Co-evolution of phytoplankton dynamics and environment at the Fram Strait

The geological record provides hints at a link between the variations in the shape of the Earth's orbit and pulses of evolution or adaptation of marine calcifying phytoplankton (i.e., coccolithophores) during the last 2 Ma of Earth's history. These pulses are expressed as a reduction in diversity and increased proliferation of certain morphotypes belonging to the Noelaerhabdaceae family, recorded almost ubiquitously in sedimentary sequences ranging from low to high-mid latitudes of the global ocean. Such eccentricity-forced changes in the biological pump and the production and export of carbon by phytoplankton populations could be an important mediator between orbital forcing and the global carbon cycle, possibly modifying the geochemistry of the global ocean reservoir by accelerating deep dissolution processes. To test whether this dynamic occurs consistently in time and across all latitudes, observations at high latitudinal extremes, where the involvement of siliceous phytoplankton populations could be susceptible to the forcing, are critically required.

Applying an innovative combination of micropaleontological, geochemical and image analysis techniques on nannofossil assemblages over selected intervals from the sediments retrieved during Expedition 403,
with a sampling of sufficient resolution for orbital scale features, we aim to characterise the patterns of variability of phytoplankton populations (amount and diversity) and net production and export of carbon through time. This will provide critical notions to elucidate the co-evolution of phytoplankton dynamics and environment at the Fram Strait, its drivers and feedbacks on the regional production of carbon and a plausible connection with the global content.