Water-borne conidia of aquatic hyphomycetes: seasonal and yearly patterns in Catamaran Brook, New Brunswick, Canada

Abstract

Over a period of 5 years, monthly samples of water-borne conidia were collected at two sites, bridge and mouth, in Catamaran Brook, a third-order salmon stream in New Brunswick, Canada. Conidial concentrations and number of aquatic hyphomycete species peaked in October; a smaller peak was generally observed in June. Evenness was lowest in October. The number of species in the five 12-month periods varied between 46 and 56 (bridge) and 41 and 47 (mouth); over the entire period, 75 (bridge) and 70 (mouth) species were identified. Of these, 30 and 26, respectively, occurred in every period. The average ranks of the 12 dominant species (based on yearly conidium production) could be divided into two groups of no significant differences: ranks 1-7 (bridge) and 1-10 (mouth), respectively, and 2-12 (both sites). Monthly abundances of the 12 top-ranked species were examined for correlations. Significant correlations found in periods measuring between 1 and 4 years were rarely validated in subsequent periods.Key words: aquatic hyphomycetes, stream spora, annual and seasonal periodicity.