• 한국패류학회지
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• 제29권3호
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• pp.197-205
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• 2013

Even though seedling production of Haliotis discus hannai has fully developed, the culture of benthic diatom as a live food for larvae is still a barrier to solve in commercial hatchery. The farmer depends on mixed microalgae which are non-selectively attached on the plate by flowing of natural seawater. The adequate diatom on the plate for the larvae in terms of quality and quantity is always significant bottleneck in the hatchery. In this study, two benthic diatom species, Caloneis schroederi and Rhaphoneis sp. were separately cultured in mass and inoculated to four tons' settlement tank of the larvae. And the larvae and the spats were cultured for nineteen and nine weeks, respectively. The result on seedling production of H. discus hannai with this method was compared to that of the farmer's traditional method as a control. With regard to variation of species composition of benthic diatom on the plate, C. schroederi and Rhaphoneis sp. were dominant for first three weeks after inoculation. But the diverse diatoms mainly, Navicula, Amphora, Cylindrotheca, Licmophora, Pleurosigma began to attache on the plate from the 4th week. The larvae attached 2.5 times more in C. schroederi tank than in the control tank. The final total biomass of the seeds in Rhaphoneis sp. tank was 3.2 times more than that of the control tank. The retared-spats in the seedling production also showed significantly higher growth and survival in the spat fed Rhaphoneis sp. or C. schroederi than those in the control group. We suggest that C. schroederi is proper for settlement of the larvae and Rhaphoneis sp. is appropriate for the growth of the larvae and spats in the commercial hatchery of H. discus hannai.

• 생태와환경
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• 제52권1호
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• pp.1-8
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• 2019

River water quality and organisms have a very close relationship with the human living environment and health, so it is very important to ensure and maintain the ecological integrity of the aquatic ecosystem. In that sense, benthic diatoms have relatively little mobility, can explain the effects of long-term exposed pollution sources, and are very suitable indicator organisms for river ecosystem evaluation. Diatom ecologists have been developed various diatom indices to assess water quality and stream ecosystem over the world. However, they so far have insufficient identification of taxa, are strongly regional, and are difficult to apply as they are domestically. Unfortunately, there has not been developed an independent diatom index suitable for the Korean stream. Therefore, management of water quality and aquatic ecosystem suitable for domestic rivers can be made, and development or improvement of comprehensive multivariate diatom index for the integrated assessment of water quality and aquatic ecosystem is urgently needed.

• 한국해양학회지:바다
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• 제26권3호
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• pp.238-247
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• 2021

돌말류는 미세조류의 일종으로서 담수 및 해양의 여러 다양한 환경의 수생태계에서 가장 중요한 1차 생산자 중 하나이다. 환경을 대표할 수 있는 생물 지표로서 널리 이용되고 있으며, 여러 지역에서 서로 다른 과학자들에 의한 연구 결과들이 과학적 통일성과 객관성을 갖추도록 하기 위해서는 돌말류 분석 자료의 정도 관리가 매우 중요하다. 현재 돌말류 분석은 형태적인 특징으로 분류하는 형태 기반의 분석과 DNA 서열로 종을 식별하는 DNA 바코드 분석이 사용되고 있다. 형태학 기반의 돌말류 분류는 분석 자료를 해석하는 분류학자들 간의 일관된 종 식별이 요구되는 한편 분자 분류 기반의 돌말류 분류는 신뢰성 있는 참조데이터가 필수적이다. 본 논문에서는 돌말류 분석 자료 정도관리의 국내외 현황을 우선 살펴보았으며, 그에 기반하여 국내 돌말류 분석 자료의 정도 관리에 대한 의견을 또한 제안하였다.

• 한국물환경학회지
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• 제27권6호
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• pp.855-861
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• 2011

Short-term effects of current velocity and turbid water on the benthic diatom community and water quality were examined in artificial channel ($20{\times}200{\times}10cm$) with two different experiments. The first and second experiments were consisted of different current velocities such as 1 L/min., and 1, 3, and 6 L/min., respectively. The concentration of turbid water is prepared with loess and fixed at 10 and 20 times of the turbidity of control inflow (10 NTU, LTW), respectively. At experiment 1 (EXP-1), introduction of turbid water increased dissolved oxygen, electric conductivity, pH and turbidity, but there were no differences between low- (100 NTU, MTW) and high-turbid water (200 NTU, HTW). However, experiment 2 (EXP-2) did not change any environmental parameters except dissolved total and inorganic nitrogen like EXP-1. MTW in EXP-1 strongly stimulated the growth of benthic diatom, while both MTW (150 NTU) and HTW (300 NTU) in EXP-2 did not increase or decrease the diatom abundance. Over the study, the dominant species was four, Aulacoseira ambigua, Cyclotella stelligera, Aulacoseira granulata and Achnanthes minutissima. In EXP-1, two highest species in abundance, A. ambigua and A. granulata were highly grown in MTW, while Achnanthes minutissima high in HTW adversely. These results indicate that the introduction of turbid water can play an important role in the shift of water quality and benthic diatom community in stream ecosystem, especially inflow of soil water in low current velocity.

• 생태와환경
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• 제43권2호
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• pp.232-241
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• 2010

섬강 수계로 유입되는 도시하천(원주천)의 유입이 부착조류 군집에 미치는 생태학적 영향을 평가하기 위하여 부착조류 및 수질조사를 실시하였다. 조사는 섬강 본류와 원주천을 포함한 지류 등 총 14개 지점을 선정하여 2007년 10월에서 2008년 9월에까지 계절별로 4회에 걸쳐 실시하였다. 조사결과, 수온과 용존산소를 제외한 대부분의 수질항목은 계절 변이가 크지 않았고, 섬강 상류에서 가장 낮은 농도를 보였으며, 섬강 중류(원주천 유입부분)에서 가장 높은 농도를 보였고, 원주천 합류 이후 하류로 갈수록 점차 농도가 감소하였다. 조사기간 동안 가장 높은 빈도와 생물량을 보인 종은 Achnanthes convergens이었고, 원주천를 비롯하여 수질오염이 심한 지점에서는 Navicula goeppertiana, Navicula subminuscula, Nitzschia palea 등이 높은 밀도를 보였다. 각 조사지점의 TDI(trophic diatom index)에 의하면, 섬강 수계는 크게 3 그룹 - 섬강 상류와 지류하천(A 또는 B등급), 원주천(D등급), 합류후 섬강하류의 본류(C등급)로 구분되었으며, 대부분의 수질과 높은 상관성을 보였다. 생물 및 수질요인을 근거로 하는 유사도 분석결과는 TDI 지수의 분포와 유사하였다. 따라서, 인구밀집과 공업단지를 관통하는 원주천은 섬강 수계에 서식하는 부착규조 및 수질에 큰 영향을 미치며, 원주천 합류 이후 하류로 갈수록 오염정도가 점차 감소하는 것으로 평가되었다.

• Journal of Ecology and Environment
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• 제37권4호
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• pp.225-229
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• 2014

Feeding behavior of Temora turbinata was investigated through laboratory experiments with special emphasis on its food preference and consequent clearance rate on diatom and microbial components given as common natural food assemblage of coastal area (Uchiumi, Uwa Sea, Japan). Among available prey items, T. turbinata showed the highest clearance rate for Thalassiosira spp. ($0.23{\pm}0.08L\;Temora^{-1}day^{-1}$) followed by Chaetoceros spp. ($0.11{\pm}0.03L\;Temora^{-1}day^{-1}$), but clearance rates for other diatom, Nitzschia spp. was lower (0.03 to $0.07L\;Temora^{-1}day^{-1}$). Bacterial abundances showed no response against 24-h feeding of T. turbinata. Feeding of T. turbinata on heterotrophic nanoflagellates (HNF) was apparent when clearance rates of T. turbinata on diatoms were relatively low, but T. turbinata did not consume HNF as well as ciliates with Thalassiosira spp. of which clearance rate was highest. The results suggest that HNF and ciliates are possible supplementary prey item for T. turbinata, but their contribution as food sources can be limited by the presence of other prey items such as preferable diatom species.

• Journal of Ecology and Environment
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• 제36권4호
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• pp.371-390
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• 2013

Remarkable diversity of diatom taxa occurs in intertidal sand-flats of the Nakdong River estuary, one of the most dynamic and productive ecosystem in Korea. Benthic diatoms were collected from the sandy sediments to clarify the taxonomic accounts and distribution of the old genus Navicula, i.e., the naviculoid flora. Total 92 taxa belonging to Navicula sensu stricto and 22 genera separated from Navicula sensu lato are reported with brief descriptions and micrographs, and many species remain unidentified. The genera are ranked by the number of diatom species: Navicula of 33 species and varieties, Fallacia of 17 species, Placoneis of five species, Fogedia and Parlibellus of four species, Austariella, Hippodonta and Petroneis of three species, Cosmioneis, Diadesmis, Luticola, Moreneis and Sellaphora of two species and variety, Berkeleya, Chamaepinnularia, Cocconeiopsis, Diademoides, Dickieia, Eolimna, Geissleria, Haslea, Lyrella and Mayamaea of one species. Through 32 samplings of the 12 areas, the important species were identified Navicula perminuta, N. gregaria, N. torneensis, Fallacia cunoniae, F. litoricola, F. subforcipata, F. tenera. The naviculoid diatoms constitute an average of 27% (range: minimum to maximum, 5-75%), of the benthic diatom assemblages. The diatom assemblages are characterized by the colonizing of a few dominant or frequent species and many occasional or rare species. The dominant species were observed to fluctuate with sampling site and time. Among the reported naviculoid diatoms, 46 taxa are newly reported in Korea.

• Ocean and Polar Research
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• 제39권4호
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• pp.245-255
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• 2017

There are a number of pieces of evidences that suggest a link between marine diatoms and microorganisms, but knowledge about related microbial communities is greatly lacking. The present study investigated the microbial community structures related to the growth of the marine diatom Cyclotella meneghiniana. We collected free-living bacteria (FLB) and particle-associated bacteria (PAB) at each growth stage (e.g., lag, exponential, stationary and death) of the diatom, and analyzed their bacterial 16S rDNA using pyrosequencing. Metagenomics analysis showed that community structures of FLB and PAB differed considerably with the progress of growth stages. FLB showed higher diversity than PAB, but variation in the different growth stages of C. meneghiniana was more evident in PAB. The proportion of the genus Hoeflea, belonging to the order Rhizobiales, was dominant in both FLB and PAB, and it gradually increased with the growth of C. meneghiniana. However, Enhydrobacter clade tended to considerably decrease in PAB. In addition, Marinobacter decreased steadily in FLB, but first increased and then decreased in PAB. These results suggest that Hoeflea, Enhydrobacter, and Marinobacter may be closely related to the growth of diatom C. meneghiniana.

• 한국해양학회지
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• 제12권1호
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• pp.13-32
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• 1977

In order to determine the distributional ecology, and to investigate factors influencing these features, the diatom communities in plankton at depths of one, twenty-five, fifty, and seventy five meters in the area were studied and measured over a fifteen month of period. Measurements of environmental factors including temperature and salinity and algal nutrients such as phosphate, silicate, nitrate, and ammonia were also made at the same depths and locations. The results indicate that the size of diatom communities and the species population changes were heavily dependent upon to season and location parameters as well as nutrient concentrations and hydrographic factors. Major factors influencing population distributions varied with principal species responsible for dominant species and species sucession. Two distinct distributional patterns in total diatom crop were observed in the study area. Maximum standing crop observed during spring and/or summer were related to the concentration of nutrients available at the onset of the spring bloom on a large scale. On a small scale, however, the distributions of total diatom standing crops were significantly correlated with both season/location factors and with hydrographic parameters as well. Vertical stratification of diatoms was observed only in the presence of the thermocline in the water column. Within the study area there was some seasonal consistancy in the composition of the species groups. However, some species association in these environments may vary with the change of season.

• Environmental Engineering Research
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• 제19권3호
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• pp.223-228
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• 2014

We investigated seasonal algae variability and its influence on water quality in an agricultural reservoir. We observed that maximal total phosphorus (TP) loads were 1,715 kg from farmland in September, which changed the ecosystem in the reservoir. At this time, Dictyosphaerium pulchellum as green algae dominated. Aulacoseira ambigua as diatom became the most dominant from November 2010 to May 2011. The diatom was sensitive to water temperature. Microcystis spp. and Oscillatoria spp. as cyanobacteria were dominant during summer and fall, and sank down to the sediment during winter and spring. Increasing water temperature during summer causes anaerobic conditions in the sediment, leading to regrowth of cyanobacteria. With regard to the ratio of total nitrogen (TN) to TP, green algae and cyanobacteria were dominant at TN:TP ratios less than 20-30. Diatoms were dominant at TN:TP ratios greater than 30-40. Statistical analysis indicated that diatom growth was dependent on water temperature and TN concentration. TP concentration and water temperature were the key factors for the growth of cyanobacteria and green algae. From these results of this study, the management of land-use was an important parameter for improving water quality in the agricultural reservoir.