REFINEROBOTS EXPLORE PLANKTON-DRIVEN FLUXES IN THE MARINE TWILIGHT ZONE
WHYUnderstanding the oceanic biological carbon pump
The Twilight Zone, located between the depths of ~ 200 m and 1000 m, is one of the least known environments on Earth: we mandatorily need to explore it as it provides essential services for our society and is pivotal to the ocean carbon cycle.
The Twilight Zone, which is out of reach of sunlight, is critically undersampled and understudied during most oceanographic ship-based cruises while its depths elude satellite remote sensing. Yet, the Twilight Zone has an essential role in regulating the sequestration of carbon dioxide from the atmosphere for centuries or longer; additionally, the Twilight Zone hosts unique ecosystems and huge fish populations, which could contribute to mitigate food insecurity4; finally, the Twilight Zone is the place of global ocean deoxygenation.
The ocean’s carbon-sequestration capacity is largely controlled by the Biological Carbon Pump. The Biological Carbon Pump is driven by processes that drive the downward export (pump strength) of biogenic carbon photosynthesized in the well-lit Euphotic Zone (between surface and ~100m), and the remineralisation (pump efficiency) of part of this sinking carbon in the underlying Twilight Zone.
According to a recently formulated paradigm, the Biological Carbon Pump is controlled by the cumulative and combined action of six different, biologically- or physically- mediated Biological Carbon Pumps. These are known as the Biological Gravitational Pump, the Mixed Layer Pump, the Eddy Subduction Pump, the Ekman Pump (or large-scale subduction), diel vertical migrations of zooplankton, and ontogenetic (seasonal) vertical migrations of zooplankton.
REFINE proposes a framework for an integrated observational approach of most of these Biological Carbon Pumps in the World Ocean.