Profiling the microbial community structure and functional diversity of a dam‐regulated river undergoing gravel bar restoration

Abstract

Abstract Comprehensive restoration programs are expected to influence sediment‐associated microbial community structure and functional diversity following changes attributed to the restoration of habitat characteristics in the dam‐impacted channel. To address if the construction or recreation of in‐channel structures, i.e., gravel bars, by implementing gravel augmentation and ecological flow restoration, resulted in habitat restoration and enhanced environmental heterogeneity, we profiled the community composition, estimated diversity, and annotated putative metabolic functions of the sediment microbial communities of the dam‐regulated Trinity River in northern California. Our results provided supporting evidence on the positive impact of habitat restoration conducted in the Trinity River with the non‐dam influenced, undisturbed tributaries as the basis of comparison. In addition, gravel bar recreation and restoration contributed to the increased microbial beta diversity, possibly through the increased environmental heterogeneity at the river scale. The significant positive correlation between the taxonomic and functional diversity of the identified microbial taxa suggests that differences in the detected putative metabolic functions were closely related to dissimilarities in community composition. We also provided valuable insights into the potential microbial processes in the sediment that might be contributing to the biogeochemical processes carried out by the microbial communities in the river. The results of this study have implications on the impact of construction and restoration of gravel bars in a dam‐impacted river on environmental heterogeneity and how this influences the taxonomic and functional diversities of sediment‐associated microbial communities.