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Volume 41, Issue 4
Displaying 1-5 of 5 articles from this issue
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Machiko NISHINO1980 Volume 41 Issue 4 Pages 185-202
Published: October 30, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSThe variations in body size, egg size and brood size of berried females among populations have not been known in Palaemon paucidens. These were examined among 28 local populations from various inland waters over its range of geographical distribution. Body size differs among the populations. Egg size is almost constant regardless of body size within a population, but differs among the populations, and the largest from Lake Akan is about seven times as large as the smallest from Lake Biwa. Brood size increases with body size, however, relative brood size is almost similar within a population. Among the populations, mean brood size and mean relative brood size vary, but fall within a limited range, except for the mean relative brood size in Lake Biwa, which is exceptionally large. Relative brood weight is almost similar in a population, as well as mean relative brood weight among the populations. Thus, mean relative brood size is almost inversely proportional to mean egg size. A geographical trend is noticeable in the variations of these two values (i. e., larger mean egg size and smaller mean relative brood size in colder waters), except for the populations in Lake Biwa and two rivers of Boso. The small body size of the population in Lake Biwa can be related to its life history, in which a longer period is spent in colder conditions, and the high relative brood size can be regarded as its adaptive strategy of allocation.View full abstractDownload PDF (2626K) -
Norio OGURA, Hideo UEHARA1980 Volume 41 Issue 4 Pages 203-211
Published: October 30, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSStudies on condensed phosphates were carried out in the polluted urban river water of the Nogawa River, Tokyo. Diurnal changes in condensed phosphates at N-2 in Nogawa River were determined in July 1976 : concentration of condensed phosphate phosphorus was 0.4-17.4μg atom/l, 2-30% (mean 17%) of the total dissolved phosphorus on weekdays (Tuesday-Wednesday) and 0.0-23.9μg atom/l, 0-32% (mean 15%) of the total on Sundays (Saturday-Sunday).
Concentration of condensed phosphate decreased along the water course of the river. These facts and experimental results suggest that condensed phosphate is easily hydrolyzed to reactive phosphate in running water.
Daily per capita loadings of phosphorus were estimated to be 2.2 g on weekdays and 1.9 g on Sundays. About half of the loadings were considered to originate from synthetic detergents.View full abstractDownload PDF (1206K) -
Naoshi C. WATANABE1980 Volume 41 Issue 4 Pages 212-224
Published: October 30, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSBoth Semisulcospira decipiens and S. reticulata are endemic species in Lake Biwa. The density of S. decipiens was inversely related to the water depth except at a few shallow sites where this species scarcely occurred, and its relation to the grain size of the substratum was hardly observed. The density of S. reticulata was related to both the depth and grain size of substratum. This species generally occurred on any bottom deeper than about 3 m and on a muddy bottom shallower than that, while its abundance showed a distinct relation neither to the depth so long as it was greater than 3 m nor to the minute difference of grain size so long as it was muddy bottom. As a whole, S. decipiens was found on a shallower bottom and. S. reticulata on a deeper bottom, although the distribution of the two overlapped. No change in habitat with the season or developmental stage was observed in either species studied here, unlike the case of S. libertina and S. niponica, which had been reported by other authors. The interspecific interference in a coexisting area was not recognized according to analysis by the MORISITA association index (Rδ).View full abstractDownload PDF (1879K) -
Morihiro AIZAKI1980 Volume 41 Issue 4 Pages 225-234
Published: October 30, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSMicrobial succession and changes in photosynthetic rate attendant on the film development of periphyton were investigated using artificial substrata in a shallow eutrophic region of the midstream of the Tamagawa River. Bacteria played the role of pioneer colonizer in the periphyton development. Algae joined the community after formation of bacterial colonies on substrata and dominated in the mature stage. Algae accounted for about 80 percent of the periphyton community in maximum and 50-70 percent in carbon weight under ordinary conditions in spring. Total numbers of aerobic heterotrophic bacteria were 107-109 cells/cm2 and 1010-1012 cells/gC in the mature stage. A number of sulfate-reducing bacteria were also found in that stage. Photosynthetic rates of sessile algae varied widely with film development of periphyton. They showed 3-20mg·O2/mg·chl.-a·hr in the early stage and 1-3mg·O2/mg·chl.-a·hr in the mature stage. An extremely low photosynthetic rate was found just before the exfoliation of periphyton occurred.View full abstractDownload PDF (2189K) -
I. Confined Ground Water in the Naka River EstuaryYoshiaki FUKUO, Tadao KAKINUMA, Yosuke KISHI, Makoto IFUKU1980 Volume 41 Issue 4 Pages 235-248
Published: October 30, 1980
Released on J-STAGE: October 21, 2009
JOURNAL FREE ACCESSIn this paper, we first presenta theoretical model on the phenomena of these a water intrusion into coastal aquifers. Withthe use of this model, the spatial distribution of fresh and salt water interface in steady stateis easily determined either in the confined or unconfined aquifer which has arbitrary plane boundaries. We next apply this model to the confined ground wate rin the estuary of the Naka River, Tokushima Pref. The variation of spatial distribution of fresh and salt water interface is investigated in detail in connection with the changes in pumping amount or in inflow rate of ground water.View full abstractDownload PDF (2024K)
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