1984 Volume 45 Issue 4 Pages 304-312
The ecological characteristics of Achnanthes minutissima KUETZ. var, saprophila H. KOB. & MAYAM., reported as one of the most pollution-tolerant diatoms by the present authors in 1982, were investigated in detail in the river waters of Tokyo and vicinity. In contrast to the distribution of the nominate variety, var. saprophila was found only in heavily to excessively polluted waters and even occurred as dominant or subdominant taxon in some samples. Vigorous growth was observed in the strongly polluted stretch of the Minamiasa-kawa (Minamiasa River), as shown by cell numbers in a given area.