八ヶ嶽湖沼群の湖沼学的研究〔英文〕-1-

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(1) The contents of the alimentary canal of Diaptomus and Daphnia collected from Lake Shirakoma were microscopically observed. The inquiry was of interest because the lake was quite destitude of phytoplankton, and therefore what might be the food stuff of these species was curious and important. (2) The food of Diaptomus and Daphnia of this lake consists exclusively of bottom materials which, as a matter of course, contain bottom organisms such as lower Cyanophyceae, Diatoms, etc. Remarkable was the fact that little or no plankton organisms were found in the alimentary canal of these species. (3) The food of Diaptomus and Daphnia was all the same in its constituents. The quantity, however, seemed to be a little more in Daphnia than in Diaptomus. (4) As to the size of food particle it was found that the size taken by Daphnia is markedly larger (maximum length-311μ) than that taken by Diaptomus (maximum length-238μ). However, the mean size of food particle was 50μ or thereabout, a size exceeding 100μ (in length) was very rare. (5) The finding that Diaptomus and Daphnia largely feed on bottom materials, at least in Lake Shirakoma, suggests the possibility of bottom materials being the cause of the vertical migration of these two species.
社団法人日本水産学会の論文