Diatoms in alkaline Osousi Spa,Hokkaido 80 Diatom ll : 80-84. December 1995. Akihiro Tuji '. Diatoms in alkaline Osousi Spa, Hokkaido Key index words 'å Alkalibiontic, alkaline spring, Achnanthes minutissima, Nitschia denticula 1 Achnanthes exigua Grun.; St. 1. 1% ; St. 2. 3% (PL3: ll) 2 A. minutissima Kutz.; St. 1. 29%; St. 2. 70% ;St. 3.43% (PI.3:3-5) 3 Amphora copulata (Kutz.} Schoeman & Archi- bald (PI. 2 : 18) 4 Aulacoseira crenulata (Ehr.) Kramm.; St. 2. 3% (PI. 2: 1) 5 Caloneis bacillum (Grun.) Cleve ; St. 1. 5% (PI. 2: 4) 6 Cymbella aspera (Ehr.) Cleve (PI. 2 : 19) 7 C. minuta Hilse (PL 2 : 12) 8 Diploneis ovalis (Hilse) Cleve ; St. 2. 2% (PI.3:9) 9 D. yatukaensis Horikawa et Okuno (PI. 3 : 12) 10 EunotiaarcusEhr. (PI. 1 : 3, 4) ll E, exigua (Brfeb.) Rabh. (PI. 1 : 9) 12 E. pectinatis var. minor Hust.; St. 1. 2% ; St. 2. 1% {Pi. 1 : 5-7) 13 E. sp. aff.paludosa Grun. (PI. 1 : 8) 14 Fragilaria capucina Desm. ; St. 3. 1% (PI. 2: 3) 15 Frustulia vulgaris (Thw.) DeToni (PL 1 : 1) 16 Gomphonema acuminatum Ehr. (PL 2 : 8-9) 17 G. affine Kutz. (PL 2 : 13) 18 G. angustatum (Kutz.) Rabh. (PL 2 : 16) 19 G. clavatum Ehr. (PL 2; 14) 20 G. gracilis Ehr. (PL 2 : 15) 21 G. sp.;St. 1.5%;St.2.5%;St.3.3% (PL2: 17) 22 Meridian circular?, var. constrictum (Ralfs) Van Heurck (PL 2 : 10-ll) 23 Navicula placenta Ehr. (PL 2 : 2) 24 M sp. aff. minima Grun.; St. 2. 2% 25 JV. veneta Kutz. ; St. 1. 2% (PL 2 : 5-6) 26 Neidiumsp. (PL 2 : 7) 27 Nitschia amphibia Grun. St. 1. 1# ; St. 2. 2% ; St.3.1% (PL3:10) 28 N. denttcula Grun. (Syn. Denticula Kuetingii Grun.) ;St. 1.38% ;St.2. 7% ;St.3.45% (PI. 3 : 6-8) 29 JV. linearis (Agardh exW. Sm.) W. Sin. ; St. 1. 12%;St.2. 3%;St.3. 4% (PL3:13) *as-f * >ffi£ (ph) &\ o^-fii Hustedt. (1937-1939) £&ffc i-f&# <« ffi3ttf%\ bilX& lQ , SifiT'ii HIkansson (1994) å MSI (1995) t£t'K£ ^XlkWi& - &T)\'ii >)&(Dt. TJI/* UftfiiaA) tr& >K pH10.0-10.4 i®a6T ffiv* pH 46£7jH-o o ^t, i££MX*& å ? fz Achnanthes minutissima, Nitzschia denticula Ko ^T <a£BB8*rt£R £ & (:3£& (1) PSHfe^ wsti-ettjii±.aE^4t8KS*f^«rtcffctt-ri * v -> iffl1l^*5WSBtaot:i3 () , 7)ci?il(i^j l5cmS$ ii It) 6m2 -T-& ^,:o S^^ftt L-Cti, Homeotkrix sp. fco *ffl(± 17.4"C, pH (i l0.0 r^^/jo SWli-^^ Station 2 : Station 1 "Cgl l ffi L7t***fflS-fS*3f (i^j 10cm -C^j 10m2 OfcZiP&v Ko JtMffmt L rti, saiig^flE^t-ct^o 7icS(i2i.rc, pH w S*afen 3 : Station 2 ro^^STJII t=aEitii"4*3f"C ttS? 30cm igSoaEM*5*ofco *8B(i 2-3cm "C, ipgli^j 20 cm -C& o fco Station 1 t ratfcfflffi-^5^ Sl^'a < fto-Cv^to S^^*i Ltli, Amo- 6ae«a sp., Lyngbya sp. ^ ^^^A LX^^tza TKimii 21.3°C, pH t± 10.1 -C*ofc0 K^-i±5±i: ^^^ (2) a a s 7 7^7 Miisnaimffit^^mii^ (%) *^1-O Accepted on Nov. ll, 1995.