@article{oai:niigata-u.repo.nii.ac.jp:00026516, author = {福原, 晴夫 and 古木, 真理華}, issue = {1}, journal = {新潟大学教育学部研究紀要 自然科学編, 新潟大学教育学部研究紀要 自然科学編}, month = {Oct}, note = {Acidification of inland waters, lakes and rivers, has been largely influenced on aquatic organisms at sensitive regions in Europe, Canada and North America. To analysis the effects of acidification on aquatic organisms in Japan, the relationships between pH gradient and standing stocks of aquatic organisms, mainly aquatic insects, were investigated using naturally acidified rivers including neutral tributaries. River water of Matsukawa and Yonagogawa and their tributaries in Sudaka district of Nagano Prefecture, containing various concentrations of SO_4^<2-> showed the pH spectrum from 2.8 to 6.4 at 16 sampling sites. Very low biomass of aquatic invertebrates was measured in acidic sites below pH 4.5, whereas high concentration of chlorophyll-a and invertebrate biomass were recorded at sites above pH 5.9. Protonemura sp. in Plecoptera and Rhyacophila sp. in Trichoptera dominated in biomass and population density in acidic water with Orthocladinae sp. The larva of Ephemeroptera dominated only in sites above pH 5.9. We may present pH 6 for chemical threshold that biological changes by acidification begin to start from this level under the considerations of our results and some papers concerning the pH-threshold for aquatic organisms.}, pages = {31--40}, title = {自然酸性河川における水生昆虫の現存量 : 長野県須高地方,松川及び米子川の例}, volume = {3}, year = {2010} }