B. Papp szerk.: Studia Botanica Hungarica 35. 2004 (Budapest, 2004)
Gönczöl, János; Révay, Ágnes: Aquatic Hyphomycetes in two streams differing in discharge and distribution of leaf litter
throughout most of the year increased to eighteen spores ml-1 after the greatest amount of leaf litter was present in the stream during November. Quite different results about stimulating effect of leaf litter on the spore concentration were obtained in another study. The role of leaf litter to conidial concentration was examined in a litter-exclusion and a reference stream in the Appalachian Mountains (North Carolina, USA) (GULIS and SUBERKROPP 2003). Both streams had low mean discharge (about 2 L s-1 ). The authors anticipated that litter-exclusion would have a drastic effect on reproduction of aquatic hyphomycetes, but only seasonal differences in maximum conidial concentration were observed in the two streams. Total conidial concentration was not significantly affected by the litter-exclusion treatment. The studied streams in the Appalachian and Börzsöny Mountains are very similar in the low mean discharge (1-2 L s _1 ) other, possibly important factors may be highly different. For example the very low conidial numbers in the Appalachian streams (about 110 to 1,400 conidia Lr 1 ) are uncommon in our woodland streams. By the authors' opinion this may be due to the short distance between the sampling sites and the sources. Increasing amount of leaf litter from the beginning of October till the end of November followed by increasing conidial concentrations is a general pattern in forested streams in temperate regions (WEBSTER and DESCALS 1981, BÄRLOCHER 19926). The results obtained for conidial concentrations in five small tributaries after leaf-fall strongly suggest that leaf litter input is a major factor affecting conidial concentrations in transport. The increase in the conidial numbers in these small streams in October and November may be drastic (Deszkametsző stream) or moderate (Bagolybükk stream) probably due to the complex effect of amount of leaf litter in the stream and actual discharge. Nevertheless small streams with very low discharge require further studies to understand better the spatial and temporal dynamics of conidial pools. Acknowledgement - This study was supported by a grant from the Hungarian Scientific Research Fund (OTKA T32081). REFERENCES BÄRLOCHER, F. (1987): Aquatic hyphomycete spora in 10 streams of New Brunswick and Nova Scotia. - Can. J. Bot. 65: 76-79. BÄRLOCHER, F. (1992a): Recent developments in stream ecology and their relevance to aquatic mycology. - In: BÄRLOCHER, F. (ed.): The ecology of aquatic hyphomycetes. Ecological Studies 94: 16-37.
