Climate change and microplastic effects on conidial fungal assemblages associated with leaf litter in an Amazonian stream

Climate change and plastic pollution threaten aquatic ecosystems, biodiversity, and ecosystem processes. Using microcosms, we experimentally investigated the combined effects of climate change and microplastics (MPs) on conidial production, fungal assemblages (richness and composition), and microbial decomposition associated with leaf-litter from an Amazonian stream. We tested the following hypotheses: (i) climate change scenarios and microplastic concentrations negatively affect conidial production and fungal species richness; (ii) the composition of conidial fungal assemblages shifts in response to climate change scenarios and MPs concentrations; (iii) microbial decomposition is negatively affected by climate change scenarios and increasing microplastic concentrations. Our results revealed a synergistic effect of climate change and microplastics on conidial production. However, fungal species richness was not affected by these stressors. Climate change and microplastic concentrations independently affected fungal assemblage composition and microbial decomposition. These results suggest that fungal taxa differ in their tolerance and adaptability to anthropogenic stressors. Furthermore, using fungi as model systems, our study provides new evidence that organic matter decomposition in tropical streams may be significantly affected by climate change and plastic pollution.