Nonsinking Organic Matter Production in the California Current

Abstract

AbstractProductive eastern boundary upwelling systems such as the California Current Ecosystem (CCE) are important regions for supporting both local and remote food webs. Several studies have reported on the temporal and spatial variability of primary production and gravitational export in the CCE. However, few studies have quantified the partitioning of net primary and new production into other reservoirs of detrital organic matter. This study tested the hypothesis that nonsinking detrital reservoirs are an exportable reservoir of new production in the CCE with samples collected by the California Cooperative Oceanic Fisheries Investigation survey between 2008 and 2010. Water column gradients in nitrate (NO3−) and total organic carbon (TOC; which excludes sinking particulate organic carbon) were used to estimate potential rates of new production (PNew) and TOC production (PTOC), respectively. The PTOC:PNew varied between 0.16 and 0.56 and often increased with indicators of enhanced autotrophic production. At times, surface stratification was also correlated with elevated PTOC:PNew. In the most productive, inshore region, PTOC exceeded previously reported sinking export rates, which identified TOC as a quantitatively significant repository of exportable carbon in the CCE. However the sum of PTOC and sinking export for these productive regions was less than both PNew and oxygen‐based estimates of net community production. These results imply that nonsinking reservoirs alone are not sufficient to explain observed imbalances between production and export for the most productive CCE regions.