The Osse River is a plain river (southwest of France) fed by the Neste Canal flowing from the Pyrénées. From 1988 to 1993, 46 samples taken from the foam in the river have shown a great temporal variability in densities of aquatic hyphomycete conidia, especially during winter. In 1992, the winter maximum density, related to the latest leaf breakdown, was 1522 conidia/mm3, and the winter minimum, in 1989, 2 conidia/mm3. This variability was much lower during spring. The water temperature varied between 3.0 and 23.5 °C. Several species of hyphomycetes appeared as extremely sensitive to temperature variations, whereas no significant correlation with pH variations was found. The effects of floods on the fungal community varied according to the flood intensity and timing and to the composition of the riparian vegetation. The role of the species composition and the phenology of the riparian vegetation on the fungal community stucture and dynamics was discussed in relation to leaf litter decomposition. This paper emphasizes the need to take into account the flood intensity for the study of hyphomycetes dynamics and the significant role of hydrodynamics in freshwater nutrient cycle. Key words: aquatic hyphomycetes, temperature, pH, vegetation phenology, vegetation composition, decomposition, hydrodynamic.
Relationship between the Ecological Factors with Community Stucture of Mangrove in Pang-Pang Bay Alas Purwo National Park