Linking microbial decomposer diversity to plant litter decomposition and associated processes in streams

The physiology, biochemistry and diversity of aquatic microbial decomposers have been largely investigated in low-order streams. However, some aspects still need further attention to better ascertain how microbial decomposer diversity can ensure ecosystem processes and services, particularly under the challenges posed by global environmental change. Aquatic microbial decomposers play a key role in processing plant litter in streams by degrading the most recalcitrant compounds and facilitating nutrient and energy transfer to higher trophic levels. Among microbial decomposers, fungi, particularly aquatic hyphomycetes, play a fundamental role at the early stages of plant litter decomposition, while the relevance of bacteria increases at the late stage of the decomposition. High-throughput sequencing and metagenomic techniques open new avenues towards a more comprehensive understanding of the microbial decomposer ecology. This chapter provides a general overview of aquatic microbial diversity and activity on decomposing plant litter. Attention will be paid to the relationships between microbial diversity and their ecological functions under the major threats posed by the ongoing global environmental change to provide the response patterns of microbial decomposers to maintain nutrient and energy fluxes in streams.This study was supported by the STREAMECO project [PTDC/CTAAMB/31245/2017] funded by Portuguese funding through FCT I.P. and ERDF through the COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI), and VF was supported by FCT (CEECIND/02484/2018