Aquatic hyphomycetes in three rivers of southwestern France. III. Relationships between communities spatial and temporal dynamics

Abstract

Spatial and temporal dynamics of individual species of aquatic hyphomycetes in three southwestern French rivers have been previously studied using water filtration techniques. In this paper, relationships between these spatial and temporal dynamics were explored using correspondence analysis. Correspondence analyses were performed for conidial concentration and presence-absence of species. The analysis of conidial concentration data indicated that species temporal dynamics is more important in determining changes in conidial communities than species spatial dynamics. However, the interconnectedness of these dynamics was revealed by a Guttman effect between the first two factorial axes. A linear gradient Tech-Adour-Nive, which corresponds to the geographical disposition of these rivers in southwestern France, was observed on the first three axes of the correspondence analysis of conidial concentrations. This gradient did not exist in the correspondence analysis of species presence-absence, but the analysis revealed a qualitative difference of the communities between the summer season and the beginning of autumn. The comparison of eigenvalues for the two correspondence analyses pointed out that conidial abundance is more significant than presence-absence of species for the structure of the data table. Key words: aquatic hyphomycete, spatial dynamic, temporal dynamic, climatic gradient.