Depth-dependent bacterial colonization on model chitin particles in the open ocean

Area of Science:

• Marine microbial ecology
• Ocean biogeochemistry
• Deep-sea ecosystems

Background:

• Sinking particles are crucial for ocean carbon transport and nutrient cycling.
• Microbial colonization of particles ('microbial gardening') supports zooplankton food webs.
• Understanding particle-attached bacteria is key to ocean ecosystem services.

Purpose of the Study:

• To identify general and depth-specific bacterial colonizers of sinking particles.
• To investigate vertical connectivity in particle-attached microbial communities.
• To assess the implications for ocean carbon cycling and trophic transfer.

Main Methods:

• Incubation of model chitin particles with North Atlantic seawater from surface to bathypelagic depths.
• Analysis of particle-attached bacterial communities using amplicon sequencing.
• Comparison of microbial communities across different ocean depths.

Main Results:

• Bacteria found on surface particles also colonized bathypelagic particles, indicating vertical connectivity.
• Bathypelagic particle-attached communities exhibited the highest diversity.
• Evidence suggests both generalist and depth-specific particle colonizers exist.

Conclusions:

• Sinking particles facilitate microbial dispersal and vertical connectivity in the ocean.
• Bacterial colonization patterns vary with depth, influencing ecosystem services.
• Depth-specific microbial communities on particles are critical for carbon cycling and food webs.