Marine sediments are an important sink of organic carbon and source of alkalinity, providing a valuable climate regulating function (“Blue Carbon”). Human activities that disturb the seabed might, however, compromise the effectiveness of the seabed in storing organic carbon through a net increase of organic carbon remineralisation, or reduction of its alkalinity-generation capacity by stimulating re-oxidation of reduced minerals. For example, intense mobile bottom fishing may lead to reductions of organic carbon and pyrite stocks, especially in muddy sediments. Other human activities that disturb marine sediment include marine construction, dredging and dumping, offshore wind infrastructure, and submarine cables and pipelines. Sediment disturbance impacts on coastal carbon cycling are largely site or region-specific and difficult to generalise due to the many mechanisms that support stock creation and responses to disturbance, often in opposing directions. In addition, the fate of the ‘lost’ organic carbon or oxidized minerals, and consequences for the marine environment and global climate are currently not well understood. The roles of benthic fauna and of the water column biological carbon pump in carbon cycling under disturbance are also unclear.

Until recently, field and modelling studies have focussed on processes in or near the seabed. It is, however, becoming increasingly clear that a holistic approach is necessary to assess the impacts. Only then will it be possible to provide robust advice for marine spatial management and policy.

We therefore invite abstracts that cover any aspects relating to understanding and quantifying the climate impacts of human activities disturbing the seabed that may be relevant for carbon cycling. These may be observational, experimental, predictive or frameworks to support management. Key topics of this session include, but are not limited to:
- Carbon stocks, accumulation rates, reactivity, and provenance
- The role of flora and fauna in mediating remineralisation, accumulation and burial of carbon, and how disturbance may alter these functions.
- Disturbance impacts on water column nutrients, ecosystem processes, inorganic carbon chemistry and alkalinity dynamics
- Management of carbon stocks under uncertain disturbance outcomes