A comparison of the freshwater fungal community during the non-rainy and rainy seasons in a small black water lake in Amazonas, Brazil

摘要

Freshwater fungi are important decomposers of submerged woody and herbaceous debris in aquatic ecosystems. This study compared the biodiversity of the fungal community between the non-rainy and rainy seasons in a small black water lake in Amazonas, Brazil. A total of four collections of submerged wood were made over a period of one year (May, August and November 2013, and February 2014). For each collection, 30 pieces of submerged woody debris were collected and examined for fungi to investigate seasonal variation. A total of 264 individual fungi were recorded comprising 25 taxa, of which 16 were meiosporic ascomycetes and 9 were mitosporic ascomycetes. The occurrence of these fungi was recorded and the Shannon-Weiner index (Ho was used to evaluatethe fungal diversity. The fungal community on woody substrates during rainy months was compared with non-rainy months and had a similarity index of 0.6842. The diversity index was higher in rainy months (H' = 2.6012) than in non-rainy months (H' = 2.1296) and this may be related to the seasonality of the rainy months due to the leaching phenomenon in the rainy period, although evenness (E = 0.600822) was higher in non-rainy months. This study shows that there is a rich and balanced freshwater fungal biodiversity in black water ecosystems. The study also highlights that future studies are needed to improve the limited knowledge of the distribution patterns, ecology, and species identities of freshwater ascomycetes in the aquatic habitats of Northern Brazil.