Aquatic plant debris changes sediment enzymatic activity and microbial community structure

Area of Science:

• Environmental Microbiology
• Aquatic Ecology
• Biogeochemistry

Background:

• Aquatic plant debris decomposition influences freshwater ecosystem nutrient dynamics.
• Microbial processes in sediments are crucial for phosphorus (P) retention.
• Understanding sediment microbial responses to plant debris is vital for P cycling.

Purpose of the Study:

• To investigate the impact of aquatic plant debris on sediment microbial enzyme activities.
• To analyze changes in sediment microbial community structure and diversity.
• To identify key microbial players involved in plant debris-mediated phosphorus retention.

Main Methods:

• Incubation of freshwater sediments with and without plant debris.
• Measurement of key extracellular enzyme activities (e.g., FDA hydrolysis, phosphatase, cellulase).
• High-throughput pyrosequencing for bacterial community structure analysis (OTUs, Shannon index).

Main Results:

• Plant debris significantly increased activities of FDA hydrolysis, alkaline phosphatase, polyphenol oxidase, cellulase, β-glucosidase, and dehydrogenase.
• Bacterial diversity (OTUs, Shannon index) decreased in plant debris-treated sediments.
• Alphaproteobacteria abundance increased, while Beta-, Delta-, and Gammaproteobacteria decreased; Azospirillum and Dechloromonas genera were enriched.

Conclusions:

• Aquatic plant debris stimulates sediment microbial enzyme activity and reshapes microbial communities.
• Specific genera, including Azospirillum and Dechloromonas, are important for plant debris-mediated phosphorus retention.
• Microbial responses to plant debris are critical for regulating phosphorus in freshwater systems.