Two Decades of Long-Term Sediment Trap Studies Across the Arctic Ocean: Evidences for Change or Continuity?

In marine environments, long-term sediment traps are moored interceptors which collect sinking particles in sequence on monthly-to-yearly time scales. The quantification and characterization of downward particle fluxes are crucial to our understanding of ecosystem functioning, since they can be seen as the ultimate output of food web activities in the water column. In this sense, sinking fluxes are key indicators of climate-related changes in biological production and organic matter transport. Given the harsh conditions of high-north latitudes and for logistic reasons, long-term particle flux dataset in the Arctic have been traditionally scarce. Nevertheless, in the last two decades, a respectable amount of multi-year sediment trap time-series have been published for distinct regions of the Arctic Ocean (i.e. Beaufort Sea, Baffin Bay, Greenland Sea, Fram Strait, Laptev Sea, and central Arctic basins). Here, we adopt an open perspective and we take a critical look at these disparate time-series. Specifically, we ask the question if any measurable changes in the magnitude and nature of downward particles fluxes have been actually related to sea ice decline in the last 20 years. Our main objective is to give an overview of our current understanding of where, when and why changes in particle flux dynamics occurred or, conversely, were not observed. In addition to sea ice retreat, we aim at listing other potential physical and biological drivers of abrupt shifts in terms of vertical and lateral particle fluxes. Aspects related to timing of events, geographical heterogeneity and depth-specific export will also be addressed in order to depict how Arctic marine ecosystems respond to short- and long-term environmental transitions.