The biomass changes of phytoplankton in Lake Balaton during the 1960s

Tamás, Gizella (1974) The biomass changes of phytoplankton in Lake Balaton during the 1960s. A Magyar Tudományos Akadémia Tihanyi Biológiai Kutatóintézetének évkönyve, 41. pp. 323-342. ISSN 0365-3005

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Abstract

The transversal sectional specific somposition of phytoplankton in Lake Balaton, the slow or sudden change in the number of individuals of these (the so-called water-bloom and discoloration of water) are the outcome of the conjugate effects of external and internal factors. On the basis of the algological data on water sample series taken sectionally in 1972 and 1973 (Herodek and Tamás, 1973; 1974; Tamás, 1974) we may establish that the growth of trophyty is faster in the southern than in the northern basin of the lake. The author, multiplying the number of individuals of the phytoplankton on 1965, 1966 and 1967 with the mean volume of species in Lake Balaton, calculated the quantity of total algae. The biomass values of species of small and moderate size, in the quantity of total algae, amount to 0.5-1.0 mg wet weight/l in the three warm water months (July—August—September). The biomass of total algae, except two maxima in July, showed maxima in August at the five transversal sections. In 1966 the highest value (12.5 mg/l) was recorded at transversal section “K” shared between Aphanizomenon (5 mg/l) and Ceratium (6.5 mg/l). At this time in the Keszthely Bay the total algae amounted to 6.2 mg/l, of which Aphanizomenon (3.8 mg/l) and Pyrrophyta (Ceratium — Gonyaulax — Diplopsalis species 1.4 mg/l) were in large quantities. The second high value was 8.1 mg/l in the Keszthely Bay in August 1965 containing 7.7 mg/l diatoms (Melosira granulata and its variety amounted to 6.9 mg/l). The values of total algae are rather influenced by the number of individuals of species predominating in the water-bloom and discoloration of water. At the third transversal section of the southern basin (Ságpuszta—Balatonszemes) the quantity of total algae was essentially lower during each of the three years. At the two transversal sections of the northern basin the values of total algal biomass were also very low (0.8-4.0 mg/l.) The average of years, except the water-bloom in 1966 (3.2 mg/l), in the southern basin varied between 1.0 and 2.5 mg/l, while in the northern one between 0.4 and 1.7 mg/l.

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