Anthropogenic impacts such as elevated pCO₂ and eutrophication threaten the structure and functioning of marine ecosystems as well as the role of the ocean in the global carbon cycle. While sinking-particle-based carbon sequestration (the biological pump; BP) has been extensively studied, the biogeochemical behaviour of dissolved organic matter (DOM) and its role in carbon sequestration (the microbial carbon pump, MCP) is largely unexplored. The BP and the MCP operate simultaneously and interactively, but their responses to environmental conditions may be regulated differently. These regulatory mechanisms have not been examined, and it is not known whether the BP and the MCP would interact to enhance or reduce their individual effects.

This special issue will bring together articles arising from discussions undertaken at IMBIZO III held in Goa in January 2013. Topics to be investigated include the organisms and microbial processes which produce and transform dissolved organic carbon in the ocean, organisms and processes which influence the interaction between the BP and the MCP, and the impact of anthropogenic perturbations such as nutrient addition and ocean acidification on oceanic carbon transformation, export and sequestration.