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Volume 69, Issue 2
Displaying 1-4 of 4 articles from this issue
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Original article
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Akifumi OHTAKA, Chieko YAMAZAKI, Seiichi NOHARA, Oze Akashibo Researc ...2008 Volume 69 Issue 2 Pages 107-119
Published: 2008
Released on J-STAGE: September 10, 2009
JOURNAL FREE ACCESSFaunal composition and distribution of invertebrates were studied in snow showing the so-called Akashibo phenomenon, a kind of red snow in the region with heavy snowfalls in Aomori Prefecture, northern Japan. The invertebrates in snow were composed of a small number of terrestrial forms occurring on the snow surface and/or in the upper layers of snow and aquatic forms which dominated the lower layers of snow. Density of the intranivean invertebrates increased toward the bottom with wet snow. Higher densities as high as 900 L-1 of intranivean invertebrates were found in the Akashibo layers. Community structure of the intranivean invertebrates in the Akashibo snow in Aomori Prefecture was similar to those in the Ozegahara mire, in that copepods, oligochaetes, chironomid and ceratopogonid larvae dominated. The aquatic forms appeared to be derived from subnivean fauna, and compare with aquatic interstitial community in sandy bottoms in their life forms. It is probable that the high density of the intranivean invertebrate community is formed in accordance with production of the reddish brown Akashibo particles at the snow-ground interface in snow-melting seasons.View full abstractDownload PDF (1392K)
Notes
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Kumiko SEKI, Akifumi OHTAKA, Susumu TANAKA2008 Volume 69 Issue 2 Pages 121-131
Published: 2008
Released on J-STAGE: September 10, 2009
JOURNAL FREE ACCESSTwenty nine species belonging to 20 genera in 7 families of cladocerans (Crustacea, Cladocera) were recorded from the Byobu-san Lakes, Tsugaru Peninsula, Aomori Prefecture, northern Japan, which is a region composed of sand dune lakes and man-made reservoirs. A poorly known daphniid, Simocephalus lusaticus Herr, is redescribed based on specimens from the lakes. Lateral prominence was described as a morphological variation in another daphniid, Ceriodaphnia quadrangula (O. F. Müller). The species richness of the cladocerans was significantly higher in densely vegetated lakes with muddy bottoms. As a whole, cladoceran faunal structure in the Byobu-san Lakes is characterized by having rich species in attaching or creeping forms, rather than planktonic forms. Such a feature could be related to the abundance of aquatic vegetation in the lakes.View full abstractDownload PDF (991K) -
Hiroki HAGA, Taisuke OHTSUKA2008 Volume 69 Issue 2 Pages 133-141
Published: 2008
Released on J-STAGE: September 10, 2009
JOURNAL FREE ACCESSWe evaluated whether or not the distribution range of submerged macrophytes in the southern basin of Lake Biwa between 1979 and 2004 had been restricted by light conditions on the lake bottom. The potential vegetated area (i. e., the area where submerged macrophytes might be expected to occur judging from the light conditions) was estimated using the data of transparency and water levels periodically measured by the Shiga Prefectural Government and the Ministry of Land, Infrastructure and Transport of Japan. Throughout this period, the potential vegetated area was mostly determined by the transparency together with a slight additional influence of variations in the water level. The evaluated vegetated area ranged 9 - 48 % of the potential vegetated area from 1979 through 1994. The extreme drawdown to -1.23 m of the standard Biwako Surface Level (B. S. L. ) in September, 1994, did not induce an expansion of the potential vegetated area, which was rather due to a simultaneous decrease in transparency. The potential vegetated area in August, September, and October, 1994, was not significantly more extensive than that in same period in preceding years. Therefore, we are persuaded that light conditions on the lake bottom were not the sole factor regulating the distributional range of submerged macrophytes in the southern basin of Lake Biwa from 1979 to 1994. Based on these results, we concluded that the catastrophic-shift model requires light limitation does not furnish an appropriate rationale to explain mechanisms of a sudden expansion of submerged macrophytes in the southern basin of Lake Biwa.View full abstractDownload PDF (845K)
Limnological record
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Hideo MIYAGUCHI, Masashi KATSUURA, Ryuta YAMAMOTO, Takashi HIRABAYASHI ...2008 Volume 69 Issue 2 Pages 143-153
Published: 2008
Released on J-STAGE: September 10, 2009
JOURNAL FREE ACCESSTo clarify the characteristics of the aquatic invertebrate fauna in Tohorogawa mire, we collected aquatic invertebrates from peat soils, peat-excavation pools and the Tohorogawa River, in May 2005 and June 2006. As a result, 83 taxa of aquatic invertebrates were found in the study site. Northern species included Radix auricularia (Linnaeus), Oxus magnus Sokolow, Libellula quadrimaculata asahinai Schmidt, Asynarchus sachalinensis Martynov and Dytiscus dauricus Gebler, while southern species were Polypylis hemisphaerula (Benson), Orthetrum albistylum speciosum (Uhler), Ilybius apicalis Sharp and Nakane Laccobius bedeli Sharp. The proportion of northern species of Odonata and Coleoptera in Tohorogawa mire was similar to that found in other mires in eastern Hokkaido. This indicates that Tohorogawa mire allows the inhabitation of northern species at the same level as the other mires in eastern Hokkaido. The northern species were distributed in peat-excavation pools where the water temperature is comparatively low, while the southern species were found in peat soil where the water temperature is relatively high. Therefore, it is concluded that the significant spatial difference in water temperature is a major factor allowing the coexistence of northern and southern aquatic invertebrates in Tohorogawa mire.View full abstractDownload PDF (644K)
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