Permeability shapes bacterial communities in sublittoral surface sediments

Area of Science:

• Marine microbiology
• Geochemistry
• Benthic ecology

Background:

• Surface sediments act as biological filters for organic matter from the water column, influencing elemental cycling.
• Benthic microbial communities play a crucial role in processing organic matter inputs.

Purpose of the Study:

• To analyze bacterial diversity and community structure in North Sea surface sediments.
• To investigate the influence of sediment properties, specifically permeability, on benthic microbial communities.
• To identify key bacterial taxa involved in organic matter degradation in surface sediments.

Main Methods:

• Illumina tag sequencing of 16S rRNA genes for bacterial diversity analysis.
• CARD-FISH (Catalyzed Reporter Deposition Fluorescence In Situ Hybridization) to confirm community composition.
• Analysis of sediment properties (permeability) across seven North Sea sites.

Main Results:

• Bacterial communities in surface sediments were richer, more even, and distinct from bottom water communities.
• Sediment permeability significantly influenced bacterial community composition.
• Specific bacterial groups like Desulfobacteraceae and Flavobacteriaceae were more abundant in impermeable sediments, while Acidobacteria dominated permeable sediments.
• Planctomycetes and Woeseiaceae/JTB255 were abundant across all sediment types.

Conclusions:

• Sediment permeability is a critical factor structuring benthic bacterial communities in the North Sea.
• Planctomycetes are proposed as key players in degrading high molecular weight and recalcitrant organic matter.
• Flavobacteriaceae, Sandaracinaceae, and Acidobacteria likely specialize in degrading low molecular weight compounds.