SPATIAL AND TEMPORAL DYNAMICS OF ALGAL COMMUNITIENS IN THE EXPERIMENTAL CONDITIONS

Abstract

The paper deals with spatial and temporal dynamics of algal communities under the microcosm conditions. The microcosm used in the experiment was filled with rainfall or storm runoff out of the rainwater pipe from the iron roof of the adjacent building. Therefore, algae could be brought to the microcosm: a) by air; b) with soil particles; c) with storm runoff from the building roof etc. The hydrochemical conditions in the microcosm were marked by high content of sulphates, chlorides, iron, and low concentrations of mineral phosphorus and silicon. During the observation period two systems formed in the microcosm: benthic system dominated by a filamentous cyanobacteria Leptolyngbya boryana (Gomont) Anagn. et Komárek and planktonic-neustic dominated by a flagellate green algae Haematococcus pluvialis Flotow. These two algal communities were linked by biotic interactions: 1) antagonistic – algal blooms by H. pluvialis caused shadowing of the water column and competition for nutrients, thus suppressing L. boryana vegetation; 2) synergetic – after the vegetation of H. pluvialis was over, the water column was enriched with nutrient, which were the autogenic energy subsidy for L. boryana development. An assumption has been made, that diverse algae can be brought to the microcosm due to mass effect, however only two species developed in large quantities owing to environment species sorting – L. boryana and H. fluviatilis. Conducting experimental studies of the qualitative and quantitative diversity of algal communities using microcosms is one of the promising areas of hydrobiological and algological research. Obtaining empirical representative data has become possible through the parallel study of the main abiotic factors that determine the diversity of algal communities and allow the influence of the environment to be taken into account in much broader conditions than in purely laboratory studies.