ABSORPTION OF MICROORGANISMS BY LUBOMIRSKIIDAE SPONGES.

Baikal sponges account for a significant proportion of lake zoobenthos. The filtration activity of sponges determines their important role in the processes of self-purification of a reservoir. In recent years, depression has been observed, and in some areas even the death of the Baikal sponges. It has been suggested that the negative phenomena observed in the sponge populations may be associated with an increase in the supply of various detergents and surfactants to Lake Baikal. The trophic activity of the Baikal sponges is studied very little. In this regard, under laboratory conditions, the filtration activity of the Baikal sponges of the family Lubomirskiidae (Baikalospongia bacillifera (Dybowski, 1880), Lubomirskia baicalensis (Pallas, 1771)) was investigated. Before the start of the experiment, the sponges were adapted in laboratory conditions in aquariums with Baikal water in low light and at a temperature corresponding to the lake. Baikal at the time of collecting material. Yeast cell cultures were used as a food substrate: Yarrowia lipolityca and Saccharomyces cerevisiae, cultures of Scenedesmus quadricauda. The exposure time in the experiments was 24 hours. The concentration of microorganisms was determined by the fluorimetric method (by chlorophyll luminescence), by direct counting in the Goryaev chamber. In all experiments with the addition of sponges, a decrease in the concentration of microorganisms — cells was observed: Y. lipolityca, S. cerevisiae, S. quadricauda. Starting from a certain concentration, sodium dodecyl sulfate - the main component of detergents - inhibited the filtration activity of sponges. It is shown that when using the luminescent method of studying the filtration activity of sponges, the output of their own symbiotic algae cells can significantly distort the results of the experiment. In direct counting in experiments with the use of yeast, large cells of some microorganisms, released from sponges and already present there, can also make a serious mistake. Thus, experiments have shown that the most reliable way to determine the absorption of microorganisms with Lubomirskiidae sponges is to determine the concentration of S. quadricauda cells by direct counting. [ABSTRACT FROM AUTHOR]