Bioturbation: impact on the marine nitrogen cycle

Area of Science:

• Marine ecology
• Biogeochemistry
• Microbial ecology

Background:

• Marine sediments are crucial for the nitrogen cycle, acting as sources or sinks of fixed nitrogen.
• Microbial remineralization reactions at the oxic/anoxic interface drive nitrogen cycling.
• Bioturbators, or burrowing macrofauna, significantly influence these microbial processes by altering sediment properties.

Purpose of the Study:

• To discuss the potential impact of bioturbation on marine nitrogen cycling.
• To review molecular techniques for studying microbial nitrogen cycling communities.
• To identify future research directions in marine nitrogen cycling.

Main Methods:

• Review of existing literature on bioturbation and marine nitrogen cycling.
• Discussion of molecular techniques for microbial community analysis.
• Analysis of how burrowing activities affect sediment physicochemical properties.

Main Results:

• Bioturbation introduces oxygenated water into deeper sediments, extending the oxic/anoxic interface.
• Burrow walls host greater microbial abundance and diversity compared to surrounding sediments.
• Bioturbated sediments exhibit higher rates of nitrification-denitrification and increased ammonium flux.

Conclusions:

• Bioturbation plays a significant role in modulating marine nitrogen cycling.
• Understanding bioturbation's effects is crucial for comprehending the marine nitrogen cycle.
• Further research using molecular techniques is needed to fully elucidate microbial roles in bioturbated sediments.