• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.6
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• pp.525-535
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• 2023

In thi study, we unveil the intricate interplay among picophytoplankton (0.2-2 ㎛) communities, warming surface water temperatures, and major inorganic nutrients within the southwestern East Sea from 2003-2022. The observed surface temperature rise, reflecting global climate trends, defies conventional seasonal patterns in temperate seas, with highest temperatures in summer and lowest in spring. Concurrently, concentrations of major dissolved inorganic nutrient display distinct seasonality, with peaks in winter and gradually declining thereafter during spring. The time course of chlorophyll-a concentrations, a proxy for phytoplankton biomass, reveals a typical bimodal pattern for temperate seas. Notably, contributions from picophytoplankton exhibited a steady annual increase of approximately 0.5% over the study period, although the total chlorophyll-a concentrations declined slightly. The strong correlations between picophytoplankton contributions and inorganic nutrient concentrations is noteworthy, highlighting their competitively advantageous responsiveness to the shifting nutrient regime. These findings reflect significant ecological implications for the scientific insights into the marine ecosystem responses to changing climate conditions.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2003.05a
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• pp.140-141
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• 2003

식물플랑크톤은 여러 환경요인들의 변화와 해역의 해양학적 특성에 따라서 매우 다른 형태의 군집구조를 나타내고(Legendre and Legendre,1978), 물리적, 화학적 환경요인의 변동에 따라 종조성이나 출현수에 있어서 뚜렷한 변동을 보이므로 생태계의 구조와 기능을 이해하는데 중요한 역할을 한다(Smayda,1978). 식물플랑크톤의 군집구조는 해양생태구조 파악이나 해역의 환경지표 및 효율적 해역이용관리를 위해 무엇보다 우선 파악되어야하며(Gou and Zang, 1996), 생태계의 구조와 기능을 이해하기 위해서는 식물플랑크톤의 분포양상 및 군집구조를 환경요인과 같이 연구하는 것이 필수적이다. (중략)

• Proceedings of KOSOMES biannual meeting
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• 2018.06a
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• pp.203-203
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• 2018

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2002.10a
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• pp.234-235
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• 2002

해양 규조류는 일차생산자로서의 중요성 이외에도 수질 오염의 정도를 파악하거나 생리학 내지는 내성 연구나 규산 대사에 관한 연구에도 가장 많이 사용되어지고 있는 주요 식물플랑크톤이다 (Werner,1977;Wear, 1999). 이 중 특정 기질에 부착하여 서식하는 규조류를 부착규조라고 하며, 해초와 같은 식물, 저질, 동물의 표면, 이 외의 여러 부착기질에 점액질을 이용하여 부착 서식한다. (중략)

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2000.10a
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• pp.260-261
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• 2000

잡식성은 대부분의 동물플랑크톤의 공통적인 전략임에도 불구하고, 식물과 동물성 먹이들의 에너지원으로서 화학적 유입에 대한 정보는 상대적으로 빈약하다. 비식물 플랑크톤 가운데 원생동물은 요각류의 번식 (reproduction)과 성장에 중요한 것으로 알려지고 있지만, 해양 무척추동물의 알이나 초기 유생단계가 요각류의 번식에 미치는 영향에 대한 연구는 거의 없다. (중략)

• Proceedings of the Malacological Society of Korea Conference
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• 2001.11a
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• pp.35-36
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• 2001

해양의 유기물 합성의 95%를 담당하는 식물프랑크톤은 해양 먹이연쇄의 1차 생산자로서 이들을 여과 섭식하는 이매패류는 식물프랑크톤의 분포나 양에 따라 그 생산이 좌우된다. 그러나 이 식물프랑크톤의 분포는 동일한 해역이라도 영양염류, 수온, 태양광선의 세기와 해수면에 입사된 광선이 해수 중에서 소멸되는 정도 등에 따라 생선속도가 달라지므로 동일해역에서도 분포의 변이가 매우 심하다. 기초생산력의 차이는 굴 성육에 관계되므로 여과섭식성 이매패류 양식장의 생산성 평가의 기초자료로 이용되고 있다(배 등, 1978; 이 등, 1991). 이 연구는 북만의 기초생산력을 조사하여, 다른 해역과 비교하고 먹이생물의 생산능력에 의한 굴양식장 수용력을 검토하는 자료로 제공하였다.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.26 no.4
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• pp.356-368
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• 2021

To understand the temporal variation of phytoplankton communities in a coastal area, the biomass and diversity were weekly investigated in the inner bay of Yeong-do, Busan. In the study area, chlorophyll a concentration ranged from 0.43~7.58 mg m^-3 during the study, indicating the study area was in mesotrophic or eutrophic status. The fractions of chlorophyll a occupied by large phytoplankton (> 3 ㎛ diameter) exhibited an average of 80% of total chlorophyll a in this study. Among the large phytoplankton, while Bacillariophyta was the most dominant in spring and summer, Cryptophyceae prevailed in the fall and winter. On the contrary, in the picophytoplankton community less than 3 ㎛ in diameter, Mamiellophyceae was the most dominant in most seasons, Cryptophyceae was relatively high with an average of 17.7 ± 17.6% throughout the year, but seasonal variations were large. Dinophyceae rarely occupied a higher fraction up to 60.4% of the picophytoplankton community. By weekly monitoring at a coastal station for 13 months, it is suggested that phytoplankton communities in coastal waters could be changed on a short time scale. If data are steadily accumulated at the time-series monitoring site for a long time, these will provide important data for understanding the long-term dynamics of phytoplankton as well as the impact of climate and environmental changes.

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

• Journal of Marine Life Science
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• v.4 no.2
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• pp.53-62
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• 2019

Heterotrophic bacteria are a major member of the microbial loop in the marine ecosystem and play an important role in the biogeochemical cycle decomposing organic matter. Therefore study of bacterial variation is important to understand the material cycle and energy flow of marine ecosystems. We investigated the monthly variations of bacteria and environmental factors in the Youngsan River estuary, and the correlation between bacteria and phytoplankton biomass (chlorophyll-a) including size-structure. As a result, bacteria of the Youngsan River estuary were higher in the surface than in the bottom layer, and higher in the summer than in winter. And the closer to the dike, the abundance increased, and it increased to the peaks in August, September, and June 2019 at the station closest to the dike. The chlorophyll-a also increases at the stations and time when the bacterial abundance was high and they correlates positively displaying no difference between size fractions. The results indicate that organic matter derived from phytoplankton has an effect on bacterial variation but no size-dependent effects. In addition, the seasonal pattern of bacteria increasing in proportion to the water temperature suggests the effect of water temperature on the growth of bacteria. No association of bacterial abundance variation with nutrient supply due to freshwater input was observed. In this study, dissolved oxygen was depleted and hypoxia was observed for a short time when a strong stratification was not developed. This may be resulted from the supply of organic matter from phytoplankton and the consumption of oxygen due to bacterial decomposition.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.3
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• pp.198-207
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• 2012

In this study, we investigated the effect of ocean fertilization by deep sea water, using an ecosystem model which contains not only phytoplankton but also zooplankton. The model is based on NEMURO which consists of eleven compartments - two species of phytoplankton, three species of zooplankton, $NO_3$, $NH_4$, $Si(OH)_4$, particulate organic nitrogen, dissolved organic nitrogen and particulate silicon. We introduced nitrogen cell quota in the both species of phytoplankton, and silicon cell quota in the large phytoplankton in addition to the eleven compartments of NEMURO. We made the experiment at Izu Oshima Island in order to investigate the effect of ocean fertilization. In this experiment, we could not find clear differences between the cases with and without deep sea water. We investigated the causes of the experiment results by the model simulations. One of the causes was high concentrations of nutrients in surface seawater used in the experiment. Another was that the increase of total concentration of inorganic nitrogen does not necessarily accelerate the photosynthetic rate because inorganic nitrogen uptake rate is related to the ratio of $NO_3$ to $NH_4$. Because the model can represent the results of the experiment, we investigated the effect of ocean fertilization by deep sea water using this model. We found that the effect of ocean fertilization hardly appeared when the interval of the addition of deep sea water was too short, or the amount of deep sea water was too much. It is supposed that if the addition of deep sea water is too frequent or too much, the dilution of plankton's concentrations will exceed the effect of promoting phytoplankton's photosynthesis.