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5. Interactions between algae and nematodes : habitat provision and detrital driven processes

Author

Kim, Hyeong-Gi and Hawkins, Stephen John

Subjects
595
Abstract

The overall aim of this thesis was to investigate marine nematode-algae interactions using a twofold approach: habitat provision by algae and the role of algal detritus in structuring nematode assemblages. Nematode assemblages living in algae on the south and east coast of Korea were compared using a hierarchical sampling design with those from the south coast of the British Isles in order to investigate nematode diversity and functional traits at different spatial scales (patch, shore, region and biogeographic realm). The cosmopolitan genus Corallina and Sargassum muticum, a native of Korea and an invader in the British Isles were investigated as algal habitat providers for nematodes. The species composition and functional traits of nematode assemblage in both species of macroalgae were significantly different at all spatial scales. The alpha, beta and gamma biodiversity of nematodes in each macroalgae were also measured at all spatial scales. The alpha, beta and gamma diversity of nematodes across four spatial scales in two different habitats are an alpha dominant relationship indicating random colonization and high species turnover at small scales. Nematode species composition and diversity on the wrack-loaded sandy shore were explored using field experiments. Mesh bags filled with three different types of macroalgae (brown, green and red) were used to test the effects of diversity of algal detritus on nematode assemblages involved in decomposition processes. The detrital treatments consisted of 10 combinations of macroalgae (monoculture, two and three species treatments), containing different proportions of algal material in order to test the impacts of detrital diversity on nematode assemblages. The density, diversity and species composition of nematodes in combinations of algae were higher than with single types of macroalgae. This indicated that the combination of two algae mixtures offered more favourable environments than the single species bags. Overall this thesis demonstrated the high diversity of nematodes inhabiting seaweeds and the role of detrital composition in driving nematode assemblages.

Published
2017

28. A comparison of epiphytic nematode diversity and assemblages in Corallina turves on British and South Korean coasts across hierarchical spatial scales.

Author

Kim, Hyeong-Gi, Hawkins, Lawrence E., Godbold, Jasmin A., Maclean, Moira, Oh, Chul-Woong, Rho, Hyun Soo, and Hawkins, Stephen J.

Abstract

Cosmopolitan habitat-forming taxa of algae such as the genus Corallina provide an opportunity to compare patterns of biodiversity over wide geographic scales. Nematode assemblages inhabiting Corallina turves were compared between the south coasts of the British Isles and South Korea. A fully nested design was used with three regions in each country, two shores in each region and replicate samples taken from three patches on each shore to compare differences in the taxonomic and biological trait composition of nematode assemblages across scales. A biological traits approach, based on functional diversity of nematodes, was used to make comparisons between countries, among regions, between shores and among patches. The taxonomic and biological trait compositions of nematode assemblages were significantly different across all spatial scales (patches, shores, regions and countries). There is greater variation amongst nematode assemblages at the scale of shore than at other spatial scales. Nematode assemblage structure and functional traits are influenced by the local environmental factors on each shore including sea-surface temperature, the amount of sediment trapped in Corallina spp. and tidal range. The sea-surface temperature and the amount of sediment trapped in Corallina spp. were the predominant factors determining nematode abundance and composition of assemblages and their functional diversity. [ABSTRACT FROM AUTHOR]

Published
2019
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29. Interactions between algae and nematodes: habitat provision and detrital driven processes

Author

Kim, Hyeong-Gi. and Kim, Hyeong-Gi.

Abstract

The overall aim of this thesis was to investigate marine nematode-algae interactions using a twofold approach: habitat provision by algae and the role of algal detritus in structuring nematode assemblages. Nematode assemblages living in algae on the south and east coast of Korea were compared using a hierarchical sampling design with those from the south coast of the British Isles in order to investigate nematode diversity and functional traits at different spatial scales (patch, shore, region and biogeographic realm). The cosmopolitan genus Corallina and Sargassum muticum, a native of Korea and an invader in the British Isles were investigated as algal habitat providers for nematodes. The species composition and functional traits of nematode assemblage in both species of macroalgae were significantly different at all spatial scales. The alpha, beta and gamma biodiversity of nematodes in each macroalgae were also measured at all spatial scales. The alpha, beta and gamma diversity of nematodes across four spatial scales in two different habitats are an alpha dominant relationship indicating random colonization and high species turnover at small scales. Nematode species composition and diversity on the wrack-loaded sandy shore were explored using field experiments. Mesh bags filled with three different types of macroalgae (brown, green and red) were used to test the effects of diversity of algal detritus on nematode assemblages involved in decomposition processes. The detrital treatments consisted of 10 combinations of macroalgae (monoculture, two and three species treatments), containing different proportions of algal material in order to test the impacts of detrital diversity on nematode assemblages. The density, diversity and species composition of nematodes in combinations of algae were higher than with single types of macroalgae. This indicated that the combination of two algae mixtures offered more favourable environments than the single species bags.

Published
2017

36. Effects of two different agents, H3PO4and NaCl, to increase the flame-retardant properties of cellulose fibers

Author

Kim, Hyeong Gi and Lee, Young-Seak

Abstract

After flame-retardant treatment by the two different agents, the thermal behaviors of Lyocell fibers are discussed. In this research, H3PO4and NaCl reduced the degradation rate and increased the char yield of the Lyocell fibers, and also increased the limiting oxygen index with the char yield increased. After treatment, the integral procedure decomposition temperature and the activation energy of Lyocell fibers are significantly increased by various concentration factors. These phenomena were indicated by the dehydration, rearrangement, formation of carbonyl groups, the evolution of carbon monoxide and dioxide, and carbonaceous residue formation. These effects were indicating the slow pathway of flame retardancy for the Lyocell fibers and are attributed to the two different flame-retardant agent treatments.

Published
2019
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39. Why Copy America's Botched Math Education?

Author

Kim Hyeong-gi

Subjects
*CALCULATORS, *MATHEMATICAL instruments, *MATHEMATICS education, *EDUCATION
Abstract

The article offers the author's comments on the proposal to introduce the usage of calculators in mathematics classes and examinations in Korea. The author says that the debate concerning the usage of calculators stems from the deep-rooted confrontation between the liberal and traditional views of education. The author mentions that U.S. is regretting its math education policy and if Korea introduces calculators in classrooms, it will be following the failed choice of the U.S.

Published
2011

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