Decoupling between particulate carbon, nitrogen and biogenic silica
export mediated by cyclonic eddies in the North Pacific Subtropical Gyre
Abstract
We identified 38 cyclonic eddies (CEs) using satellite altimetry that
traversed Station ALOHA in the North Pacific Subtropical Gyre from 1993
to 2018. We separated CE-induced particle export, measured using free
floating sediment traps deployed at 150 m, at the center versus the edge
and with time since eddy evolution. The fluxes of particulate carbon,
nitrogen and biogenic silica (PC, PN and BSi) varied significantly
within and among individual eddies depending on season and age. On
annual time scales, there was little to no significant PC (1.1-1.3-fold)
or PN (1.1-1.2-fold) CE enhancement relative to non-eddy and non-bloom
periods. In contrast, BSi fluxes were elevated by an average of 200
{plus minus} 80% (1.3-2.7-fold). Our results confirm that CEs more
efficiently export BSi relative to C, suggesting that these elements,
central to marine food webs, differ in their mechanisms of export to
depth and may contribute to long term ecological change.