Macrofaunal control of microbial community structure in continental margin sediments

Area of Science:

• Marine Ecology
• Geomicrobiology
• Biogeochemistry

Background:

• Bioturbation, a process driven by burrowing macrofauna, significantly alters seafloor habitats and influences global carbon cycling.
• The impact of bioturbation on the community structure of seafloor microorganisms remains largely unexplored.

Purpose of the Study:

• To investigate how bioturbation affects microbial community structure in continental margin sediments.
• To identify the key environmental drivers shaping microbial communities in bioturbated versus non-bioturbated environments.

Main Methods:

• Comparative analysis of microbial communities across geochemically and sedimentologically diverse continental margin sites.
• Geochemical analyses of solid and solute phases.
• Modeling of bioturbation activities.
• Assessment of dissolved oxygen and organic matter distribution.

Main Results:

• Microbial communities in bioturbated sediments were highly similar across different sites, contrasting sharply with those in non-bioturbated surface and subsurface sediments.
• Dissolved oxygen introduced by burrow ventilation was identified as the primary driver of archaeal community structure.
• Solid-phase reworking, controlling fresh algal organic matter distribution, was the main factor influencing bacterial community structure.

Conclusions:

• Bioturbation homogenizes microbial communities in seafloor sediments, with distinct drivers for archaeal and bacterial community structures.
• In non-bioturbated sediments, microbial communities exhibit greater divergence, primarily influenced by site-specific organic carbon sources.