Quantitative plankton studies on Lake Balaton X. Notes on the distribution of Leptodora Kindtii Focke

Sebestyén, Olga (1960) Quantitative plankton studies on Lake Balaton X. Notes on the distribution of Leptodora Kindtii Focke. A Magyar Tudományos Akadémia Tihanyi Biológiai Kutatóintézetének évkönyve, 27. pp. 131-138. ISSN 0365-3005

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Abstract

Using a newly constructed simple sampler by which in a shallow water entire watercolumns can be filtered, data gained by filtering 5022 1 water altogether from different parts of the lake - refer to 317 individuals of Leptodora and 66 899 other crustaceans (nauplii and metanauplii not included in this number). Evaluating these data it could be established that population of Leptodora from the-beginning of the season grows toward the end of summer and then decreases. Population density at its peak is only about 0,1 e/1, which represents but 0,4% of all plankton crustaceans. In two sample series pumped from different depths most individuals were hauled from the middle layers. Leptodora is distributed all over the Lake, highest values originating from samples taken both at the Bay off Keszthely and next to the mouth of the Zala River. In the sample taken from the former locality 1. October three larvae of Leptodora were found. The proportion between the top predator and its food crustaceans varies between 200 and 2000 throughout the year, and represents at the same time the numerical relation of the two final sections of the pyramid of numbers within the plankton community, both in trophical sense and size. The lower parts of the food web of the plankton in Lake Balaton - excluding the basic level - is very intricate and can not be expressed as a pyramid. It has been pointed out that if we endeavour to learn more of the role of Leptodora in the circulation of substances in the Lake both in the qualitative and quantitative senses, there are many problems still to be faced.

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