Changes in conidial numbers of aquatic hyphomycetes in water passing
through a concrete pipe were investigated by water
filtration. Retention in the pipe was low and concentrations of conidia
of
Alatospora acuminata, Anguillospora longissima, Clavariopsis
aquatica, Clavatospora longibrachiata, Heliscella
stellata, Lemonniera terrestris, Lunulospora curvula,
Pyricularia submersa, Tetrachaetum elegans
and Tetracladium marchalianum were unchanged after 1·8
km
drift. Only one species, Articulospora tetracladia,
showed significant
decrease, resulting in part from fragmentation of the conidia. These
results suggest that studies of communities of aquatic
hyphomycetes in natural environments by sampling conidia by water filtration
need to account for differences in stream retention as
well as species specific differences in conidial fragmentation.