Freshwater trophic status mediates microbial community assembly and interdomain network complexity

Area of Science:

• Microbial Ecology
• Freshwater Ecosystems
• Biogeochemistry

Background:

• Microbial communities drive freshwater nutrient cycling, but their interactions are sensitive to nutrient levels.
• The effect of water trophic status on bacterial-archaeal interdomain interactions is not well understood.

Purpose of the Study:

• To investigate how trophic status influences the interdomain interactions of freshwater microbial communities.
• To assess the relationship between trophic state index (TSI) and microbial network complexity.

Main Methods:

• Analysis of microbial communities from 45 ponds in Hangzhou, China.
• Characterization of trophic status using the Trophic State Index (TSI).
• Network analysis to examine bacterial-archaeal interdomain interactions and community assembly processes.

Main Results:

• A mesotrophic to lightly eutrophic wetland (TSI ~49-57) exhibited significantly higher bacterial-archaeal network connectivity compared to lower or higher trophic states.
• Light eutrophication was linked to increased negative associations with organic carbon, potentially causing carbon loss.
• Microbial network complexity showed a non-linear response to nutrient increase, with a turning point around TSI 50.
• Chlorophyll-a, total nitrogen, and total phosphorus explained 50% of the variation in network complexity by influencing microbial community assembly.

Conclusions:

• Microbial interdomain network complexity can serve as a sensitive bioindicator for ecological changes in freshwater systems.
• Findings provide insights into freshwater eutrophication assessment and management.
• Understanding these interactions is crucial for predicting ecosystem responses to nutrient enrichment.