• Korean Journal of Ecology and Environment
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• v.37 no.2 s.107
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• pp.241-247
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• 2004

Isolation and identification of alga-lytic bacteria were carried out. Fifteen isolates of alga-lytic bacteria were screened by the double layer method using A. cylindrica NIES-19 as a sole nutrient and four isolates among them were compared with their alga-lytic activity. The isolate AK-05 exhibiting the highest alga-lytic activity was identified as Acidovorax temperans base on its 16S rDNA sequence. The culture supernatant of the isolate AK-05 was reliable for the alga-lytic. Alga-lytic activity assays of culture supernatant revealed that the major substances for alga-lytic activity were non-proteins and heat stable. The highest alga-Iytic activity was practical under alkaline conditions and at 25${\sim}$$30^{\circ}C$. It is indicating an advantage for the application of water blooms by cyanobacteria in eutrophic lakes where the pH is generally in alkaline region.

• Journal of Korean Society on Water Environment
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• v.33 no.5
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• pp.538-545
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• 2017

The purpose of this study is to investigate growth response and toxigenicity under various temperature and nutritional conditions, in order to understand the physioecological characteristics of Aphanizomenon flos-aquae, which is a bloom-forming cyanobacterium in the Nakdong River. The strain was inoculated into media under combinations of four temperatures (4, 12, 21, $30^{\circ}C$) and three nutrients (modified CB medium, P-depleted CB medium, N-depleted CB medium) for 28 days. The algae-inhibition tests were performed to assess the potential allelopathic effects of the strains' filtrates on the growth of four algae strains (Microcystis aeruginosa, Aulacoseria ambigua f. spiralis, Aphanizomenon flos-aquae, Scenedesmus obliquus). Toxin production of a strain was measured by Enzyme-Linked ImmunoSolbent Assay (ELISA). The optimal growth temperature (Topt) of strains was $19.9^{\circ}C$ ($18.3-21.2^{\circ}C$), and the temperature range for growth was from $-0.3^{\circ}C$ to $34.3^{\circ}C$. Specific growth rate (${\mu}$) in modified CB medium varied from 0.10 to $0.16day^{-1}$, and the maximum growth rate (${\mu}_{max}$) was $0.17day^{-1}$. Although growth curves under N-existed and N-depleted conditions were almost the same, growth under N-depleted condition was relatively slowed (${\mu}=0.09$ to $0.14day^{-1}$), with a decreased maximum cell density. However, growth under the P-depleted condition was restricted for all temperatures, Two stains of Aphanizomenon flos-aquae were confirmed as not producing toxins, because saxitoxin and cylindrospermopsin were not detected by ELISA. The exudates or filtrates from the Aphanizomenon flos-aquae (DGUC003) resulted in significant inhibition of algal growth on the Aulacoseira ambigua f. spiralis (DGUD001) and Aphanizomenon flos-aquae (DGUC001) (p < 0.01).

• Journal of Aquaculture
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• v.18 no.2
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• pp.86-91
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• 2005

Three haptophyte algae, Isochrysis galbana, Prymnesium parvum and P. patelliferum were offered to the marine copepod Tigriopus japonicus as food. Growth rate of larvae, egg production, mortality and comsumption rates of T. japonicus were measured for each of the haptophyte species offered. The growth rate of larvae, egg production and algal ingestion of T. japonicus fed on P. parvum and P. patelliferum were much lower than those fed on I. galbana and corresponding high mortality rates were also observed during the experimental period. The harmful effects observed during the present study indicate that bloom-forming haptophyte algae, P. parvum and P. patelliferum are not suitable feed species for culture of copepod, T. japonicus.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.1
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• pp.52-62
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• 2014

As a case study of the changed aquatic environment due to an estuary dam, the Geum River Estuary Dam System (GREDS) has been investigated for the last two decades. We sought the similarities and differences in the disrupted aquatic environment between the estuarine and lacustrine sides of the GREDS. Both sides of the GREDS shared similar aquatic disruptions, such as elongated hydraulic residence times, deteriorated water quality, highly accumulated organic-rich sediments, and considerable siltation of river-transported materials prior to reaching coastal waters. The disruptions of water quality such as high nutrients concentration and frequent bloom of blue-green algal are much more noticeable in the reservoir than in the estuary. However serious siltation problem has been reported from the estuary, which will possibly threaten the proper functioning of the natural Kunsan Estuarine System.

• ALGAE
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• v.28 no.4
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• pp.343-354
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• 2013

To explore the interactions between the mixotrophic dinoflagellate Biecheleria cincta (previously Woloszynskia cincta) and heterotrophic protists, we investigated whether the common heterotrophic dinoflagellates Gyrodinium dominans, Gyrodinium moestrupii, Gyrodinium spirale, Oxyrrhis marina, and Polykrikos kofoidii, and the ciliate Strobilidium sp. were able to feed on B. cincta. We also measured growth and ingestion rates of O. marina and Strobilidium sp. on B. cincta as a function of prey concentration. In addition, these rates were measured for other predators at single prey concentrations at which the growth and ingestion rates of O. marina and Strobilidium sp. were saturated. All grazers tested in the present study were able to feed on B. cincta. B. cincta clearly supported positive growth of O. marina, G. dominans, and Strobilidium sp., but it did not support that of G. moestrupii, G. spirale, and P. kofoidii. The maximum growth rates of Strobilidium sp. and O. marina on B. cincta (0.91 and 0.49 $d^{-1}$, respectively) were much higher than that of G. dominans (0.07 $d^{-1}$). With increasing the mean prey concentration, the specific growth rates of O. marina and Strobilidium sp. on B. cincta increased, but either became saturated or slowly increased. The maximum ingestion rate of Strobilidium sp. (1.60 ng C $predator^{-1}\;d^{-1}$) was much higher than that of P. kofoidii and O. marina (0.55 and 0.34 ng C $predator^{-1}\;d^{-1}$) on B. cincta. The results of the present study suggest that O. marina and Strobilidium sp. are effective protistan grazers of B. cincta.

• ALGAE
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• v.29 no.2
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• pp.153-163
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• 2014

Mesodinium rubrum is a cosmopolitan ciliate that often causes red tides. Predation by heterotrophic protists is a critical factor that affects the population dynamics of red tide species. However, there have been few studies on protistan predators feeding on M. rubrum. To investigate heterotrophic protists grazing on M. rubrum, we tested whether the heterotrophic dinoflagellates Gyrodiniellum shiwhaense, Gyrodinium dominans, Gyrodinium spirale, Luciella masanensis, Oblea rotunda, Oxyrrhis marina, Pfiesteria piscicida, Polykrikos kofoidii, Protoperidinium bipes, and Stoeckeria algicida, and the ciliate Strombidium sp. preyed on M. rubrum. G. dominans, L. masanensis, O. rotunda, P. kofoidii, and Strombidium sp. preyed on M. rubrum. However, only G. dominans had a positive growth feeding on M. rubrum. The growth and ingestion rates of G. dominans on M. rubrum increased rapidly with increasing mean prey concentration < $321ngCmL^{-1}$, but became saturated or slowly at higher concentrations. The maximum growth rate of G. dominans on M. rubrum was $0.48d^{-1}$, while the maximum ingestion rate was 0.55 ng C $predator^{-1}d^{-1}$. The grazing coefficients by G. dominans on populations of M. rubrum were up to $0.236h^{-1}$. Thus, G. dominans may sometimes have a considerable grazing impact on populations of M. rubrum.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.11
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• pp.4649-4655
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• 2010

The aim of this study was to investigate the effect of flowing the industrial wastewater effluents into the K lake which is located in the A city on the eutrophication. The lake was modelled as a continuous stirred-tank reactor. Phosphorus and Chl-a concentration in the lake were calculated to $0.29\;/m^3$과 $4.0\;g/m^3$ at steady state, respectively. Those simulated concentrations were very close to the monitored mean concentration of the lake, indicating that the simulation could be used a tool for characterizing the lake. The non-steady state concentrations of the phosphorus and Chl-a were proposed as a function of time as well. Phosphorus loading ($L_p$) and depth to retention time ratio ($H/{\tau}w$) was calculated in order to analyze the current state of eutrophication. We proposed a strategy to change the lake from eutrophic to permissible oligotrophic state using a graph consisting of two variables, $L_p$ and $H/{\tau}w$.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.478-478
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• 2016

4대강 다기능 보 건설 이후 보 내에서 발생하는 녹조를 효과적으로 저감시키기 위해 다양한 방법들이 시도되고 있으며, 댐-보 및 보-보간 연계운영 기법은 수량을 이용하여 대규모 구간에 걸쳐 효과적으로 조류를 저감시킬 수 있어 최근 주목을 받고 있다. 본 연구에서는 영산강 수계 승촌보와 죽산보를 대상으로 조류저감을 위한 다기능보 연계 운영 시나리오에 대해 2차원 모델링을 이용하여 효과를 분석하고 향후 조류저감을 위한 가동보 운영방안 수립에 적용하고자 수행되었다. 시뮬레이션 기간은 2014년 7월 1일부터 7월 15일까지 남조류가 다량으로 발생하였던 시기를 모의기간으로 하였다. 분석시나리오는 최근 낙동강에서 적용된 바 있는 pulse형 방류를 실시하여 수체내에 유속과 난류를 증가시키되 승촌보와 죽산보를 연계하여 순차적인 방류와 담수를 반복하는 형태를 가정하였다. 또한 방류 규모에 따라 수위 저하범위를 0.3~2 m로 차등 적용하여 조류저감 효과를 예측하였다. 예측결과 소수력 발전방류를 이용한 pulse형 방류 연계운영 CASE에서는 최대 승촌보 3.8% 죽산보 8.4%의 저감 효과가 예측되었다. 반면 소수력과 수문방류를 동시에 이용하여 수위 저하범위를 크게 적용하는 CASE에서는 승촌보에서 최대 12.5%, 죽산보 4.7%의 저감율로 방류규모 증가에도 불구하고 죽산보의 저감율은 증가하지 않는 결과를 나타내었다. 이는 상대적으로 저수량이 큰 죽산보에서 큰 폭으로 수위를 저하시킬 경우 수위회복 기간이 길어지고 이 시기에 조류가 성장할 수 있는 조건을 제공하기 때문인 것으로 판단된다. 따라서 조류의 발생 규모와 공간적 분포, 보별 유입지류 유입특성과 저수량 등 조류발생에 관련된 다양한 인자를 복합적으로 고려하여 효율적인 운영방안이 수립되어야 할 것으로 판단된다.

• Journal of Korean Society on Water Environment
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• v.27 no.5
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• pp.670-679
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• 2011

Chlorophyll-a is a major water quality indicator for an algal bloom in streams and lakes. The purpose of the study is to estimate chlorophyll-a concentration in tributaries of the Seonakdonggang by an artificial neural network (ANN). As the tributaries are ungauged streams, a watershed runoff and quality model was used to simulate water quality parameters. The tributary watersheds include urban area and thus Storm Water Management Model (SWMM) was used to simulate TN, TP, BOD, COD, and SS. SWMM, however, can not simulate chlorophyll-a. The chlorophyll-a series data from the tributaries were estimated by the ANN and the simulation results of water quality parameters using SWMM. An assumption used is as follows: the relation between water quality parameters and chlorophyll-a in the tributaries of the Seonakdonggang would be similar to that in the mainstream of the Seonakdonggang. On the assumption, the measurement data of water quality and chlorophyll-a in the mainstream of the Seonakdonggang were used as the learning data of the ANN. Through the sensitivity analysis, the learning data combination of water quality parameters was determined. Finally, chlorophyll-a series were estimated for tributaries of the Seonakdonggang by the ANN and TN, TP, BOD, COD, and temperature data from those streams. The relative errors between the estimated and measured chlorophyll-a were approximately 40 ~ 50%. Though the errors are somewhat large, the estimation process for chlorophyll-a may be useful in ungauged streams.

• ALGAE
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• v.36 no.4
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• pp.299-314
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• 2021

Some species in the dinoflagellate genus Alexandrium are bioluminescent. Of the 33 formally described Alexandrium species, the bioluminescence capability of only nine species have been tested, and eight have been reported to be bioluminescent. The present study investigated the bioluminescence capability of seven Alexandrium species that had not been tested. Alexandrium mediterraneum, A. pohangense, and A. tamutum were bioluminescent, but A. andersonii, A. hiranoi, A. insuetum, and A. pseudogonyaulax were not. We also measured the bioluminescent intensity of A. affine, A. fraterculus, A. mediterraneum, A. ostenfeldii, A. pacificum, A. pohangense, A. tamarense, and A. tamutum. The mean 200-second-integrated bioluminescence intensity per cell ranged from 0.02 to 32.2 × 10⁴ relative luminescence unit per cell (RLU cell^-1), and the mean maximum bioluminescence intensity per cell per second (BL_Max) ranged from 0.01 to 10.3 × 10⁴ RLU cell^-1 s^-1. BL_Max was significantly correlated with the maximum growth rates of Alexandrium species, except for A. tamarense. A phylogenetic tree based on large subunit ribosomal DNA (LSU rDNA) showed that the bioluminescent species A. affine, A. catenella, A. fraterculus, A. mediterraneum, A. pacificum, and A. tamarense formed a large clade. However, the toxicity or mixotrophic capability of these species was split. Thus, their bioluminescence capability in this clade was more consistent than their toxicity or mixotrophic capability. Phylogenetic trees based on LSU rDNA and the luciferase gene of Alexandrium were consistent except for A. pohangense. The results of the present study can provide a basis for understanding the interspecific diversity in bioluminescence of Alexandrium.