Hidrológiai Közlöny 1998 (78. évfolyam)

4. szám - Fülöp István Antal–Józsa János: A neruális hálózatok világa

292 Irodalom Dortch, Q. (1990) The interaction between ammónium and nitráté uptake in phytoplankton. -Mar. Ecol. Prog. Ser. 61:183-201. Flett, R.J., R.D. Hamilton & N.R.E. Campbell (1976) Aquatic acetylenereduction techniques: solutions to several problems. - Can. J. Microbiol. 22: 43-51. Harrison, WG„ L.R. Harris & B.D. Irwin (1996) The kinetics of nitrogén utilization in the oceanie mixed layer: Nitráté and ammónium interactions at nanomolar concentrations. - Limnol. Oceanogr. 41: 16-32. Herodek, S„ L. Laczkó & Á. Virág (1988) Lake Balaton: research and management. - Nexus Nyomda, Budapest: pp. 110. Istvánovics, V., HM. Shafik, M. Présing & J. Szilveszter (1997) Phosphorus dependent growth and phosphate uptake of the cyanobacterium Cylindrospermopsis raciborskii in continuous culture with implications to eutrophication managament (subm. toLimn. Oceanogr.) Mackereth, FJ.H., J. Heron, & J.F. Talling (1989) Water analysis: Somé revised methods for limnologists. - Freshwater Biological Association, Scientific Publication N° 36, Ambleside, pp. 120. Newell, B.S., B. Morgan &J. Candy( 1967) The determination of urea in seawater. - J. Mar. Res. 25: 201-202. Platt. T„ C.L. Gallegos & W.G. Harrison (1980) Photoinhibition of photosynthesis in natural assemblages of marine phytoplankton. - J. Mar. Res. 38: 687-701. Présing. M„ S. Herodek, L. Vörös & I. Kóbor (1996) Nitrogén fixation, ammónium and nitráté uptake during a bloom of Cylindrospermopsis raciborskii in Lake Balaton. -Arch. Hydrobiol. 136: 553-562. PrésingM., Herodek S„ Vörös L. & Kovács Gy. (1997a) Az algák nitrogénfelvételének fényfiiggése a Balatonban. -Hidrol. Közi. 77: 11-13. Présing, M„ K. V.-Balogh, L. Vörös & HM. Shafik (1997b): Relatíve nitrogén deficiency without occurrence of nitrogén fixing blue-green algae in a hypertrophic reservoir. - Hydrobiologia 342/343: 55-61. Reynolds, C.S. (1984) The ecology of freshwater phytoplankton. - Cambridge University Press: pp. 384. Utermöhl, H. (1958) Zur Vervollkommnung der quantitativen Phytoplankton-Methodik. - Mitt. int. Ver. Limnol. 9: 1-38. Vollenweider, RA. (1969) A manual on methods for measuring primary production in aquatic environments. - IBP Handbook 12: 1-213. Blackwell Scientific Publications. Vörös, L„ I. Oldal, M. Présing & K. V.-Balogh (1997) Size selective filtration and taxon specific digestion of planktonic algae by silver carp (Hypophthalmichthys molitrix Val.). Hydrobiol. 342/343: 223-228. Nitrogén uptake preferences of phytoplankton in shallow waters 1 Présing, M., L. Vörös

1, S. Herodek? and Gy. Kovács

2 'Balaton Limnological Research Institute ofthe Hungárián Academy of Sciences, P.O.Box.35, H-8237 Tihany, 2Central-Transdanubian District Water Authority, Balatoni út 6, H-8000 Székesfehérvár, Hungary Abstract: The contribution of nitrogén forms to the nitrogén demand of phytoplankton has been estimated in two basins ofthe oligomesotrophic Lake Balaton and its two hypertrophic pollution control reservoirs. The uptake rates were determined using l

3N methodology, and by measuring concentration changes with time. N2-fixation were measured by the acetylene-reduction technique. The light dependence of uptake and N

2-fixation was described with an exponential saturation equation. The dark uptake velocity of ammónium, nitráté and urea were 60-80 %, 4-66 % and 16-74 % of light-saturated uptake, respectively. Ammónium, urea and nitráté uptake were 51-85 %, 12-42 % and 2-8 % of the totál daily nitrogén uptake. In contrast, N

2fixation was insignificant (0-4 %). The interaction of ammónium and nitráté uptake was determined in separate experiments which demonstrated suppression of nitráté uptake at ammónium addition. Keywords: nitrogén uptake, light-dependence, cyanobacteria, ammónium preference