Extreme Salinity Change Governs Microbial Community Assembly and Interactions

Area of Science:

• Environmental microbiology
• Coastal ecology
• Biogeochemistry

Background:

• Coastal wetlands face increasing salinization due to climate change.
• Salinity shifts significantly impact microbial processes crucial for nutrient cycling and ecosystem stability.

Purpose of the Study:

• To investigate the influence of varying salinity levels on sediment microbial community composition and function.
• To understand microbial community assembly and resilience mechanisms in response to salinization.

Main Methods:

• Analysis of sediment microbial communities across a salinity gradient (estuarine, intermediate, hypersaline) in the Coorong Lagoon.
• Assessment of microbial community composition, diversity, and assembly processes.
• Identification of key microbial groups involved in sulfur and carbon cycling.

Main Results:

• Salinity was the primary driver of microbial community structure, diversity, and assembly.
• High salinity promoted specialist microbes and homogenous communities; generalists thrived in intermediate salinities, enhancing resilience.
• Distinct microbial groups were associated with specific salinity ranges, influencing sulfur and carbon cycling.

Conclusions:

• Microbial community assembly is dominated by deterministic processes, intensifying with extreme salinity.
• Community complexity varied with salinity, indicating reorganization under osmotic stress.
• Understanding the roles of specialists and generalists is vital for predicting ecosystem responses to climate-driven salinization and informing mitigation strategies.