• 생태와환경
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• 제37권3호통권108호
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• pp.319-331
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• 2004

본 연구는 실험적으로 조성된 인공연못(2 m ${\times}$ 2 m ${\times}$ 2 m)에서 패류의 여과 섭식이 수체 내 물질순환과 플랑크톤 군집에 미치는 영향을 평가하기 위해 이루어졌다. 실험의 초기에는 처리구와 대조구 enclosure 모두에서 남조류인 Microcystis viridis와 M. aeruginosa 등이 우점하였고, 세포밀도와 생물량의 큰 차이는 없었다. 패류 100개체 투입 이후에 처리구에서 세포밀도의 감소와 수중 내 N/P의 증가와 더불어 우점종은 Microcystis에서 Scenedesmus로 바뀌었다. 반면에, 대조구에서의 세포밀도는 증가와 더불어 Oscillatoria spp.가 우점하였다. 패류 600개체 투입 이후에는 처리구와 대조구 모두에서 Selenastrum spp.와 Cryptomonas sp.가 우점하였다. 실험 초기 대조구에서의 동물플랑크톤 밀도는 처리구에 비해 높았으나 100개체 투입 이후에는 처리구에서 높았다. 패류 600개체 투입 이후에는 처리구에서 크기가 작은 윤충류와 요각류 유생들의 밀도가 감소하였으나, Bosmina longirostris, Diacyclops thomasi와 같은 크기가 큰 동물플랑크톤의 밀도와 생물량은 대조구에 비해 높았다. 실험기간 동안 엽록소 a농도의 증가는 처리구에서 수체 내 DIP농도가, 대조구에서는 암모니아농도가 상승한 직후에 나타났다. 처리구에서 600개체 투입 전후 시기동안 대조구에서는 TSI (Chl. a-TN)과 TSI (Chl. a-TP)가 모두 증가하였으나 처리구에서는 암모니아 농도의 증가로 인하여 질소 제한에 대한 변화가 나타나지 않았다. 이러한 결과들은 패류의 여과섭식이 수체내 영양염 이용율을 변화시키고, 동물플랑크톤과의 동일한 먹이원에 대한 경쟁 혹은 직접적인 섭식을 통해 수환경에서 물질 순환과 플랑크톤 군집 변화에 중요한 영향을 미칠 수 있음을 의미한다.

• Ocean and Polar Research
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• 제32권3호
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• pp.269-289
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• 2010

In Summer 2008, a multidisciplinary survey was conducted onboard R/V Haeyang 2000 to understand plankton response to the three distinct physico-chemical settings that developed in the Ulleung Basin of the East Sea. Baseline settings of hydrographic conditions included the presence of the thin (<20 m) Tsushima Surface Water (TSW) on top of the Tsushima Middle Water (TMW). It extends from the Korea Strait to $37^{\circ}N$ along the $130^{\circ}E$ and then turns offshore and encompasses the relatively saline (T>$26^{\circ}C$, S>33.7) Ulleung Warm Eddy surface water centered at $36.5^{\circ}N$ and $131^{\circ}E$. A relatively colder and saline water mass appeared off the southeastern coast of Korea. It was accompanied by higher nutrient and chlorophyll-a concentrations, suggesting a coastal upwelling. Most of the offshore surface waters support low phytoplankton biomass (0.3 mg chl-a $m^{-3}$). A much denser phytoplankton biomass (1-2.3 mg $m^{-3}$) accumulated at the subsurface layer between 20-50 m depth. The subsurface chlorophyll-a maximum (SCM) layer was closely related to the nutricline, suggesting an active growth of phytoplankton at depth. The SCM developed at shallow depth (20-30 m) near the coast and deepened offshore (50-60 m). A fucoxanthin/zeaxanthin ratio was high in coastal waters while it was low in offshore waters, which indicated that diatoms dominate coastal waters while cyanobacteria dominate offshore waters. The community structure and biomass of phytoplanktonare closely related to nitrogen availability. Zooplankton biomass was higher in the coastal region than in the offshore region while species richness showed an opposite trend. Zooplankton community structure retained a coastal/offshore contrast. These suggest that summer hydrography is a stable structure, lasting long enough to allow a hydrography-specific plankton community to evolve.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
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• pp.557-561
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• 2004

A comparison was made between chlorophyll a from OSMI and SeaWiFS determined with the standard method during the NFRDI's research cruises. The simple algorithm for calibrating and validating of OSMI chlorophyll a as level 2 data in the East China Sea in specially winter season was made by relationship between the estimated chlorophyll a and the measured chlorophyll a in the field. We compared the distributions of OSMI chlorophyll a, sea surface temperature and zooplankton biomass, catch amounts of the Pacific mackerel in the East China Sea.

• ALGAE
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• 제30권1호
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• pp.67-79
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• 2015

Planktivorous fish which limit zooplankton grazing have been predicted to increase algal biodiesel production in wastewater fed open reactors. In addition, tanks with higher algal diversity have been predicted to be more stable, more productive, and to more fully remove nutrients from wastewater. To test these predictions, we conducted a 14-week experiment in Houston, TX using twelve 2,270-L open tanks continuously supplied with wastewater. Tanks received algal composition (monocultures or diverse assemblage) and trophic (fish or no fish) treatments in a full-factorial design. Monocultures produced more algal and fatty acid methyl ester (FAME) mass than diverse tanks. More than 80% of lipids were converted to FAME indicating potentially high production for conversion to biodiesel (up to $0.9T\;ha^{-1}y^{-1}$). Prolific algal growth lowered temperature and levels of total dissolved solids in the tanks and increased pH and dissolved oxygen compared to supply water. Algae in the tanks removed 91% of nitrate-N and 53% of phosphorus from wastewater. Monocultures were not invaded by other algal species. Fish did not affect any variables. Our results indicated that algae can be grown in open tank bioreactors using wastewater as a nutrient source. The stable productivity of monocultures suggests that this may be a viable production method to procure algal biomass for biodiesel production.

• Fisheries and Aquatic Sciences
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• 제23권7호
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• pp.19.1-19.14
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• 2020

Three generalized additive models were applied to the distribution of anchovy eggs and oceanographic factors to determine the occurrence of anchovy spawning grounds in Korean waters and to identify the indicators of their occurrence using survey data from the spring and summer of 1985, 1995, and 2002. Binomial and Gaussian types of generalized additive models (GAM) and quantile generalized additive models (QGAM) revealed that egg density was influenced mostly by ocean temperature and salinity in spring, and the vertical structure of temperature, salinity, dissolved oxygen, and zooplankton biomass during summer in the upper quantiles of egg density. The GAM and QGAM model deviance explained 18.5-63.2% of the egg distribution in summer in the East and West Sea. For the principle component analysis-based GAMs, the variance explained by the final regression model was 27.3-67.0%, higher than the regular models and QGAMs for egg density in the East and West Sea. By analyzing the distribution of anchovy eggs off the Korean coast, our results revealed the optimal temperature and salinity conditions, in addition to high production and high vertical mixing, as the key indicators of the major spawning grounds of anchovies.

• 환경생물
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• 제28권2호
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• pp.86-94
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• 2010

본 연구는 국내 31개 호소 지점을 대상으로 동식물플랑크톤 생체량 및 생태학적 모델 적용을 고려한 호소간의 플랑크톤 동태 비교에 목적이 있다. 조사기간 동안 총 89종의 동물플랑크톤(윤충류 70종, 지각류 14종, 요각류 5종)과 554종의 식물플랑크톤(규조류 176종, 녹조류 237종, 남조류 68종 그리고 기타 73종)이 동정 확인 되었다. 플랑크톤 밀도 및 종 다양도는 지점별 및 계절별 상이한 차이를 나타내었다. 전체 호소의 연평균 총 식물플랑크톤 밀도는 $7,350{\pm}15,592$ cells $mL^{-1}$ (n=124)이었으며, 가장 낮은 지점에서는 평균 $855{\pm}448$ cells $mL^{-1}$ (n=4), 가장 높은 지점에서는 평균 $72,048{\pm}13,4631$ cells $mL^{-1}$ (n=4)인 것으로 파악되어 호소별 식물플랑크톤 밀도 차가 매우 높은 것으로 조사되었다. 동물플랑크톤 군집은 소형 동물플랑크톤인 윤충류가 우점하였으며, 지각류 및 요각류의 출현 종수는 낮은 것으로 파악되었다. 각 조사지점별 출현한 총 동물플랑크톤 종수는 상이하였으며, 호소별 평균 출현 종수는 약 3~10여 종인 것으로 나타났다. 상관관계 분석 및 SOM 모형의 적용 결과 동식물플랑크톤의 종수와 밀도는 호소의 규모가 작을수록 높아지는 경향이 존재하고 있음을 파악할 수 있다. 조사대상 호소에 대해서 플랑크톤 군집 구조 관점에서 수자원 관리가 실시될 경우 대형 호소보다는 중소형 호소에 보다 초점을 맞추어야 할 것으로 사료된다.

• Journal of the korean society of oceanography
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• 제37권4호
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• pp.212-223
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• 2002

Cochlodinium polykrikoides bloom in 1995 was studied with a focus on an unusual coastal environment in the South Sea of Korea. Data on temperature, salinity, and zooplankton biomass during 1965-1998 and nutrients during 1990-1998 and chlorophyll-a during 1995-1998 were used in this study. These data were obtained from the serial oceanographic observations in Korean waters carried out by the National Fisheries Research and Development Institute. In 1995 the C. polykrikoides bloom began in the coastal area around Narodo Island in August and consequently occurred to the whole coastal area of the South and East Seas of Korea. During June-October 1995, the coastal environment was unusual compared with the long-term means during 1965-1998. In June 1995, sea surface temperature was 1-2$^{\circ}C$ warmer than in other years in all coastal areas, while salinity was high only to the east of Jeju Island. In August 1995, a strong coastal front appeared inshore of a line between Jeju and Tsushima Islands. In particular, a strong coastal front which showed the characteristics of upwelling front occurred in the coastal area around Narodo and Sorido Islands, not only because of a strong intrusion of the Tsushima Warm Current but also because of the upwelling of cold bottom water. Salinity was low in the neighboring waters of western side of Jeju Island. Nutrients and chlorophyll-a were high in the inshore area between Narodo and Sorido Islands in 1995 in contrast with the other years and areas. Zooplankton showed an unusually high abundance in the coastal area in October 1995. We conclude that the Tsushima Warm Current strongly influenced the South Sea of Korea in 1995 and created strong upwelling front bordering cold upwelled water in the coastal area around Narodo and Sorido Islands. It leads us that these physical structures introduce the favorable environment for the development of C. polykrikoides blooms. We suggest that C. polykrikoides has a bio-physical tolerance of high shear and stress and prefers frontal and upwelling relaxed areas as its habitat. We also find that nutrients were not supplied to the coastal area from the offshore where a low salinity water mass with high nutrients appeared around Jeju Island. Because the strong upwelling front protect the reach of offshore low saline water mass. The main source of nutrients was the upwelled water mass in the coastal area of Wando-Narodo-Sorido.

• Ocean Science Journal
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• 제43권1호
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• pp.1-7
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• 2008

Physical and biological environmental variations in the East Sea were investigated by analysing time-series of oceanographic data and meteorological indices. From 1971 to 2000, dominant periodicity in water temperature variations had two apparent periods of 3 to 4 years and of decades, especially in the southwestern part of the East Sea affected by the influence of inflowing Tsushima warm current. Fluctuating water temperature within a certain period appears to respond to El $Ni{\tilde{n}}o$ events with a time lag. It was found that there was a strong correlation between water temperature and El $Ni{\tilde{n}}o$ events with a time lag of 1.5 and 5.5 years for periods of 3 to 6 years and of decades, respectively. Corresponding with El $Ni{\tilde{n}}o$ events, water temperature variability also showed strong correlation with shift and/or changes in biological and chemical environments of nutrient concentrations, zooplankton biomass, and fisheries. However, there also occurred a short-term periodicity of water temperature variations. Within a period of 1 to 4 years, a relatively short-term cycle of water temperature variation had strong correlation with other climate indices such as Pacific Decadal Oscillation and monsoon index. After comparing coherence and phase spectrum between water temperature and different climate indices, we found that there was a shift of coherent periods to another climate index during the years when climate regime shift was reported.

• 한국환경과학회지
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• 제23권1호
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• pp.47-52
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• 2014

Antarctic krill (Euphausia superba) is typical of a enormous biomass of marine zooplankton that could provide good nutrition in human body. This study was conducted to identify the nutrition of krill, a live in Antarctic Ocean. The analysis result of fatty acids of krill meal was as follow. The compositions of fatty acid were saturated fatty (SFA) acid 41.41%, monounsaturated fatty acid (MUFA) 21.69%, polyunsaturated fatty acid (PUFA) 36.89%, and p/s ratio was 0.89. The major fatty acids in all parts were eicosapentaenoic acid (EPA, 21.54%), palmitic acid (27.51%), oleic acid (13.35%) and docosahexaenoic acid (DHA, 12.42%). Especially, EPA and DHA were occupied 33.96% of polyunsaturated fatty acid. The mineral contents of krill meal were calcium 24477.21 mg $kg^{-1}$, sodium 14728.69 mg $kg^{-1}$, magnesium 6973.49 mg $kg^{-1}$, potassium 3981.67 mg $kg^{-1}$, iron 395.33 mg $kg^{-1}$ and manganese 5.74 mg $kg^{-1}$. The contents of major vitamin were retinol 86717.37 ${\mu}g$ RE, ${\beta}$-carotene 44.87 ${\mu}g$ RE, tocopherol 2.60 mg, pantothenic acid 1.61 mg, indicating that krill meal contains large amount of retinol and ${\beta}$-carotene.

• 한국물환경학회지
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• 제29권6호
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• pp.746-753
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• 2013

The aim of this study was to evaluate artificial fish shelter, which was known to increase prey survival and expand habitat space to improve species diversity and fish communities in a freshwater ecosystem. The experiment was performed at an outdoor test-bed for three months from 2011 by comparing the responses to adjustments in the volume of the artificial patch (juvenile fish shelter, JFS) in the control and experimental groups. Analysis of the environmental conditions over two periods (Period1 ~ 2) showed minor differences in the physichemical characteristics of water quality, phytoplankton, and zooplankton biomass, thus, allowing comparative analysis of feeding ecology. However, high water temperature conditions in Period1 ($25.6{\pm}2.0^{\circ}C$), affected the predation activity of the piscivorous fishes, Coreoperca herzi (C. herzi, size $89{\pm}4mm$). Survival rates of the prey fishes, Rhynchocypris oxycephalus (R. oxycephalus, size $29{\pm}1mm$), improved as the patch volume increased and were higher than those of the control group by 35.9 ~ 46.7%. Analysis showed that JFS reduced the chances of predator-prey encounter, and thereby minimized prey vulnerability.