Japanese Journal of Limnology (Rikusuigaku Zasshi)
Online ISSN : 1882-4897
Print ISSN : 0021-5104
ISSN-L : 0021-5104
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Volume 59, Issue 2
Displaying 1-14 of 14 articles from this issue
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  • Estimation of Water Surface Temperature by Infrared Remote Sensing at Shiozu Bay in Lake Biwa
    Yasumasa ITAKURA, Shuichi ENDOH
    1998 Volume 59 Issue 2 Pages 115-124
    Published: June 01, 1998
    Released on J-STAGE: June 12, 2009
    DOIhttps://doi.org/10.3739/rikusui.59.115
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    Thermal infrared mapping can provide useful data on the surface temperature distributions of a restricted observation area, such as a bay in a lake.
    This paper describes a method for estimating the surface temperature of the water, in which the estimation of the equivalent background radiation temperature (EBRT) is a key factor. The results from the first field experiment show that the optimal EBRT is 4.4°C lower than the atmospheric temperature. A comparison of the estimated temperature and the temperature measured by a thermistor towed by a boat shows that the minimum deviation is within 1.1°C. The second field experiment for measuring water surface temperature at a station in the middle of Shiozu Bay gives a continuous comparison during over 24 hr between the measured temperature and the estimated temperature using the optimal EBRT obtained from the first field experiment. The results show that the deviation is also within 1.1°C.
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  • Life History and Dispersal Pattern of the Polychaete Worm Neanthes japonica (IZUKA) in the Nanakita River Estuary, Miyagi Prefecture
    Eisuke KIKUCHI
    1998 Volume 59 Issue 2 Pages 125-146
    Published: June 01, 1998
    Released on J-STAGE: June 12, 2009
    DOIhttps://doi.org/10.3739/rikusui.59.125
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    The breeding, dispersal, recruitment and life span of Neanthes japonica were investigated in the tidal flats of the Nanakita River estuary. Dispersal was examined by collecting larvae in water and assessing the recruitment of worms into settling buckets filled with air-dried azoic sediment. The results indicated that the spawning season extended from May to November with two peaks of breeding activity in late-spring and autumn. Migration and recruitment of N. japonica occurred mainly in larval stages, especially the 4- and 5-setiger nectochaete stages, in May-June and from September to October, respectively. From April to August the larger juveniles also migrated and colonized the buckets, while in autumn the juveniles with peristomial width of more than 0.75 mm, which were found in the surrounding sediments, rarely colonized. Analysis of the size structure of the population and rearing experiments suggested that N. japonica had about a half-year life cycle with terminal reproduction. In this study, all female worms examined had eggs of a diameter greater than 180 μm, suggesting that the description of the life cycle of N. japonica in the Nanakita River estuary relates to individuals of the large-egg type. This paper may be the first detailed study focused on the life cycle of a large-egg type.
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  • Simultaneous Measurement of N2, O2, Ar, CO2, CH4, H2 and CO in Aqueous and Gaseous Samples: a Detection of N2/Ar Shifts in Environments
    Muneoki YOH, Makoto TAKEUCHI, Hideshige TODA
    1998 Volume 59 Issue 2 Pages 147-157
    Published: June 01, 1998
    Released on J-STAGE: June 12, 2009
    DOIhttps://doi.org/10.3739/rikusui.59.147
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    A gas chromatographic system which accurately analyzes major gas constituents in environments is described. The system, which consists of three separation columns and two gas chromatographs equipped with a thermal conductivity detector, is capable of determining N2, O2, Ar, CO2, CH4, H2 and CO simultaneously in both aqueous and gaseous samples. For gaseous samples, a special injection port was devised in the analytical line to eliminate air contamination during sample handling. A test measurement of air-equilibrated water confirmed that the measured concentrations of dissolved gases agreed well with their theoretical values calculated from solubility and atmospheric partial pressures. The preliminary results of groundwater and wetlands samples demonstrate that the entire gas composition in environments could be fully accounted for by the detected gas species. The N2/Ar ratio given by this analysis could be an effective parameter to evaluate both N2 production (denitrification) and N2 consumption (nitrogen fixation) in nature.
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  • Horizontal Distribution Profiles of 238U, 137Cs and Stable Elements in the Bottom Sediments of the Brackish Lake Obuchi in Aomori Prefecture
    Shinji UEDA, Hitoshi KAWABATA, Hidenao HASEGAWA, Sakurai NAOYUKI, Kuni ...
    1998 Volume 59 Issue 2 Pages 159-173
    Published: June 01, 1998
    Released on J-STAGE: December 11, 2009
    DOIhttps://doi.org/10.3739/rikusui.59.159
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    The horizontal distribution of radionuclides such as 238U, 117Cs and 40K, and stable elements in the bottom sediments of the brackish Lake Obuchi was surveyed in 1995. Samples were collected at a network of thirty stations in the lake. The following results were obtained from the analysis of the relationships between the concentrations of radionuclides or stable elements in the bottom sediments and the shape of the water basin, water currents, grain size of bottom sediments, the content of organic matter in the bottom sediments and so on.
    1) The concentration of their elements in the bottom sediments were classified into two characteristic distributions. On the one hand, 238U, 137Cs, 40K and Mn concentrations were high in the area (>3 m, water depth) from east to west part of Lake Obuchi. On the other hand, Al, Co and Ba concentrations were high at the influx vicinity of the Futamata River which is located on the west side of the lake.
    2) The correlation coefficient between salinity and 238U or 137Cs in the water of Lake Obuchi showed high values at 0.95 and 0.89, respectively. These results suggest that the source of 238U and 137Cs in the bottom sediments are mainly sea water.
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  • Identification of Three Cheumatopsyche Species (Insecta: Trichoptera) in Japan by Enzyme Polymorphism
    Yoshio HAYASHI
    1998 Volume 59 Issue 2 Pages 175-183
    Published: June 01, 1998
    Released on J-STAGE: December 10, 2009
    DOIhttps://doi.org/10.3739/rikusui.59.175
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    Enzyme polymorphism of three species of the genus Cheumatopsyche in Japan was studied by polyacrylamide gel electrophoresis. Adults and larvae were collected from the field. Adults that had emerged in the laboratory were also used. These insects were dissected and separated into morphological materials (e.g., genitalia and wings from adults, head and thorax from larvae) and enzyme analytical materials (e.g., metapleuron and some abdominal sections). Malate dehydrogenase (MDH) was detected only from adults. Glutamate dehydrogenase (GDH) and alkaline phosphatase (AP) were detected only from larvae. Esterase (EST), however, was detected at a high level from both male and female adults as well as from larvae. Zymograms of EST in male adults clearly distinguished among three species : Cheumatopsyche brevilineata (IwATA), C. infascia MARTYNOV and Cheumatopsyche sp. (undescribed species). The zymograms were similar among male and female adults and larvae of the same species. Thus, this isozyme analysis is an effective method of distinguishing the species of Cheumatopsyche and of associating larvae with adults.
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  • Morphology of Early Instar Larvae and Life History of Ephoron eophilum (Ephemeroptera: Polymitarcyidae)
    Ikuo AOYAGI, Masako TETSUKA, Kazuo NAKAMURA
    1998 Volume 59 Issue 2 Pages 185-198
    Published: June 01, 1998
    Released on J-STAGE: June 12, 2009
    DOIhttps://doi.org/10.3739/rikusui.59.185
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    The life history of a burrowing mayfly, Ephoron eophilum ISHIWATA, was studied in the Kinu River, Ibaraki Prefecture, Japan, which a congener E. shigae (TAKAHASHI), inhabits sympatrically. E. eophilum had a univoltine life cycle. First instar larvae were found during the long period from April to July, and adults appeared from July to October, which is in contrast to the more syncronous life history pattern of E. shigae. Another distinct difference between these two species is the diurnal timing of the emergence of imagos and subimagos : E. shigae emerged after sunset, while E. eophilum emerged at early dawn. E. eophilum females had fewer (352-1863) larger (0.25 mm in diameter) eggs than E. shigae females which had as many as 634-3420 eggs 0.16 mm in diameter. Hatchings of E. eophilum were larger in body size than those of E. shigae, and had well developed mandibles which may be adapted to life in harder clay stream beds.
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  • Seasonal and Diurnal Timing of Emergence of Ephoron shigae (Ephemeroptera: Polymitarcyidae) from Four Japanese Rivers
    Naoshi C. WATANABE, Koukichi HATTA, Kazuo HISAEDA, Kazuaki HOSHI, Shin ...
    1998 Volume 59 Issue 2 Pages 199-206
    Published: June 01, 1998
    Released on J-STAGE: June 12, 2009
    DOIhttps://doi.org/10.3739/rikusui.59.199
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    Seasonal and diurnal patterns of emergence were compared in unisexual and bisexual populations of Ephoron shigae (TAKAHASHI) from four rivers, including two near the northern and southern periphery of the species range. During the emergence periods in 1991 and 1992 winged mayflies were collected every day in the same way in the four rivers. Seasonal timing and synchrony of adult emergence varied depending on the locality and year. The daily start of emergence gradually became earlier with sunset during the emergence period, except for an unusually early emergence on a heavily rainy day, suggesting that light intensity may affect the time of emergence. In the bisexual populations, males began to emerge earlier than females. Females in the unisexual populations began to emerge as early after sunset as males did in the bisexual populations. Sizes of winged stages gradually decreased during the emergence period : hypotheses of decreasing size for cohorts developing under increasing temperatures cannot be applied to E. shigae which spends its later nymphal stages under temperatures fluctuating around the highest level of the year.
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  • Preliminary Report on Diel Changes in Dissolved Oxygen Concentration in Filamentous Green Algal Mats in Littoral Zone of Lake Biwa
    Kentaro NOZAKI, Hiromune MITSUHASHI, Akihiro TUJI
    1998 Volume 59 Issue 2 Pages 207-213
    Published: June 01, 1998
    Released on J-STAGE: June 12, 2009
    DOIhttps://doi.org/10.3739/rikusui.59.207
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    During the summer time (June - August) of 1994 and 1995, filamentous green alga Spirogyra sp. largely dominated the littoral zone in the north basin of Lake Biwa. Algal mats which were mainly composed of Spirogyra had a thickness of over 20 cm. Diel changes in dissolved oxygen concentra-tion were measured in the Spirogyra community to predict the effect of Spirogyra growth on the lake's littoral ecosystem. A decrease in dissolved oxygen concentration was clearly observed at night. It was suggested that the reduction in dissolved oxygen concentration by the Spirogyra community had a harmful influence on other organisms at this study site.
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  • ERRATUM
    1998 Volume 59 Issue 2 Pages 233a-235
    Published: 1998
    Released on J-STAGE: June 12, 2009
    DOIhttps://doi.org/10.3739/rikusui.59.2_233a
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  • ERRATUM
    1998 Volume 59 Issue 2 Pages 233b-235
    Published: 1998
    Released on J-STAGE: June 12, 2009
    DOIhttps://doi.org/10.3739/rikusui.59.2_233b
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  • ERRATUM
    1998 Volume 59 Issue 2 Pages 233c-235
    Published: 1998
    Released on J-STAGE: June 12, 2009
    DOIhttps://doi.org/10.3739/rikusui.59.2_233c
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  • ERRATUM
    1998 Volume 59 Issue 2 Pages 233d-235
    Published: 1998
    Released on J-STAGE: June 12, 2009
    DOIhttps://doi.org/10.3739/rikusui.59.2_233d
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  • ERRATUM
    1998 Volume 59 Issue 2 Pages 233e-235
    Published: 1998
    Released on J-STAGE: June 12, 2009
    DOIhttps://doi.org/10.3739/rikusui.59.2_233e
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  • ERRATUM
    1998 Volume 59 Issue 2 Pages 233f-235
    Published: 1998
    Released on J-STAGE: June 12, 2009
    DOIhttps://doi.org/10.3739/rikusui.59.2_233f
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