Occurrence of Plumatella casmiana Oka (Bryozoa) in Lake Balaton

Sebestyén, Olga (1961) Occurrence of Plumatella casmiana Oka (Bryozoa) in Lake Balaton. A Magyar Tudományos Akadémia Tihanyi Biológiai Kutatóintézetének évkönyve, 28. pp. 125-133. ISSN 0365-3005

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Abstract

The fresh-waters of Hungary - Lake Balaton being included - are not thorughly investigated for bryozoans since J. Vángel (1864—1918). Data of occurrences have been summarized by Vángel (1897b) and recently by Sebestyén (1959). The bryozoans take a rather unimportant part in the life of fresh—water bodies. Some members of the microfauna find shelter and substratum of the second order in the colonies. Fresh—water animals, browsing and grazing in the coating of the various submerged substrates, may devour the polypids also. Colonies of certain bryozoan species may grow in waterworks in such extent as to cause considerable trouble. Pluma tella casmiana Oka has not been recorded from European waters as yet. Its distribution in a world-wide sense is scattered and - using Pennak’s expression - is “puzzling” (Pennak 1953, 268). It has been noted from Japan, North-America, West-Java and the USSR (Pennak 1953, Rogick 1941, Rogick and van dee Schalie 1950). In the late summer of 1960 (27th August, 8th September) its occurrence in Lake Balaton has been established by the author. In an Elodea canadensis - patch amidst other macrovegetation-growths several free swimming individuals, newly hatched from the thin walled floatoblast characteristic to this species, were found. In September several young colonies attached to Elodea leaves occurred. (Fig. 1) Floatoblasts of the ordinary kind and the thin walled type were enclosed in the tubes, however no sessoblast came to sight. (Figs . 3-7) Measurements of the floatoblasts agree fairly with same of the North-American samples. (Rogick 1941.) According to Y. Beehm (1930, 100, 107) the wheel-animalkule Cupelopagis (Apsilus ) vorax Leidy was very likely introduced into some European waters by means of Elodea canadensis. This Rotifer has not been noted as yet from Hungarian waters (Vabrga in lit.). The occurrence of Plumatella casmiana in Elodea-growth in Lake Balaton can not prove its spread by means of Elodea , but at the same time it stands not against such possibility. Bryozoans recorded from Lake Balaton are the following: Fredericella sultana Blumenbach Plumatella emarginata Allmann Plumatella repens (L.) Plumatella casmiana Oka Plumatella fungosa (Pallas) Plumatella fungosa f. coralloides Keaepelin Both Plumatella fruticosa Allman and Lophopus crystallinus (Pallas) are represented only by one single floatoblast so far.

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