Diversity and distribution of zoosporic fungi (Blastocladiomycota and Chytridiomycota) in three tropical reservoirs

The zoosporic fungi of Blastocladiomycota and Chytridiomycota are important components of eukaryotic communities in freshwater ecosystems, acting in decomposing of organic matter and/or parasitism of several hosts. In Brazil, these fungi in lentic habitats such as reservoirs and lakes are still poorly studied, leaving the sediment totally unexplored. Thus, the aim of this study was to analyze the diversity and distribution of these phyla in the water column and sediments of three tropical reservoirs located in Brazilian Atlantic rainforest areas using morphological and phylogenetic approaches. Samples of the water column depths (surface, medium depth and bottom) and sediment were collected from August/2014 to July/2015 (four samplings), and baited with substrates to allow the fungal development. The taxa purified on agar medium were included in phylogenetic reconstructions (SSU, ITS and/or LSU regions of rDNA) to corroborate their morphological identifications. In total, we identified 24 taxa and calculated their frequency, occurrence and abundance during the study. Nine of them were isolated on pure cultures, which were included in phylogenic reconstructions at order level. In general, the zoosporic fungi presented a higher species richness in the sediment. Asterophlyctis sarcoptoides, Cladochytrium replicatum, Nowakowskiella crenulata and N. hemisphaerospora were the taxa more frequent and abundant. The genus Avachytrium is recorded for the first time in Brazil. These data corroborate the importance of the sediment to obtain a more comprehensive overview of the zoosporic fungi community in lentic ecosystems.