• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1246-1248
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• 2003

Internal wave with a soliton-like, large amplitudes within several kilometers, is frequently observed in the sea surface caused by tidal rectification due to sill or rough topographic changes. Internal waves can perturb current and density field, initiate bottom sediment re -suspension and mix nutrients to photic zone. Previous studies indicate that the appearance of internal wave in the Lombok Strait have been detected in SAR image data. This paper studies effect of internal wave in the Lombok Strait to chlorophyll distribution in the surrounded areas using SeaWiFS and ERS SAR images data during 1996-2001 periods. The preliminary result concludes that the internal waves presumably affect phytoplankton distribution spreading southeastward in the coast off Bali Island. The distribution of phytoplankton at southern coastline off Bali Island when internal wave occurred is elongated and distributed further to westward (from 8.8$^{\circ}$ to 10.7$^{\circ}$LS) than the area when internal wave did not occur on August 2000 (from 9.25$^{\circ}$ to 10.25$^{\circ}$LS) as shown in figure 3. It shown that the surface phytoplankton concentration near coastal area, i.e. from 8.8$^{\circ}$ to 9.25$^{\circ}$ LS, increased when internal wave is occurred.

• Journal of the korean society of oceanography
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• v.37 no.1
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• pp.35-44
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• 2002

To assess the relative contribution of bacterial and phytoplankton biomasses to particulate organic matter (POM) in the water column, microbial abundance and biomass were from two transects in the western channel of the Korea Strait in 1996. Bacterial abundance had a mean value of $5.9{\times}10^5$ cells/ml and chlorophyll-a averaged 0.14 ${\mu}g/l$. Bacterial abundance in the Korea Strait showed a positive relationship with chlorophyll-a concentration, while the distribution of POM did not covary with chlorophyll-a. Particulate organic carbon (POC) and nitrogen (PON) concentrations were greater in August than in October. Bacterial carbon (POC) and nitrogen (PON) concentrations were greater in August than in October. Bacterial carbon and nitrogen biomasses were 7.29 ${\mu}gC/l$ and 1.24 ${\mu}gN/l$, respectively, during the study periods. Bacterial biomass was larger in October than in August due to the autumn phytoplankton bloom. Phytoplankton biomass based on chlorophyll-a was 7.67 ${\mu}gC/l$ for carbon and 1.10${\mu}gN/l$l for nitrogen. The ratio of bacterial carbon (BC) to phytoplankton carbon (Cp) averaged 0.95 in the Korea Strait in 1996. Bacteria may play a more significant role in the dynamics of POM than phytoplankton do in August, with BC/Cp ratio of 1.26. The ratio of BC to Cp increased with a decrease in chlorophyll-a concentration. Averaged over all the samples in both cruises, the contribution of microbial biomass to POC and PON was about 43% and 51%, respectively. Bacterial assemblage constituted a significant fraction of POC (21%) and PON (27%). Phytoplankton accounted for 22% of POC and 24% of PON. Microbial biomass played a more important role in the dynamics of POC and PON in October than in August due to a significant increase in microbial biomass in the southern transect (transect-B) in October by the autumn phytoplankton bloom. This study showed that marine microbes may constitute a significant part in the reservoir of POM in the Korea Strait.

• Journal of Ecology and Environment
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• v.37 no.1
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• pp.1-11
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• 2014

To understand the effects of fluctuations in dam discharge due to river environments and phytoplankton communities, we monitored such environments and phytoplankton communities biweekly, from February 2001 to February 2002 and from February 2004 to February 2005, in the lower Han River (LHR), South Korea. The phytoplankton abundance during the dry season was approximately two times higher than that during the rainy season. In particular, fluctuations in diatom assemblages, which constituted over 70% of the total phytoplankton abundance, were affected severely by the changes in the discharge. When a large quantity of water in a dam was discharged into the LHR, the conductivity and the concentrations of total nitrogen (TN), total phosphorus (TP), and dissolved inorganic phosphorus (DIP) decreased rapidly, whereas the concentrations of suspended solids (SS), dissolved inorganic nitrogen (DIN), and dissolved silica (DSi) increased immediately. Time-delayed relationship also revealed that the dam discharge had an immediately significant negative relationship with phytoplankton abundance. On the whole, fluctuations in phytoplankton communities in the LHR were influenced much more by hydrodynamics such as dam discharge than by the availability of nutrients. Thus, the variability in these concentrations usually parallels the strength of river flow that is associated with summer rainfall, with higher values during periods of high river discharge.

• Proceedings of KOSOMES biannual meeting
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• 2017.04a
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• pp.191-191
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• 2017

• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.5
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• pp.446-457
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• 1993

Monthly distribution of marine bacteria and phytoplankton in Suyeong Bay were investigated with laboratory experiment of dominant algal species and bacterial flora. During the periods of study, the highest density of phytoplankton and bacteria occurred in May with the number of $3.3{\times}10^6cells/l$ and $1.93{\times}10^8cells/ml$, respectively. 10 genera of bacteria and 22 genera of phytoplankton were isolated and identified. In May when phytoplankton bloom occurred, dominant species of bacteria were Acinetobacter calcoaceticus($29.1\%$) and Bacillus subtilis($22.9\%$), and dominant species of phytoplankton were Chaetoceros spp.($62.8\%$) and Skeletonema spp. ($19.4\%$). Pseudomonas spp., which was the most abundant bacterial species during the study periods, were rapidly decreased in May. In laboratory studies of culturing bacteria and phytoplankton isloated in May, the growth of Pseudomonas vesicularis seems to be influenced by the concentrations of excretion matter of Chaetoceros spp. To examine the result colsely, the problem of pure isolation for phytoplankton must be solved and more experimental process have to be conducted.

• Korean Journal of Ecology and Environment
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• v.37 no.4 s.109
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• pp.455-461
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• 2004

Effects of the different strengths and intervals of the periodic outer water intrusions (kyuchos and bottom intrusions) on the dynamics of phytoplankton biomass in a small embayment were examined with a simple numerical model. Environmental conditions of Kitanada Bay in the Bungo Channel were applied to the model. As the interval of the intrusion became longer and the amplitude became smaller, phytoplankton biomass In the bay became higher. On the other hand, as the interval became shorter and the amplitude became larger, the growth rate of the phytoplankton became higher. It suggested that when the intrusion was weaker, water exchange of the bay decreased and the phytoplankton in the bay accumulated at a high density, When water exchange was improved by active intrusions, availability of light would become more efficient and the growth rate of the phytoplankton was enhanced.

• Ocean Science Journal
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• v.41 no.1
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• pp.31-41
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• 2006

Seasonal changes of abundance of the main phytoplankton groups of species (diatoms, dinoflagellates, chrysophytes, small flagellates and cryptophytes) and a set of environmental parameters were investigated in coastal and pre-estuarine waters of Peter the Great Bay (East/Japan Sea) in May-October of 1998 and 1999. Three periods of mass development were revealed: spring, summer and autumn blooms, with successive change of species. The conditions favourable for each group of species were determined. Driving mechanisms of the succession include nutrients transport through seasonal pycnocline by turbulent mixing, terrestrial nutrients supply by monsoon floods, nutrients supply by upwellings, and light control by the thickness of upper mixed layer. Summer succession could be explained by a simple SST-MLD diagram similar to Pingree S-kh diagram with sea surface temperature as indicator of stratification (S) and mixed layer depth as indicator of light availability (kh).

• ALGAE
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• v.28 no.2
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• pp.173-183
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• 2013

Sodium hypochlorite (NaOCl) is widely used to disinfect seawater in power plant cooling systems in order to reduce biofouling, and in ballast water treatment systems to prevent transport of exotic marine species. While the toxicity of NaOCl is expected to increase by ongoing ocean acidification, and many experimental studies have shown how algal calcification, photosynthesis and growth respond to ocean acidification, no studies have investigated the relationship between NaOCl toxicity and increased $CO_2$. Therefore, we investigated whether the impacts of NaOCl on survival, chlorophyll a (Chl-a), and effective quantum yield in three marine phytoplankton belonging to different taxonomic classes are increased under high $CO_2$ levels. Our results show that all biological parameters of the three species decreased under increasing NaOCl concentration, but increasing $CO_2$ concentration alone (from 450 to 715 ${\mu}atm$) had no effect on any of these parameters in the organisms. However, due to the synergistic effects between NaOCl and $CO_2$, the survival and Chl-a content in two of the species, Thalassiosira eccentrica and Heterosigma akashiwo, were significantly reduced under high $CO_2$ when NaOCl was also elevated. The results show that combined exposure to high $CO_2$ and NaOCl results in increasing toxicity of NaOCl in some marine phytoplankton. Consequently, greater caution with use of NaOCl will be required, as its use is widespread in coastal waters.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.2
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• pp.178-186
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• 2003

Seasonal variation of phytoplankton was investigated with surface mixed layer ecosystem model in the East Sea. The model consisted of four compartments (phytoplankton, zooplankton, nutrient, detritus) forced by mixed layer depths, photosynthetically available radiation and nutrient concentrations. From model results we estimated entrainment rate $2.5-4.0\;m{\cdot}day^{-1}$ to reproduce the two annual blooms, and reproduced seasonal variation of phytoplankton at southern and northern regions by the difference of surface winter mixed layer depth (MLD) using the entrainment rate value $3.0\;m{\cdot}day^{-1}$. The spring blooms in the southern and northern regions closely related to deepening of a winter surface MLD. In the southern region where MLD was shallow and phytoplankton spring bloom occurs one month in advance to the northern region where MLD was deep. The amount of light increases within the MLD during the onset of stratification and water temperature increases faster in spring in the southern region than the northern region. Decrease of phytoplankton was mainly affected by zooplankton grazing in the southern region and by nutrient exhaustion in the northern region. The fall bloom in the two regions was caused by the nutrient availability and entrainment on the phytoplankton.

• Korean Journal of Environmental Biology
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• v.40 no.4
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• pp.374-386
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• 2022

Phytoplankton communities, with emphasis on picoplankton and nanoplankton, were investigated in Gamak Bay, South Korea, where freshwater input and coastal water intrusion shape ecosystem functions. Shellfish farms and fish farms are located in the inner bay and outer bay, respectively, and tides translocate uneaten food and urine production from aquaculture farms toward the inner bay. Water masses were distinctly different based on a significantly different density between the surface and bottom layer and among three water masses, including the inner bay, outer bay, and Yeosu Harbor. Phytoplankton communities were quantified using flow cytometry and size-fractionated chlorophyll-a (chl-a) was measured. Salinity was a principal variable separating phytoplankton communities between the surface and bottom layer, whereas Si(OH)₄ controlled the communities in the inner bay, and NH₄⁺ and PO₄^3- governed the outer bay communities. While phycocyanin-containing (PC) cyanobacteria dominated in the outer bay, phycoerythrin-containing (PE) cyanobacteria dominance occurred with cryptophyte dominance, indicating that nutrients affected the distribution of pico- and nanoplankton and that cryptophytes potentially relied on a mixotrophic mode by feeding on PE cyanobacteria. Interestingly, picoeukaryotes and eukaryotes larger than 10 ㎛ were mostly responsible for the ecological niche in the western region of the bay. Given that chl-a levels have historically declined, our study highlights the potential importance of increased small phytoplankton in Gamak Bay. Particularly, we urge an examination of the ecological role of small phytoplankton in the food supply of cultivated marine organisms.