Profiling microbial communities in a watershed undergoing intensive anthropogenic activities

Area of Science:

• Microbial ecology
• Environmental microbiology
• Ecosystem science

Background:

• Lotic ecosystems are vulnerable to human activities, yet environmental influences on their microbial communities are not fully understood.
• Understanding these microbial dynamics is crucial for managing and restoring these vital ecosystems.

Purpose of the Study:

• To investigate the impact of environmental variables on microbial communities in the hyporheic sediments of a human-impacted watershed.
• To explore the relationship between physicochemical factors, tidal influences, and microbial community structure and function.

Main Methods:

• Next-generation sequencing of 16S rRNA gene V4-V5 hypervariable regions to profile microbial communities.
• Co-occurrence network analysis to assess tidal impacts.
• Canonical correspondence analysis to link microbial composition with environmental variables.

Main Results:

• Core microbiomes were dominated by archaea methanogens and bacteria (Proteobacteria, Chloroflexi, Bacteroidetes, Acidobacteria, Synergistetes, Firmicutes), particularly gram-negative anaerobic genera involved in biogeochemical cycling.
• Site-specific microbiomes indicated local environmental conditions, with Oceanospirillales abundant in areas with salt intrusion.
• Distinct microbial co-occurrence networks were observed across non-tidal, inter-tidal, and tidal zones.
• Nitrate, bicarbonate, sulfate, dissolved organic carbon, electrical conductivity, and manganese were key environmental drivers of microbial community composition.

Conclusions:

• Environmental perturbations significantly influence microbial community structure in lotic systems.
• Microbial communities can serve as indicators of local environmental conditions and anthropogenic impacts.
• Findings provide insights for developing remediation and restoration strategies in impacted watersheds.