The primary production of phytoplankton in Lake Balaton October 1972 — March 1973

Herodek, Sándor and Tamás, Gizella (1974) The primary production of phytoplankton in Lake Balaton October 1972 — March 1973. A Magyar Tudományos Akadémia Tihanyi Biológiai Kutatóintézetének évkönyve, 41. pp. 205-216. ISSN 0365-3005

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Abstract

The biomass and the primary production of phytoplankton were measured throughout a whole year fortnightly in the pelagial two kilometres east of Tihany at four depths. Data of the first half-year were published earlier. The present paper surrenders d ata of the second half-year and summarizes the results of the whole year. Algae were counted by the Utermöhl’s microscope, and the biomass of the single species was obtained by multiplying these counts with the average volume of the individuals. The biomass was low during autumn and in the icecovered lake, and increased rapidly after the ice had thawed. Its average was 2.5 g · m⁻² in this cold half-year. During the whole year the biomass ranged between 19.5 g · m⁻² (11th July) and 1.0 g · m “2 (28th December) its yearly average being 1.9 g · m⁻² alike at 25, 100 and 200 cm depths and 1.7 g · m⁻³ at 300 cm depths. The production of phytoplankton was determined by the ¹⁴C technique. The vertical distribution of the production varied much, depending on the turbidity of the water. The maximum was usually found at 1 m or 2 m depths, but in storms the uppermost layer, during long calms and in the snow-free frozen lake the deepest layer were the most productive. The production was lower in autumn and winter than in spring and summer, but this difference is smaller than in other lakes, and smaller than the seasonal changes of the biomass. The annual primary production of phytoplankton was 114 g C · m⁻². This production falls within the range of the productivity of natural eutrophic waters, and forms the main source of organic matter in this lake.

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