Quantifying Dissolved Organic Carbon Release by Canopy‐Forming Kelps

Abstract

Kelp forests fix tremendous quantities of carbon, yet little is known about the process whereby kelps release fixed carbon as dissolved organic carbon (DOC). We used 13 C stable isotope incubations to quantify DOC release by kelp blades in relation to carbon fixation, nutrient uptake, tissue nitrogen content, and light availability. The annual kelp Nereocystis luetkeana released an average of 16% of fixed carbon into the seawater as DOC. Carbon isotopes revealed that carbon is rapidly fixed and released, within hours, but DOC release was decoupled from recent photosynthesis and was partly correlated with nitrogen availability. Weigel, B. L., and C. A. Pfister.