Acta Botanica Croatica, Vol. 38 No. 1, 1979.
Izvorni znanstveni članak
Bacteriological investigations of Bijela and Crna rijeka and some of the lakes of Plitvice
Božidar Stilinović
; Hrvatska
Sažetak
The number of saprophytic bacteria and the presence of some physiological groups of bacteria were examined in the supplying waters of Plitvice Lakes, as well as in some of the Upper and Lower lakes. The investigations were carried out in the autumn 1977, and in the spring and autumn 1978.
One of the main supplying waters of Lake Prošćan, the Crna rijeka, does not display signs of pollution, while the Bijela rijeka — following bacteriological parameters (Escherichia coli and Clostridium perfringens) is constantly polluted by domestic waste waters. The presence and a more significant representation of the groups of proteolytic and phosphomineralizing bacteria than in other parts of the examined region, point not only at the enlarged concentrations of organic nitrogenous and phosphorous compounds in the river water, but also at a possibility of hastening the processes of eutrophization, as the result of their mineralization. Concequently, the water of the Bijela rijeka which after joining the Crna rijeka flown into Lake Prošćan as Matica, would be one of the important factors for speeding the eutrophization processes in the lake, especially in the zone of the river mouth. (Table 2, 3).
Relatively low values of all the groups of bacteria were found in the upper and lower lakes, which can be the result of dilution of more polluted supplying waters and the processes of selfpurification. The mean values of number of saprophytic bacteria on MPA in the lakes ranged from 225 (in spring) to 1.480 (in autumn) in 1 ml, which would correspond to I—II class of bonity or oligo-betamesosaprobic level after Kohl (1975).
The number of bacteria of the investigated groups increased considerably in autumn, probably as a result of larger quantities of dead organic matter in the water of the lakes (Table 4).
The bacteriological analysis of samples of shallow water from the littoral of Lake Galovac, where a thick layer of fallen leaves and reed stems decayed (autumn 1978), showed high numbers of bacteria of all groups, which is a sign of intensive decomposition and mineralization of dead plant material. That is probably the main cause of today’s evident and strong overgrowth by helophytic vegetation of the shores of the lakes.
Ključne riječi
Hrčak ID:
158345
URI
Datum izdavanja:
31.12.1979.
Posjeta: 873 *