Ontogenetic niches of a planktonic copepod in Lake Biwa studied on a fine temporal scale

1995 ◽  
Vol 10 (2) ◽  
pp. 207-215 ◽  
Author(s):  
Keiichi Kawabata
2020 ◽  
Vol 85 ◽  
pp. 131-139
Author(s):  
S Shen ◽  
Y Shimizu

Despite the importance of bacterial cell volume in microbial ecology in aquatic environments, literature regarding the effects of seasonal and spatial variations on bacterial cell volume remains scarce. We used transmission electron microscopy to examine seasonal and spatial variations in bacterial cell size for 18 mo in 2 layers (epilimnion 0.5 m and hypolimnion 60 m) of Lake Biwa, Japan, a large and deep freshwater lake. During the stratified period, we found that the bacterial cell volume in the hypolimnion ranged from 0.017 to 0.12 µm3 (median), whereas that in the epilimnion was less variable (0.016 to 0.033 µm3, median) and much lower than that in the hypolimnion. Additionally, in the hypolimnion, cell volume during the stratified period was greater than that during the mixing period (up to 5.7-fold). These differences in cell volume resulted in comparable bacterial biomass in the hypolimnion and epilimnion, despite the fact that there was lower bacterial abundance in the hypolimnion than in the epilimnion. We also found that the biomass of larger bacteria, which are not likely to be grazed by heterotrophic nanoflagellates, increased in the hypolimnion during the stratified period. Our data suggest that estimation of carbon flux (e.g. bacterial productivity) needs to be interpreted cautiously when cell volume is used as a constant parametric value. In deep freshwater lakes, a difference in cell volume with seasonal and spatial variation may largely affect estimations.


1985 ◽  
Vol 17 (10) ◽  
pp. 127-138
Author(s):  
Hisashi Sumitomo

Chlorination has been believed to be the best sterilization method in water supply engineering for many years. However, the recent carcinogenic problem of trihalomethanes (THM) formed from organic compounds by chlorination requires us to assess the public health risk of THM. The author tried an assessment of a suitable chlorination technique considering both the effects of THM and viruses on human health, using Lake Biwa as a representative example of a water resource in Japan. Statistical handling of data was revealed to be important because of the statistical nature of the data. In other words, since both concentrations are very low in tap water, we need to quantify both the effects and concentrations with probabilities. In the first part of this paper, a statistical procedure and numerical results of the assessment of virus and THM risks are shown. In the second part some results of accuracies in virus experiments are briefly shown. These experiments concerning statistical problems are particularly important for more precise assessment of the public risk of viruses in tap water.


1995 ◽  
Vol 31 (11) ◽  
pp. 153-158 ◽  
Author(s):  
M. Kajino ◽  
K. Sakamoto

Musty odor has occurred annually in Lake Biwa since 1969. Osaka municipal waterworks, which is located downstream of Lake Biwa, has made many efforts to treat musty-odor compounds produced in Lake Biwa from spring through autumn. With the development of analytical methods for the determination of musty-odor compounds, we have been able to confirm that planktonic blue-green algae are the major causes of the musty-odor occurrences. The relationship between the growth of blue-green algae and the water quality was not so apparent. However, through our data analysis focusing on the relationship between musty-odor occurrences due to Phormidium tenue or Oscillatoria tenuis and some nutrients in Lake Biwa, we found that the concentration of nitrate in water may be an important parameter for the estimation of growth of the algae and the musty-odor behavior.


Humanities ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 43
Author(s):  
Kiley M. Kost

The complex narrative composition of image and text in Max Frisch’s Der Mensch erscheint im Holozän discloses entanglements between humans and nonhuman entities that impact the narrative and that demand careful consideration. The story depicts the aging protagonist’s struggle with memory loss and his careful examination of the valley’s mountain formations in fear of a landslide. In this analysis, I show that both of these threats can be read as entangled with nonhuman agents. By focusing on the material dimension of the text, two central and related shifts occur: the background element of rain becomes foregrounded in the narrative, and the natural formations of the valley that are assumed to be static are revealed to be dynamic. These shifts lead to an interpretation of Frisch’s text focused on the impacts of rain and the temporal scale of the text’s geologic dimension. Approaching the text through the lens of material ecocriticism unveils the multiple agencies at play, decenters the human, and illustrates the embodied experience of climate change.


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