Unraveling microbial roles in stream ecosystem functioning: Insights into stressor impacts and community interactions through metatranscriptomics and metabarcoding

Streams are subjected to multiple stressors that interact in complex ways, significantly impacting biodiversity and ecosystem functions. These interactions make it challenging to predict changes in these systems. A comprehensive mechanistic understanding of ecosystem degradation and recovery is still lacking, which hinders our ability to predict stressor impacts on biodiversity and ecosystem functioning and to manage the restoration of degraded freshwater systems.

In our recent work, we have investigated diverse stressor effects, including changes in temperature, salinity, hydrology, inundations, and treated wastewater discharge, on prokaryotic and eukaryotic microbes. Further, we are currently investigating a key ecosystem function: leaf litter degradation in streams, mediated by bacterial and fungal heterotrophs. The specific taxa involved, their interactions within microbial decomposer communities, and the enzymatic and metabolic pathways driving these processes remain largely unexplored and are not yet well understood, potentially varying with environmental conditions. This project aims to elucidate the roles of different fungal and bacterial groups in the enzymatic decomposition of coarse particulate organic matter (CPOM) under single and multiple stressor scenarios. By employing metatranscriptomics, metabarcoding, and DNA-SIP, we seek to uncover the contributions and interactions of these microbial groups. Specifically, we investigate functional redundancy and interrelationships between taxonomic groups to better understand ecosystem resilience and functionality.