A quantitative study of the saprophytic and total bacterioplankton in the open water and the littoral zone of Lake Balaton in 1968

Oláh, János (1969) A quantitative study of the saprophytic and total bacterioplankton in the open water and the littoral zone of Lake Balaton in 1968. A Magyar Tudományos Akadémia Tihanyi Biológiai Kutatóintézetének évkönyve, 36. pp. 197-212. ISSN 0365-3005

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Abstract

1. By the application of plate-pouring and the direct method, the seasonal quantitative conditions of the saprophytes and the total bacterioplankton have been investigated in five standard and one investigated detailed sections of Lake Balaton. 2. On the basis of the amount of both saprophytes and the total bacterioplankton, a definite differentiation can be found between the litoral zone and the open water. The quantity of the bacterioplankton was 2-3, that of the saprophytes 40-120 times greater in the former zone. The differentiation was the most conspicuous during the spring. 3. The littoral zone of high bacterial content was narrow along the reedless southern shore during the entire period of investigation. On the other hand, the littoral zone of high saprophyta content along the northern shore margined with reeds is wide during springtime (1500 m), but shrink to the area of the reeds during summer. The considerable springtime expanse of the northern coastal zone coincides with the wide sedimentary zone, rich in organic substances, extending before the shoreline. 4. The quantitative dynamics of the saprophytes and the total bacterioplankton reveals the intensive self-purifying ability of Lake Balaton; its most important factors are the high summer temperatures of the water, the full oxygen saturation, the constant movement of the water, and the high lime content. 5. In the open water, the amount of the total bacterioplankton was above 5·10⁵/ml, and the maximum value reached was 2.3 millions. These data are essentilly greater than those obtained in 1966/67. 6. The saprophyte content of the open waters of Lake Balaton is generally low, 10—100/ml on nutrient agar, and 20—500/ml on casein-glucose agar. Both mediums yielded very high values (10,000—40,000/ml) for Keszthely- bay and its neighnourhood during June and July. 7. The amount of actinomyces present in the plankton is not significant. 8. The ratio of the total bacterioplankton and the saprophytes is favourable with respect to the purity of the water (10,000); however, this ratio decreases to 40-50 in Keszthely-bay and its neighbouring waters during June and July. 9. The increase of the amount of the total bacterioplankton was not followed by a similar increase in the number of saprophytes.

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