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Volume 68, Issue 3
Displaying 1-13 of 13 articles from this issue
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Original article
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Michinori GODO, Syuhei BAN2007 Volume 68 Issue 3 Pages 375-389
Published: 2007
Released on J-STAGE: December 31, 2008
JOURNAL FREE ACCESSEffects of temperature on survival, respiration and excretion rates of an endemic amphipod species, Jesogammarus annandalei, in Lake Biwa was examined in January, March, May, June and October 2004 in the laboratory. J. annandalei, a univoltine bottom-dweller is distributed in the basin at depths over 40 m and a temperature of 7-8°C in the daytime during the stratified period. In the laboratory, its survival rate declined to 50% within 24 hours when the ambient temperature rapidly changed from 8 to 20 or 25°C, though almost all animals were able to survive a change from 8 to 15°C. Respiration rates of J. annandalei increased with temperature in all seasons, being higher in May and June than in January, March and October. Its respiration rate (R) is expressed as a function of its body dry mass (W) and water temperature (T), logR = 0.695·logW + 0.03·T–0.34. On the other hand, its excretion rates of ammonia and phosphorus also increased with the temperature in May and June, but rather decreased over 20°C in the other months, when it was still young. These negative effects of high temperature on survival and excretion rates may explain why the horizontal distribution of this amphipod was restricted to lake basin depths of over 40 m.View full abstractDownload PDF (867K) -
Takashi NAGAI, Kiyotaka TSUNEMI, Akemi KAWAMOTO2007 Volume 68 Issue 3 Pages 391-401
Published: 2007
Released on J-STAGE: December 31, 2008
JOURNAL FREE ACCESSMetal bioavailability of and toxicity to aquatic organisms depend on their speciation. The chemical speciation of Ni, Cu, and Zn in two Japanese rivers was measured by diffusive gradients in thin-films (DGT) and estimated by a chemical equilibrium model. Using a standard DGT device, we obtained labile metal concentrations. Visual MINTEQ and its default thermodynamic database were used to obtain the fractions of inorganic metal species. The fractions of labile Ni concentration measured by DGT at one site were very low and not well predicted by MINTEQ. The fractions of labile Cu concentration at all sampling sites were low and were consistent with the model estimation. Both DGT measurements and the model estimation resulted that most Zn was present as free ion. Measured and estimated metal speciations near the wastewater treatment plant were in agreement once EDTA was incorporated into the model estimation. Our results suggest that we should take into account the existence of non-humic chelators at the model estimation of water samples containing wastewater organic matter.View full abstractDownload PDF (793K)
Notes
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Shigeko KIMURA, Syuhei BAN, Toru YOSHIKAWA, Miki SUDO2007 Volume 68 Issue 3 Pages 403-413
Published: 2007
Released on J-STAGE: December 31, 2008
JOURNAL FREE ACCESSThe effects of pesticides and nutrient loading from paddy fields on the growth of natural phytoplankton assemblages collected from Lake Biwa were examined by bioassay using the waters from Lake Biwa, a river connected by a drainage canal from near by paddy fields, and the drainage from mid-April to late June 2003. Rice-planting is carried out in early May around Lake Biwa, and high levels of pesticides and fertilizers are used in the paddy fields. According to a bioassay using natural phytoplankton assemblages collected from the lake, nutrient limitations on phytoplankton growth were detected in the surface water throughout the study period except for mid-May, but not in the water from the river or the drainage canal. In mid-May, phytoplankton growth was not limited by nutrients even in the lake water. On the other hand, the bioassay also suggested the deleterious effect of pesticides on phytoplankton growth from early to mid-May. This negative impact was significantly correlated with the concentration of the herbicide Pretilachlor in the water tested. Such results suggested that, although the negative effect of pesticides on phytoplankton growth could be detected even in Lake Biwa water, the positive effect of nutrient loading from paddy fields seemed to exceed the negative effect of pesticides during the study period.View full abstractDownload PDF (727K) -
Masahiro MARUO, Masanori TODA, Tomoko SATORI, Hajime OBATA2007 Volume 68 Issue 3 Pages 415-423
Published: 2007
Released on J-STAGE: December 31, 2008
JOURNAL FREE ACCESSThe extraction method of Fe(II)-ferrozine complex was modified to achieve detection of nanomolar concentrations of Fe(II) in freshwaters. This method was applied to investigate the distribution of trace Fe(II) concentrations in the oxic environments of Lake Biwa and its inflowing rivers. In the north basin of the lake in November 2005, surface water samples showed the maximum concentration of dissolved Fe(II), and its ratio to total Fe(II) concentration had also showed the maximum compared with those sampled at depths of 5, 10 and 20 m. Fe(II) in inflowing river waters existed almost solely in a dissolved fraction, in spite of the variation in pollution levels of these rivers. At the Inukami River that receives a massive groundwater supply, Fe(II) at 6 sampling points was measured. The Fe(II)/Fe(III) ratio in water tended to decrease with an increase in pH, indicating that the Fe(II) in groundwater mixed with the oxic river water and slowly oxidized. This finding was supported by an increase in concentrations of chloride ion in river water corresponding with a decrease in the Fe(II)/Fe(III) ratios.View full abstractDownload PDF (513K) -
Hirokatsu UTAGAWA, Noriko TAKAMURA2007 Volume 68 Issue 3 Pages 425-432
Published: 2007
Released on J-STAGE: December 31, 2008
JOURNAL FREE ACCESSIn recent years, a singular phenomenon of white turbid water has often been observed in Lake Kasumigaura and has become a focus of great concern for its impact on the ecosystem. We investigated the chemical and mineral compositions of suspended solids (SS) in that white turbid water with the aim of identifying the compounds causing this phenomenon. In a comparison between the chemical compositions of SS during in the presence and absence of turbidity, we found that the Ca content of SS turbidity was significantly higher than usual. X-ray diffraction patterns for SS during the period of turbidity showed a sharp peak at 0.30 nm. This peak disappeared following hydrochloric acid treatment, and dropped to 0.28 nm under heat treatment at 1050 °C for 1 hour. These facts suggested the presence of calcite (CaCO3) in SS. Scanning electron microscopy and energy-dispersive X-ray spectroscopy revealed that the calcite in SS consisted of small cubic crystals with a particle size of less than 1μm. The saturation index, on the other hand, showed that the water quality of Lake Kasumigaura was often in equilibrium with the calcite, leading us to conclude that the phenomenon is due to a suspension of fine calcite particles precipitated in the water by the mass balance of dissolved chemical components.View full abstractDownload PDF (1137K) -
Seiko FURUTA, Miki YOSHIDA, Takahiro OKAMOTO, Tetsuya WAKABAYASHI, Sat ...2007 Volume 68 Issue 3 Pages 433-441
Published: 2007
Released on J-STAGE: December 31, 2008
JOURNAL FREE ACCESSBlackish brown particles of manganese oxide usually derived from the microorganism Metallogenium were observed for the first time in November, 2002 at the center of the north basin of Lake Biwa off Imazu (water depth, 90 m). However, the taxonomic position and biochemistry of Metallogenium remain poorly understood since a stable culture of this microorganism has seldom been successfully established. Using Lake Biwa water samples, the authors have prepared several stable cultures that continually produce Metallogeium -like particles of manganese oxide. In some cultures, suck particles were produced in association with fungi, though only bacteria were found in the other cultures. Since fungi are generally rare in lake waters, the production of Metallogenium by bacteria is presumably the major agent for the oxidative precipitation of Mn2+ in those waters. Metallogenium appeared within 2 weeks after inoculation in the coexisting fungus cultures. However, in the cultures with bacteria only, it took 4-6 weeks before Metallogenium could be detected in the medium. In this paper, we mainly reported morphological variations of Metallogenium observed by light and scanning electron microscopy during the development of those cultures in which only bacteria were found.View full abstractDownload PDF (692K)
FEATURES:Present status of exotic freshwater benthic macro-invertebrates and challenges for their control in Japan
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Yasuhiro TAKEMON2007 Volume 68 Issue 3 Pages 445-447
Published: 2007
Released on J-STAGE: December 31, 2008
JOURNAL FREE ACCESS
Supplementary materialDownload PDF (317K) -
Shoji KANADA, Ryoichi B. KURANISHI, Shin-ichi ISHIWATA, Koji TOJO, Tak ...2007 Volume 68 Issue 3 Pages 449-460
Published: 2007
Released on J-STAGE: December 31, 2008
JOURNAL FREE ACCESS
Supplementary materialThe crangonyctid amphipod, Crangonyx floridanus, originating from North America, has invaded the freshwaters of Japan. Based on specimens and the literature, C. floridanus was recorded in 28 Japanese prefectures. Since the previous study by Morino et al. (2004), the number of records for this amphipod has significantly increased in the Tokyo metropolitan area and Kanagawa Prefecture of the Kanto District. In addition, the amphipod was discovered from previously unrecorded geographic areas such as Nagano and Niigata Prefectures, as well as the Tohoku, Kansai and Shikoku Districts. Morphological differences between the non-native C. floridanus and three native amphipod families are shown.View full abstractDownload PDF (989K) -
Masaharu KAWAKATSU, Machiko NISHINO, Akifumi OHTAKA2007 Volume 68 Issue 3 Pages 461-469
Published: 2007
Released on J-STAGE: December 31, 2008
JOURNAL FREE ACCESS
Supplementary materialA total of 8 species of exotic planarians (5 families, 2 subfamilies, 6 genera) are now known from Japan. They are: Dugesia austroasiatica Kawakatsu, 1985; Girardia tigrina (Girard, 1850); Girardia dorotocephala (Woodworth, 1897); Bipalium kewense Moseley, 1878; Bipalium nobile Kawakatsu and Makino, 1982; Platydemus manokwari de Beauchamp, 1962; Rhodax evelinae? Marcus, 1946; Temnosewellia minor (Haswell, 1887). Among these species, naturalized populations in Japan of G. tigrina, G. dorotocephala, B. kewense and B. nobile have gradually increased. Artificial removal in Japan of Platydemus manokwari has been prohibited by the Invasive Alien Species Act since 2006.View full abstractDownload PDF (426K) -
N. USIO, Kazuyoshi NAKATA, Tadashi KAWAI, Satoshi KITANO2007 Volume 68 Issue 3 Pages 471-482
Published: 2007
Released on J-STAGE: December 31, 2008
JOURNAL FREE ACCESS
Supplementary materialOn 1 February 2006, the American signal crayfish Pacifastacus leniusculus together with another American crayfish (Orconectes rusticus), Cherax (native to Australasia) and Astacus (native to Europe) were designated ‘ invasive alien species’ (hereafter termed IAS) by the Ministry of the Environment of Japan. Under the IAS Act, raising, importing, transferring, releasing, sowing and planting live IAS (including eggs, seeds and/or organs) are strictly regulated. Mitigation of ecological impacts and control of IAS are also important components of the IAS Act. Here, we report the current distribution and control status of the signal crayfish in Japan for the purpose of future management planning. Signal crayfish were originally imported from the Columbia River basin in northwestern North America between 1926 and 1930. The official records and anecdotal evidence suggest that signal crayfish had been intentionally or unintentionally introduced into streams or lakes in Hokkaido (the northernmost island of Japan) and Honshu (the main island of Japan). Although some founder populations have since disappeared, signal crayfish have been rapidly expanding their distribution ranges in Hokkaido as well as in Honshu over the last few decades. As of July 2007, the signal crayfish is distributed along the northern, eastern and central parts of Hokkaido as well as in three prefectures (Fukushima, Nagano and Shiga Prefectures) in Honshu. Since the enforcement of the IAS Act, crayfish control has been started in Hokkaido (in four lakes from 2006 and in four further lakes or streams from 2007) using baited traps and/or by hand with the aid of SCUBA equipment. On the other hand, the townspeople of Imazu (Shiga Prefecture) are proposing to protect the signal crayfish in Tankai Reservoir because the population has a unique Japanese name due to its introduction history. We discuss some of the problems and possible future directions concerning crayfish control.View full abstractDownload PDF (857K) -
Akifumi OHTAKA2007 Volume 68 Issue 3 Pages 483-489
Published: 2007
Released on J-STAGE: December 31, 2008
JOURNAL FREE ACCESS
Supplementary materialFour exotic species of branchiobdellidans (Annelida: Clitellata) have so far been unintentionally introduced into Japan, in accordance with introduction of host crayfishes or shrimps from abroad. Three of the introduced species (Sathodrilus attenuatus Holt, 1981, Xironogiton victoriensis Gelder and Hall, 1990 and Holtodrilus truncatus(Liang, 1963)) are established in Japan along with the hosts. Discriminating morphology, introduction history and present distribution are briefly described for each species.View full abstractDownload PDF (443K) -
Misako URABE2007 Volume 68 Issue 3 Pages 491-496
Published: 2007
Released on J-STAGE: December 31, 2008
JOURNAL FREE ACCESS
Supplementary materialThe New Zealand mudsnail Potamopyrgus antipodarum is now on record from 15 prefectures of Japan, including the Hokkaido, Honshu and Kyushu islands. Due to its invasiveness, this species should be carefully monitored although its ecological impacts on indigenous organisms have not been fully demonstrated yet. The mudsnails are thought to have been successfully spread through contamination with the intentional introduction of aquatic organisms such as cultured fish, snails, and macrophytes. In addition, this snail may be introduced as a substitute for native Semisulcospira snails as food for aquatic larvae of a firefly. There must be other vectors for unintentional invasions. Therefore, the careful treatment of water gears (drying, freezing, soaking in hot water, chemical treatment) is recommended after use in areas where the mudsnails are distributed.View full abstractDownload PDF (435K) -
Keiji IWASAKI2007 Volume 68 Issue 3 Pages 497-500
Published: 2007
Released on J-STAGE: December 31, 2008
JOURNAL FREE ACCESS
Supplementary materialDownload PDF (316K)
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