木崎湖, 青木湖, 中綱湖, 野尻湖ならびに諏訪湖の底生動物相の研究
1973 年 34 巻 1 号 p. 12-23
詳細
1973 年 34 巻 1 号 p. 12-23
1. Five lakes, Kizaki-ko, Aoki-ko, Nakatsuna-ko, Nojiri-ko and Suwako, in Nagano Prefecture were investigated in 1972, in regard to their bottom fauna. The results obtained were compared with the data by MIYADI during the years from 1927 to 1930.
2. Lake Kizaki-ko : On the deep bottom Chironomus plumosus-b larva occurred abundantly, while Calopsectra sp. J occurred on the bottom shallower than 10m. Chaoborus larva was found on almost all over the bottom. According to MIYADI, Lake Kizaki-ko belongs to a “mesotrophic Sergentia lake”. At present, however, Sergentia (Endochironomus) larva which seems to be identical with Phaenopsectra is few in numbers, and Chironomus plumosus-b not recorded by MIYADI are found abundantly. Now-a-days, this lake seems to belong to a “eutrophic Plumosus lake”.
3. Lake Aoki-ko : Calopsectra sp. J larva, though not abundant, is distributed widely in this lake. MIYADI has pointed out this lake belongs to an “oligotrophic Tanytarsus lake”. At present Calopsectra sp. J is found only in winter and not in summer. Now Phaenopsectra sp. B-5 occurs not only in winter but also in summer, especially very abundant in the latter season.
4. Lake Nakatsuna-ko : Chironomus plumosus-b and Spaniotoma akamusi larvae were found all over the bottom, though not abundant, except the deepest zone. Some other kinds of Chironomidae larvae are distributed on the shallow bottom. MIYADI (1937) has designated this lake as a “Corethra lake” (=Chaoborus lake).
5. Lake Nojiri-ko : Chironomus plumosus-b-2 is the dominant species in this lake. Calopsectra sp. J, which occurred abundantly in MIYADI's paper, occurred scarcely. This lake has been pointed out by MIYADI in 1937 as a “mesotrophic Plumosus lake, ” but is a “eutrophic Plumosus lake” at present.
6. Lake Suwa-ko : Chironomus plumosus-b and Spaniotoma akamusi are the dominant species in this lake. Now Lake Suwa-ko may belong to a “polytrophic Plumosus-Akamusi lake”.
7. The types of bottom fauna of five Japanese lakes compared with MIYADI's data Are shown in Table 12.
