抄録
(1) The main dominant species of attached microalgae are Homoeothrix janthina and Cloniophora plumosa in both August and December.
(2) The contents of a digestive tract consist mainly of the detritus including small amount of micro-algae and inorganic materials.
(3) The main dominant species in the contents of a digestive tract are Navicula seminulum among the all Asellus hilgendorfii examined at every stations in August. Another common species is Gomphonema subangur which appeares more than 10%.
(4) The contents of a digestive tract in December are occupied mostly with the detritus which might derive from the decomposition of the leaves.
(5) The similarity index Cλ of the micro-algal composition in the digestive tract between A. hilgendorfii at the same station are strongly affected by the appearance of filamentous algae, H. janthina and C. plumosa
(6) To measure the algal electivity by A. hilgendorfii based on the method of Ivelv (1961), there is a tendency for both H. janthina and C. plumosa to be avoided, while N. seminulum are selected in August.
