Diurnal variation in aquatic hyphomycete spore concentrations in an Australian stream

The aquatic hyphomycete spora of Lees Creek, an Australian upland stream, was examined by membrane filtration at twelve hourly intervals (06.00 and 18.00 h) over three successive days. Total spore counts increased from morning to evening each day and decreased each night. This same diurnal pattern of abundance was shown by each of the ten most abundant species examined. A field-based experiment could not attribute the diurnal fluctuations in spore concentrations to an alternating light regime.