Impact of bottom trawling on shelf sea biogeochemistry and carbon storage: insights from a sediment-pelagic biogeochemical model

Coastal and shelf sediments play a key role in the storage and recycling of Carbon and other nutrients, significantly contributing to the regulation of Earth's climate. These processes can be affected by anthropogenic disturbance, with bottom trawling likely to be among the most impactful. While the ecological impacts of trawling are well-documented, its effects on nutrient recycling and carbon storage remain less understood. First-order estimates have assumed that trawling promotes a significant remineralisation of organic carbon that elevates seawater CO2 and results in a large CO2 flux to atmosphere. Further observational and modelling studies indicate that sediment reworking from trawling can profoundly affect biogeochemical processes and increase CO2 emissions. Here we  we explore the interaction of different factors, and consider the coupled sediment water column system to quantify the feedbacks and processes translating dissolved carbon release into seawater and the changes in surface water CO2 concentration that control the air-sea CO2 flux. Using a sediment-pelagic biogeochemical model that incorporates biogeochemical, carbonate chemistry, and basic ecosystem processes, we provide insights on how trawling can influence different biogeochemical processes and the resulting changes in carbon storage under different disturbance regimes.