抄録
Diatoms were sampled on 4 February 2001 from two spas, Mine Spa and Katase Spa located in central part of Japan. The salinity at both spas ranged from 0.08% to 0.28% and so they may be termed oligohaline according to Kolbe (1927). The dominant species at station 1 were Pinnularia joculata and Nitzschia frustulum, while N frustulum, Cymbella pusilla, Amphola veneta, N microcephala, Rhopalodia gibberula and P. joculata appeared commonly at station 2 in Mine Spa. One of the dominant species, P. joculata, is regarded as tropical species, since it was originally found in tropical islands and described from a greenhouse in botanical garden in Europe. N. frustulum was dominant in Katase Spa.
