• Korean Journal of Ecology and Environment
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• v.47 no.4
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• pp.273-281
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• 2014

We conducted the weekly monitoring (December 2012~April 2013) to evaluate the temporal variation and identification of Stephanodiscus spp. that are generally dominant during winter in the Yeongsan River. Phytoplankton species were identified and counted using the optical microscope and scanning electron microscope (SEM). Phytoplankton in the river were grouped into 6 classes (bacillariophyceae, chlorophyceae, cryptophyceae, cyanophyceae, dinophyceae, euglenophyceae), 30 genus and 41 species. Phytoplankton composition showed high abundance of diatoms in winter and Aulacoseira sp., Cyclotella sp. and Stephanodiscus spp. were dominant. Among the species, Stephanodiscus spp. was relatively abundant compared to other diatom species. Stephanodiscus spp. appeared from December 2012 to April 2013 and their abundance peaked in January. Abundance of diatoms especially peaked ($21,080cells\;mL^{-1}$) in January 15, 2013 when Stephanodiscus spp. also bloomed ($20,560cells\;mL^{-1}$). The abundances of Stephanodiscus spp. were gradually decreased from March and reached as low as $60cells\;mL^{-1}$ in April 26. Cyclostephanos (C. invisitatus), Cyclotella (C. meneghiniana), Discostella (D. pseudostelligera, D. woltereckii) and Stephanodiscus (S. hantzschii, S. minutulus, S. parvus) were classified in the circular diatoms. Abundance of S. hantzschii was extremely high compared to S. minutulus and S. parvus.

• Korean Journal of Ecology and Environment
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• v.42 no.1
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• pp.19-25
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• 2009

The effects of artificial floating island on the changes in phytoplankton and zooplankton community structure were investigated monthly from September 2006 to May 2007 in Shingu reservoir. The total cell number of phytoplankton under the artificial floating island was three times less than those of control (without artificial floating island). The dominant species of phytoplankton were Lyngbya sp. on September, Cryptomonas sp. from October to January, Aulacoseira granulata on February and Oscillatoria sp. from March to May at lake water. Cyanophyta was dominated from February to March at lake water but it was dominated from March at artificial floating island area. The total individual number, species number of zooplankton and species diversity of phytoplankton and zooplankton under the artificial floating island were higher than those of lake water.

• Korean Journal of Environmental Biology
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• v.37 no.1
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• pp.19-30
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• 2019

To investigate the characteristics of seasonal environment and phytoplankton community structure in the coastal area of Dokdo, a survey of Dokdo around waters was conducted during the four seasons. Phytoplankton of 4 phylum 72 species in four seasons were collected in Dokdo around water. The seasonal mean abundance of phytoplankton were $3.32{\times}10^4cells\;L^{-1}$ in winter, $1.04{\times}10^4cells\;L^{-1}$ in spring, $0.28{\times}10^4cells\;L^{-1}$ in summer, and $4.86{\times}10^4cells\;L^{-1}$ in autumn in Dokdo around water. During winter, the diatoms Chaetoceros spp. had dominated. During spring, when the nutrients in the euphotic layer were depleted, the nano-flagellates and Cryptomonas appeared at surface layer. In summer, the abundance of phytoplankton was relatively low, which lead to occurrence of diatoms such as genus of Chaetoceros, Rhizosolenia, and Skeletonema. In autumn, Pseudo-nitzschia spp. was the most dominant species and tropical species such as Amphisolenia sp. and Ornithocercus magnificus were observed, implying that they may have introduced within warm water current such as Kurosiwo Current. Therefore, although natural phytoplankton communities in the vicinity water of Dokdo are mainly influenced by Tsushima Warm Current branched Kurosiwo Current, their population dynamics was affected on the spatio-temporal change of physicochemical factors by short-term wind events, namely "island effect". Long-term survey research is needed to facilitate food-web response in marine ecosystem associated with phytoplankton biomass and physicochemical factors including the warm water current in oligotrophic offshore water of Dokdo, which may have significant role for sustainable use of Dokdo.