• 한국수산과학회지
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• 제38권1호
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• pp.55-64
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• 2005

Spatio-temporal variations of phytoplankton abundance and nutrient concentrations were investigated in the Namdaechon estuary, Yangyang, from April to December, 2003. A total of 51 phytoplankton species were identified with 32 diatom species in the study area. Phytoplankton abundance ranged from 14 cells/mL to 3,798 cells/mL. Small sized benthic and pennate-type diatoms like Cymbella spp., Fragilaria spp., Navicula spp., Synedra spp. were dominant at throughout the whole study area. Various planktonic species like Chlamydomonas sp., Peridinium spp., Euglena spp., Cryptomonas spp. etc. were abundant especially at the estuary of the Namdaechon, from May to August. Phytoplankton bloom (>3,000 \;cells/mL) occurred from the late May to mid June. After September when the sandbank of estuary was broken by the typhoon 'Maemi', planktonic species disappeared. These planktonic species were followed by oceanic diatoms, Skeletonema costatum and Chaetoceros spp.. Concentrations of dissolved inorganic nitrogen (DIN) and silicate were relatively high at the upstream in summer. In May, before phytoplankton bloom, high concentrations of phosphate $(>3.5\;{\mu}mol/L)$ were observed at all the study area. These results suggested that spatio-temporal variation of phytoplankton in the Namdaechon estuary was related to formation of sandbank at the mouth of the estuary, fluid speed affected by sandbank and nutrients supplied in spring. High correlation $(r^2=0.928)$ between chlorophyll a and biological oxygen demand (BOD) implies that BOD was related to phytoplankton abundance in the Namdaechon estuary.

• Journal of the korean society of oceanography
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• 제39권4호
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• pp.234-242
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• 2004

The pigment composition and concentration of phytoplankton assemblages using HPLC in the adjacent waters of four nuclear power plants (Yonggwang, Kori, Wolsong and Ulchin) were investigated during the spring blooming in 2004. The mean concentration of chlorophyll a ranged from 563.8 to 2,949.0ng $l^{-1}$, with the lowest concentration at Kori and the highest concentration at Wolsong. Among the carotenoids, the amounts of fucoxanthin and chlorophyll $C_2$ were relatively higher than those of other pigments in the study site. As minor pigments, zeaxanthin, chlorophyll b, 19'-butanoyloxyfucoxanthin, diadinoxanthin, 19'-hexanoyloxyfucoxanthin, chlorophyll $C_3$ and peridinin were detected. The results of pigment composition and concentration showed that diatoms had an important proportion of phytoplankton community when a spring bloom occurred. Cyanobacteria was present relatively low density at the Wolsong and the green alga such as chlorophytes and prasinophytes were abundant at the Yonggwang and Kori, while dinoflagellates characterized by peridinin were common at Ulchin and Kori. The pigment composition and concentration of phytoplankton after passing through the cooling-water system of nuclear power plant were highly variable. No distinct trend of the change of each pigment composition and amount was detected but the variation of fucoxanthin and chlorophyll $C_2$ highly coupled with that of chlorophyll a. We pointed out that the diatom controlled the overall variation of phytoplankton biomass during the spring season.

• Ocean Science Journal
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• 제41권1호
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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).

• 한국해양학회지:바다
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• 제12권3호
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• pp.147-158
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• 2007

본 연구는 마산만의 적조원인 식물플랑크톤의 천이와 대발생 변화 양상을 밝히고자 이 지역을 대표할 수 있는 1개 정정에서 2003년 11월부터 2004년 10월까지 강우와 연평균 기온차를 포함한 기후학적 요인, 물리 화학적 요인 그리고 식물플랑크톤 군집을 조사하였다. 영양염은 타해역과 비교하였을 때, 암모니아염은 높은 농도를 보였으나, 질산염은 비슷한 농도를 보였다. 그리고 규산염은 타 해역에 비해 낮은 농도를 보였으며, 인산염은 빈영양 수역에 포함될 정도로 낮은 농도를 보여 식물플랑크톤 성장의 제한요소로 작용하였다. 식물플랑크톤 현존량의 탄소량은 2003년 동계와 2004년 하계에, 엽록소-${\alpha}$는 2003년 늦은 추계부터 동계까지 그리고 2004년 하계에 높게 나타나 비슷한 경향을 보였으며, 개체수는 2003년 동계와 2004년 추계에 높았다. 조사기간 동안 출현한 식물플랑크톤은 총 78종으로 동정되었으며, 이 중 우점종은 규조류 Skeletonema costatum, Cylindrotheca closterium, 와편모조류 Heterocapsa triquetra, Prorocentrum minimum, P. triestinum, 침편모조류 Heterosigma akashiwo로 나타났다. 우점종의 계절적 변화 양상을 살펴보면 P. minimum은 늦은 추계부터 동계까지, H. triquetra는 늦은 동계에 우점하였다. P. triestinum은 늦은 춘계부터 이른 하계까지, H. akashiwo는 춘계부터 조금 높은 경향을 보이다가 늦은 하계에 C. closterium이 그리고 S. costatum은 추계에 가장 우점하였다. CCA 분석결과, 개체수로 표현되는 현존량은 규조류와 관계가 있으며, 환경요인 중에서 수온, 질산염과 인산염의 영향을 받는 것으로 나타났다. 탄소량과 엽록소-${\alpha}$로 표현되는 현존량은 규조류 뿐만 아니라 와편모조류와 침편모조류와 관계가 있으며, 염분, 규산염과 인산염의 영향을 받는 것으로 나타났다. 조사기간을 포함한 최근 6년 동안의 기온의 상승에 따른 수온의 상승은 동계 적조를 발생시키는 원인이 되었다. 또한, 동계 적조에 따른 영양염 고갈과 춘계의 강우량 감소에 따른 영양염 공급의 제한은 마산만에서 상습적으로 발생되는 춘계 적조의 발생을 억제하였을 것으로 판단된다. 결과적으로 2004년도의 전형적인 대발생 양상의 변화는 수온의 상승과 강우량의 감소가 중요한 영향을 미쳤을 것으로 추정된다.

• 생태와환경
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• 제44권4호
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• pp.337-346
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• 2011

We investigated nutrient loading and trophic states in a coastal estuarine system in the Asan estuary by assessing phytoplankton biomass and using the trophic index (TRIX). The monthly and yearly nutrient loading (TN, TP) from freshwater discharge from the Asan and Sapgyo reservoirs into the estuary were estimated and analyzed with related factors. Monitoring data (physio-chemical and biological variables) collected at five estuary stations were used to assess trophic states. Descriptive statistics of total phytoplankton cells, chl a concentrations and primary productivity were also used to assess seasonal trophic status. N loading from freshwater ranged $1.0{\sim}1.3{\times}10^4$ ton yearly. The yearly P loading ranged between 350 and 400 ton during 2004~2006, increasing to 570 ton in 2007. Regression results suggest that DIN and DSi were correlated with freshwater discharge at the upper region. Based on phytoplankton biomass and total cell abundance, the trophic state of the estuary was found to be eutrophic during spring due to phytoplankton bloom. Primary productivity level was remarkably high, especially in summer coinciding with high nutrient loading. Pheopigments increased during warm seasons, i.e. summer and fall. Trophic index results indicate that the trophic state varied between mesotrophic and eutrophic in the estuary water body, especially in the upper region. The results suggest that phytoplankton production was regulated by nutrient loading from freshwater whereas biomass was affected by other properties than nutrient loading in the Asan Estuary ecosystem.

• Journal of Species Research
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• 제10권1호
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• pp.46-56
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• 2021

Diatoms have been used in examining water quality and environmental change in freshwater systems. Here, we analyzed molecular profiling of seasonal diatoms in the Han River, Korea, using the hypervariable region of 18S V1-V3 rRNA and pyrosequencing. Physicochemical data, such as temperature, DO, pH, and nutrients showed the typical seasonal pattern in a temperate region. In addition, cell counts and chlorophyll-a, were recorded at high levels in spring compared to other seasons, due to the diatom bloom. Metagenomic analysis showed a seasonal variation in the phytoplankton community composition, with diatoms as the most frequently detected in spring (83.8%) and winter (69.7%). Overall, diatom genera such as Stephanodiscus, Navicula, Cyclotella, and Discostella were the most frequent in the samples. However, a large number of unknown Thalassiosirales diatoms were found in spring (35.5%) and winter (36.3%). Our molecular profiling revealed a high number of diatom taxa compared to morphological observation. This is the first study of diatoms in the Han River using molecular approaches, providing a valuable reference for future study on diatoms-basis environmental molecular monitoring and ecology.

• 생태와환경
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• 제41권4호
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• pp.530-540
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• 2008

The temporal and spatial variations of size-structured phytoplankton dynamics in Youngsan Lake were investigated to explore potential mechanims controlling the dynamics in the Youngsan Lake. Field data were collected monthly from February to October, 2003 at 6 stations along the axis of Youngsan Lake. In this study, phytoplankton (chlorophyll $\alpha$) were categorized into three size classes: micro-size ($>20{\mu}m$), nano-size ($2{\sim}20{\mu}m$) and pico-size ($<20{\mu}m$). Water temperature, light attenuation coefficients, PAR (photosynthetically active radiation) and suspended solids were measured to analyze relationship between physical-chemical properties and size structure of phytoplankton. Phytoplankton blooms developed during March, July and October in the upper region of the main stem whereas small-scaled spring bloom was observed in the lower region. The scales of phytoplankton blooms were higher in the upper regions than the lower region and blooms were predominated by micro-size class in upper region but predominated by nano-size class in lower region. Growth of size-structured phytoplankton appeared to be controlled by rather light availability than temperature-dependant metabolisms in the system. Phytoplankton growth may be also supported by ambient nutrients available in the water column from analyses of chlorophyll $\alpha$ vs. nutrient concentrations including nitrite+nitrate and orthophosphate. Growth of nano-sized phytoplankton alone appeared to be supported by orthophosphate as well as nitrite+nitrate indicating that response of phytoplankton to nutrient inputs may be size-dependent.

• 환경생물
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• 제36권2호
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• pp.156-164
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• 2018

본 연구에서는 강풍에 의한 연안 용승 및 섬효과를 구체적으로 파악하기 위해서 춘계 강한 저기압 통과 전후를 대상으로 위성자료, 해양환경 및 물리적인 수직 구조와 함께 식물플랑크톤의 군집구조를 파악하였다. 5월 3일 강한 저기압이 통과하면서 남풍계열의 바람이 우점하였고, 10일 정도의 시간차를 둔 5월 12일에는 동한난류가 이동한 경로주변해역에서 높은 엽록소값이 관찰되었다. 식물플랑크톤 수평적 군집조성은 동한난류의 영향을 강하게 받은 울진 연안과 울릉도 사이의 정점에서는 규조류가 극히 높은 밀도로 우점하였고, 상대적으로 외양인 울릉도와 독도 섬주변에서는 섬효과에 의하여 침편조류 H. akashiwo가 높은 개체수를 유지하였다. 엽록소의 수직적 분포는 울진에서 울릉도로 이어지는 정점에서 엽록소 아표층극대 (Sub-surface Chl-a Maximum)가 20 m 층에서 관찰되었고, 울릉도와 독도 섬주변의 대부분 정점에서는 30~40 m 층까지 전 수층에 걸쳐 균일하게 높은 엽록소 형광값이 관찰되었다. 이는 섬효과에 의하여, 강한 수층혼합이 일어난 것을 의미하고, 그 결과 유광층 상부에 공급된 영양염류에 의하여 식물플랑톤이 대발생하였다. 결과적으로 춘계 한반도 남동해역(울진-울릉도-독도)에서는 남풍계열의 바람이 우점하면, 연안 용승이 발생할 수 있고, 이는 식물플랑크톤의 대발생에 중요한 역할을 하는 것으로 관찰되었다. 아울러, 동해 연안해역에서 기인된 식물플랑크톤은 동해 중앙 및 남서해역으로 공간이동하면서 울릉도-독도의 섬효과와 함께 동한난류의 사행, 소용돌이의 발달 등에 따라서 종조성이 다르게 나타날 가능성을 시사하였다.

• 한국환경생물학회:학술대회논문집
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• 한국환경생물학회 2003년도 학술대회
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• pp.103-107
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• 2003

Spatial distribution of phytoplankton was investigated in the southwestern sea of Korea in May 2000 in terms of phytohydrography. The sampling was done at the 0m, 30m, 50m of 15 selected stations, and permanent slides of each samples were prepared by QPS method for quantitative and qualitative analyses. Phytoplankton standing crops ranged from 3.23${\times}$10$\^$-4/ to 1.09${\times}$10$\^$-7/ cellsㆍ$\ell$$\^$-1/ in the study area. Dominant species comprised of 9 diatoms and 2 phytoflagellates, showing higher dominance of diatom and most predominance of Skeletonema costatum in all layers of most stations. Phytohydrographic results indicate that the study area might be divided into 4 categories, that is, I area is designated as neritic area where occurrence of terrestrial and coastal species is frequent, II area as intermediate area, III area as offshore area where oceanic species dominate, and IV area as other's. Especially in the II area, Skeletonema costatum was most predominant at both surface and 30m layer in most stations and represent an characteristic of northward expansion with spring massive bloom.

• Ocean and Polar Research
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• 제27권1호
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• pp.45-58
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• 2005

Temperature, salinity, dissolved oxygen, COD, dissolved inorganic nitrogen(DIN), dissolved inorganic phosphorus (DIP), and chlorophyll were measured in the surface and bottom waters of Cheonsu Bay in April, August, December 2003, and Hay 2004. DIN showed a large seasonal variation, with higher values in summer and lower in spring. The significant decrease in DIN concentration was observed from April to May, which may imply the occurrence of spring phytoplankton bloom sometime in these periods. In contrast, DIP did not show distinct seasonal variation, with relatively low values compared with other coastal regions. The low DIP concentration in Cheonsu Bay is ascribed to a limited phosphorus input around Cheonsu Bay. The Nf ratios of Cheonsu Bay much higher than the Redfield ratio(16) in all season indicate that phytoplankton growth is limited by phosphorus. Based on low chlorophyll concentrations and eutrophication index, Cheonsu Bay has not been in eutrophic condition during our observation periods. In the artificial lakes located around Cheonsu Bay, however, chlorophyll concentrations were very high, mostly over $10{\mu}g\;l^{-1}$, indicating that they are now in severe eutrophic condition.