Hidrológiai Közlöny 1997 (77. évfolyam)

32 Tamás. G.. 1974. 'lile occurrcncc of Rha/iliidiopsis meJUcrranea Skuja in (Jie plankton of Lakc Balalon. Annál. Biol. Tihany 41:317-321. Uherkovich, G., Lantos, T., 198 7. Angaben zur Kcnntnis der Algcnvegetalion auf dcr Sedinicnlobcrdfichc int llalaton (I'lallensee), Ungani. Linuiologica (Berlin) 18(1): 29-67. Vörös, L„ 1982. Quanlilalivc and slruclural clianges of phytoplankton itt lakc Balaton betwccn 1965-1978. Ac|uacullura Ilungarica (Szarvas) 3: 137-144. Anabaena Contpacía (Nygaard) Ilickcl A ncw bluc-green algal species iu (he scdimcnts and plankton of lakc lialalon Aulhors' addrcss: lialalon Limnological Insíiíuíe, Hungáriáit Academy of Seicncc, 11-8237 Tihany, Hungary Sunimary: Anabaena compacta (Nygaard) Ilickcl was isolalcd froni a sediment corc laken in Oclobcr 1994 in tlic hypcrlrophic Keszthely Bay of lakc Balaton, tlic largcsl shallow lakc of Ccnlral Europe. The sainplc were incubalcd in rooin temperature in N-frcc BG11 médium (Rippka, 1979). Tlicn íilaincnls were moved to agar platcs conlaining N-frce BG11 médium. The slrain was isolalcd from agar platcs and gol the namc ACT-9510. It is mainlaincd in liquid and agar-platc cultures bolh conlaining N-frcc BG11 médium. A single filamcnt was found in a plankton saniple laken in Keszthely Bay of Ihc Balaton on 29 August 1996. Morphologicai deseription of nianicnts of Ihc ACT-9510 A. compacta slrain: Filamenls arc solilary, frcc-floating and mosl arc rcgularly hclical (Fig la, b). Thcir average lenglh is 55-85 pin along whicli 7-8 lighl windings can bc countcd. The widlli of Ihc windings is 13-16 jtm. Longcr filamenls, up lo 2530 windings, alsó occur. Vcgclalivc cclls arc sphacrical or slighlly cllipsoid, llicy conlain numerous gas-vacuoles, Iheir sizes are 4.5-5.5 x 5-6.5 |im. Akinclcs arc alsó spcrical or slighlly cllipsoid and Ihcy arc somewhal bigger (56.5 x 5.5-7 fim). Wc did nol find akinclcs in Ihc cullurcs. Aflcr 5 minutes of microscopic investigation Ihc filamenls bccoinc incrcasingly looscr (Fig lc) tlicn they complclcly brakc to 1-11 ccllcd segments (Fig ld). Il occurs usually bul nol exclusivcly besidc tlic hctcrocylcs. Filamenls of tlic ACT-9510 A. compacta slrain did nol loosc thcir originál morphology afier 2 ycars of cullivalion as it was observed in other cases (Hickel, 1982). The single fiiaméul thai was found in Keszthely Bay ofthe Balaton in August 1996 had even tighlcr windings (Fig. le). Sizes of vcgclalivc cells and hctcrocylcs felt intő tbc rangé ofthe ACT-9510 culturc malcrial. Anabaena compacta is ncw for Ihc fiora of lakc Balaton and of Hungary. Tlic first part of llie paper discusscs tlic reccnt laxonomic position of hclcrocytic bluc-grccn algac deseribed from Laké Balaton unlil now (sec Tablc 1).