奈良県吉野川での底生動物の現存量 : IV. 1965年10月
1967 年 17 巻 3 号 p. 104-111
詳細
1967 年 17 巻 3 号 p. 104-111
In October 1965,the benthic communities at four stations in the River Yoshino-gawa, were investigated by the quadrat (50×50cm) sampling method with the following results : 1. The aquatic insect larvae amounted to more than 98 per cent in number and 97 per cent in standing crop of all the benthic animals. More than 99 per cent of the aquatic insects consisted of the members of the next four orders ; Ephemeroptera, Plecoptera, Trichoptera and Diptera. 2. Comparing with the results obtained in August at the same stations as in the previous paper, the individual numbers of benthos per one square meter of water surface were similar or remarkably increased in October. Standing crops of them, however, decreased at all stations. 3. The features mentioned above were due to the following changes, that the small chironomid larvae remarkably increased in number, but the other benthos all decreased, mainly owing to the effect of the successive three floods that occurred during the middle ten days of September.
