Fungi and fungus-like organisms growing in selected lotic oxbow lakes and tributaries of the Narew River

Mycological and hydrochemical research was conducted in two different types of reservoirs connected with the Narew riverbed (three tributaries and three lotic oxbow lakes) in two growing seasons. The obtained results seem to indicate that more favorable conditions for the development of the analyzed microorganisms prevailed in the studied tributaries of the Narew. A total of 36 species of fungi and fungus-like organisms were identified in these tributaries in spring and 35 in autumn, while respectively 32 and 26 species in the lotic oxbow lakes. Six taxa not identified in the oxbow lakes were found only in the tributaries of the river. They were: Alternaria alternata, Allomyces moniliformis, Catenaria anguillulae, Leptomitus lacteus, Rhipidium parthenosporum and Saprolegnia diclina. On the other hand, only two species occurred only in the oxbow lakes (not recorded in tributaries) (i.e. Catenophlyctis variabilis and Rhizophlyctis rosea).

The differences observed in the microfungi species composition in the studied ecosystems are associated, among others, with the time of the year and physicochemical properties of the water. Hydrochemical parameters such as temperature, pH, Mg, N-NH₃, N-NO₃, P-PO₄ and suspended solids showed positive correlation, and sulfates, chlorides, Ca, Fe correlated negatively with the number of taxa observed.