Environmental drivers and sampling techniques influence neotropical hyphomycetes composition in lakes and streams

Freshwater hyphomycetes are decomposer fungi whose community composition is shaped by multiple environmental factors, including temperature, water velocity, nutrient availability, substrate type, and habitat type, such as lakes and streams. This poses a challenge for accurate monitoring of these fungal communities, requiring the use of diverse sampling strategies to better represent and understand their dynamics, particularly in tropical ecosystems. In this study, the composition of aquatic hyphomycetes was compared between two habitat types (lakes and streams), over two substrate types (leaves and twigs), and over time, using two different sampling methods: moist chamber and submerged incubation. The relationship between freshwater hyphomycetes composition and physicochemical variables was also investigated. Substrates and water samples were collected from two lakes and two streams in a coastal region of Northeastern Brazil. The results indicated that time, and its interaction with habitat types, were the main drivers of changes in hyphomycetes composition. However, total phosphorus, ammonia, dissolved oxygen, temperature, and water velocity also significantly influenced community assembly. Furthermore, the study showed that different sampling methods can lead to varied conclusions in ecological and taxonomic studies. For instance, a significant species turnover between substrates was detected only with the submerged incubation method, whereas the effect of time and its interaction with habitat was evident only with the moist chamber method. Moreover, a high rate of taxon substitution was observed between sampling methods. These observed differences emphasize the need to combine different sampling strategies and habitat types to achieve a more comprehensive and accurate representation of the richness, diversity, and distribution of fungal communities in continental aquatic ecosystems.