Seasonal Changes in the Epiphytic Animals on the Potamogeton malaianus in Lake Kita-ura, with Special Reference to Oligochaetes
1986 年 47 巻 1 号 p. 63-75
詳細
1986 年 47 巻 1 号 p. 63-75
A quantitative investigation of the epiphytic animals living on a freshwater submerged plant, Potamogeton malaianus, was carried out in Lake Kita-ura from December 1980 to December 1981. The total individual number of epiphytic animals except for protozoans, rotifers and aeolosomatid annelids fluctuated between 0.5 (cm-2 leaf area) in September and 22.1 (cm-2 leaf area) in January, showing a high peak in the winter period and a lower one in the summer. This fluctuation was correlated with the abundance of epiphytic matter. Among the epiphytic animals examined, both oligochaetes and nematodes predominated in most seasons, while cladocerans, copepods, tardigrades and chironomids also commonly occurred. Three naidid groups, Chaetogaster spp., Nais, bardalis (thick-setae form and normal-setae form) and N. barbata dominated among oligochaetes. Seasonal peaks of population densities in these dominant groups were slightly different from each other. Inspection of gut contents of epiphytic animals and microscopic observation of structure of epiphytic matter suggested that the epiphytic matter supplied not only food but also living space for epiphytic animals.
