The Biological Pump

Phytoplankton in the ocean perform almost half of the photosynthesis on Earth, absorbing CO2 from the atmosphere while feeding the rest of the oceanic food web. Several biological and physical processes then work together in a process collectively termed the “biological pump” to aggregate and transfer part of this carbon to the deep ocean, where it can potentially be stored for thousands of years.

Despite the immense impact of the biological pump on the global carbon cycle and climate, the biomolecular processes that control it remains poorly characterized. Among the key processes that limit this downward flux of carbon are microbial degradation, consumption, and fragmentation of sinking organic particles and faecal pellets. Yet, those processes are typically inferred from bulk measurements, which group together all variables involved and limit our ability to pinpoint the main driving forces that regulate them. Thus, a major gap in knowledge persists due to the lack of molecular understanding of the microbiota that drives particle degradation in the ocean.

In this project, we investigate this microbial “digestive system of the ocean”. Our main goal is to generate a mechanistic understanding of the microbes and the enzymatic processes they use to determine the magnitude of the biological pump.