. Species in the genus Diploscapter have a visibly annulated cuticle. The stoma of D. coronatus is 1.5 times longer than the lip region width. The pharyngeal corpus is clearly separated from the isthmus and the vulva is situated around the mid-body. However, it differed by higher ratio of "a", filiform tail and had relatively blunt labial hooks. The Korean population is well matched and within the range of D. coronatus as described from Iran and Ethiopia in de Man's of L, b, c, c', and V. Female length, however, varied between populations: the Ethiopia population female length is longer than in the Korea population (396.4 vs 427.0) while females in the Iran population are smaller than in the Korea population (396.4 vs 350.0). Nematode size may vary due to environmental conditions such as food sources. The position of excretory pores in the Korean population were shorter 53.9-72.5 than in other populations (67-82 and 70-89). Males were uncommon. Males in the Korean population are smaller than females but larger(356.0) than males in the Indian population (306.0).

• The Korean Journal of Ecology
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• v.19 no.6
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• pp.543-562
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• 1996

Zooplankton community structure and the factors correlated with community differences were examined in sandusky Bay (SB) and the open water of Lake Erie (LE, U.S.A.). SB zooplankton communities differed from those in LE by having a greater rotifer density and species richness. Keratella spp., Brachionus spp., and Pompholyx complanata dominated SB rotifers; Brachionus and Pompholyx were rarely seen in LE. Of 19 rotifer species observed, nine species were found only at SB sites. Ordination of zooplankton species abundance by detrended correspondence analysis (DCA) showed an overlap between SB and LE sites, but indicated a portion of the space that was occupied by only SB communities. The seasonal trajectories of zooplankton dynamics in the ordination space at SB sites differed from that of LE. The zooplankton most important in forcing site separation along a DCA Axis I at SB sites were Brachionus angularis, Pompholyx complanata, Keratella valga, Keratella quadrata, Filinia terminalis (rotifers), and Eubosmina coregoni and Daphnia (cladocerans). These species had axis scores which were significantly correlated (p<0.01) with bacterial density and bacterial phosphorus, total phosphorus, and algal density. Very high baterial density and very abundant bacterivorous rotifers in SB suggest that the transport of bacterial carbon through rotifers may be a relatively important link to higher trophic leaels. We believe that this "microbial carbon flow" from the base of the food web may be important in determining the suitability of SB as a spawning site and nursery for larval and juvenile fish.nile fish.

• Korean Journal of Environmental Agriculture
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• v.35 no.1
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• pp.39-45
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• 2016

BACKGROUND: This study aimed to evaluate the combined effects of three components (NPK) of chemical fertilizers with basal application of compost on soil organisms.METHODS AND RESULTS: The soil was treated with five treatments continuously for 15 years: control, PK, NK, NP and NPK. The application of N increased plant growth or biomass, and enhanced organic matter content in the soils. Levels of microbial phospholipid fatty acids (PLFAs) in the soils did not show marked differences among the soils treated with different treatments. However, the principal component analysis showed the changes in the structure of the microbial community in the soil, depending on treatments added. Nitrogen application caused a decrease of pH and an increase of EC in the soils, and these environmental stresses appeared to offset the promoting effect of increased organic matter content on microbial abundance. The abundance of bacterivorous nematodes was the highest in the soils after treating NPK; however, the abundance of fungivorous nematodes was unaffected. There was no significant correlation between the abundances of microbial groups and their feeders. Organic matter content was significantly correlated with the abundance of nematodes in the soils.CONCLUSION: Our results showed that chemical fertilizers affect the soil food chains through both biotic and abiotic factors, and a trophic cascade in the soils may not occur in response to long-term fertilization.

• Korean Journal of Environmental Biology
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• v.36 no.4
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• pp.471-478
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• 2018

The purpose of this study was to investigate effects of reusable organic wastes, on soil organisms and chemical properties. Bone meal, de-oiled cake, and oyster shell were applied and abundances of soil organisms were measured at 3 and 15 months, after treatment in soil under sawleaf zelkova cultivation. Soil organisms are affected, by the quality of applied organic wastes. Abundance of microorganisms was higher in oyster shell treated soils than in untreated soils, suggesting that soil pH is a driving force, altering abundance and structure of the microbial community. Increase in abundance of bacterivorous nematodes was observed under treatment with bone meal and de-oiled cake, but there was slight change in abundance of fungivorous and herbivorous nematodes. Abundance of herbivorous nematode was positively correlated with plant growth, at 15 months after treatment. Response of microarthropods in the Collembola and Oribatida was not apparent. Abundances of primary consumers were not significantly correlated with microorganisms. This study suggested that organic waste influences soil organisms primarily by altering soil chemical properties and bottom-up effects may not occur in trophic reactions.