A sweeping new study has uncovered global patterns in how bacteria thrive and interact within lakes and reservoirs, offering new insights into the invisible forces that sustain freshwater ecosystems. The research, led by scientists from Xi'an University of Architecture and Technology, analyzed hundreds of samples from around the world to understand how geography, temperature, and nutrients shape bacterial communities in water and sediments.
Freshwater ecosystems are vital sources of drinking water, biodiversity, and economic activity, yet they are increasingly threatened by pollution, eutrophication, and climate change. Microorganisms, though microscopic, play a central role in keeping these systems healthy. They recycle nutrients, break down organic matter, and help maintain water quality. Despite their importance, few studies have compared bacterial communities across different continents and habitats on a global scale.
In this new work, the researchers synthesized bacterial community data from 247 water and 131 sediment samples collected across six continents. By combining datasets from 80 studies, they created the most comprehensive global database to date on bacteria living in freshwater lakes and reservoirs. The analysis revealed that sediments host richer and more diverse bacterial populations than surface waters, mainly because sediments offer more stable and nutrient-rich microhabitats.
The team also found that temperature, nutrient levels, and geographic location strongly influence the diversity and structure of bacterial communities. In water samples, total phosphate was linked to lower bacterial diversity, while in sediments, nitrogen had a stronger effect. Structural equation models showed that both latitude and nutrient concentrations jointly drive global variations in bacterial diversity. Lakes closer to the equator, where temperatures and nutrient inputs are higher, tend to support more diverse bacterial ecosystems.
Proteobacteria emerged as the most dominant bacterial group worldwide, found in both nutrient-poor and nutrient-rich environments. Cyanobacteria and Actinobacteria were more common in eutrophic, or nutrient-enriched, waters, which aligns with their known ability to thrive under high nutrient conditions. Using random forest analysis, the study also identified temperature as the most important environmental factor shaping bacterial communities in water, while nitrate nitrogen was most influential in sediments.
Network analysis revealed that bacterial communities in water form more complex and interconnected relationships than those in sediments. The dynamic nature of aquatic environments, where oxygen, light, and nutrient levels change rapidly, appears to foster stronger ecological interactions among bacterial species. In contrast, the more stable conditions of sediments lead to simpler but specialized microbial networks.
These findings provide a global picture of how bacterial life forms the foundation of freshwater ecosystem health. By linking microbial patterns to environmental conditions, the study offers valuable tools for predicting changes in water quality and ecosystem stability under global warming and human pressures.
"Our work highlights the importance of bacteria as sensitive indicators of environmental change," said corresponding author Professor Haihan Zhang. "Understanding these microbial patterns at a global scale will help improve water quality monitoring and guide sustainable management of freshwater resources."
The study, titled "Exploring bacteria communities in lakes and reservoirs: a global perspective," was published in Biocontaminant on October 31, 2025.
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Journal reference: Zhang H, Huang Y, Liu X, Ma B, An S. 2025. Exploring bacteria communities in lakes and reservoirs: a global perspective. Biocontaminant 1: e003 https://www.maxapress.com/article/doi/10.48130/biocontam-0025-0003
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About Biocontaminant :
Biocontaminant is a multidisciplinary platform dedicated to advancing fundamental and applied research on biological contaminants across diverse environments and systems. The journal serves as an innovative, efficient, and professional forum for global researchers to disseminate findings in this rapidly evolving field.
