Hydrological variations shape diversity and functional responses of streambed microbes

Area of Science:

• * Environmental microbiology
• * Ecology
• * Hydrology

Background:

• * Streamflow reduction due to climate change impacts intermittent streambed microbial communities.
• * Microbial life in streambeds is crucial for essential in-stream ecosystem processes.
• * Understanding microbial responses to drying and rewetting is vital for stream health.

Purpose of the Study:

• * To investigate the impact of prolonged desiccation and rewetting on streambed microbial diversity and function.
• * To compare the responses of total (DNA) and active (RNA) microbial diversity.
• * To assess microbial functional diversity using community-level physiological profiles (CLPP).

Main Methods:

• * Examined microbial communities (prokaryotes and eukaryotes) in surface and hyporheic streambeds.
• * Applied a 5-month desiccation, 1-week rewetting, and intermittent storm interruption regime.
• * Analyzed genomic DNA and RNA, and community-level physiological profiles (CLPP).

Main Results:

• * Active microbial diversity (RNA) showed a stronger relationship with environmental conditions and resource acquisition than total DNA.
• * Prokaryotic communities were more responsive to environmental changes via RNA expression.
• * Microbial functional diversity was linked to extracellular enzyme activities and vulnerable to hydrological changes.

Conclusions:

• * Active microbial diversity (RNA) is a more sensitive indicator of environmental changes in streambeds than total DNA.
• * Prolonged desiccation negatively impacts microbial functional diversity, emphasizing vulnerability to hydrological shifts.
• * Complementary metrics are needed to fully assess streambed microbial dynamics under fluctuating water conditions.