The Ocean Floor

Our research activities focus on the export of biogenic particles from the surface to the deep ocean, lateral transport of carbon from shelves towards the deep ocean, dynamic interactions between the pools of particulate and dissolved organic matter and the turnover of specific compound classes, notably of polysaccharides, and their role in particle stabilization.

Our work has revealed a surprising functional resilience of the biological carbon pump. In several regions, including Cape Blanc upwelling, the Arctic Fram Strait, and the Southern Ocean, drastic changes in plankton communities have occurred due to climate change. These changes in upper ocean ecosystems impacted the efficiency of the biological carbon pump, but they did not significantly alter its strength. Further research is required to establish a mechanistic explanation of this conundrum.

Particle transport processes also turn out to be vital for nutrient cycling. The release of an inorganic nitrogen compound (ammonium) from small slow-sinking particles in oxygen-minimum zones controls the activity of certain bacteria which in turn act as nitrogen sink, revealing a so far underestimated role of particle transport for oceanic nutrient budgets.