Growth and reproduction in aquatic hyphomycetes

Decay rates of four leaf species and birch wood in a softwater stream, changes in ergosterol content of the substrate, and release of conidia of aquatic hyphomycetes from these substrates were followed over time. On all leaves, maximum conidium production occurred before ergosterol content peaked; on birch wood, the two peaks coincided. Sporulation rates generally declined to very low levels after reaching the maximum; ergosterol content declined more gradually. There were significant correlations between the exponential breakdown coefficient, maximum ergosterol content and log(peak sporulation rate). On leaves, Anguillospora, filiformis produced > 80% of all conidia. In pure culture on beech leaves, its sporulation peak preceded maximum ergosterol content. On birch wood, the two peaks coincided. With another dominant species, Articulospora tetracladia, the two peaks coincided on leaves, while the sporulation lagged behind ergosterol on birch wood.