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The Effects of Nonylphenol on Freshwater Phytoplankton and Zooplankton Communities
Katano, Toshiya,Park, Chong-Sung,Baek, Seung-Ho,Han, Myung-Soo The Korean Society of Limnology 2008 생태와 환경 Vol.46 No.1
Recent studies reveal that the endocrine disrupter nonylphenol can also influence the growth of planktonic organisms. To clarify the effect of nonylphenol on the whole planktonic community, we monitored planktonic abundances after addition of nonylphenol using small-scale microcosms in a laboratory. Nonylphenol was added at final concentrations of 1.25 and $2.5{\mu}g\;L^{-1}$, close to the EC50 for the growth of the rotifer, Brachionus calyciflorus. Chlorophyll $\alpha$ concentration increased significantly between 2 to 5 days after nonylphenol treatment compared to the control. The abundance of the predominant phytoplankton, Stephanodiscus hantzschii, followed the same pattern as chlorophyll a concentration. While there was no negative effect on the abundance of ciliates and rotifers, crustacean zooplankton abundance was higher in nonylphenol treatments. Although the relationship did not reach significance, the growth rate of rotifers tended to decline with increasing nonylphenol dosing. It is likely that the decreased rotifer grazing on S. hantzschii caused significant increase in their abundance. This study emphasizes the importance of considering indirect effects of environmental pollutants when predicting the response of biological community to toxicant exposure.
Effect of Temporary Loading of Nonylphenol on a Summer Planktonic Community in a Eutrophic Pond
Baek, Seung-Ho,Katano, Toshiya,Han, Myung-Soo The Korean Society of Limnology 2008 생태와 환경 Vol.46 No.1
Recent studies reveal one of the representative endocrine disrupters of nonylphenol affects on the composition of a planktonic community. Since nonylphenol is sometimes discharged into eutrophic waters, we monitored planktonic community composition of a eutrophic pond after receiving nonylphenol when cyanobacterium Microcystis aeruginosa mainly dominated. The experiment was carried out two times using small-scale microcosms in a laboratory. In both two experiments, ciliate abundances significantly decreased when nonylphenol was added. On the seventh day, the ciliate abundances in $10{\mu}g\;L^{-1}$ added treatments decreased by 36.9% in the first experiment and 33.6% in the second, when compared to the control. The response of other planktonic groups was less obvious to nonylphenol addition. In particular, in the first experiment, Chl. b/Chl. $\alpha$ and Chl. c/Chl. $\alpha$ significantly increased with the addition of nonylphenol, while total Chl. $\alpha$ concentration did not change. Indeed, bacillariophyceae and chlorophyceae abundances tended to increase with nonylphenol dosing. From these results, we tentatively hypothesized that nonylphenolloading positively affects on abundances of edible phytoplankton such as Scenedesmus spp. and diatoms by releasing from grazing pressure due to decrease in ciliate abundances. The present study emphasizes that the indirect effect of endocrine disrupters should be paid more attention when freshwater resources are polluted by them.
Bo-Kyung Lee,Toshiya Katano,Shin-Ichi Kitamura,오명주,한명수 한국미생물학회 2008 The journal of microbiology Vol.46 No.3
The red tide of dinoflagellate, Cochlodinium polykrikoides has frequently occurred in coastal waters, causing severe damage to fisheries. In the present study, the algicidal bacterium Alteromonas sp. A14 isolated from the southern coast of Korea was applied to a red tide of C. polykrikoides in a laboratory experiment. In the experiment, the abundance of the strain A14 was monitored using fluorescence in situ hybridization. Inoculation of the A14 at a final cell density of 9.0×10^5 cells/ml caused a significant decrease in C. polykrikoides abundance from 1,830 to 700 cells/ml during 2 days, while abundances of harmless diatoms rapidly increased from 3 days. Abundances of both A14 and other bacteria increased to 1 day. After 1 day, with flagellate abundance increased, bacterial abundance decreased. Finally, algicidal bacterial abundance decreased to 3.5×10⁴ cells/ml. In the biological control of harmful algal blooms, in addition to decrease in target algal abundance and not occurrence of other harmful blooms, decrease in abundance of utilized organism is also important. This study emphasizes the importance of monitoring the inoculated bacterium when applying bacterium to natural seawater.
Baek, Seung H.,Ki, Jang S.,Katano, Toshiya,You, Kai,Park, Bum S.,Shin, Hyeon H.,Shin, Kyoungsoon,Kim, Young O.,Han, Myung‐,Soo Blackwell Publishing Asia 2011 Phycological research Vol.59 No.4
<P><B>SUMMARY</B></P><P>We investigated the seasonal abundance of the dinoflagellate <I>Heterocapsa triquetra</I> (Ehrenberg) F. Stein, as well as the relevant <I>in situ</I> environmental factors, in brackish Lake Shihwa, Korea. We also examined the growth rates and morphological characteristics of the species in laboratory cultures. In the field, the population densities of <I>H. triquetra</I> remained at low levels from late spring to early summer, and then completely disappeared from August to November 2007. Interestingly, a dense bloom of <I>H. triquetra</I> appeared below the ice surface on 17 January 2008; identities of the cells were confirmed by rDNA sequence comparisons. The second peak reached a density of 672 × 10<SUP>3</SUP> cells L<SUP>−1</SUP> on 28 March 2008, at a water temperature of 9.1°C. Laboratory experiments showed that growth rates of <I>H. triquetra</I> increased with incremental temperature increases within the range of 10 and 20°C. The highest growth rate reached by <I>H. triquetra</I> was 0.62 d<SUP>−1</SUP> at 20°C with a salinity of 30. Above 25°C, the dinoflagellate was unable to grow between salinities of 10 and 15, and reached only relatively low growth rates (<0.12 d<SUP>−1</SUP>) under other salinity conditions. However, under continuous cultures at 5°C and 8°C, <I>H. triquetra</I> cells retained its growth capability for more than 12 days, implying that <I>H. triquetra</I> can survive and grows even at very low temperatures. The equivalent spherical diameter (ESD) of <I>H. triquetra</I> did not change markedly between 10 and 25°C, but the equivalent spherical diameter was significantly different at 5°C. The cell volume buildup of <I>H. triquetra</I> at low temperatures is one of the important survival strategies to overcome the harsh environmental conditions. These characteristics make <I>H. triquetra</I> a consistently dominant dinoflagellate in Lake Shihwa during the cold winter season.</P>