PDFFirst Paragraph
The vast subtropical regions of the ocean account for at least 30% of the carbon export to the deep ocean. It is predicted that these regions will get larger as a consequence of global warming. Traditionally, they have been considered relatively homogeneous, and observations at one site have been extrapolated to the region as a whole. Two main conundrums remain unresolved: (1) in the western province of the subtropical North Atlantic (NASW), direct measurements of nutrient supply have been considerably lower than indirect estimates, and (2) in the eastern province of the subtropical North Atlantic (NASE), instantaneous oxygen production rates by bottle incubations indicate net heterotrophy prevailing throughout large areas. Episodic nutrient inputs into the photic layer and net oxygen production associated with mesoscale activity have been proposed to reconcile both discrepancies. Here, we compare recent findings obtained at the Bermuda Atlantic Time-series Study (BATS) station in NASW, and in a region between ca. 22–35°N and 15–34°W (NASE), including the European Station for Time-series in the Ocean, Canary Islands (ESTOC) located north of the Canary Islands. These findings show how important spatial heterogeneity is in understanding the biogeochemistry of this biome.