Abstract
Planktonic diatoms from Lake Oike, Tsugaru-Juniko, Aomori Prefecture were investigated from August 1986 to June 1988. One hundred and four taxa from 24genera were recorded. The relative abundance of each taxon was measured. Seven taxa had the relative abundance of more than 5 %,22 taxa did one ranging between 1 % and 5 %, and 75 taxa did one of less than 1 %. Asterionella formosa var. formosa, Fragilaria crotonensis var. crotonensis and Aulacosira granulata var. angustissima were major diatoms in this lake. A. formosa var. formosa, F. crotonensis var. crotonensis and A. granulata var. angustissima were dominant from February to June, from June to October and from October to December, respectively. Tabellaria fenestrata which had been abundant in this lake in October tober 1952 (KAWAMURA 1956) did not appear in the present study.
