The present paper deals with the ecology of microbe in the Sunuma Lake group of Volcano Bandai, Fukushima Prefecture. Many lakes fill small basins on the surface of mud streams. Nine lakes were studied in early May 1959. According to the microbiological and the limnological specificity, the lakes may be classified into 4 types. The details of their features are seen in table 6.
The effluents of two copper mines, Ikuno Mine in Hyogo Prefecture and Yanahara Mine in Okayama Prefecture were studied, with regard to their effect on stream organisms. The water insects were collected quantitatively at several stations of the rivers in the drainags of the mine-water (Figs. 1,2,3,4 and 5). 1. At Ikuno Mine, the effluents give the influence to the aquatic insects of the Ichikawa River, as far as to 10km downstream. 2. In Yanahara Mine, the mine-effluents make little or no influence on the stream insects. 3. In the concentrations of 10 γ/L of copper and 300 γ/L of zinc, no influence was observed on the stream insects. 4. The influence of copper is stronger than that of zinc.
A simplified method(biotic index)is proposed by BECK for reporting the biological investigations in connection with stream quality surveys. The biotic index proposed is 2A+B, where A is the number of the intolerant species and B is that of the tolerant species. We wish to suggest the next restrictions : (1) The sampling should be made from an area of 50×50cm. (2) The sampling should be made from the stony bottom with the velocity of 50-10cm/sec.We show two examples, one from the Kamogawa River and the other. from the Yodogawa River.
In 1958,the algal flora and insect communities were studied in Ukawa, a small river which is situated in the north coast of Kyoto Prefecture and flows into the Japan Sea. The aquatic communities, especially "Ayu" community, of this river have been studied by the members of the Zoological Institute of the Kyoto University since some years. We here report our results of the investigation of the above-mentioned year. 1) The Cyanophyceae, especially Symploca sp. was dominant in both riffle and pool, and was more abundant in the riffle than in the pool. 2) Among the diatoms, Navicula cryptocephala and Cymbella trugidula were found in all stations and were very abundant. 3) The diatoms increased in autumn. 4)IIn general, the net-spinning caddis-worms were rather few in this year. 5) Mataeopsephenus japonicus was found widely and dominantly in the reaches lower than Tanaka. 6) The species constitution of benthic insects was not very different among the stations studied. The number of species was far more in the riffles than in the pools. 7) All stations were distinguished into three groups of stations ; that is (1) Kurokawa, (2) Sukawa, and (3) the region from Tanaka to Onge.
The biotic community of the standard trickling filter and its accessory installations of the Okubo Camp of National Guards was studied. The points where the sampling was made are shown in Figs. 1-4. The biotic communities of all points were composed of relatively small number of species and predominated by large populations of few colony-forming species(Table 1). The characteristic colony-forming organisms may be important from the stand point of pollution biology. Judging from the species that appeared, the influent water to the trickling filter is β-polysaprobic, and filtrated water is regarded as intermediate between β-polysaprobic and α-mesosaprobic. These results are supported by the data of B.O.D. measurement. It is noteworthy that green algae such as Stigeoclonium sp., Hormidium sp., and Schizomeris sp., or diatoms, Pinnularia gibba var.(A), P. gibba var. sancta, P. gibba var. parva, P. gibba var.(B)etc., were found in large numbers at the sampling points interpreted as β-polysaprobic. It has been thought that these species, when found in large numbers, should indicate α-mesosaprobic or less polluted habitats, but the result obtained here shows that these algae can live in more polluted waters as well. The efficiency of sewage purification of the trickling filter examined is not so high as can be expected. This low efficiency may be due to insufficient volume of sewage to be filtrated. (The plant was originally planed for more quantity of sewage.)