Tomales Bay, California: A case for carbon‐controlled nitrogen cycling

Abstract

Data collected over the summer–autumn dry season in Tomales Bay, California, demonstrate that system to be exporting dissolved P and importing dissolved fixed N. A simple explanation for the observed pattern is net system heterotrophy by about 8%, with <2% of the system primary production of organic C being oxidized by denitrification. The loss of fixed N to denitrification consumes the dissolved inorganic N (DIN) liberated through the 8% excess organic oxidation over organic production. There is a small hydrographic loss of dissolved organic N (DON). The DIN deficit for primary production is therefore caused by the system C metabolism. Thus, C metabolism has profound effect on the N cycle, even though this denitrification rate is trivial to the C cycle. We believe that this pattern of C#x2010;controlled N cycling has wide general application.