Surface transport of DOC acts as a trophic link among Mediterranean sub-basins

Abstract. Characterizing carbon cycling and redistribution in the ocean is an important issue for Mankind, because it may affect key ecosystem services, e.g., support to climate system and food provision. In this paper, using an integrated approach, we explore the impact of the surface circulation on carbon dynamics in the Western Mediterranean Sea, where strong inter-basin differences in primary production do exist. Detailed information on the surface circulation, derived from high-resolution model simulations, is combined with the analysis of accurate, repeated dissolved organic carbon (DOC) data. Our work indicates that the advection of the Atlantic Water acts as a trophic link between the Algerian Basin and the Tyrrhenian Sea, determining a flux of 8.8–37.9 × 10¹² g DOC yr⁻¹ into the basin. Thus, surface transport of DOC can redistribute chemical energy among regions with different trophic regimes. We hypothesize that this overlooked mechanism plays an important role also in the global ocean.