日光湯ノ湖の湖岸帯でえた水生小動物の消化管内容物
1972 年 33 巻 4 号 p. 82-91
詳細
1972 年 33 巻 4 号 p. 82-91
1. Aquatic small animals collected in the littoral region of Lake Yuno-ko on November3, 1968 were investigated concerning the contents of their digestive tracts.
2. One individual of Ephemera sp. (Ephemeroptera) seems to take algae attached to the shore or deposited on the bottom.
3. A large quantity of algae was found in 11 individuals of Nemoura sp. (Plecoptera). It seems likely that they take attached or deposited algae.
4. As regards Trichoptera, only each one individual of Goera japonica and Polycentropus sp. and an undetermined species were examined concerning their foods. Goera japonica mainly takes attached or deposited algae, while Polycentropus sp. takes abundantly either floating Chlamydomonas sp. or that which may be a zoospore of any green alga. In the digestive tract of the species of undetermined genus contains abundant planktonic diatoms.
5. No alga was found in Platambus sp. (Coleoptera) Helichus sp. belonging also to the same order takes a large quantity of attached algae.
6. The main contents of the digestive tracts of 21 individuals of a crustacean, Asellus sp. are Chlamydomonas sp., Melosira italica f, curvata, Ulothrix sp. and Fragilaria sp., all of which are the species mostly attached to fallen leaves on the lake bottom.
7. For comparison of similarity in the composition of algal flora in the digestive tracts of the larval samples collected at the same place, it is attempted to analyse according to the c'λ method.
8. The floral composition is similar among Nemoura sp. and among Asellus sp. It implies that the composition of the flora in the same species of aquatic small animals is similar, but that similarity is not found between the different species.
s. In regard to the construction of the flora in the digestive tracts of the same species collected at the different places, a great similarity is found in the individuals collected at the resembling environments, while there is less similarity between the individuals collected at the different environments.
Such a phenomenon will attribute to the construction of different algal communities at the different environments.
