• Ecology and Resilient Infrastructure
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• 제3권1호
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• pp.22-34
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• 2016

유해 남조류 Microcystis와 Dolichospermum의 친환경적인 제어를 위해 생물유래 물질을 기반으로 한 Naphthoquinone(NQ) 계열의 녹조제어 물질을 개발하였다. NQ의 기본구조를 바탕으로 치환기 ($R_n$)를 변화시켜 총 92종의 NQ 유도체를 합성 확보하였고, 대상 남조류 Microcystis와 Dolichospermum에 대하여 농도별 살조효과를 평가하여 $1{\mu}M$의 농도에서 80% 이상의 제어가 가능한 NQ 화합물을 각각 22종을 선정하였다. 그 중에서, NQ 40 물질은 최적 적용 농도인 $1{\mu}M$에서 Microcystis와 Dolichospermum 종에 각각 99.6%과 100%의 높은 제어효과가 관찰되었다. NQ 40 물질 ($1{\mu}M$)은 규조류 Stephanodiscus, Cyclotella와 와편모조류 Peridinium에는 살조효과가 없었으며, 대상 유해 남조류 Microcystis와 Dolichospermum에만 선택적으로 작용하였다. 또한, NQ 40 물질의 급성독성을 평가 결과, Selenastrum capricornutum, Daphnia magna 및 Danio rario 종에 대하여 $EC_{50}$/$LC_{50}$ 값이 각각 3.2, 14.5 및 $15.7{\mu}M$로 측정되었다. 더불어, D. magna를 이용한 만성독성 평가 결과, NQ 40 물질 $1{\mu}M$에서 생존, 성장, 번식에 대한 영향은 없었다. 따라서, 최종 선정된 NQ 40 물질을 현장에서 $1{\mu}M$로 적용한다면, 다른 수생생물에 미치는 영향 없이 대상 조류인 Microcystis와 Dolichospermum 종만 선택적으로 제어 가능한 친환경적인 살조물질로 사용될 것으로 판단된다.

• 환경생물
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• 제37권4호
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• pp.741-748
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• 2019

본 연구에서는 바이오매스 폐기물인 Corynebacterium glutamium을 Alg를 이용한 고정화와 PEI 표면개질 과정을 통하여 유해 미세조류인 Microcystis aeruginosa를 제거할 수 있는 흡착소재인 PEI-AlgBF를 개발하였다. 녹조의 발생단계에 상관없이 PEI-AlgBF는 수계로부터 M. aeruginosa를 성공적으로 제거할 수 있었으며 유해조류 제거과정에서 M. aeruginosa 세포의 파괴를 유발하지 않았다. 흡착소재의 표면적은 M. aeruginosa의 제거효율에 매우 큰 영향을 주는 주요인자로 확인할 수 있었다. PEI-AlgBF를 사용한 M. aeruginosa 흡착/제거 방식은 기존 기술에 비하여 환경영향성이 낮기 때문에 보다 안전하고 안정적인 유해조류의 제어 방식이 될 것이다.

• ALGAE
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• 제32권2호
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• pp.139-153
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• 2017

The ability of a red tide species to take up nutrients is a critical factor affecting its red tide dynamics and species competition. Nutrient uptake by red tide species has been conventionally measured by incubating nutrient-depleted cells for a short period at 1 or 2 light intensities. This method may be applicable to certain conditions under which cells remain in oligotrophic water for a long time and high nutrients are suddenly introduced. Thus, a new method should be developed that can be applicable to the conditions under which cells are maintained in eutrophicated waters in healthy conditions and experience light and dark cycles and different light intensities during vertical migration. In this study, a new repletion method reflecting these conditions was developed. The nitrate uptake rates of the red tide dinoflagellate Prorocentrum micans originally maintained in nitrate repletion and depletion conditions as a function of nitrate concentration were measured. With increasing light intensity from 10 to $100{\mu}E\;m^{-2}s^{-1}$, the maximum nitrate uptake rate ($V_{max}$) of P. micans increased from 3.6 to $10.8 pM\;cell^{-1}d^{-1}$ and the half saturation constant ($K_{s-NO3}$) increased from 4.1 to $6.9{\mu}M$. At $20{\mu}E\;m^{-2}s^{-1}$, the $V_{max}$ and $K_{s-NO3}$ of P. micans originally maintained in a nitrate repletion condition were similar to those maintained in a nitrate depletion condition. Thus, differences in cells under nutrient repletion and depletion conditions may not affect $K_{s-NO3}$ and $V_{max}$. Moreover, different light intensities may cause differences in the nitrate uptake of migratory phototrophic dinoflagellates.

• ALGAE
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• 제35권3호
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• pp.225-236
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• 2020

Gymnodinium smaydae is a newly described mixotrophic dinoflagellate that feeds on only Heterocapsa spp. and Scrippsiella acuminata among 19 tested algal prey. It is one of the fastest growing dinoflagellates when feeding, but does not grow well without prey. To investigate its spatial-temporal distributions in Korean waters, we quantified its abundance in water samples that were seasonally collected from 28 stations along the Korean Peninsula from April 2015 to October 2018, using quantitative real-time polymerase chain reactions. This dinoflagellate had a wide distribution, as reflected by the detection of G. smaydae cells at 23 of the sampling stations. However, this distribution had a strong seasonality; it was detected at 21 stations in the summer and only one station in winter. The abundance of G. smaydae was significantly and positively correlated with chlorophyll a concentration as well as with water temperature. However, there were no significant correlations between the abundance of G. smaydae and salinity, concentrations of nutrients, or dissolved oxygen concentration. During the study period, G. smaydae was present when water temperatures were 7.6-28.0℃, salinities were 9.6-34.1, concentrations of NO₃ were not detectable-106.0 μM, and concentrations of PO₄ were not detectable-3.4 μM. The highest abundance of G. smaydae was 18.5 cells mL^-1 in the coastal waters of Jinhae in July 2017 when the chlorophyll a concentration was 127 mg m^-3 and water temperature was 23.8℃. Therefore, the spatial-temporal distribution of G. smaydae in Korean coastal waters may be affected by chlorophyll a concentration and water temperature.

• ALGAE
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• 제32권4호
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• pp.275-284
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• 2017

Microcystis aeruginosa causes harmful algal blooms in the Nakdong River of Korea. We studied the effect of different concentrations and ratios of ammonium ($NH_4{^+}$), nitrate ($NO_3{^-}$), and phosphate ($PO{_4}^{3-}$) on growth of this species in BG-11 medium: each nutrient alone, $NO_3{^-}:NH_4{^+}$ ratio, the N : P ratio with fixed total N (TN), and the N : P ratio with fixed total P (TP). The single nutrient experiments indicated that M. aeruginosa had the highest growth rate at $NH_4{^+}$ and $NO_3{^-}$ concentrations of $500{\mu}M$, and at a $PO{_4}^{3-}$ concentration of $5{\mu}M$. The $NO_3{^-}:NH_4{^+}$ ratio experiments showed that M. aeruginosa had the highest growth rate at a ratio of 1 : 1 when TN was $100{\mu}M$ and $250{\mu}M$, and the lowest growth rate at a ratio of 1 : 1 when the TN was $500{\mu}M$. The N : P ratio with fixed TN experiments indicated that M. aeruginosa had the highest growth rates at 50 : 1, 20 : 1, and 100 : 1 ratios when the TN was 100, 250, and $500{\mu}M$, respectively. In contrast, the N : P ratio with fixed TP experiments showed that M. aeruginosa had the highest growth rates at 200 : 1 ratio at all tested TP concentrations. In conclusion, our results imply that the $NO_3{^-}:NH_4{^+}$ ratio and the $PO{_4}^{3-}$ concentration affect the early stage of growth of M. aeruginosa. In particular, our results suggest that the maximum growth of M. aeruginosa is not simply affected by the $NO_3{^-}:NH_4{^+}$ ratio and the N : P ratio, but is determined by the TN concentration if a certain minimum $PO{_4}^{3-}$ concentration is present.

• ALGAE
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• 제32권4호
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• pp.309-324
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• 2017

Recently, the heterotrophic nanoflagellate Katablepharis japonica has been reported to feed on diverse red-tide species and contribute to the decline of red tides. However, if there are effective predators feeding on K. japonica, its effect on red tide dynamics may be reduced. To investigate potential effective protist predators of K. japonica, feeding by the engulfment-feeding heterotrophic dinoflagellates (HTDs) Oxyrrhis marina, Gyrodinium dominans, Gyrodinium moestrupii, Polykrikos kofoidii, and Noctiluca scintillans, the peduncle-feeding HTDs Luciella masanensis and Pfiesteria piscicida, the pallium-feeding HTD Oblea rotunda, and the naked ciliates Strombidium sp. (approximately $20{\mu}m$ in cell length), Pelagostrobilidium sp., and Miamiensis sp. on K. japonica was explored. We found that none of these heterotrophic protists fed on actively swimming cells of K. japonica. However, O. marina, G. dominans, L. masanensis, and P. piscicida were able to feed on heat-killed K. japonica. Thus, actively swimming behavior of K. japonica may affect feeding by these heterotrophic protists on K. japonica. To the contrary, K. japonica was able to feed on O. marina, P. kofoidii, O. rotunda, Miamiensis sp., Pelagostrobilidium sp., and Strombidium sp. However, the specific growth rates of O. marina did not differ significantly among nine different K. japonica concentrations. Thus, K. japonica may not affect growth of O. marina. Our findings suggest that the effect of predation by heterotrophic protists on K. japonica might be negligible, and thus, the effect of grazing by K. japonica on populations of red-tide species may not be reduced by mortality due to predation by protists.

• ALGAE
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• 제31권1호
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• pp.17-31
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• 2016

To explore the feeding ecology of the newly described heterotrophic dinoflagellate Aduncodinium glandula in the family Pfiesteriaceae, its feeding behavior and prey species were investigated. Additionally, the growth and ingestion rates of A. glandula on the mixotrophic dinoflagellates Heterocapsa triquetra and Akashiwo sanguinea, its optimal and suboptimal prey, respectively were measured. A. glandula fed on prey through a peduncle after anchoring to the prey using a tow filament. A. glandula ate all algal prey and perch blood cells tested and had the most diverse prey species in the family Pfiesteriaceae. Unlike for other pfiesteriacean species, H. triquetra and A. sanguinea support the positive growth of A. glandula. However, the cryptophytes Rhodomonas salina and Teleaulax sp. and the phototrophic dinoflagellate Amphidinium carterae did not support the positive growth of A. glandula. Thus, A. glandula may have a unique kind of prey and its optimal prey differs from that of the other pfiesteriacean dinoflagellates. With increasing mean prey concentration, the growth rates of A. glandula on H. triquetra and A. sanguinea increased rapidly and then slowed or became saturated. The maximum growth rates when feeding on H. triquetra and A. sanguinea were 1.004 and 0.567 d⁻¹, respectively. Further, the maximum ingestion rates of A. glandula on H. triquetra and A. sanguinea were 0.75 and 1.38 ng C predator⁻¹ d⁻¹, respectively. There is no other pfiesteriacean species having H. triquetra and A. sanguinea as optimal and suboptimal prey. Thus, A. glandula may be abundant during blooms dominated by these species not preferred by the other pfiesteriacean dinoflagellates.

• 미생물학회지
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• 제52권3호
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• pp.306-312
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• 2016

미세조류는 수환경으로 유입되는 독성물질의 배출기준을 설정하거나 환경영향을 평가하기 위한 환경변화의 잠재적 생물지표이다. 본 논문에서 해양 미세조류인 녹조류 Tetraselmis suecica, 규조류 Ditylum brightwellii, 와편모조류 Prorocentrum minimum에 대한 내분비 교란물질(EDCs) 비스페놀 A (BPA)와 Aroclor 1016의 영향을 평가하였다. 처리한 EDCs에 대하여 각각의 종은 매우 다른 민감도 차이를 보였다. 각 종에 대한 50% 영향농도($EC_{50}$)는 Aroclor 1016가 BPA보다 더 유해하였다. 실험에 사용한 미세조류중에서 규조류 D. birghtwellii(0.037 mg/L BPA과 0.002 mg/L Aroclor 1016)가 다른 종보다 매우 민감하게 반응하는 것으로 조사되었다. 본 연구 결과는 수서생태계에로 배출되는 기준 농도 이상의 EDCs가 해양 생물에게 유해 효과가 있다는 것을 제시해 준다.

• ALGAE
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• 제28권4호
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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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• 제29권2호
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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.